Here's installment #2 of the bearing platter discussion. Toward, 1/17 is where the discussion started to get hot 'n heavy. Fear not, I think all of this pressure is going to squeeze a diamond out of this lump of coal. The activity of the next few days (1/18 - 1/21) are encouraging, but as I wrote to Igor, giving birth is never painless. Cheers, Thom ----- Original Message ----- From: Igor Kuznetsoff To: Steve Zettel ; Chris Brady Sent: Friday, January 14, 2000 12:05 AM Subject: Re: Scheu-Bearing & Platter --- Steve Zettel wrote: > on 1/13/00 09:22, Chris Brady at cbrady@sgi.com > wrote: > > My plan was for the ball bearing to be press fit > into the > > shaft. I don't follow you about the delrin. > > If the bottom of the bearing spindle is slightly > concave, and the delrin > plate at the bottom of the well is also slightly > concave, a loose ball > bearing between the two will be self-centering. As > long as the radius of the > concave surfaces is sufficiently larger than the > radious of the ball > bearing, there will still be low-friction point > contact between the ball > and the surfaces. That's it ! That's what I've been trying to say all along ! No wobbling shaft bottoms for us. Thanks for putting it together, Steve. ----- Original Message ----- From: Igor Kuznetsoff Sent: Friday, January 14, 2000 1:52 AM Subject: Re: Scheu-Bearing & Platter --- Steve Zettel wrote: > on 1/13/00 17:54, Igor Kuznetsoff at > gorkuz@yahoo.com wrote: > > > Tetra Bike or Tetra Gun comes in 2oz bottles most > typically. Couple of bucks > a bottle. I will get in contact with the factory and > distributor and see > what kind of deal I can get on a dozen or more. > Every good turntable has an > accessory kit! > > Steve > Good-o . Sounds like a very good idea. If it is suitable for my skates, as per my private message, I'd be interested in a couple of extras. A kit with bearing sets, two spindle tips, and a bottle of oil sound right. ----- Original Message ----- From: Igor Kuznetsoff To: Steve Zettel ; Chris Brady Sent: Friday, January 14, 2000 2:32 AM Subject: Re: Scheu-Bearing & Platter All, Once again you've done most of the work and I just get to sweep up. Following is my impression of what appears to be the general consensus, which I am happily in agreement with : A 3" platter to fit Chris's new bearing drawing with larger bearing and oil sump area, and Thom's nice platter drawing with top outer edge record lip rebate. The tightest hand-assemblable, stress-free fit possible (as per Ken & Steve's excellent analyses and summaries) . A little grease here might be a good idea, it is good at keeping things quiet, while reducing the influence of any remaining clearance, as well as thermal expansion. A complete bearing kit consisting of a well housing, lock nut, concave delrin thrust washer, ball bearing, spindle, two tips, and a bottle of Tetra Bike Oil. Great machining price quote & advice, thanks to brother Brady. Steve sums up the following nicely : >>The brass pucks in the platter sound neat, but they >>don't fit into my personal KISS philosophy so I will >>probably opt to go without them. Ken >> but Alex's brass puck idea sounds cool. It goes >>against my "keep it simple" approach but may have >>merit. Chris > >>From a cosmetic standpoint, the pucks would not be >>visible since the edge and top of the platter will >>be frosted. Adding more mass would most easily be >>accomplished by a milled ring, although it's my >>preference to gain this extra mass by increasing the >>thickness of the platter to 3". Any of the above >>solutions would drop the center of gravity to lower >>down the bearing shaft, but the deeper platter would >>get us closer to having the pull of the belt at the >>center of the bearing shaft. Thom >Not wishing to be a party pooper, you are on your >own with this one! I like the looks, too, but we are >adding multiple requirements for maintaining >tolerance with individual masses, maintaining >tolerance with balance/concentricity, attachment >decisions, etc. It may be possible to have a wide, >very shallow band machined into the underside of the >platter to serve as a precise locating area for brass >weights, dampening material, etc. Steve > Finally ; > Last of all we need to come up with a name for > this project. It certainly is not going to be a >Sheu and "the turntable" will not work for >long. Lets get some suggestions so we can take a > vote and find a name for our beloved project. > > Actually, "The Table" makes kind of a nice, proud > statement about the project. 8^) > > Steve > "The Team Table" is even more descriptive. Igor ----- Original Message ----- From: Schei, Kenneth Sent: Friday, January 14, 2000 7:48 AM Subject: RE: Scheu-Bearing & Platter Removing material in the middle of the bearing would reduce friction and also make it easier for oil to migrate to all of the bearing surfaces. Because of the teeter-totter effect, the maximum bearing forces will be at the top of the bearing on one side and the bottom of the bearing on the opposite side, in line with the direction of the teeter. Thus the middle of the bearing doesn't have much to do so we can get rid of it and still have plenty of bearing area. It's a common technique in machine design. Ken ----- Original Message ----- From: Mackris, Thom G. To: 'Chris Brady' ; Igor Kuznetsoff Sent: Friday, January 14, 2000 9:40 AM Subject: RE: Scheu-Bearing & Platter Igor, More great work. Thanks. This project is "spinning" rapidly to a vortex. Another good name for a 'table, except that there are speakers named Vortex Screens (scooped again). I'll measure the Merrill platter tonight and then re-measure in the presence of either Ken or Chris this weekend (measure twice, cut once). I too was having thoughts about the maximum subchassis thickness that the bearing would pass through. I think I'd like to see a bit more thickness capacity (all by extending the solid portion of the bottom of the bearing). Even if the entire subchassis is only 1" thick, I can envision a reinforcing block, say a 4" diameter disk centered at the bearing hole. I think that this is a "no compromise" area where we need to go all out with very little extra material or expense. Consistent with this thinking: (1) We should extend the solid bottom portion of the bearing housing a bit to pass through 1.5" to 2.0" of subchassis (plus reinforcement disk) thickness. (2) A nut which would thread onto the 1.125 bottom of the bearing will be fairly tall - at least .75". We should allow for this thickness too. I'll go to Home Depot this weekend and look at their large nuts. Spindles: I'll check my thread pitch as well the diameter of my spindle. I have a dial indicator - accurate to .001. If George can get some standard machine threads from the hardware store (or bring his VPI clamp to the hardware store for a matching bolt), we'll have specifications for all three threaded interfaces (Merrill, Oracle, VPI). I'm guessing that they'll all be 1/4" x 20 (as Steve Reports - see attachment, below). Regarding press-fit of ball bearing, I will defer to the more learned in this area. Cheers, Thom ========================= from Steve's Report: The dimensions from my table are: 11/32" from top surface of the table to the top of the smooth, unthreaded portion of the full-diameter record spindle (don't have an accurate way to measure the diameter, but it fits a standard record hole snugly, but doesn't require pushing to put the record on), the thread portion extends up from there another 11/32". The threading and diameter is standard 1/4" X 20. The top is chamfered a little to knock off the sharp edge of the top thread. ========================= -----Original Message----- From: Chris Brady [mailto:cbrady@sgi.com] Sent: Friday, January 14, 2000 9:12 AM Subject: Re: Scheu-Bearing & Platter Last night I created a cross-section drawing of the turntable components. It's nice to be able to see how all of the parts will fit together. It looks like we have agreement on the majority of the details. Here is a list of things we still need to pin down: 1) The current bearing design will mount on a base plate up to 1" thick. Is this enough? 2) We seem to agree on the general platter design but we need the actual dimensions. Thom, you mentioned that you would like to use the dimensions from your Merrill platter. If you would send me the numbers I have a drawing ready that just needs the numbers. 3) We need the diameter and height for the smooth spindle insert. Based on Steve's input I added the threaded insert to the bearing drawing. I also did a best guess for the smooth insert. Please review both. 4) From the start I have planned for the ball bearing to be pressed into the bottom of the spindle. This would essentially make the bearing part of the spindle. With this arrangement there would be no need for having a concave piece of delrin. So are we just miscommunicating on this issue or are we in disagreement about this part of the design. 5) We need to decide on a name. Here are the suggestions so far: Sofia Saturn Jupiter Spin Doctor Calliope Carousel Brass Ring Teres Clarus Sereno Tersus I would suggest that we accept name suggestions through the weekend and then take a vote on Monday. Chris ----- Original Message ----- From: Steve Zettel Sent: Friday, January 14, 2000 9:58 AM Subject: Re: Scheu-Bearing & Platter This is moving really fast! I previously wrote, re bearing sump: >> >> All that need be done is to neck down the diameter >> of the bearing shaft the >> last half inch, so that there is some clearance >> between the sides of the >> well and the shaft to hold some oil. >> >> Steve >> I would like to retract this in favor of Chris' brother's recommendation to relieve the bearing well in the middle. As Igor stated, it still gives us most support at the top and bottom of the bearing spindle, where it is most important, an will do us the most good, and reduces friction as well. Steve Z ----- Original Message ----- From: Mackris, Thom G. Sent: Friday, January 14, 2000 10:18 AM Subject: RE: Scheu-Bearing & Platter Indeed ... faster and faster !! Steve, I spoke with Chris & he's going to ask his brother about the advantages of both. His take is that with CNC machining, that cost will not be the determining factor between the two options. With respect to strength, I honestly don't know. Bicycle spokes are butted (hourglass shaped, if you will). I'll certainly defer to the collective wisdom of the experts in thi area. Intuitively, I'd guess that this means to relieve the bearing well in the middle rather than to neck down the shaft ... but what do I know ?? Cheers, Thom -----Original Message----- From: Jeremy Epstein [mailto:jepstein@shwd.com] Sent: Friday, January 14, 2000 9:54 AM Subject: Re: Scheu-Bearing & Platter I have a couple of questions, maybe I missed these when they came up earlier. 1) Will each of us be responsible for having our platters machined locally, or will there be a bulk purchase of these too? 2) Are people going to design their own chassis and arm mounting schemes? Or will there be a standard bottom plate design and bulk purchase of these parts? 3) What about arms? I assume that is an area where people have favorites and preferences (and cartridge compatibility issues) so each person is on their own here? 4) Motor speed control circuit. As I understand it, this is yet to be designed, right? And there is some variety of approaches which need to be sorted through still? I expect that this is a pretty critical module, right? 5) Motor pulley - where will these come from? I'll admit it, I am shamelessly piggybacking on this project. If I build one, frankly I doubt whether I will be able to contribute much to the design process because there is little expertise on my end to bring to bear here, especially in comparison with others. So I am wondering how much will be "left to the individual builder as an exercise" at the end. -j -- ----- Original Message ----- From: Mackris, Thom G. Sent: Friday, January 14, 2000 11:32 AM Subject: RE: Scheu-Bearing & Platter Jeremy, Your questions are spot-on, and I've been ruminating about them over the last few days. Let me first summarize a phone conversation I just had with Chris, and then I'll answer your remaining questions one by one. Chris distributed a first swipe at the bearing design to us last weekend in response to: (a) my suggestion of a project schedule and (b) his initial gut feeling that we'd have bearings made by the end of February. Consistent with solidifying the design and with having *no* regrets once we "pull the trigger" and make the order, Chris brought up an excellent point. We should sit on the bearing/platter design until *no* new ideas percolate through the group for a period of 2 to 3 weeks. At this point, we'll be as confident as is possible that the design is thoroughly "cooked" and ready for production. So ... assuming we see no significant activity/changes on the bearing/platter design after say Monday (1/17), we'd be ready to commit this to a physical reality by the first week in February. Assuming a 3-4 week delivery time, we'd have bearings in our hands by the first week in March ... not bad, huh? As far as platters are concerned, we need to start talking to plastics shops more seriously. The platters are definitely another area where a bulk purchase makes sense, as they also involve CNC machining. There will be equivalent savings to those on the bearing when we purchase in quantities of 6-12 from the same supplier. Based on previous research I did when I was thinking about a new 3/4" platter for my Merrill (the quoted price was $218), I'm guessing that the difference between a single platter and 6 to 12 is in the order of $325 vs $125. I'm assimilating Ken's initial research along with my research on my Merrill, while trying to take into account that Ken's research was based on 2" thick platters and we're now going with 3" platters. These are *very* rough guesses. The end result is the same, however ... this is definitely a part that bulk buying makes sense. With respect to your expertise, you won't get into trouble here, Jeremy. I envision 3 epicenters of activity on this project, with each one having a set of localized skills (in conjunction with the entire group) necessary for success: (1) Denver Front Range (2) NY/NJ (3) Misc: Beaverton, OR, Libby, MT and Brittish Columbia. Subchassis. It appears as if this is the single area which will be subject to the most experimentation as well as to variations in personal taste. I'm thinking that we initially work in MDF in order to try to center on a design that makes physical sense. Considering that we are seating the subchassis in sand, we might not ever feel the need to go to acrylic for this part, although many of us may choose to do so, if only for cosmetic reasons. Cosmetics and size are reasons that we may never settle in on a shape that appeals to everyone. In any event, intitial work in MDF would teach us a lot at very little expense. Because there is no precision machining involved in making the subchassis, we may end up making any acrylic ones locally at relatively little expense. The answer to this will certainly unfold in the coming months. A further note with respect to the subchassis & bearing. Chris likes the idea of allowing for the bearing to pass through 1.5" of subchassis material with additional length for the fastening nut. This would add on to the solid material at the bottom of the bearing. If we went with a 3/4" subchassis for starters, we'd reinforce the area under the bearing with a 3/4" thick, 4" diameter disk to bring the thickness up to 1.5". If our ultimate design was say, a 3" subchassis, we could just remove 1.5" of matrial in the area around the bearing, sufficient to fit the fixing nut. In other words, 1.5" seems like a workable, flexible compromise. Project Breakdown - It appears as if we have three distinct phases: 1) Bearing & Platter 2) Inital Subchassis/Arm Mounting (in MDF), Sandbox/Suspension, Motor/Controller/pulley 3) Final Subchassis (as desired), Misc. experimentation (idler pulleys, etc.), suspension, etc. We need to get through step #2 in order to begin experimenting. For those of you without woodshop capabilities, maybe we'll rough up some MDF subchassis for starters. We'll need to discuss this further. Anyhow, as we let the bearing/platter design settle in, we can return to discussing the subchassis/suspension & motor (controller) designs starting next week some time. An area which we're going to depend on Ken and Steve is the motor controller and pulley diameter. I know nothing about how to figure this stuff out (i.e. can a certain motor run with a bigger pulley at lower speed?). Ken and Steve are critical to our success in this area, and fortunately they are real jazzed about solving this problem. Perhaps the answer to pulley size will be solved by making up very crude pulleys which will be made up purely for the purpose of seeing how they push the load of the platter. With respect to arms, this is another reason why MDF subchassis experimentation will be beneficial. I see different solutions for how to route the tonearm cable, for example. Additionally, I'm not clear as to whether we want removable armboards or not - will this compromise the design? I don't know. Many of us are going to go with our existing arms, and some want to allow for a future upgrade. As far as purchase of new arms is concerned, several in the group are thinking of taking Thorsten Loesch's advice and buying an Origin Live, modded RB-250 (see: http://www.originlive.com/index.htm and http://www.tnt-audio.com/sorgenti/olrb250_e.html ). More to follow, Thom ----- Original Message ----- From: Schei, Kenneth To: 'Chris Brady' Sent: Friday, January 14, 2000 12:03 PM Subject: RE: Scheu-Bearing & Platter Great Job, Chris. I think that a 1" thick acrylic base plate is ample if we increase it to 2" around the bearing with another lamination, similar to Thom's suggestion. I recommend that the part of the bearing passing through the base plate be an unthreaded shoulder so we can achieve a close fit in the hole in the base plate. For structural bolts and nuts, the thickness of the nut is usually the same as the bolt diameter, in this case 1-1/8". I imagine a finer thread machine nut would be similar. Maybe we can find special thinner nuts which would be neat. We also want a washer under the nut which would add about 1/8" or so, plus 1/8" to 1/4" extra thread length past the nut. The washer protects the acrylic, distributes the load, and allows tightening the nut without hitting the shoulder. Thus we would need an unthreaded shoulder of at least 2" or whatever we decide on, plus 1-1/2" of threaded length, or proportionally less if we use a thinner nut. