Because of the topic renaming, a lot of posts on bearing/subchassis = didn't thread properly. As a result, here are posts from as early as 12/23 up = to 1/17. Some may appear to be duplicates to what you have, due to = extensive use of quoted text, but I made an effort to make this package of posts unique ... I'm pooped. There remain 81 posts on bearing/platter (as of tonight) which I have not consolidated into digests. Hopefully, I'll = finish up the bearing/platter by tomorrow (Friday) or at worst by Saturday. Thom ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Thursday, December 23, 1999 12:05 AM Subject: Re: Scheu-Bearing & Platter [note: the conversation had to do with having at least one idler = pulley in addition to the drive pulley, with the platter to pulley distances not = being equal. The idea being to test if any harmonics set up by the belt = might audible if the distances were the same, but broken up if there were different pulley to platter distances]. Igor, All - Indeed, you are correct. I was thinking of the case where there is = only the motor pulley & one idler pulley, rather than haveing 2 idler pulleys, = one of which is driven by the motor pulley. Thom ----- Original Message ----- From: Igor Kuznetsoff Sent: Wednesday, December 22, 1999 5:14 PM Subject: RE: Scheu-Bearing & Platter --- "Mackris, Thom G." wrote: [ snip ] > The off center platter experiment could be carried > out in a one motor, > balanced system. With a motor on a movable base, > different length belts > could be substituted to vary the distance from the > motor pulley to the > platter vs. the fixed distance of the idler pulley > to the platter. > > Thom Actually, I don't think this will accomplish what we need because it is the distances between the idlers and platter that are critical to tuning the timing/sychronization/balancing of the forces that I was describing. Tuning the length of the motor drive pulley may also be beneficial to make it work its best with the rest of the system (i.e. to make sure that no resonances can build between the two belt systems), but this would have to *follow* the tuning of the platter belt system. This *could* be done in a one motor system. The number of motors is immaterial to this, I am only looking for a second motor for the AR because it should be easier to find than an idler, given how many AR's must be still laying about. The problem here would be that something must *move*, either the idlers, or the platter location, and doing this would be pretty difficult, where the quickie recombination of AR parts as described would allow a relatively simple if both down & rather dirty mockup of the concept, which may or may not have a clean enough noise floor to be definitive. If someone among us has a dead old AR laying about.... ----- Original Message ----- From: Igor Kuznetsoff Sent: Thursday, January 06, 2000 1:31 AM Subject: Re: Scheu-Subchassis / Idler thoughts > > On another note, I received one of my (seemingly) > semi-monthly Audio Advisor > > mailings yesterday. In it, they were pushing a > VPI TNT 'table. I noticed > > that VPI is doing what I was suggesting as far as > the idler pulleys are > > concerned ... keeping them on separate "pods" > isolated from the subchassis > > in the same manner as the motor. The idler > pulley's pass through a hole in > > the subchassis. > > > > Thom Makes a lot of sense, to isolate possible bearing noise. A multi-level subchassis system such as the Clearaudio has would lend itself to accomplishing this. >2. I think I mentioned before that I read of one of >the "hot tweeks", and perhaps now even a VPI->sanctioned modification for better sonics was the >elimination of the idlers and flywheels associated >with the top of the line VPI tt's Thom's take on this could be right on. If nothing else, it would = certainly be cheaper to make, wouldn't it ? What was the explanation for the improvement? To excerpt an unintended definition of engineering from another post : > This all seems to be about trading off one > compromise for another... I ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Wednesday, January 12, 2000 7:50 PM Subject: Re: Scheu-Bearing & Platter All, After lobbying for a larger diameter, subplatter-like disk (the part = with the 0.25" dimension on the right side - the bearing shaft), I can see problems with this idea - at least in the context of having the bearing partially imbedded in the platter. Increasing the diameter of this = "disk" would take an awful lot of material out of the platter. Additionally, = as this "disk" got larger in diameter, we'd probably want to make it = thicker than 1/4" in order to minimize ringing. Keep in mind that it would = have to grow upwards and not downwards, because the object of this exercise is = to have as much bearing shaft as possible extending upward from the bottom = of the platter. I think this would take altogether too much material out = of the platter. It seems as if the only way we'd want to go with a subplatter like = assembly is if we abandoned the concept of having the bearing partialy inside = the platter. There is good rational for keeping it imbedded, Alex. The = idea behind getting part of the bearing surface inside the platter is to accomplish what Scheu is doing with his inverted bearing - to allow the = pull of the belt to approximate pulling at the middle of the bearing shaft, thereby minimizing the teter-tottering effect. This does appear to be = a brilliant solution, irrespective of whether idler pulleys are in the = design ...I think . While we're at it, I know somewhere (either in conversation or in = e-mail) the idea was raised by someone that if 2" is good, maybe a 3" thick = platter is better. Since we're laminating 1" thick stuff (the most cost = effective size), maybe we should consider this. Can a delrin thrust plate take = the extra 5 pounds? My original reason for thinking subplatter was to provide a larger = surface that would ensure that the platter is perfectly perpendicular to the = bearing shaft. With precision machining, this shouldn't be a problem. I'm = having thoughts of a tight fit which