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 ----- Original Message ----- From: Schei, Kenneth Sent: Friday, January 14, 2000 12:07 PM Subject: RE: Scheu-Bearing & Platter Chris: Is it any easier, hence cheaper, to neck down the middle of the shaft rather than enlarging the well in the middle? Ken ----- Original Message ----- From: Schei, Kenneth Sent: Friday, January 14, 2000 12:12 PM Subject: RE: Scheu-Bearing & Platter The 3/4" shaft would still be plenty strong if it were necked down in the middle. A 1/16" relief would still leave a 5/8" shaft section which is much thicker than most turntable shafts. I tend to prefer the relief in the shaft rather than the well if only because I will be able to see it clearly (paranoia?). :>) Ken ----- Original Message ----- From: Schei, Kenneth Sent: Friday, January 14, 2000 12:18 PM Subject: RE: Scheu-Bearing & Platter If we use a 3" platter, or even 2", then whatever we mount the tonearm on will have to be raised above the subchassis. That would allow us to standardize a subchassis if we wanted to, and each individual could customize the support block for the tonearm. But we may also want to individualize subchasses to taste. Ken -----Original Message----- From: Jeremy Epstein [mailto:jepstein@shwd.com] Sent: Friday, January 14, 2000 12:03 PM Subject: Re: Scheu-Bearing & Platter OK, Thom, these are about the answers I expected and I am comfortable with everything so far. Note that I do have a router and can probably knock out some MDF, or even maybe acrylic (can acrylic be carved with a standard woodworking router and bit?) subchassis. Doing the second one will take about four minutes longer than doing the first one, I anticipate a "jig it and go" type of process, so there will be some economy of scale at least in time spent. These parts will not be made to CNC tolerances, however, if I have anything to do with them. :-) Hey, so I do have some expertise to lend after all, how about that. I will say that, given the economics of shipping, probably the MDF hacking should be done in local groups as you described, there is no sense in shipping a piece of MDF given the simplicity of the shaping work I think we are talking about. > As far as platters are concerned, we need to start talking to plastics shops > more seriously. The platters are definitely another area where a bulk > purchase makes sense, as they also involve CNC machining. There will be > equivalent savings to those on the bearing when we purchase in quantities of > 6-12 from the same supplier. Based on previous research I did when I was > thinking about a new 3/4" platter for my Merrill (the quoted price was > $218), I'm guessing that the difference between a single platter and 6 to 12 > is in the order of $325 vs $125. I'm assimilating Ken's initial research > along with my research on my Merrill, while trying to take into account that > Ken's research was based on 2" thick platters and we're now going with 3" > platters. These are *very* rough guesses. The end result is the same, > however ... this is definitely a part that bulk buying makes sense. The 325 end seems expensive to me, but not the 125. So if we end up at 225 I guess that's sorta middle ground. Still a hell of a lot cheaper than going out and buying something! -j ----- Original Message ----- From: Mackris, Thom G. To: 'Jeremy Epstein' ; Mackris, Thom G. Subject: RE: Scheu-Bearing & Platter 1) I'm glad there's a router in the NYC part of this project, now that Igor has limited access to his shop. This covers you, Igor & George M. 2) Regarding $325 vs $125. The $325 referred to a single platter price guess. The $125 was a guess at the pricing for 6-12. IOW, we should hit $125 or at *worst* $150 for the platters. I'm not sure how much routing acrylic will take. I've cleaned up edges with my router, but I haven't done major surgery. I suspect it's a function of keeping the heat level down (all of this was done with carbide bits). Cheers, Thom ----- Original Message ----- From: Steve Zettel Sent: Friday, January 14, 2000 2:09 PM Subject: Re: Scheu-Bearing & Platter My comments appended to each section below: on 1/14/00 09:40, Mackris, Thom G. at tgmackris@vicorpinc.com wrote: > I too was having thoughts about the maximum subchassis thickness that the > bearing would pass through. I think I'd like to see a bit more thickness > capacity (all by extending the solid portion of the bottom of the bearing). > Even if the entire subchassis is only 1" thick, I can envision a reinforcing > block, say a 4" diameter disk centered at the bearing hole. I think that > this is a "no compromise" area where we need to go all out with very little > extra material or expense. Consistent with this thinking: > > (1) We should extend the solid bottom portion of the bearing housing a bit > to pass through 1.5" to 2.0" of subchassis (plus reinforcement disk) > thickness. I agree. Looking at the drawing emphasized to me the disparity between our massive 3" platter and a 1" subchassis. We want something able to handle the load without flexing or distorting. (Different topic, have we started any discussion on subchassis shape yet?) > (2) A nut which would thread onto the 1.125 bottom of the bearing will be > fairly tall - at least .75". We should allow for this thickness too. I'll > go to Home Depot this weekend and look at their large nuts. There are low profile nuts and washers of large diameter, but I don't think you'll find them at Home Depot. I will check in McMaster-Carr and some of the other industrial supply catalogs at the Dam. We *do* have more than a few very large nuts at Libby Dam (me, included!). I suspect we will be able to find carbon steel, stainless and brass. No need, I am sure for Monel or Inconel alloys. > > Spindles: > > I'll check my thread pitch as well the diameter of my spindle. I have a > dial indicator - accurate to .001. If George can get some standard machine > threads from the hardware store (or bring his VPI clamp to the hardware > store for a matching bolt) That's exactly what I did. > we'll have specifications for all three threaded > interfaces (Merrill, Oracle, VPI). I'm guessing that they'll all be 1/4" x > 20 (as Steve Reports - see attachment, below). That would be sweet. I really like my Oracle clamp, and they are still available from Oracle, though one that worked similarly would be simple to make, especially if using a standard 1/4 X 20 thread pitch. > > Regarding press-fit of ball bearing, I will defer to the more learned in > this area. I understand both points of view, and guess I don't have a preference. The ball bearing between concave surfaces has the advantage of being self-centering; the ball press-fit into the bottom of the bearing shaft is more common (my Oracle does this), and if we trust the machining on the rest of the assembly there is no reason to question this. The flat delrin plate in this instance will take care of any microscpic "hunting". > > Cheers, > Thom > > ========================= > from Steve's Report: > > The dimensions from my table are: > > 11/32" from top surface of the table to the top of the smooth, unthreaded > portion of the full-diameter record spindle (don't have an accurate way to > measure the diameter, but it fits a standard record hole snugly, but doesn't > require pushing to put the record on), > > the thread portion extends up from there another 11/32". The threading and > diameter is standard 1/4" X 20. The top is chamfered a little to knock off > the sharp edge of the top thread. > > ========================= ----- Original Message ----- From: Mackris, Thom G. Sent: Friday, January 14, 2000 2:15 PM Subject: RE: Scheu-Bearing & Platter I continue to be amazed at how much we all agree on the bearing and platter. This will most certainly change when it comes to the subchassis 8-) Thom -----Original Message----- From: Steve Zettel [mailto:zettel@libby.org] Sent: Friday, January 14, 2000 2:10 PM [ all of Steve's intelligent stuff snipped, leaving nothing left ] ----- Original Message ----- From: Alex Mitaru Sent: Friday, January 14, 2000 2:37 PM Subject: RE: Scheu-Bearing & Platter At 02:15 PM 1/14/00 -0700, Mackris, Thom G. wrote: >I continue to be amazed at how much we all agree on the bearing and platter. >This will most certainly change when it comes to the subchassis 8-) so allow me to start it...;-) I was thinking of glass....it looks cool, not too expensive, and these are the only arguments in favor I could bring...I talked a while ago with a mechanical engineer, and he suggested to build the platter from bullet proof glass, if I could afford it...well, I priced it, and a 2" think platter would cost $2000...so totally out of question, but I was left with the urge for glass...;) A 16" X 19" with a 2" hole of regular glass 3/4" is $60 at my local glass shop, haven't checked more... what do you guys think? alex ----- Original Message ----- From: Mackris, Thom G. Sent: Friday, January 14, 2000 3:17 PM Subject: RE: Scheu-Bearing & Platter I'm thinking that the choice is going to come down to several considerations: 1) Ability to mount the arm in a secure fashion so as to drain "tone arm release energy" (thanks to George Merrill for this term) 2) Ability to affix threaded inserts for tip toes (& possibly a removable arm board) 3) Aesthetics I would guess that the vibration characteristics of the subchassis won't be that important if it's resting on a bed of sand & rubber chips as Igor suggestted. As a result, I'm seriously thinking that I might end up with a high gloss black finish over MDF due to the interesting shapes that can be routed out of the material. This will certainly take me through the first 6 months. After that, who knows? Glass could be very pretty, but I'm not sure how to do the tonearm mounting. If threaded inserts or T-nuts can be inserted into the armboard, then the subchassis would only need the holes for the bolts to pass through into the armboard block. Because the armboard will have to be approximately 2.5" to 3.0" high (in order to bring the mounting plane of the tonarm into the proper position), we can get creative with our armboard. This would probably be 3-4 layers of 0.75" Acrylic or MDF and certainly 3 or 4 T-Nuts could be snuck in there. These are all prelimanary thoughts ... The Mana Stand folks use tempered glass plates ... but then again, in this application, we're talking about tuning a pass band for something like a Linn turntable ... a different engineering problem. Cheers, Thom ----- Original Message ----- From: Steve Zettel Sent: Saturday, January 15, 2000 1:11 AM Subject: Re: Scheu-Bearing & Platter on 1/15/00 00:15, Thom Mackris / Joan Panzella at tmackris@earthlink.net wrote: > Convergence ... > > The Merrill also has a 1/4" x 20 thread. I'm taking a nut which I threaded > onto the spindle to the hardware store tomorrow to confirm this, but I'm 99% > certain. When you think about it, starting with a fixed dimension (a record > hole) and the fact that both Oracle and Merrill are not using metric > threads, you'd expect them to be the same. > That pleasantly surprised me about the Oracle, being a French-Canadian table I expected metric. After Ken's post about working with acrylic, I will no doubt be fabricating my subchassis out of MDF, too. Though I like the looks of acrylic, I don't have the access to the proper tools to work it without ending up with lots of expensive rejects. MDF, wood putty, bondo and paint cover a multitude of sins! Also, I think I am the only one so far that wants to do a two tonearm table, so my subchassis design might be a little different than a group-buy acrylic one. I found another RB-300, wired with Cardas, for a very low price. With my existing AudioNote/RB-300 this will give me two identical arms. Since I know this project is going to turn out to be an "Oracle-killer", I'll swap my arm and cartridge from the Oracle, and sell it when the (Teres?, Clarus?, The Table?) is up and running. The only caveat with the Rega arms is the lack of convenient VTA adjustment, but since we are dealing with a 3" platter, that gives lots of height to use for some sort of adjustable base. Any good ideas? Steve ----- Original Message ----- From: Steve Zettel Sent: Saturday, January 15, 2000 1:40 AM Subject: Re: Scheu-Bearing & Platter My thoughts so far on Jeremy's good questions: > I have a couple of questions, maybe I missed these when they came up > earlier. > > 1) Will each of us be responsible for having our platters machined > locally, or will there be a bulk purchase of these too? I think this has been answered -- a group buy of materials, discs cut and laminated, and finished dimensions CNC milled. > > 2) Are people going to design their own chassis and arm mounting > schemes? Or will there be a standard bottom plate design and bulk > purchase of these parts? Either way is do-able, but MDF vice acrylic is cheap, readily workable, and lends itself to the individual design. I think acrylic looks great, and with an acrylic platter, would be awesome, but personally, I lack the skills and tools to do much with acrylic. I saw a machinist who I have the utmost respect for have all kinds of problems cutting and drilling an armboard insert for me out of 3/4 acrylic. > > 3) What about arms? I assume that is an area where people have favorites > and preferences (and cartridge compatibility issues) so each person is > on their own here? Waaaay down the line I might take a stab at this, but I really kind of doubt it. The Regas are excellent arms for the money, and the Origin Live mods to the "bargain basement" RB-250 are reputed to be the equal of arms costing in the $1000 range. > > 4) Motor speed control circuit. As I understand it, this is yet to be > designed, right? And there is some variety of approaches which need to > be sorted through still? I expect that this is a pretty critical module, > right? This was an area I wanted to contribute to. We really have the choices here to make it as simple or as complex as we like. I confess I haven't had much off time to play with the Pittman motor, or the Pabst I ordered, and if I don't get to it soon, I will be on active duty with my Navy Reserve unit from 30 Jan to mid-Feb. We can go battery/rheostat (and charger); unregulated DC power supply/rheostat; regulated DC power supply/rheostat; adjustable regulated DC power supply all the way up to something similar to the programmable SDS VPI-style power supply. My inclination is to keep it somewhere in the middle. An adjustable regulated DC power supply, and a simple strobe disc probably gives us the right combination of accuracy and simplicity (read: economy) that we are looking for. As a minimum we could come up with a schematic, parts list and drawings for all. If we get enough people who want one, a parts kit might be feasible. > > 5) Motor pulley - where will these come from? Another CNC job, if we all settle on the same motor. Or perhaps we can find them from outfits like Small Parts in Florida. > > I'll admit it, I am shamelessly piggybacking on this project. If I build > one, frankly I doubt whether I will be able to contribute much to the > design process because there is little expertise on my end to bring to > bear here, especially in comparison with others. So I am wondering how > much will be "left to the individual builder as an exercise" at the end. Well, I think you have done more than just piggy-backing. 8^) All good questions, and thing we all have to think about. Steve ----- Original Message ----- From: Igor Kuznetsoff Sent: Saturday, January 15, 2000 1:48 AM Subject: RE: Scheu-Bearing & Platter Alex, I think that both MDF and acrylic would be a much less resonant subchassis, and MDF also much cheaper. I ----- Original Message ----- From: Steve Zettel Sent: Saturday, January 15, 2000 1:45 AM Subject: Re: Scheu-Bearing & Platter on 1/14/00 12:26, Chris Brady at cbrady@sgi.com wrote: > I don't see that it would make any difference if we make the relief in > the bearing well or on the shaft. How about I leave it to my brother > to do which ever is easiest or best? By all means, go with what your brother recommends. I agree that the shaft is not the weakest link in this whole thing! Steve ----- Original Message ----- From: Igor Kuznetsoff Sent: Saturday, January 15, 2000 3:37 AM Subject: Re: Scheu-Bearing & Platter *Strength* should not be the issue here. The bearing will be strong enough for that carousel & calliope as well. What is important here, I believe, is **stability**. Perhaps I mislead the issue yesterday by using the phrase "mechanical advantage". By placing our support points at the far ends of the bearing, what we really most importantly gain is a minimization of wobble / teeter-totter / play. "Necking" the end of the shaft shortens that "arm", giving up some of that advantage. All in microscopic terms, of course. I would like to add that I feel that the additional .1" is only .05" in radius, and is not really enough to allow much of sump area. I would suggest doubling that differential for a total bore size of at least .975", still a modest, but adequate sump. >4) From the start I have planned for the ball bearing >to be pressed into the bottom of the spindle. This >would essentially make the bearing part of the >spindle. With this arrangement there would be no >need for having a concave piece of delrin. So are we >just miscommunicating on this issue or are we in >disagreement about this part of the design. Pressing the ball into the shaft is a fine idea. For starters, this means that we would not have to fish the ball out of the well with a magnet when re-lubricating, or whatever. All that was said about auto-centering and shaft wander still *does* apply to the Delrin thrust plate, though !! Had the ball not been pressed into the shaft, this would just have meant that wandering would have occured at *two* locations instead of one, without the concavitieS . > (1) We should extend the solid bottom portion of the >bearing housing a bit to pass through 1.5" to 2.0" >of subchassis (plus reinforcement disk) thickness. > >I agree. Looking at the drawing emphasized to me the >disparity between our massive 3" platter and a 1" >subchassis. We want something able to handle the >load without flexing or distorting. Amen to that. My suggestion would be to start with the 1.5" base dimension, add ~1/8" for the possibility of a constrained layer lamination between the 3/4" layers of MDF (or whatever), plus 1/8" for a fender washer, and, perhaps a spare 1/8" past the nut, or for whatever strikes anyone's fancy in their individual realizations of the subchassis design. This would total a 1.875" opening, plus the nut. It would be a big plus if the nut was thin, to reduce the necessary clearance under all this, keeping in mind that this could affect the cone/footing size necessary. >Maybe we can find special thinner nuts which would be >neat. We also want a washer under the nut which >would add about 1/8" or so, plus 1/8" to 1/4" extra >thread length past the nut. The washer protects the >acrylic, distributes the load, and allows tightening >the nut without hitting the shoulder. Thus we would >need an unthreaded shoulder of at least 2" or There are low profile nuts and washers of large >diameter, but I don't think you'll find them at Home >Depot. I will check in McMaster-Carr and some of >the other industrial supply catalogs at the Dam. We >*do* have more than a few very large nuts at Libby >Dam (me, included!). I suspect we will be able to >find carbon steel, stainless and brass. No need, I am >sure for Monel or Inconel alloys. What, you mean we can't find audiophile grade platinum alloy with Rhodium speckling in a golden-section non resonant pattern ? >> 5) Motor pulley - where will these come from? >Another CNC job, if we all settle on the same motor. >Or perhaps we can find them from outfits like Small >Parts in Florida. Perhaps we should think about this before ordering the CNC work, so as not to lose whatever advantages the possibility of CNC package pricing might offer ? Ditto for the possible (and recommendable) idlers. Igor ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Saturday, January 15, 2000 9:04 AM Subject: Re: Scheu-Bearing & Platter All, A quick background note subsequent to a phone conversation with Chris last night. Chris will be publishing a new platter drawing complete with all dimensions. Please take extra time to review the numbers on this drawing. I will be double checking it too but *please* don't trust us fools on this! Suggestions and comments, as always are welcomed and encouraged. I backed off on full compatibility with the Merrill periphery clamping ring because I did not think it would have aesthetic appeal to the group as a whole. As a compromise, I did give Chris the outside diameter of my Merrill platter, which is 12- 9/16" and we plugged this into the drawings. This number was very close to Scheu's and so we felt that from a cosmetic standpoint, the visual effect would be the same. The area I'm referring to is the small rebate at the edge of the platter with the 45 degree angle which facilitates handling the record. At the end of this communique is a description of the rebate which would be required for full Merrill compatiblilty, why I nixed it, and what you lose (very little - because the clamp can still be used, it just can't be stored on the platter with a record placed *over* it). In arriving at the dimensions, we considered three major items: (1) The diameter of an LP (11-7/8" = 11.875"). (2) Scheu's dimensions (3) The outer diameter of the Merrill platter. There is one measurement which we're still wrestling with: The depth of the label rebate. My dial indicator measures the Merrill at .020" and the Scheu (from the drawing) is .098" (2.5mm). Quite a difference! We're thinking of going to .04 but are still wondering if maybe this is a dimension where it's safer to err on the deep side - closer to or equal to Scheu's dimensions. The diameter of the label rebate was also an area of minor disagreement between Merrill and Scheu. The Scheu was 96mm to the beginning of the 45 degree angle (= 3.779") and 100mm (3.937"). Merrill uses a rebate of 4.25". We're thinking of 4.0" subject to revision, of course. Chris and I each measured several LPs and agreed that an LP is 11-7/8" in diameter (11.875"). The rebate at the edge of the table is designed so that the outer 3/32" of the LP does not contact the record. The thinking here (which is apparently shared by Scheu, as well as by Sota, according to Blair Hansen) is that some LP's are slightly thicker at the edge of the record. By rebating the platter here, contact with the platter will be less compromised. Additionally, it's pretty and makes lifting the record simpler! Notes on the Merrill Platter / Periphery Clamp Design: With the above suggested platter diameter (the same outer diameter as a Merrill platter), the periphery clamping ring can still be used. What you give up is the ability to "store" the ring on the platter while playing an LP. Storing the ring involves placing the ring on the platter before putting a record on it. The record is then placed *over* the clamp, bypassing its clamping effect. This usage maintains the same platter mass and weight distribution over the suspension springs. Merrill uses very a soft (compared to Linn & Thorens) suspension & it's important in his design that the clamp is always on the 'table, so that the weight distribution on all three springs is held constant. The rebate which I nixed on all of your behalf is a right angle one: .140" deep and .322" wide. This is fairly ugly in comparison with Scheu's sense of aesthetics and it's only advantage is that it places the clamp a few hundredths of an inch below the platter surface when you place it on the platter prior to an LP. This allows playing an LP with the clamp underneath it. The clamp is ~ .75" tall, and with Merrill's .5" thick platter, it lends the appearance of a .75" thick platter. With our 3" platters, it woud be an ugly .75" bump at the top. Cheers, Thom ----- Original Message ----- From: Igor Kuznetsoff Sent: Saturday, January 15, 2000 2:25 PM Subject: Re: Scheu-Bearing & Platter All, This might be a good time for me to follow up on what I wrote about placing the *working* bearing surfaces as far apart as possible on the spindle for stability. It was very late last night, and I was too tired to be more thorough, but perhaps this will save Chris another redraw. So long as we are lengthening the entire assembly, we could also concomitantly lengthen the spindle and sump well rebate in order to stretch the distance between those areas. The sump well area should also be stretchad to limit the working bearing areas to keep friction down, and increase the sump itself. This may pay off additional benefits as the oil bath around the middle of the spindle may, in some small part, help to damp any vibration the spindle may be carrying. Remember that any rod or string shaped vibrating object has its maximum amplitude in the middle. This may be an extremely fine (or even inconsequential point, but it's a freebie. As to the label area rebate on the platter, wouldn't the larger one be a safer bet, as it will accommodate smaller labels (I never really paid enough attention to that to notice variations), but the reverse... I ----- Original Message ----- From: Steve Zettel Sent: Saturday, January 15, 2000 7:33 PM Subject: Re: Scheu-Bearing & Platter on 1/15/00 09:04, Thom Mackris / Joan Panzella at tmackris@earthlink.net wrote: > I backed off on full compatibility with the Merrill periphery clamping ring > because I did not think it would have aesthetic appeal to the group as a > whole. As a compromise, I did give Chris the outside diameter of my Merrill > platter, which is 12- 9/16" and we plugged this into the drawings. This > number was very close to Scheu's and so we felt that from a cosmetic > standpoint, the visual effect would be the same. The area I'm referring to > is the small rebate at the edge of the platter with the 45 degree angle > which facilitates handling the record. At the end of this communique is a > description of the rebate which would be required for full Merrill > compatiblilty, why I nixed it, and what you lose (very little - because the > clamp can still be used, it just can't be stored on the platter with a > record placed *over* it [ snip ] > The rebate which I nixed on all of your behalf is a right angle one: .140" > deep and .322" wide. This is fairly ugly in comparison with Scheu's sense > of aesthetics and it's only advantage is that it places the clamp a few > hundredths of an inch below the platter surface when you place it on the > platter prior to an LP. This allows playing an LP with the clamp underneath > it. The clamp is ~ .75" tall, and with Merrill's .5" thick platter, it > lends the appearance of a .75" thick platter. With our 3" platters, it woud > be an ugly .75" bump at the top. > > Cheers, > Thom Thanks, Thom. With our basically suspensionless turntable, keeping the mass the same is nowhere near as critical (the clamp's mass I am sure would be swamped by our massive platter), and I appreciate you sacrificing convenience for aesthetics. Steve ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Saturday, January 15, 2000 10:53 PM Subject: Re: Scheu-Bearing & Platter I do like things pretty also . The fact that I'm not all that certain if I'll buy another Merrill clamp (assuming that I love our table so much & end up selling the Merrill) made this decision easier. I think that you are correct about our 'table's mass swamping the mass of the clamp. As long as I leave myself (and everyone else) with the option of using the periphery clamp, I'm cool. It is a great clamp, but it's an extra operation in order to play a record side. I'm getting lazy :-) Your's and George's (VPI) reports about the success of your (similar) clamping schemes makes me think that I won't care even it ends up that Merrill's clamp is marginally superior. Life is too short & I'll gain it back in some other tweak. The current design allows the clamp to be used if desired, but not to be stored on the platter while still playing a record on top of it. No biggie. Cheers, Thom ----- Original Message ----- From: Igor Kuznetsoff Sent: Sunday, January 16, 2000 1:39 AM Subject: Re: Scheu-Bearing & Platter --- Thom Mackris / Joan Panzella wrote: > Regarding sump capacity, indeed, oil is a great > damping medium, and as you > note, it's a freebie. > > I'm not sure if I follow you with respect to > lengthening the spindle & sump > well rebate, but I think I do. Let me rephrase & > see if I got this right. > I think you're saying that bearing contact area at > each end of the bearing > should be minimized and *not* that the shaft itself > should be lengthened at > the same time. > > I think that we got the bearing shaft just length > just right. Now that we > decided on the 3" platter, the geometry looks like > we can align the belt's > pull so that it is perpindicular to the center of > the bearing shaft. If the > shaft were lengthened, we'd be pulling at a point > above the shaft's center > point. Am I missing something? > > Cheers, > Thom Our bearing system is quite different from the Scheu type. Let me say, for starters, that it is a far superior design from the git-go due to its inherently stabler basic configuration, as well as the much larger shaft diameter. If we do nothing more to fine tune it, I believe it will already outperform. But, at this point, nothing has been invested into the machining, so there is no investment cost to be lost to redoing anything yet. So why not optimize to get everything we can out of it ? The Scheu bearing spindle is free-floating at both ends, if I read the drawing right. The bottom end sits (relatively) stably in a well somewhat similar to ours, but the top does not. The top fits into a relatively short sleeve which offers poor stability. In that configuration, aligning the belt pull is critical, and must be done so that it aligns with the(most) teeter-totter resistant point at the top. In our design, the *spindle shaft* balance point, t-t wise, is relatively insensitive, and is optimum anywhere from the middle of the top contact area all the way down to the median point between the contact areas. However, analysis of the platter / spindle interface, meaning the way the spindle fits into the platter cutout, indicates that that point occurs much higher up for that system, somewhere just below the center of the spindle shoulder which the platter sits on, and below only due to the mass of the platter that is hanging below that point. True, the mass of the platter is such that it certainly is not going to do any rocking, but, that *is* where that system is balanced side-pull wise. The net result of these balance systems will be somewhere very near, but *above* the center of the upper contact area. As I believe (correct me if you see fault with this analysis) that the spindle shaft balance point is by far the more significant, I would not place the belt above the center of the upper contact area. I am going by the drawing, and depending on the accuracy of its scale somewhat. The precise point of total system balance would require some fancy physics. If you feel like jockeying numbers, have at it, but, as that point will end up being somewhere just *above* the aforementioned contact center, I don't think knowing it precisely will matter a goose fart's worth in a hurricane. To align the two centers more perfectly than there is any necessity for, the platter would probably have to be even (slightly) thicker. Now, knowing that the side-pull balance point is optimal at or (not too much) below the center of the upper contact area, we realize that the longer the spindle is between there and the lower contact area, the stabler the spindle will be. True, we may be bracing the brick shithouse here with gilded girders, and could live just fine with it as is, but if we are optimizing, then....Now, assuming that I haven't blundered in my analysis, does my suggestion to take advantage of the lengthened housing to lengthen the shaft make sense ? Now, as to the bearing contact areas. Their size should be scaled to optimize their function while minimizing the drag. Probably our best bet for this would be to rely on Chris's brother's experience and expertise in this area. Unless someone else in our talent pool is expert in this, let's leave this detail for him to set. ----- Original Message ----- From: Steve Zettel Sent: Sunday, January 16, 2000 10:14 AM Subject: Re: Scheu-Bearing & Platter [ editor's note: the following was in reponse to a comment elswhere in this dialog about a glue which bonds acrylic with no evidence of the seams. multiple layers appear like a single casting - even if all edges are polished and transparent. ] on 1/15/00 23:57, Igor Kuznetsoff at gorkuz@yahoo.com wrote: > That glue must be the solvent type. I was shown the > results of the bond once, and thought they were > pulling my leg. The piece looked cast. I guess this > means it really was glued. This is good news, as is > the possibility of having all the work done by one > sympathetic, interested machinist experienced with > fine,precise, work (and with blood ties, yet)! > I > I agree, fantastic news. I think it is well worth having Chris' brother do the bearings and platters for us, given his obvious expertise and enthusiasm for the project. I really like the sound of the bonding process. And he certainly understands our concern for balance, concentricity, and (lack of) run-out. I know that mention was made of flame polishing or frosted (bead blasted?) finishes. I weighed in on the side of the frosted finish, based on my concern with eventual scratching and the overall difficulty, at least in my house of keeping things fingerprint and dust-free. Any other comments? I had a thought about the frosted finish, and that though it doesn't show the dust or scratches, if it gets oily (fingerprints or lubricant) or wet (cleaning solutions?) the spots tend to discolor and don't come out easily if at all. Will we be doing the finishing separately or will that be part of the delivered platter from Chris' brother? Either type of finish will look very elegant, and I can live with either one. Now, if only those motor/controller gurus would get their butts in gear. Oh, yeah, that would be me! Steve ----- Original Message ----- From: Steve Zettel Sent: Sunday, January 16, 2000 10:33 AM Subject: Re: Scheu-Bearing & Platter I just had a wild-ass thought (Montanan for brainstorm). What about having a 1/4 x 20 hole tapped into the bottom of the bearing assembly? The bottom of the bearing well will more than likely be the lowest projecting point of the entire turntable/subchassis assembly. We are going to put TipToe-like cones on the subchassis to be pushed into sand/rubberchips, why not put a cone on the bottom of the bearing well too? Though I expect our assembly to be silky smooth, won't this be another little tweek to further dampen the bearing? OK, tell me I'm full of it. But this tweeking stuff is contagious. Steve ----- Original Message ----- From: Steve Zettel Sent: Sunday, January 16, 2000 10:57 AM Subject: Re: Scheu-Bearing & Platter Good reasoning, Thom. I am cool with machined rather than polished, for all the points you listed. Thanks, Steve on 1/16/00 10:33, Thom Mackris / Joan Panzella at tmackris@earthlink.net wrote: > I agree with either a frosted or etched finish for both functional reasons > as well as aesthetic ones. We'll get a milky appearance for "free" in the > record label rebate and the platter edges as a result of the machining > process. It remains to be determined how this is accomplished on the > remainder of the record playing surface - etching? grinding? bead blasting? > >> From a long term aesthetic viewpoint, even if clear is appealing, scratches > innevitibly happen & the frosting or etching would hide them. > >> From a functional perspective, as has been previously noted, a little extra > friction along the platter's edge would certainly help the belt to get a > grip. So, it would appear to me that with respect to the side of the > platter, a rough surface is a functional consideration. > > As far as the playing surface is concerned , we need to keep in mind that > the record label rebate area will already have been machined and restoring a > glossy finish might (a) cost and (b) throw the dimensions out of whack (is > the polishing done mechanically, chemically, or by heat? Would it screw up > our "perfect" platter. I'm inclined to leave this area alone. > > Without knowing the exact process, I't think that after the circle was cut, > that the entire top would be machined (perhaps as a truing operation) and > then the record label rebate and the rebate along the edge of the platter > would be cut. This would lend uniform machining marks over the entire top > and side. Maybe this is overkill. Once again, I'm just guessing and Chris' > brother is the expert. > > My vote from a functional standpoint (as well as an aesthetic standpoint) is > to leave well enough alone and stay frosted on the top and side of the > platter. My guess (to be confirmed by Chris) is that a totally complete > platter and bearing will be shipping from Chris' brother's shop. > > Cheers, > Thom > > ----- Original Message ----- From: Mackris, Thom G. Sent: Monday, January 17, 2000 12:52 AM Subject: RE: Scheu-Bearing & Platter All, I had a brief conversation with Chris this evening about the spindle length. We are apparently at the maximum spindle length in terms of the stock that is attainable at reasonable cost. I thought I had previously heard this, but I wasn't sure if it was only with respect to the width of the platter support surface (the 1.75" ==> 2.0" dimension). This is not bad news, however. We have apparently hit a sweet spot ... beginner's luck. Let me attempt to relate Chris' brother's points as Chris explained them to me. I hope I'm repeating this correctly. Firstly, our theoretical analysis is indeed correct. A longer shaft *if* machined to equal tolerances is indeed better. The problem arises in maintaining the same accuracy as you increase the length of the bore. You reach a point of diminishing returns due to physical flexion of the equipment (Chris'inference). It's fairly obvious that for a given resistance to flexion (X thousandths per distance Y) a longer bit will flex proportionately more than a shorter one. Because of this, Chris' brother can machine a .5" long shaft/bearing assembly to the same effective tolerance as a 2.0" bearing/shaft. In other words, he can machine with ~ 4 times more precision over a .5" length than a 2" length. The point where there is some falloff in effective precision is beyond approximately 2.5"! The length we chose!! Better to be lucky than smart, I suppose. On a project scheduling note, Chris' brother is fairly busy at the moment and it looks as if doing the bearings and platters won't happen until the first week or two in March as I was guessing. Chris has to go to Oregon (where his brother is located) on the second week in March, and is thinking of actually delaying the process until then. This would only be a delay if his brother actually frees up early. Chris' thinking is that he'd like to be there in case any questions pop up in order to see them first hand and communicate them to the group as necessary. I am beginning to think that this project is blessed! This is most serendipetous in my opinion. Whle he's there, he can take pictures of the whole process for his web site. I'll bet Alex could drop on by an report his impressions of the operation back to us. That's it for now ... Thom ----- Original Message ----- From: Schei, Kenneth Sent: Monday, January 17, 2000 7:46 AM Subject: RE: Scheu-Bearing & Platter [regarding subchassis and/or sandbox underneath it] MDF with a nice wood veneer appeals to me also. The contrast between the high-tech acrylic platter and the traditional wood deck may be the way I will want to go. It would also be cheaper. Ken ----- Original Message ----- From: Schei, Kenneth Sent: Monday, January 17, 2000 8:10 AM Subject: RE: Scheu-Bearing & Platter The more I think about it, the more I like a subchassis consisting of two layers of 3/4" MDF, with a fine veneer finish and solid wood trim. The under layer can be routed out for things like motor control pots, etc. With my Falhauber motor, I'm not sure I will need to isolate it from the subchassis because it's so smooth. I will probably run the motor off of battery power with a little battery bracket hidden in the subchassis. No power cord! Here are some parameters for the motor pulley. It has to be small enough so that the motor doesn't have to run too slowly, but it needs to be big enough to have enough friction area so the belt doesn't slip. It has to have a groove compatible with the shape of the belt. And it needs to be concentric and true. Acrylic is the material of choice due to expansion characteristics. Chris - do we want to include the pulley in you're brother's contract? Ken ----- Original Message ----- From: Schei, Kenneth Sent: Monday, January 17, 2000 8:32 AM Subject: RE: Scheu-Bearing & Platter I agree with Igor that lengthening the sump rebate and reducing the two end bearing areas somewhat are beneficial in that they would reduce friction. I think we all understand that the two bearing areas should be as far apart as our geometry allows, for the greatest moment arm or lever length against the "teeter-toter" effect. After mulling it for awhile, I've decided that it's definitely better to put the rebate in the shaft, not the well. That will reduce the diameter of the center portion of the shaft and will thus reduce the drag friction of the shaft running through the oil in the sump. Ken ----- Original Message ----- From: Schei, Kenneth Sent: Monday, January 17, 2000 8:50 AM Subject: RE: Scheu-Bearing & Platter Thom, Chris: Thanks for the report, Thom. I think that we should think about having Chris's brother to do the motor pulley also, since it needs to be precise and will be of acrylic. That means if Chris's brother does the platter and pulley, those of us who use a non-acrylic base won't have to worry about sourcing acrylic at all. One problem is that we are working with a small variety of motors (Pittman, Falhauber, maybe Pabst) each of which probably has a different shaft diameter. We need to do more work on the motor system before we can finalize the pulley. We should be able source an appropriate drive belt from MCM Electronics (http://www.mcmelectronics.com/) or other source. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 ----- Original Message ----- From: Schei, Kenneth Sent: Monday, January 17, 2000 9:05 AM Subject: RE: Scheu-Bearing & Platter I agree with Igor here. The vertical placement of the belt has two conflicting requirements. Lowering the belt places it closer to the center of the bearing, reducing the T-T effect, but raising it places it closer to the center of the contact area between the platter and the bearing shaft, reducing its tendency to want to tip the platter on the bearing. However, with our massive bearing, 15# platter, and precise interfaces, it really doesn't matter much. I would like to reiterate here my opinion that the rebate for the sump should be in the shaft, not the well, to reduce friction. The reduced shaft diameter will result in less surface area and a lower perimeter velocity, which will reduce the drag of the shaft in the oil. The drag reduction will be proportionate to the surface area and to the square of the perimeter velocity. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 ----- Original Message ----- From: Schei, Kenneth Sent: Monday, January 17, 2000 9:05 AM Subject: RE: Scheu-Bearing & Platter > --- Thom Mackris / Joan Panzella > wrote: > > > > I think that we got the bearing shaft just length > > just right. Now that we > > decided on the 3" platter, the geometry looks like > > we can align the belt's > > pull so that it is perpindicular to the center of > > the bearing shaft. If the > > shaft were lengthened, we'd be pulling at a point > > above the shaft's center > > point. Am I missing something? > > > > Cheers, > > Thom I agree with Igor here. The vertical placement of the belt has two conflicting requirements. Lowering the belt places it closer to the center of the bearing, reducing the T-T effect, but raising it places it closer to the center of the contact area between the platter and the bearing shaft, reducing its tendency to want to tip the platter on the bearing. However, with our massive bearing, 15# platter, and precise interfaces, it really doesn't matter much. I would like to reiterate here my opinion that the rebate for the sump should be in the shaft, not the well, to reduce friction. The reduced shaft diameter will result in less surface area and a lower perimeter velocity, which will reduce the drag of the shaft in the oil. The drag reduction will be proportionate to the surface area and to the square of the perimeter velocity. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 ----- Original Message ----- From: Schei, Kenneth Sent: Monday, January 17, 2000 10:46 AM Subject: RE: Scheu-Bearing & Platter > -----Original Message----- > From: Thom Mackris / Joan Panzella [SMTP:tmackris@earthlink.net] > Sent: Monday, January 17, 2000 9:58 AM > Subject: Re: Scheu-Bearing & Platter > > The question about what kind of lubricant we're going to use has surfaced > a > couple of times. I thought that the object of the game is to have the > most > viscuous lubricant possible. The idea being that anything that increases > drag without increasing bearing noise is a good thing. Lubricant "drag" > is > like adding mass to the platter, from the point of view of swamping the > varying drag of the stylus in the record groove. > > This brings up one point that I forgot to mention in my recounting of > Chris' > conversation with his brother. He can machine to tolerances that > anticipate > the weight of oil that we're going to use !! > > Cheers, > Thom > Granted, more drag may be better, but remember that we're using a far bigger bearing and platter than is standard, and we need to be able to have the motor and drive belt spin the platter. Although not necessary, I also would like my platter to start turning without a push-start. I think that the better approach is to use a thinner lubricant with closer tolerances. After we get the bearings machined, we will undoubtedly have to play around with lubricant viscosities to find the optimum. Ken ----- Original Message ----- From: Schei, Kenneth Sent: Monday, January 17, 2000 10:57 AM Subject: RE: Scheu-Bearing & Platter > -----Original Message----- > From: Thom Mackris / Joan Panzella [SMTP:tmackris@earthlink.net] > Subject: Re: Scheu-Bearing & Platter > > Since we're re-iterating things here (), let me phrase my statement > in > the form of a question ("turntables for a thousand, Art"): Isn't > increasing > bearing drag (while keeping noise at an absolute minimum) a *good* thing? > > Cheers, > Thom If so, only to the point that the motor-belt system can spin the platter. But I'm not sure that minimizing friction isn't the better approach. Keeping spin uniform is best achieved by high mass which results in high inertia, which is a perfectly smooth, linear governing system. We are certainly doing that with our 3" platter. Using bearing friction seems a bit crude to me; I'm afraid that the bearing friction will cause the speed to hunt as the bearing resistance builds up and releases micrscopically, which may have an audible signature. I think that the easier our bearing spins, the better it will be. Ken ----- Original Message ----- From: Steve Zettel Sent: Monday, January 17, 2000 11:10 AM Subject: Re: Scheu-Bearing & Platter Large, unvarying drag in relation to the small, varying drag of the stylus in the modulated groove, would seem to be a good thing *provided* the motor is robust enough to handle it, and not operating right at the point of stalling. My off the cuff read on this. I like the idea of letting the inertia of the massive, free-spinning platter handle this concern, rather than introducing an additional load. But I haven't done much studying on this aspect of turntable design. Steve ----- Original Message ----- From: Igor Kuznetsoff Sent: Monday, January 17, 2000 2:00 PM Subject: RE: Scheu-Bearing & Platter I'm in agreement with Ken, on friction. Friction is always undependable & problematic. I would rather depend on mass augmented with oil damping for stability. I don't mind the extra drag from the oil, though. I've had great results from super-thick oil, *from* the drag. I ----- Original Message ----- From: Chris Brady Sent: Monday, January 17, 2000 2:42 PM Subject: Re: Scheu-Bearing & Platter What we are talking about is the friction from the oil film. The more surface with an oil film the greater friction, from the oil. Unless there is an error in the machining there should not be any other significant sort of friction. Chris ----- Original Message ----- From: Igor Kuznetsoff Sent: Monday, January 17, 2000 3:02 PM Subject: Re: Scheu-Bearing & Platter I may be picking nits, but there is a (if fine) difference between the drag behavior of a constrained film of oil (and the changes that occur as it ages & becomes contaminated) in the contact areas, and that of it in the open sump area, where the operative mechanisms are surface tension and turbulence. I wasn't figuring on metal -to-metal contact! The bearing wouldn't be of any use if there was. I ----- Original Message ----- From: Steve Zettel Sent: Monday, January 17, 2000 9:02 PM Subject: Re: Scheu-Bearing & Platter on 1/17/00 10:57, Schei, Kenneth at SCHEIKE@asa.org wrote: > If so, only to the point that the motor-belt system can spin the platter. > But I'm not sure that minimizing friction isn't the better approach. > Keeping spin uniform is best achieved by high mass which results in high > inertia, which is a perfectly smooth, linear governing system. We are > certainly doing that with our 3" platter. Using bearing friction seems a > bit crude to me; I'm afraid that the bearing friction will cause the speed > to hunt as the bearing resistance builds up and releases micrscopically, > which may have an audible signature. I think that the easier our bearing > spins, the better it will be. > > Ken > I am with Ken on this one. Steve ----- Original Message ----- From: Steve Zettel Sent: Monday, January 17, 2000 9:48 PM Subject: Re: Scheu-Bearing & Platter on 1/17/00 18:53, Thom Mackris / Joan Panzella at tmackris@earthlink.net wrote: > In one of the huge volume of posts today, Igor asked about the 11.68" > dimension & whether it would clear the lump in the record's lead-in groove. > Here's how we arrived at that number: > > Record diameter = 11- 7/8" = 11.875" > Lead-in groove "lump" = 3/32, or in terms of diameter - 2 x 3/32 = 3/16" = > ..1875" > Diameter to clear the "lump" = 11.875 - .1875 = 11.6875" rounded down to > 11.68" > > On the records I looked at, the lumps were barely evident. I was thinking > about calling them 4/32" which would put two of them at 8/32 or 1/4". This > revised diameter would then be 11.875 - .25 = 11.625. > > Chris & I don't really have problems with this dimension *but* we don't want > to complicate matters by specifying dimensions in ten thousandths of an > inch: Adopting this revised "lump-clearance" would result in the following > three diameters: > > 11.680 ==> 11.625 > 12.080 ==> 12.025 (this would maintain a 45 degree bevel with a 0.2" drop). > 12.280 ==> 12.280 (constant for compatibility with Merrill periphery clamp). > > The 45 degree edge would still maintain a 0.2" drop. The horizontal "lip" > would increase from 0.1 to 0.1275 > > Personally, I think this is another "goose fart in a hurricane". If the > dimensions are specified so that the 0.1275 is "what's left over" then we > don't have to specify it and I'm comfortable going either way. > > Cheers, > Thom The logic and the dimensions seem very good to me. Steve ----- Original Message ----- From: Steve Zettel Sent: Monday, January 17, 2000 10:07 PM Subject: Re: Scheu-Bearing & Platter on 1/17/00 18:32, Igor Kuznetsoff at gorkuz@yahoo.com wrote: > > I really must reiterate my worries here. I first saw > Steve's paper & yardstick thing around 6th grade or > so, and have never forgotten it or much else of the > science > I was taught. Since I learned to speak English ( I'm > one o' dem furrin' borned types), I have always been > in accelerated classes with a lot of science, math, > and > Fizzics (oops). 'N' I's a tellin' ya, I's a consarned. > I have a feeling that removing it will be a little > more than just a nuisance. It will be one thing to > leave the insertion process to itself & time, another > to have to stand/sit (& curse) while trying to slowly > drag it out of the well. An additional concern of > mine, and perhaps no one else's, involves my wish to > experiment with *really* thick, STP like oils, once > the bearing breaks in with lighter oil. I intend, > once that is done, to lightly coat the spindle with > Steve's Tetra > (what do those little fish have to do with this stuff, > should the anti-vivisectionists be notified?) Bike > Oil, in order to leave a tracery of Teflon on it, and > replace the oil with the thick stuff. It will be one > thing to install/remove the spindle with light oil in > there, entirely another to do that with the STP !!! > Perhaps we can have Bryce perform a test fitting (with lube) of a bearing spindle/well assembly at the point of final machining completion (without relief passages). If difficulty with assembly and dissassemby by hand is an issue, we could have him proceed with machining a pressure relief (if we can agree on what type to use -- from the bottom or the top) Steve This digest has one early post from Bill Mollard - a response from Hartmut about some tweaks (relating to bearing and platter interface, among others). It then picks up with the 1/18 posts and continues through 1/28. This catches you up with all of the Bearing and Platter e-mails. I have 130 misc. e-mails still remaining and will attempt to "digest" them by the end of the weekend. Cheers, Thom ----- Original Message ----- From: WilliamB Sent: Friday, December 17, 1999 8:42 AM Subject: Harmut improves the Scheu Hey Thom, As mentioned... I contacted Harmut regarding his comment. FWIW best bill [Hartmut's comments follow] William, first I have to say, that now the Scheu in USA is only available over a distributor. Mods in decreasing effectiveness soundwise: replace the rubber ring between platter and bearing with a washer of same thickness use thin oil For myself I use a Cotter slate/rubber suspended base and a Swiss Maxxon motor. I also have a special bearing with ceramic ball riding on a brass piece instead of PTFE. Then I have a special platter from higher density (but that makes only the least improvement) regards, Hartmut ----- Original Message ----- From: Igor Kuznetsoff Sent: Tuesday, January 18, 2000 12:13 AM Subject: Re: Scheu-Bearing & Platter [regarding the bearing, sump, oil viscosity, and the bearing surface area ...] I'm for damping. My preference, gleaned from long experience with many things, is for realizing it with heavier oil. I like the looks of the present design, and, if, the Scheu design has *more* contact area, I would say leave our present design as is because this will give us a value of viscous damping which should be adjustable from below to above that of the Scheu, just by changing the oil, if within the limits of the clearance tolerance for that. I ----- Original Message ----- From: Igor Kuznetsoff Sent: Tuesday, January 18, 2000 12:15 AM Subject: Re: Scheu-Bearing & Platter --- Steve Zettel wrote: Perhaps we can have Bryce perform a test fitting (with lube) of a bearing spindle/well assembly at the point of final machining completion (without relief passages). If difficulty with assembly and dissassemby by hand is an issue, we could have him proceed with machining a pressure relief (if we can agree on what type to use -- from the bottom or the top) Steve ---------- Good idea. I ----- Original Message ----- From: Igor Kuznetsoff Sent: Tuesday, January 18, 2000 12:32 AM Subject: Re: Scheu-Bearing & Machining --- Thom Mackris / Joan Panzella tmackris@earthlink.net> wrote: O.K. folks. As much as I love this project, I'm also trying to live the other part of my life. Amen, this out of hand for me ,too. The time it's taking is killing me at a time when I really have none. ----- Original Message ----- From: Steve Zettel Sent: Tuesday, January 18, 2000 9:06 AM Subject: Re: Scheu-Bearing & Machining on 1/17/00 22:13, Thom Mackris / Joan Panzella at tmackris@earthlink.net wrote: [snip] > I'm still going to see how STP fits in my Merrill this weekend. The reason > is merely to try to predict whether we'll need a pressure relief hole. If I > don't need it with the Merrill, I think we are safe in assuming that we will > find an oil light enough in our tight tolerance bearing which will *not* > require pressure relief. > > As I write this, I'm moving toward the position of the tightest possible > bearing tolerance and the heaviest light oil that can be used with it. > > Cheers, > Thom > I got fired up about putting this issue to rest last night, so before going to bed I performed the following two experiments -- I cleaned out the bearing well of my Oracle and popped the top on a can of STP I had in the garage. I put several cc's in the well, gave a light coating to the bearing shaft and assembled and dissassembled them several times. It *seemed* to take a little longer than dissassembling it with the usual lube, but if it did, it was just a little longer (hard to tell). Next, I swabbed it out again, and put in a few cc's of SAE 80-90 gear lube from the garage. Oh yeah, the garage temperature has been in the low 30's for the last month or so. So this stuff is on the thick side! Same results, assembly and dissassembly were possible, if a *little* longer (maybe). What does this prove? Well, unless the Oracle tolerances are much sloppier than ours (possible), increasing our tolerances to allow use of heavier lube does not seem warranted, at least from an assembly/disassembly standpoint. Also, relief passages do not seem warranted, either. Thom mentioned that Bryce can machine to account for the viscosity of lube to be used. I would like to still keep to the tightest (least) clearance between spindle and well possible, since it does not seem to affect assembly using lube the consistancy of cold Karo syrup. RECOMMENDATION: Have Bryce test assembly a completed bearing with heavy lube, prior to drilling relief passages. If needed, drill relief passages. Unless Bryce recommends otherwise, keep clearance the minimum practical. Second issue, Beneficial dampening via viscous lube vs. minimizing drag/bearing contact area. My gut feeling is that increasing drag to swamp the effect of stylus drag is much more of an issue with light platters than heavy platters. That being said, I feel confident enough that I can vary my dampening and/or drag to my heart's content by using powdered dry Teflon or Karo syrup with our bearing design. I certainly can't prove that the location of bearing well rebate (shaft or well) will or won't make an audible difference, but it doesn't matter to me at this point. Ditto the surface area of the bearings. RECMMENDATION: Follow Bryce's expert advice in this design decision, and each individual vary the viscosity of lube as desired. Report findings back to the group at some later date. Preliminary findings: I left the 80-90 weight gear lube in my Oracle and put the same LP back on that I was listening to prior to all the experimentation. I honestly cannot tell with any certainty that there is any difference. Nor can my wife (disinterested party with very good ears, she is my ultimate "credibility check" for audio experimentation). This morning I followed up with several "test LPs" that I use to check set up, etc. Still no positive differences discernable. Does this prove viscosity doesn't matter -- no; it may prove that the changes are below the resolution ability of my system, or that the Delphi is compromised enough that these changes don't make an audible difference, or the Delphi is *good* enough that these changes don't make an audible difference. . . . At this point, I will simply state that we follow Bryce's recommendations, keep the tolerances and clearances as close as practical and go on. I also propose, that after taking a breather, getting on with our other responsibilities, and after I have a chance to load up my Oracle platter to simulate our more massive platter and make a test jig for motor experimentation, that we try to hash out motor/pulley/control/power supply issues. Thanks for your indulgence. Steve Does this prove that viscosity doesn't matter ----- Original Message ----- From: Mackris, Thom G. Sent: Tuesday, January 18, 2000 9:42 AM Subject: RE: Scheu-Bearing & Machining Perfect Steve! I'd say that we're back on track. Thanks for taking this one on. We machine the closest tolerance possible and experiment with viscosities on our own. I don't thiink that there's anyone who would argue for a sloppy bearing merely to accommodate a thicker oil. The arguement is instead that viscosity is relative to bearing tolerance, as I had previously posited. Perhaps this would be a more complex problem to solve if the temperatures involved were higher - like those in an internal combustion engine, but fortunately they're not. Cheers, Thom -----Original Message----- From: Chris Brady [mailto:cbrady@sgi.com] Sent: Monday, January 17, 2000 10:52 PM Steve Zettel wrote: > > on 1/17/00 10:57, Schei, Kenneth at SCHEIKE@asa.org wrote: > > > If so, only to the point that the motor-belt system can spin the platter. > > But I'm not sure that minimizing friction isn't the better approach. > > Keeping spin uniform is best achieved by high mass which results in high > > inertia, which is a perfectly smooth, linear governing system. We are > > certainly doing that with our 3" platter. Using bearing friction seems a > > bit crude to me; I'm afraid that the bearing friction will cause the speed > > to hunt as the bearing resistance builds up and releases micrscopically, > > which may have an audible signature. I think that the easier our bearing > > spins, the better it will be. > > > > Ken > > > I am with Ken on this one. > > Steve Guys, this discussion is not making any sense. Perhaps it is my fault for using the term "friction". A better word would have been viscous damping. Damping will not introduce noise, but rather reduce it. The bearing contact area and the viscosity of the oil will determine the amount of damping or dare I say resistance. Up until this weekend we had what seemed to be a consensus for a bearing with a high degree of viscous damping. By definition a large diameter shaft with a heavy oil, particularly something like STP will have a lot of damping. If what we want is simply a bearing that spins easily, low friction, damping, or whatever, then our design is completely wrong. A low friction bearing would have the smallest possible diameter with small contact areas and a very light oil or better still powdered graphite. Not even close to what we have been talking about. I am confident that what we do want is some viscous damping. To make my point here is a exerpt from a Sound practices article written by J. C. Verdier about the topic: [Verdier's comments follow ...] > Since the player stylus consumes variable amounts of energy, we have to mask > that consumption by permanently consuming much more energy by the use of a > brake. The larger the ratio between the the energy consumed by the brake > and the energy consumed by the stylus, the better the turntable works. > On my turntable, the brake is present but invisible to the casual eye - it > is furnished by the axle and the bearing. The two parts are unusual in > their very large dimensions. The two facing surfaces of about 60cm^2 > separated by lubricating viscous oil form the brake. > Numerous times I had to explain to customers that it would be a bigmistake > to replace my viscous oil with a more fluid oil to "allow the platter to > turn for a longer time". This total mis-understanding of the problem is > unfortunately very widespread. [Back to Chris ...] Our current design with a .75" shaft and .625" high contact areas yields an overall area of 19 cm^2, less than a third of the Verdier. BTW the Verdier shaft is 20mm or .79 inches in diameter. Don't get me wrong. I am not implying that we make the platter difficult to spin or go overboard with viscous damping. However, it seems clear that some damping is beneficial and with the choice of oil we should be able to tune the amount of damping to some degree. I think the correct question at this point is "how much contact area do we want for employing viscous damping?" For what it is worth, my vote is to stay with the current design or to increase the contact area slightly. Chris ----- Original Message ----- From: Mackris, Thom G. Sent: Tuesday, January 18, 2000 9:14 AM Subject: RE: Scheu-Bearing & Platter Not to waffle away from last night's waffling, but here's the common ground I see between what Chris wrote (Verdier's quoted text), Steve's light & close tolerance approach, and Igor's advocacy of STP. Firstly, let me say that the closer the tolerance the bearing is machined too, the better it will be. Period. Within that framework, there will be a range of oils that will work. I'd personally guess that the highest viscosity will be the one that I will end up with, although obviously being a tortured soul, I'd investigate a range of viscosities. Furthermore, my guess is that viscosity is a relative term - 20 W in our world class bearing might be considered heavy (from a drag perspective), whereas in a production bearing (sloppier tolerances) it might be considered to be a light oil. With respect to bearing shaft diameter, I think we're on the right track with a big one. Verdier advocates one. Did you catch the copy of the review I sent you of the Nottingham Hyper Space Deck? It uses a .5" thich shaft! Cheers, Thom ----- Original Message ----- From: Jeremy Epstein To: Thom Mackris / Joan Panzella Sent: Tuesday, January 18, 2000 11:36 AM Subject: Re: Scheu-Bearing & Platter I must say this - there have been a **gazillion** times when I wished I could clamp the periphery of an LP, this is definitely a feature I would very much like to have on this turntable - what about a CNC machined acrylic jobbie to match the platter? In my experience there are a certain percentage of records that have a ripple near the outside edge and these "whoops"'s are among the hardest grooves to track. Murphy's law states that Cut 1 is always the one you want to hear on these particular records, too. How big a deal would it be to get matching clamp-rings made at the same time as the platters? I think the clamp-storage issue is a non-issue - I have som much crap all over my house already, what's one more little ring? How much does an aftermarket perimeter clamp run? How does it work - what pulls it down onto the LP? A clamp to the bottom of the platter or just weight? -j ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Saturday, January 29, 2000 5:52 AM Subject: Merrill Periphery Clamp Jeremy, As I was going through the e-mails to create digests, I found this question which I don't ever recall having answered. The Merrill periphery clamp is an aluminum ring which has a thin, tapered lip that grabs approximately half of the record's lead-in groove. As you'd imagine, this lip has to be thin enough to clear the outer bottom edge of the cartridge as it plays on the lead-in groove. The clamp weighs about 2 pounds and flattens just about any edge warp I've ever encountered. There are some cartridge bodies that it interferes with marginally. I once had a Linn cartridge which I had to file about a 1/16" off the bottom outside edge of the cartridge (creating a slope, or taper) in order to clear the clamp. All in all, it works well but adds an additional step to playing an LP. Bass improves (tightens up), even on flat records. Overall resolution is slightly better with the clamp, also. I'm inclined to mess with the reflex clamp concept that Oracle & VPI use first. If it's 90% as good as the Merrill clamp, I'll probably stay with it. The clamp costs ~ $225, and I *ruined* mine !! The lip I described above is somewhat fragile. I used to have a turntable stand (250 lbs of MDF & sand !!) which I put one of those plastic dip hooks on the side of. While changing records, I'd hang the clamp this hook. I ended up putting little ripples in the lip I described above. When I tried to straighten them, the lip detached from the body of the clamp :-(( When I contacted Merrill about a replacement, he said to send in my platter to match up the platter to the clamp. These are obviously "one-off's". Knowing what I do about CNC machining (thanks to this project), I can see that the price he's charging is reasonable. Whether I want to pay that price is another question, of course. The idea of a CNC machined acrylic jobbie is indeed provocative. I hadn't thought of going in this direction. It might actually be cheaper too! I can envision a ring made of acrylic, on top of which, a thin, stainless or aluminum lip is bonded. This would probably be cheaper than ordering from Merrill (if we got the order size up to 4 to 6). Thom ----- Original Message ----- From: Jeremy Epstein To: Thom Mackris / Joan Panzella Sent: Tuesday, January 18, 2000 11:39 AM Subject: Re: Scheu-Bearing & Platter Thom Mackris / Joan Panzella wrote: > It appears as if Chris's brother is gung ho to > machine the platters too! > I'm getting more jazzed about this with each new tidbit of information. This is **very** good news IMHO! I'm getting pretty jazzed myself. -j -- ----- Original Message ----- From: Jeremy Epstein Sent: Tuesday, January 18, 2000 12:33 PM Subject: Re: Scheu-Bearing & Platter Steve Zettel wrote: > Perhaps we can have Bryce perform a test fitting (with lube) of a bearing > spindle/well assembly at the point of final machining completion (without > relief passages). If difficulty with assembly and dissassemby by hand is an > issue, we could have him proceed with machining a pressure relief (if we can > agree on what type to use -- from the bottom or the top) > > Steve This strikes me as a workable way to figure this out - we aren't going to have anything but conjecture without doing it this way as I see it. -j -- ----- Original Message ----- From: Igor Kuznetsoff Sent: Tuesday, January 18, 2000 2:47 PM Subject: RE: Scheu-Bearing & Platter All, I would **not** want sloppy bearings for *any* reason !!! Viscosity issues aside, sloppy bearings would encourage loss of stability through teeter-tottering. I would prefer to work with whatever range of viscosities the tightest tolearances would practically allow and in a *large* bearing. I ----- Original Message ----- From: Mackris, Thom G. To: 'Igor Kuznetsoff' ; Mackris, Thom G. ; 'Chris Brady' ; Sent: Tuesday, January 18, 2000 2:46 PM Subject: RE: Scheu-Bearing & Platter By jove !! I think we've closed out all open issues relating to the bearings. The only question I believe remains to be answered is how viscuous a lube will fit into our world class bearing and if an (optional) pressure relief hole is necessary (and where to put it). Inspecting this after the first one is made up is the way to go here, and Chris' physical presence will be invaluable. I return to my previous state of optimism ... the train is on the tracks. Cheers, Thom ----- Original Message ----- From: Igor Kuznetsoff Sent: Tuesday, January 18, 2000 4:01 PM Subject: RE: Scheu-Bearing & Machining [regarding Steve's test fitting of STP into his Oracle bearing] Good work, Steve. I will now endeavor to not worry about this. Just for the record, I never did suggest looser, much less sloppy, bearing tolerances. What I *did* suggest was a pressure relief. Had I realized how much time this was going to cost me (and everyone else), I would have skipped it. After all, I am used to modifying everything I get my hands on, anyway. I can drill it out myself, by hand, if I have to, to improve it, should the need arise. Hopefully, our bearing will act as Steve's did, and I can just feel foolish about it when it's all set up and working, which may be some time in my case. ----- Original Message ----- From: Steve Zettel Sent: Tuesday, January 18, 2000 4:53 PM Subject: Re: Scheu-Bearing & Machining I know, Igor. I got concerned when Thom mentioned Bryce spec'ing clearances based on lube to be used. And I also realized that until I tried it and found out for myself, I didn't know what I was talking about. I respect your experience and expertise in these matters, and sure didn't mean to "lecture" with the newspaper/yardstick analogy. Your concerns may still prove to be valid, 'cause I have the strong feeling our bearing will be much tighter than my Oracle's. There is no perceptable side to side play in it, but I would be surprised if a 1985/6 vintage production table at it's particular price point would have the extraordinary machining tolerances now available to us today at an affordable price. Steve ----- Original Message ----- From: Mackris, Thom G. To: 'Steve Zettel' ; Igor Kuznetsoff ; Mackris, Thom G. ; Sent: Tuesday, January 18, 2000 4:58 PM Subject: RE: Scheu-Bearing & Machining This spec'ing clearences based on lube definitely threw me off - too many choices for my numb brain to ponder. The problem should have been presented as: make a *way* cool bearing (techno-speak) with the best tolerance that is fiscally reasonable 8-) Thom ----- Original Message ----- From: Mackris, Thom G. Sent: Tuesday, January 18, 2000 4:03 PM Subject: RE: Scheu-Bearing & Machining We've all done such a good job of remaining egoless through this entire process that perhaps we got a bit spoiled, expecting to not hit a single snag. I may have been the one who steered this conversaton in the direction considering a slightly looser bearing. Just put your fingers in your ears and hum loudly when I speak in the future Looking back (and forward) I am absolutely thrilled about the group that we've assembled for this project. Go Team Table ! (Team Teres ?). Thom ----- Original Message ----- From: Igor Kuznetsoff Sent: Tuesday, January 18, 2000 4:20 PM Subject: RE: Scheu-Bearing & Platter Issues yes, suggestions no. I noticed, last night, while looking at bearing & platter drawing that the top of the spindle is flush with the label area surface of the platter. This looks so natural that it did not occur to me, previously, that this may not be optimal. Is there a reason that the record itself should contact, tightly, any more of the bearing assembly than it must at the spindle tip/hole interface, improving the (possible transmission of whatever (and however) miniscule noise the bearing may have ? Is there any reason we shouldn't take the freebie, and shave whatever thousandths would separate them off of the spindle top dimension ? Clamps typically press the outer perimeter of the label area. It would seem that this should be a cost-free improvement. Igor ----- Original Message ----- From: Steve Zettel Sent: Tuesday, January 18, 2000 4:55 PM Subject: Re: Scheu-Bearing & Platter Excellent point, Igor. Steve ----- Original Message ----- From: Mackris, Thom G. Sent: Tuesday, January 18, 2000 4:26 PM Subject: RE: Scheu-Bearing & Platter So, we shorten the 1.0" top dimension by .05 to say, .95? Off the top of my head, I can't see that this would hurt in any way. I'm not sure it would make any positive improvement, since the bearing is in intimate conact with the platter, which is in contact with the record. I suppose that by shaving .05 (or less) off this surface, that we'd be guaranteed that it did not extend *above* the plane of the label rebate if we experienced differential thermal expansion/contraction between the two materials (stainless & acrylic). Attached, is what I believe is the current bearing drawing (hard to keep this straight). Thom ----- Original Message ----- From: Igor Kuznetsoff Sent: Tuesday, January 18, 2000 4:49 PM Subject: RE: Scheu-Bearing & Platter It *is* in intimate contact with the *large* mass of the platter, but why should it be having intimacy with with our delicate, precious, (more) easily influenced records of tender, *low* mass ? Any more than it has to, anyway ? Why not take the thermal guarantee ? These are small points, but, unless someone can think of other considerations, it's a freebie. I ----- Original Message ----- From: Igor Kuznetsoff Sent: Tuesday, January 18, 2000 5:25 PM Subject: RE: Scheu-Bearing & Platter Thinking a little about how much to take off the top of the the spindle, it occurred to me that even more could be done with this tweak. Suppose we took off a few thousandths less than the typical (should be measured for precision) 1/8" thickness of Sorbothane sheet off the spindle ? A disk of Sorbo can then be laid in there. Then, when the clamp presses down on the label, the Sorbo will squash just a bit against, and damp, both sides of the spindle/vinyl interface. The periphery of the clamp, where it presses the label, will ground whatever remnant vibration is still passing through into the platter. This will force any vibration there may be in the spindle body to pass through the massive acrylic platter, which it will do much more reluctantly than through the stainless steel spindle, in order to reach the area the stylus is traversing. Whether we take off ~.05" or ~.120" makes no difference, other than to allow this possibility to those who wish to use it. I ----- Original Message ----- From: Mackris, Thom G. Sent: Tuesday, January 18, 2000 5:49 PM Subject: RE: Scheu-Bearing & Platter You read my mind. Up until this point, I was thinking ... gee the record is still coupled to the spindle, so what's the big deal about recessing the bearing surface? Then I got to thinking about Steve's and George's reflex clamps which utilizes a (rubber?) washer in this same position in order to raise the record in the area around the spindle. While I think that all of this is fairly extreme, I don't have a problem with it either, & knowing me, I'll probably end up doing it. Thom ----- Original Message ----- From: Steve Zettel Sent: Tuesday, January 18, 2000 6:21 PM Subject: Re: Scheu-Bearing & Platter Actually, the Oracle uses a hard plastic tapered washer, but since it is most usually placed under the sorbothane mat, it effectively *is* a sorbo washer. If we use a thin sorbothane disk under our label, and squish it down when the periphery of the label is pushed down by the clamp, do we gain much by recessing the bearing top? If we *do* recess the bearing top, remember to add the same amount to the record spindles we are going to thread into the bearing top (overall length of the smooth spindle increased by the amount of the recess; bottom, unthreaded part of the threaded spindle to be increased by the amount of recess). Steve ----- Original Message ----- From: Chris Brady Sent: Tuesday, January 18, 2000 10:11 PM Subject: Re: Scheu-Bearing & Platter I am going to make another attempt to summarize the outstanding issues for the bearing/platter design. I am finding it difficult to understand where everyone stands on these issues. So if I get it wrong please let me know. I am not listing any of the issues that I think were closed and I am adding several new issues. Again please let me know if I missed something. I am also attaching the drawings for your enjoyment. 1) Insertion of the shaft into the bearing. It sounds like we are in agreement that Bryce will test assemble to make sure there are no problems. ## CLOSED ## 2) Bearing clearance. Quite a bit of discussion but there seems to be agreement. We want as little wobble as possible while still maintaining an oil film in the bearing. Too tight and we get metal to metal. I think that we can adequately describe this to Bryce and I am confident that he will know what we need. ## CLOSED ## 3) The depth of the record label rebate. It's hard to say what the right numbers are. Our references the merrill and Sheu were a long way apart. However, everyone seems to agree that we are better off to error on the side of too deep. My opinion, stay with 0.05". ## OPEN ## 4) The height of the spindle top. Some have advocated lowering the dimension a bit to avoid contact with the record label. With the rebate the record should not be in contact anyway. And even if it did make contact, as Thom points out it should not make any difference. I also agree with Thom that it is of little consequence either way. ## OPEN ## 5) The length of the bearing housing that extends through the base plate. I think that we are in agreement to accommodate a 2" thick base with washers and a nut. Since there is a desire for a low profile nut I was waiting for Bryce to get back to me about what size nuts are available. The attached design may need some adjustment when we know the nut size. ## CLOSED ## Chris ----- Original Message ----- From: Chris Brady Sent: Tuesday, January 18, 2000 11:49 PM Subject: Re: Scheu-Bearing & Platter Since we are getting closer to having parts made there are couple of non-design issues that I would like to bring up. 1) Time frame. This project has been in high gear in the last week and we are currently projecting having platters and bearings finished and delivered in late March. Is this a good time frame for everyone? Does anyone have a desire to speed up or slow down the process? 2) Machining the platters. We seem to be in agreement to have Bryce machine the platters. However, he strongly suggests that we get a local (Denver) quote for doing the work. We all have a lot of confidence in Bryce but he may not be able to give us a suitable price due to his extra costs. Bryce typically works with small high precision parts. While his machines and skills are certainly up to the task he would have to create faceplates for turning the platters. He estimates that the extra setup to be about 4 hours. A local machine shop the regularly works with larger material will most likely already have the faceplates. If Bryces prices are at all close I expect that we will want him to do the work. However, the cost difference may warrant going to another machinist. Chris ----- Original Message ----- From: Brian Sent: Wednesday, January 19, 2000 12:16 AM Subject: Re: Scheu-Bearing & Platter > 1) Time frame. This project has been in high gear in the last > week and we are currently projecting having platters and bearings > finished and delivered in late March. Is this a good time frame > for everyone? Good for me. Brian Day ----- Original Message ----- From: Igor Kuznetsoff Sent: Wednesday, January 19, 2000 12:57 AM Subject: Re: Scheu-Bearing & Platter --- Chris Brady wrote: > 4) The height of the spindle top. Some have > advocated lowering the > dimension a bit to avoid contact with the record > label. With the > rebate the record should not be in contact > anyway. Even if pressed down by a clamp ? And even if it > did make contact, as Thom points out it should > not make any > difference. I also agree with Thom that it is of > little > consequence either way. ## OPEN ## But costs nothing to adjust the dimension. ----- Original Message ----- From: George Munger To: Sent: Wednesday, January 19, 2000 7:50 AM Subject: Re: Scheu-Bearing & Platter Thom, any timeframe is a good timeframe for me, so whatever you guys do is OK with me, thanks. If you want, I can also ask my machine shop friend for his 'second opinion' on anything you need; just send me the 'final' spec. GM ----- Original Message ----- From: George Munger ToSent: Wednesday, January 19, 2000 8:06 AM Subject: Re: Scheu-Bearing & Platter FYI... The disc spacer material on my 'stock' VPI Jr seems to be neoprene (I am not absolutely sure), but it is NOT sorbo; it would appear to compress only slightly under full clamp compression, with the VPI threaded clamp. GM [Thom previously wrote 01/18 9:24 PM ... ] Good point Steve about adding onto the spindle if we recess the bearing surface. I thought about the reflex clamp issue on the drive home. It serves me right for responding so spontaneously. With respect to Oracles & VPI's (two known systems) you correctly noted that you'd still need a harder surface than sorbo inorder to raise the center of the disk. If you use the hard, convex Oracle washer and it's a larger diameter than the hole, then you gain nothing from the recess, as you pointed out. If it's smaller than the hole diameter, you're still contacting the bearing and you haven't solved anything. I suppose I was thinking of a slightly denser washer like neoprene to accomplish the raising of the disk. In this case, you'd still accomplish nothing. The only beneficiaries of this recess would be those who would not use this kind of reflex clamp arrangement. I think we need to be careful where we take this suggestion as I ponder it more. Soon, we'll be thinking of increasing the label rebate to accomodate sorbo & where it stops, I don't know. So... where do I stand on this (at 7:15 pm mountain time, that is )? I can go either way, depending on the group's collective conciousness. If forced to vote one way or another, I'd go for some small rebate of say, .02" to .03" and leave it at that. Just enough to allow for differential thermal expansion, plus .01 for good measure. Either way, I'm easy. I reserve the right to having further information revealed to me in my dream state, however 8-) Cheers, Thom ----- Original Message ----- From: Chris Brady Sent: Wednesday, January 19, 2000 9:37 AM Subject: Re: Scheu-Bearing & Platter > And even if it > > did make contact, as Thom points out it should > > not make any > > difference. I also agree with Thom that it is of > > little > > consequence either way. ## OPEN ## > > But costs nothing to adjust the dimension. Good point, it may not help but since it will not hurt lets do it. How about making this dimension 0.95". Chris ----- Original Message ----- From: Schei, Kenneth Sent: Wednesday, January 19, 2000 9:48 AM Subject: RE: Scheu-Bearing & Machining Thom: STP was originally created to put in old junker cars to make their lousy bearings tolerable and to get a few more thousand miles out of them. It has never been recommended for new cars and car makers such as Porsche and BMW prohibit its use. Why would we want to design our bearing to mimic an old lousy one, when we have the ability to obtain any reasonable precision we want? I understand your desire to isolate from vibration, but what is the source of vibration Here? Answer - the bearing. It's a fact of bearing design that the closer tolerances and thinner lubricant you can use, the more likely that the lubricant in the interface will be laminar rather than turbulent. Using a looser tolerance and thicker lubricant will tend to introduce turbulence which is one source of vibration. What happens is that the shaft doesn't remain centered in the well but vibrates from side to side, with one side having a thin laminar oil surface and the other side having a thicker turbulent one. Automobiles have to use thicker oils than we do because they have to accommodate tremendous changes of temperature, higher stresses, etc. I firmly believe that commercial turntable manufacturers who are using viscous lubricants in their bearings are doing so for economic reasons - to get by with a cheaper bearing. I thought that we wanted to do better than that. I firmly recommend that we produce a bearing with close tolerances that requires a thin, high-quality lubricant, not STP. I think that will give us a better, quieter bearing. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 ----- Original Message ----- From: Mackris, Thom G. Sent: Wednesday, January 19, 2000 9:45 AM Subject: RE: Scheu-Bearing & Platter Dropping from 1.00 to 0.95 is fine with me. A couple of comments about the process we've gone through over the last few days ... They been a bit frustrating for some of us but in the end, highly productive. Things were moving *so* much more smoothly than anyone had a right to expect, that when we hit these minor snags, they seemed much bigger than they really were. When you think about the fact that there were 5 active contributors in this design, not many items ended up being compromises at all. This dialog has really squeezed out a universal design that I truly believe to be "killer". There were really only two "snags": 1) Bearing fit / pressure relief - this can still happen if the test fit shows this to be necessary. 2) Taking a bit off the top of the bearing housing in order to recess it. Too many different clamping and mat schemes to try to accomodate fitting sorbo in this area. With respect to bearing fit, I probably threw this one off a bit with my comment that Bryce can machine to different tolerances in order to accomodate different lubes. Instead of the group picking up on it *immediately* and saying that "the best clearance possible - period" is what we want, it just got internalized & surfaced as peripheral issues. The art/skill of project management is a difficult one to master and I certainly don't claim to be an expert here. Deciding when you're through & how much to drag the process out requires a blend of management skills and technical skills & these two diciplines are always at odds with each other. I think it is *now* time for all of us to let the design "settle in" and to get back to the other priorities in our lives for a couple of weeks. Cheers, Thom ----- Original Message ----- From: Schei, Kenneth Sent: Wednesday, January 19, 2000 10:08 AM Subject: RE: Scheu-Bearing & Platter Chris: See my post elsewhere. Wasn't the Scheu turntable reported to be better than the Verdier? I don't think that a large-diameter bearing with thin lubricant is a contradiction. A large bearing is more stable because it has more surface area. I still think that using the drag of a viscous oil is a mistake. Drag in viscous oil virtually guarantees turbulent flow rather than laminar, and I think that turbulence is one thing we should be trying to eliminate. With our 3" platter we will have plenty of inertia and we shouldn't be relying on viscous drag. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 ----- Original Message ----- From: George Munger Sent: Wednesday, January 19, 2000 10:20 AM Subject: Re: RE: Scheu-Bearing & Platter Would there be any reason to add a flywheel to the motor pully? >>> "Schei, Kenneth" 01/17 10:10 AM >>> The more I think about it, the more I like a subchassis consisting of two layers of 3/4" MDF, with a fine veneer finish and solid wood trim. The under layer can be routed out for things like motor control pots, etc. With my Falhauber motor, I'm not sure I will need to isolate it from the subchassis because it's so smooth. I will probably run the motor off of battery power with a little battery bracket hidden in the subchassis. No power cord! Here are some parameters for the motor pulley. It has to be small enough so that the motor doesn't have to run too slowly, but it needs to be big enough to have enough friction area so the belt doesn't slip. It has to have a groove compatible with the shape of the belt. And it needs to be concentric and true. Acrylic is the material of choice due to expansion characteristics. Chris - do we want to include the pulley in you're brother's contract? Ken ----- Original Message ----- From: Mackris, Thom G. Sent: Wednesday, January 19, 2000 10:34 AM Subject: RE: RE: Scheu-Bearing & Platter George, Indeed, this question has come up and certainly will be batted around over the next couple of weeks. You've probably noted that the Nottingham Hyper Space Deck (review I sent you) embraces this pulley/flywheel concept. It seems as if we'll have to see where we're headed in this area before Chris heads out to Oregon with the plans in early March. We might want to spec out two WAGS (wild ass guesses) as far as pulley diameter. At least this way, Ken & Steve would have something to play with. Part of the problem here is determining the pulley diameter, consistent with the torque that the motors can put out. I believe we want the load on the motor to be such that it can barely turn the platter at the required speed & therefor influence the rotation of the platter the minimum amount. I recall Steve talking about a start-up voltage (to get the platter up to speed) and a run voltage. Ken does not want to have to manually help the platter up to speed. I personally don't mind this, and I'm in the habit manually assisting my Merrill coming up to speed in order to avoid belt slippage. It also is consistent with my KISS ethics 8-) Steve and Ken are critical resources in this area (no pressure, guyz). The catch-22 here, is that without the platter (and hence it's load on the motor) in hand, they can't empirically arrive at the proper load. I know that I'm not fully stating the design problem & attendant issues in this response. I'm merely trying to hint at them. Cheers, Thom ----- Original Message ----- From: Steve Zettel Sent: Wednesday, January 19, 2000 10:34 AM Subject: Re: Scheu-Bearing & Platter I agree with your assessments on all points, Chris. All points that were of major concern to me have been closed, and I have no substantive input on the open items. Thanks, Steve ----- Original Message ----- From: Steve Zettel Sent: Wednesday, January 19, 2000 10:45 AM Subject: Re: Scheu-Bearing & Platter on 1/18/00 23:49, Chris Brady at cbrady@sgi.com wrote: > 2) Machining the platters. We seem to be in agreement to have Bryce > machine the platters. However, he strongly suggests that we get a > local (Denver) quote for doing the work. > > Chris I'd prefer to have Bryce do all the work, but let's put it out for bids once we have a formal drawing and specifications (balance, run-out, concentricity, finish, type of lamination, visibility of lamination, surface finish, etc.) and see what the cost breakout is. Steve ----- Original Message ----- From: Steve Zettel Sent: Wednesday, January 19, 2000 11:06 AM Subject: Re: Scheu-Bearing & Platter on 1/19/00 06:56, Thom Mackris / Joan Panzella at tmackris@earthlink.net wrote: > 3) Label Rebate - splitting the difference between Merrill (0.02") and Scheu > (~0.0984") at .05" seems like a good compromise to me. Steve or anyone else > with a dial indicatior to cross validate? > Thom Nope, No rebate on my Oracle platter, so nothing to measure. I have everything from RCA Dynafloppies to Mobile Fidelity UHQRs in my collection, as well as some very old 33 1/3's that have no discernable difference in profile from edge to center. I intend to use the Oracle-style clamp and washer, with or without mat, until I strike the best combo for 'my-fi', so I will go with whatever the group thinks. I may ever experiment with a 'mini-mat' of resilient material that just goes under the label, the thickness of the rebate. Steve ----- Original Message ----- From: Steve Zettel Sent: Wednesday, January 19, 2000 11:15 AM Subject: Re: Scheu-Bearing & Machining on 1/19/00 09:48, Schei, Kenneth at SCHEIKE@asa.org wrote: > Thom: > > STP was originally created to put in old junker cars to make their lousy > bearings tolerable and to get a few more thousand miles out of them. It has > never been recommended for new cars and car makers such as Porsche and BMW > prohibit its use. [snip] > having a thicker turbulent one. Automobiles have to use thicker oils than > we do because they have to accommodate tremendous changes of temperature, > higher stresses, etc. I firmly believe that commercial turntable > manufacturers who are using viscous lubricants in their bearings are doing > so for economic reasons - to get by with a cheaper bearing. I thought that > we wanted to do better than that. I firmly recommend that we produce a > bearing with close tolerances that requires a thin, high-quality lubricant, > not STP. I think that will give us a better, quieter bearing. > > Ken > > Ken Schei, P.E. > Project Engineer > Antarctic Support Associates > Email address: scheike@asa.org > Phone: 303-643-0163 > > Hear, hear! I think we all concur on this one, now. Steve ----- Original Message ----- From: Schei, Kenneth Sent: Wednesday, January 19, 2000 11:33 AM Subject: RE: Scheu-Bearing & Platter Right on, Thom. I agree. Ken > -----Original Message----- > From: Mackris, Thom G. [SMTP:tgmackris@vicorpinc.com] > Sent: Tuesday, January 18, 2000 9:14 AM > Subject: RE: Scheu-Bearing & Platter [ snip ] Firstly, let me say that the closer the tolerance the bearing is machined too, the better it will be. Period. Within that framework, there will be a range of oils that will work. I'd personally guess that the highest viscosity will be the one that I will end up with, although obviously being a tortured soul, I'd investigate a range of viscosities. Furthermore, my guess is that viscosity is a relative term - 20 W in our world class bearing might be considered heavy (from a drag perspective), whereas in a production bearing (sloppier tolerances) it might be considered to be a light oil. Cheers, Thom ----- Original Message ----- From: Schei, Kenneth Sent: Wednesday, January 19, 2000 11:44 AM Subject: RE: Scheu-Bearing & Platter I have some erasers that consist of a holder with a 1/4" diameter eraser insert. When I get my platter I intend to experiment with replacing the finely machined spindle with a length of 1/4" eraser insert, which will be compatible with my hockey puck record clamp. Different composition eraser fillers are available, perfect for tweaking. :>) Ken ----- Original Message ----- From: Schei, Kenneth Sent: Wednesday, January 19, 2000 11:47 AM Subject: RE: Scheu-Bearing & Platter [commenting on Chris' issues summaries] Chris: Kudos. Great work sorting out our collective madness. :>) Ken ----- Original Message ----- From: Schei, Kenneth Sent: Wednesday, January 19, 2000 12:00 PM Subject: RE: RE: Scheu-Bearing & Platter Good idea. It's worth considering because it wouldn't cost much, wouldn't hurt, and may be quite beneficial. Caboose Hobbies, Denver's world-class train shop, has precision flywheels for just that purpose, to fit various motor shafts. They're brass, inexpensive, and would look cool. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: George Munger [SMTP:GMunger@mnr.org] > Sent: Wednesday, January 19, 2000 10:21 AM > Subject: Re: RE: Scheu-Bearing & Platter > > Would there be any reason to add a flywheel to the motor pully? > > > -----Original Message----- > > From: Igor Kuznetsoff [SMTP:gorkuz@yahoo.com] > > Sent: Saturday, January 15, 2000 3:30 AM > > Subject: Re: Scheu-Bearing & Platter > > 5) Motor pulley - where will these come from? > > >Another CNC job, if we all settle on the same motor. > > >Or perhaps we can find them from outfits like Small > > >Parts in Florida. > > > > Perhaps we should think about this before ordering the > > > > CNC work, so as not to lose whatever advantages the > > possibility of CNC package pricing might offer ? > > Ditto for the possible (and recommendable) idlers. > > > > Igor ----- Original Message ----- From: Schei, Kenneth Sent: Wednesday, January 19, 2000 12:07 PM Subject: RE: RE: Scheu-Bearing & Platter If we use a flywheel, it would be independent from the pulley because we want the pulley to be of acrylic but the flywheel to be heavier to be effective. I don't see the flywheel changing the configuration of the pulley much, except that they both need to fit on the same shaft length. I'm not sure that the motor needs to be close to the stalling point for best operation. If it's close to the stalling point, it may be less able to maintain a constant speed. Just a thought. Ken ----- Original Message ----- From: Mackris, Thom G. Sent: Wednesday, January 19, 2000 11:59 AM Subject: RE: RE: Scheu-Bearing & Platter This is great news Ken! Strength in numbers ... what a great design team we have! BTW, for those of you in Denver, Caboose hobbies is a *way* cool place to go. These train folks are at least as weird as we are 8-; Cheers, Thom P.S. note extensive snipping to keep this stuff readable :^) ----- Original Message ----- From: Mackris, Thom G. Sent: Wednesday, January 19, 2000 12:03 PM Subject: RE: RE: Scheu-Bearing & Platter Ken, With respect to operating the motor near the stalling point, we'll certainly want to experiment, for reasons you note below. Good point about the flywheel being a separate item from the pully. This keeps the thermal expansion of the pulley and the platter the same since they're the same (acrylic) material (previously noted somewhere in our massive archive of posts). Thom -----Original Message----- From: Schei, Kenneth [mailto:SCHEIKE@asa.org] Sent: Wednesday, January 19, 2000 12:08 PM If we use a flywheel, it would be independent from the pulley because we want the pulley to be of acrylic but the flywheel to be heavier to be effective. I don't see the flywheel changing the configuration of the pulley much, except that they both need to fit on the same shaft length. I'm not sure that the motor needs to be close to the stalling point for best operation. If it's close to the stalling point, it may be less able to maintain a constant speed. Just a thought. Ken ----- Original Message ----- From: Chris Brady Sent: Wednesday, January 19, 2000 2:20 PM Subject: Re: Scheu-Bearing & Platter I am not a motor expert but based on the "Turn Your Table" Sound Practices article a flywheel would degrade performance. I know this is counter-intuitive, but the article seems to make sense. One of the criteria for selection of a motor is low "moment of inertia". A brief quote: > To follow the platter's motion immediately the rotor of the engine must > have a moment of inertia of zero. This is what physical science demands. > They can't built it, yet it forms the first and most important condition > to choose an engine. (1) the rotors moment of inertia should be low, low > down. That's why all engines with high mass rotors like syncronous > engines don't fit. They can't follow the platters motion. For those that will be working on the motor/controller design, I suggest that you read this article. The author may or may not be correct in his views, but he does lay out some quite interesting ideas. I can try scanning in the article or if need be send copies to those interested. Thanks to Thom who gave a copy of this article some time ago. Chris ----- Original Message ----- From: Schei, Kenneth Sent: Wednesday, January 19, 2000 2:43 PM Subject: RE: Scheu-Bearing & Platter Good point. The Falhauber motors have a coreless armature which has a very low moment of inertia and a flywheel would counteract that advantage. Just when I was starting to like the looks of a brass flywheel. I will try to take apart the Pittman motor and see what its armature looks like. Ken ----- Original Message ----- From: Mackris, Thom G. Sent: Wednesday, January 19, 2000 2:24 PM Subject: RE: Scheu-Bearing & Platter Same here - obviously, I can hand-deliver articles to the local folks. There's another interesting turntable article which discusses various design issues. It was written by Art Dudley waaaay back when he was writing for Hi Fi Heretic (~ 1987). It covers a lot of interesting ground. The review is of the original Roxan Xerxes. Thom ----- Original Message ----- From: Jeremy Epstein To: Chris Brady Sent: Wednesday, January 19, 2000 2:25 PM Subject: Re: Scheu-Bearing & Platter Chris Brady wrote: > For those that will be working on the motor/controller design, I suggest > that you read this article. The author may or may not be correct in his > views, but he does lay out some quite interesting ideas. I can try scanning > in the article or if need be send copies to those interested. Thanks > to Thom who gave a copy of this article some time ago. I have an original and I can make copies from it if needed. -j -- ----- Original Message ----- From: Steve Zettel Sent: Wednesday, January 19, 2000 4:58 PM Subject: Re: Scheu-Bearing & Platter I am wondering what advantage adding mass at the motor affords above and beyond the already massive platter. As long as the belt is not slipping, the system would seem to be locked together. I am starting to get concerned about the ability of the Pittman's to start and drive our platter, but that may not be a valid concern. I am also thinking about the sizing of the pulley and the operating range of the motor. One concern is operating the motor very close to stalling, with the resultant higher current that implies. High current = higher motor winding heat, which might impact reliability or longevity of the motor. Question for Ken -- feasibility from a cost-effectiveness standpoint of using a train power supply as our motor controller and power supply? One of the simplest solutions, though it requires some operator intervention, would be to use a variable DC power supply that would allow us to crank up the voltage for starting and record cleaning, back it off for 33.3 record playing, and if our motors will handle the massive platter over a wide enough range, maybe even allow 45 rpm. Strobe discs that utilize the 60hz flashing of household incandescent lights are available (some of my older records even have them on the label). Just a thought. Other things I have been musing about: I am going to press my Oracle into service as a test-bed for the motor/pulley experimentations by adding a weight plate from the athletic club to the platter and setting up a holder for the motor(s). I will try to get some of this done before going on active duty with the Navy 30 January. Otherwise, it will be at least until 15 February before I have a chance to take this back up. Steve ----- Original Message ----- From: Steve Zettel Sent: Wednesday, January 19, 2000 4:58 PM Subject: Re: Scheu-Bearing & Platter on 1/19/00 11:44, Schei, Kenneth at SCHEIKE@asa.org wrote: > I have some erasers that consist of a holder with a 1/4" diameter eraser > insert. When I get my platter I intend to experiment with replacing the > finely machined spindle with a length of 1/4" eraser insert, which will be > compatible with my hockey puck record clamp. Different composition eraser > fillers are available, perfect for tweaking. :>) > > Ken You *are* a wild and crazy guy, Ken! I love it. I don't think I'd ever have thought of this. Something more to try. Steve ----- Original Message ----- From: Steve Zettel Sent: Wednesday, January 19, 2000 5:54 PM Subject: Re: Scheu-Bearing & Platter on 1/19/00 14:24, Mackris, Thom G. at tgmackris@vicorpinc.com wrote: > Same here - obviously, I can hand-deliver articles to the local folks. > > There's another interesting turntable article which discusses various design > issues. It was written by Art Dudley waaaay back when he was writing for Hi > Fi Heretic (~ 1987). It covers a lot of interesting ground. The review is > of the original Roxan Xerxes. > > Thom I have some of the articles J. Peter Moncrieff wrote in IAR concerning turntable design, mostly Well-Tempered and Oracle. Steve ----- Original Message ----- From: Mackris, Thom G. Sent: Thursday, January 20, 2000 8:33 AM Subject: RE: Scheu-Bearing & Platter All, If I recall, the LM317 is recommended on the Sound Practices article "Turn Your Table" (by Dr. Wilimizig - issue (#10). Lots of good points as well as controversial ones. I believe Ken and Jeremy have this issue as well as Verdier's response in issue #11 (which Chris referenced yesterday). Steve and Igor need to read this. It will mainly serve to validate most of the points we've already raised and resolved, although there is remains some controversy. Low intertia motors is desirable, although Verdier and Dr. Wilimizig disagree as to why. Wilimizig is *definitely* opinionated. One interesting note which indirectly validates Steve's comment about why the need for high inertia pulley when the pulley/belt/platter should be intimately tied to each other. As I mentioned above, Verdier & Wilimizig advocate low inertia motors. Both Verdier (string) and Wilimizig (recording tape) use the uncompliant materials (referenced in parenthesis) in place of rubber for drive belts, in order to more closely couple the motor and the platter. Cheers, Thom ----- Original Message ----- From: Chris Brady Sent: Thursday, January 20, 2000 11:03 PM Subject: Teres-Bearing & Platter I had a long conversation with Bryce about our turntable design last night. I was amazed about how quickly and thoroughly he understood some of the design issues we have been pouring over for weeks. I described stylus drag and with out any prompting from me he said something like "oh yea, you probably need to rely on viscous oil in the bearing to swamp the effect of the stylus". It was almost like he was reading a script! And then I went on to describe how the right kind of motor could help. Before I could say it, he said "you need one with low inertia". If he would have thrown in the word "moment" I would have been sure that he had hacked into our e-mail. I was duely impressed! The point is we have a machinist that REALLY understands what we need, probably better than we do. Our discussion led to the specifications for the bearing. We discussed oil viscosity, surface area, possible assembly problems, noise, etc. Bryce thinks our design is sound but thought that we may want to increase the bearing contact area. However, we did find one area of concern, the smoothness of the spindle shaft. Bryce can machine a very smooth surface but was concerned that microscopic flaws might contribute to noise. To give him an idea of the degree of smoothness that is required I sent him a few close-up pictures of the shaft in my Thorens 165 taken with my digital camera. After looking at the pictures he is confident that he can machine a finish that exceeds that of the Thorens bearing. But since we want something considerably better than the Thorens, he thought it advisable to spend some time polishing the shaft to get a better finish. All in all I think this is very good news. Chris ----- Original Message ----- From: Schei, Kenneth Sent: Friday, January 21, 2000 10:44 AM Subject: RE: Teres-Bearing & Platter Chris: That's great news. I recommend that we spend the extra $10 and get the shaft polished. Ken ----- Original Message ----- From: Steve Zettel To: Schei, Kenneth ; 'Chris Brady' Sent: Friday, January 21, 2000 10:59 AM Subject: Re: Teres-Bearing & Platter on 1/21/00 10:44, Schei, Kenneth at SCHEIKE@asa.org wrote: > That's great news. I recommend that we spend the extra $10 and get the > shaft polished. > > Ken I agree wholeheartedly. Steve Z ----- Original Message ----- From: Mackris, Thom G. Sent: Friday, January 21, 2000 11:15 AM Subject: RE: Teres-Bearing & Platter For the record (as if you didn't know). Polishing the shaft is good with me, as are all of Bryce's recommendations. Does the female surface also need polishing? Cheers, Thom ----- Original Message ----- From: Chris Brady Sent: Friday, January 21, 2000 12:03 PM Subject: Re: Teres-Bearing & Platter I asked Bryce about polishing the female surface. He indicated that it is impractical and not necessary. Evidently having one of the surfaces very smooth is sufficient. Chris ----- Original Message ----- From: Steve Zettel To: Chris Brady Sent: Friday, January 21, 2000 12:54 PM Subject: Re: Teres-Bearing & Platter I think the prices are a tremendous bargain, and the extra polishing well worth the additional cost. Steve ----- Original Message ----- From: Steve Zettel To: Thom Mackris / Joan Panzella ; Chris Brady Sent: Sunday, January 23, 2000 2:25 PM Subject: Teres Bearing detail I just noted something that had been nagging at me subconsciously for awhile about the bearing drawing at the website: There is no shoulder on the bottom portion of the bearing, just above the threaded portion, to locate or hold the bearing housing from dropping through the subchassis. Perhaps you have already noted and corrected this, or there is some other mounting solution I didn't note. Other topic: I copied some old articles touching on turntable design from Peter Moncrieff's International Audio Review. Interesting reading and background. Moncrieff is a bit of a strange duck (not to imply that he is a quack! 8^) and can be pedantic at times, but having met him once, and having read his articles off and on over the years, the guy can really hear. My intent is not to second guess anything we've done so far, but just to add some views about speed control, motor and bearing considerations, and overall turntable design. I will be sending the copies to Thom if anyone is interested. Steve ----- Original Message ----- From: Thom Mackris / Joan Panzella To: Steve Zettel ; Chris Brady Sent: Sunday, January 23, 2000 6:05 PM Subject: Re: Teres Bearing detail Steve - Depending on what graphics program I open up the bearing "gif" file with (Kodak Imaging, Paint, etc.), not all of the construction lines are visible. When I open it up in Graphics Workshop (share ware), everything is viewable. I think we're just fine, although your comment made me take a gulp. It would be just like us to miss something obvious after going through all of the hard stuff. We should still take a step back while the activity is at a welcomed lull and go through these drawings 3 or 4 more times. BTW, for simplicity of filing all of these e-mails, (I'm up to over 300 e-mails on this project !!), I'll send out a separate e-mail with my cross-validation of the spindle diameter, label rebate depth/diameter dimensions. Back to your concern ... The top portion of this part is a cylinder 2.0" high, and 1.5" in diameter. The lower portion (which contains the threads at the very bottom) is stepped down to 1.125". IOW, the hole in the subchassis will be 1.125" to 1.30" in diameter. As I write this, it sounds as if either: (a) A washer should slip over the shaft, situated between the top surface of the subchassis and the 1.5" portion of the bearing, or (b) This 1.5" dimension should be widened to perhaps 1.75". Regarding Peter Moncrief, indeed, I've heard that he is quite the iconoclast. At one point, I chalked him off as somewhat of a nut; what with his challenging the priests of the "high-end". Having modified my opinions of the big names at $tereo-Fool and The Absolute Sound, (Lynn Olson calls them the Stanta Fe Bugle & the Sea Cliff Herald), it might well be that I discover myself aligned with Moncrief after all !! In the words of that great bicycle racing comentator, Phil Ligett: "My goodness me" !! Cheers, Thom ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Sunday, January 23, 2000 6:36 PM Subject: Re: Teres-Bearing & Platter - Dimensions All, I was at Blair's yesterday and had the opportunity to measure his Sota platter. Here's a compilation of the dimiensions from various 'tables I've measured: Spindle Diameter: ------------------------- My Merrill: .280 Blair's Sota: .282 Chris' Thorens: .283 Scheu Metric to English Conversion: .280 Blair reports that there is a small minority of records that are a tight fit (at .282). Chris has actually had to shave an occasional record hole inorder to fit the record over the .283 spindle. Conclusion... .280 is the way to go. There are some advocates of the "as tight as possible" fit. I can think of at least two reasons why this is not correct: (a) Why tightly couple the LP to the bearing? (b) A tight fit does not nothing to improve the centering of records. Chris agrees with this for both of the above reaons, BTW. With respect to (b), recall the Nakamichi 'table which centered records irrespective of off-center stamping. Robert Green (TAS) owned one of these tables and continually ranted about off-center record wow, and how sensitive he realized he was to it once he eliminated it. I don't know how the 'table accomplished this task, and I'm certainly not suggesting that we add complexity and delays to this design by engineering something like this - it will be next Spring before we get there from here. What I am saying is that you are *not* necessarily improving record centering by ensuring a tight spindle fit. Let's say that next Spring, we all brain storm about a centering device for either the existing platter or a new one. We machine a new platter or adapt the existing one. The removable spindle will certainly facilitate any changes we might decide to make to the existing platter. Label Diameter: ------------------------- My Merrill: 4.25" Blair's Sota: 4.025 (probably 4.0" - no way to position my dial indicator perfectly). Chris' Thorens: n/a Scheu Metric - English Conversion: 3.937" Conclusion: anything from 4.0" on up is fine - I vote for 4.0 as drawn by Chris - for most contact between record grooves & platter. Label Rebate Depth: ---------------------------- My Merrill: .020" Blair's Sota: .040 Scheu Metric - English Conversion: .0984" Conclusion: .050 as drawn by Chris - split the difference. Cheers, Thom ----- Original Message ----- From: Igor Kuznetsoff Sent: Monday, January 24, 2000 12:12 AM Subject: Re: Bearing detail Steve, According to the drawing, the upper portion of the bearing is 1.5", the lower is 1.125", or .375" smaller, for a smallish shoulder of .1875", which is not enough by itself, which is why I suggested the following on 1/16 : P.S.- When I added up the opening needed, I specified one fender washer. Actually, if we are to use any, we should really use two- one above, one below, so add another 1/8". I (snip) ----- Original Message ----- From: Igor Kuznetsoff Sent: Monday, January 24, 2000 12:32 AM Subject: Re: Bearing & Platter > > (a) A washer should slip over the shaft, situated > between the top surface > of the subchassis and the 1.5" portion of the > bearing, or > (b) This 1.5" dimension should be widened to > perhaps 1.75". This would be a very good idea, although 1.75" sounds a bit tight, what with the platter clearance being specified at 1.8"-1.75"/2=.025". Rather tight. Perhaps limiting it to 1.7" and /or increasing the platter opening to say 2", or so would be a good idea. I ----- Original Message ----- From: Steve Zettel Sent: Monday, January 24, 2000 12:58 AM Subject: Re: Teres Bearing detail Thom and Igor both pointed out to me that I need to read the numbers as well as look at the pictures! 8^) Much ado about nothing at all. Sorry for the alarums. Steve ----- Original Message ----- From: George Munger Sent: Monday, January 24, 2000 7:55 AM Subject: Re: Teres-Bearing & Platter OK to polish. Thanks, GM >>> Chris Brady 01/21 1:03 AM >>> But since we want something considerably better than the Thorens, he thought it advisable to spend some time polishing the shaft to get a better finish. All in all I think this is very good news. Chris ----- Original Message ----- From: Jeremy Epstein Sent: Monday, January 24, 2000 9:44 AM Subject: Re: Teres-Bearing & Platter I'll say - 10 dollars to get your shaft polished would be a bargain over by the Holland Tunnel entrance, never mind in a machine shop. -j ----- Original Message ----- From: Chris Brady Sent: Monday, January 24, 2000 12:10 PM Subject: Re: Bearing detail I agree, the shoulder on the top of the bearing is a bit small. If the plinth is made of something like acrylic then it might be ok but it would not be enough for a softer material like MDF. Based on your earier suggestion I am planning to make the threaded part of the bearing long enough for a 2" base + 2 washers + the nut. Right now I am waiting to hear back from Bryce about the available nut sizes. I'll update the drawing once I know what the nut size will be. Chris ----- Original Message ----- From: Mackris, Thom G. Sent: Tuesday, January 25, 2000 9:05 AM Subject: RE: Spindle Rebate All, Not wanting to raise a fuss about a closed issue, Igor sent this to me privately. I think he was being a bit too shy and thought I'd pass along the info. If you recall, Merrill uses a sheet of lead between subplatter and platter. This is consistent with Hartmut's tweak of the Scheu, where he replaced this compliant washer with a stiffer one. Background for Chris Beck. Late in the design of the plater/bearing, Igor suggested that the bearing/spindle top which was going to be flush with the label rebate on the platter be machined so that it is recessed enough to accomodate a 1/8" sheet of sorbothene. In keeping with Scheu's treatment of the interface (a compliant washer between bearing and platter), Igor suggested that creation of this rebate can easily be accomplished via a lead washer. Thom -----Original Message----- From: Igor Kuznetsoff [mailto:gorkuz@yahoo.com] Sent: Tuesday, January 25, 2000 12:24 AM To: Thom G. Mackris Subject: Spindle Rebate Thinking a little about how much to take off the top of the the spindle, it occurred to me that even more could be done with this tweak. Suppose we took off a few thousandths less than the typical (should be measured for precision) 1/8" thickness of Sorbothane sheet off the spindle ? A disk of Sorbo can then be laid in there. Then, when the clamp presses down on the label, the Sorbo will squash just a bit against, and damp, both sides of the spindle/vinyl interface. The periphery of the clamp, where it presses the label, will ground whatever remnant vibration is still passing through into the platter. This will force any vibration there may be in the spindle body to pass through the massive acrylic platter, which it will do much more reluctantly than through the stainless steel spindle, in order to reach the area the stylus is traversing. Whether we take off ~.05" or ~.120" makes no difference, other than to allow this possibility to those who wish to use it. T- There is more than one way to skin that cat. I figure on using something like that Scheu tweak-between the Scheu platter and spindle. I figure on putting something like just under a 1/8" thick lead washer between our platter and spindle. This will raise the platter by the distance I wanted as space in the previous post above, while decoupling the platter better from the spindle (without the slop of the Scheu rubber washer which probably allowed the platter to rock on the spindle microscopically). This will leave only the outer edges of the spindle shoulder & upper in direct, intimate contact with the platter, albeit only half of the shoulder's side (vertical) area will now contact. This will reduce the transmissive area. Plus, the weight of the platter does not rest on those surfaces, so the coupling is not reinforced in that manner, as it is at the top of the shoulder, where the lead will now damp that interface. This lead washer can create the space I had wanted for a constrained Sorbo washer above. Damned if I know how I'll form such a precise lead washer, though. Perhaps I'll first try a rubber O-Ring (or maybe two concentric ones), since, in this design, this will not allow any rocking, unlike in the Scheu, since the spindle body above the shoulder controls that. I ----- Original Message ----- From: Chris Brady Sent: Friday, January 28, 2000 11:14 PM Subject: Re: Teres Bearing & Platter I have been out of town for a few day so I apologize for not responding in a more timely fashion. Here's the status on a list of issues: 1) The bearing & spindle drawings. Thom pointed out that the center of the threaded insert was the wrong size. I will update the drawing with the correction. Thanks Thom! I not received any other comments so we must be getting the wrinkles worked out. 2) Orders. Thanks for those who have responded. Currently there are commitments for 9 bearings and platters. For those willing to make a single, up front payment (thanks) I am sure that we will be able to pin down the total cost, including shipping before the first payment deadline. Regarding shipping via USPS it will be less convenient for Bryce but I am sure that we can work it out. After the good deal he is giving us and also his valuable free advise I would like to make things as easy as possible for him. Oh I forgot to mention that Bryce gave me a price of $560 for a single bearing & platter. This does not include some of the setup costs that are covered in the initial order otherwise it would be a lot more. So get yours now! 3) The web page. Thom has provided some good background info that I am working on adding to to the web page. I also added info about the active participants based on Thom's earlier e-mail. However, I mistakenly included it in a web page update before it was ready and there were a lot of typos, sorry. If anyone would like to add to or revise their info please let me know. Chris