might require putting a bit of dry ice on = the bearing shaft to cool it down and shrink it a thousandth or so prior to inserting into the platter. Removing it would be a nuisance then, = however. I'm guessing that the left side of the drawing (the female) will be = threaded on the outside, and a big honkin nut will bind it down to the = subchassis as in Scheu's design. Thanks for putting your thoughts to paper Chris - I think these are the ideas we were working towards !! It's not quite time for Igor to get online. I'm really curious about his thoughts. Cheers, Thom ----- Original Message ----- From: Alex Mitaru Sent: Wednesday, January 12, 2000 6:08 PM Subject: RE: Scheu-Bearing & Platter At 05:27 PM 1/12/00 -0700, Mackris, Thom G. wrote: >(a) to consider expanding the horizontal disk in to be more of a true = sub >platter I tend to agree with this, though I'm concerned that it can't machined then anymore of a single piece of steel, so it might add to the cost = (but, remember I'm totally incompetent in mechanical things...) Also, I don't understand what it is gained by pushing the disk within = the platter, I feel that cutting in the platter will weaken it... alex ----- Original Message ----- From: Chris Brady Sent: Thursday, January 13, 2000 9:22 AM Subject: Re: Scheu-Bearing & Platter Comments below: > I'd suggest saving the money from this to put into the > threaded spindle tips. In fact, to take advantage of > scale economy, perhaps we should consider a complete > dual (with/wo thread) tip package with every bearing > set for everyone. This way, no regrets for anyone > later when they discover that they have to pay to get > a single part machined, or if they are willing to get > one machined for a hot new clamp, only it can't be > screwed in. I like this idea. A screw in tip as part of each bearing assembly. We need to pin down the specs for this part. > > 1)The little ballbearing cup in the bottom of the > spindle : the drawing shows it as a square cut well. > perhaps this was just an artifact of sketching, but my > thought is that the well should be radiused so as to > encourage the ball to center, rather than wander > within the well, improving (however microscopically) > the stability of the spindle shaft movement within the > (main) bearing well (or outer shell, to be sure that I > am causing no confusion). The radius should be > significantly larger than the diameter of the ball, so > there is point contact for minimum friction. If the > ball is to be pressed in, ignore the previous. For > the same reason, perhaps the Delrin insert can also be > radiused ? My plan was for the ball bearing to be press fit into the shaft. I don't follow you about the delrin. > 2) This is an upward facing bearing that *can* *hold* > oil, but I see no provision for a *sump*. A sump is a > storage area, like an oil pan in a car. We do not > need a *large* sump, but the thin film the present > design allows will not give us the long-term viscosity > breakdown-free quieting and smoothness that a true > sump system can give us. Off the top of my head, to > keep this simple, go along with other concepts > discussed today, and because it is getting very late > (I will think about this some more in the next few > days) my suggestion would be to take advantage of the > increased 2" spindle disk diameter, and increase the > top of the bearing well diameter from 1.5" to just > *under* the 2" size. This will allow enough room > between the spindle shaft and its outer edge to sink > 2-4 largish "sump" bores around the perimeter plus > smaller angled (oil) feed holes going from the bottom > of those into the spindle cavity. Good point. I had not thought of providing any sort of well. Unfortunately, this would add quite a bit to the cost since the drilling and then cross drilling would be separate setup steps. It may double the bearing cost. I need to think about this and also run it by my brother. Chris ----- Original Message ----- From: Chris Brady Sent: Thursday, January 13, 2000 9:53 AM Subject: Re: Scheu-Bearing & Platter The interface between the spindle and the platter is something that I have been thinking about. I can see 3 possible approaches. 1) A net fit with no clearance. This would give a friction fit but if the tolerances are good it could be inserted and removed with some effort. There would probably be minor thermal stresses and no decoupling. 2) Minimal clearance. With 1 or 2 thousandths of clearance there would be some friction during assembly. This would be easy to disassemble and there would probably be a small amount of decoupling. 3) Greater clearance with a decoupling medium. Placing a thin layer of rubber, felt or whatever between the spindle and platter would provide some decoupling. This would be more like the Sheu design. However, we need to remember that one of the Sheu tweaks was to = replace the medium with something more rigid. Like Ken, my leaning is for a minimal clearance, slip fit. If we = wanted to play with decoupling a thin washer of some lossy material could be placed between the bottom of the platter and the lip of the spindle. = With the close fit between the top of the spindle and the platter the = decoupling would be a bit limited, but perhaps beneficial. Chris > > I would rather not have a shrink fit between the spindle and the = platter for > several reasons. You have already noted the difficulty of = disassembling > them. Also, as the spindle expanded inside the platter, it would = stress the > platter somewhat. That stress would make the platter a little less = inert, > thus losing some of the advantages of using acrylic. Also, I think a shrink > fit would couple the vibrations of the spindle to the platter more > efficiently, which is what we are trying to avoid. I would prefer a > reasonably close slip fit. > > Ken > > > -----Original Message----- > > From: Thom Mackris / Joan Panzella [SMTP:tmackris@earthlink.net] > > Sent: Wednesday, January 12, 2000 7:51 PM > > Subject: Re: Scheu-Bearing & Platter > > ..... I'm having > > thoughts of a tight fit which might require putting a bit of dry = ice on > > the > > bearing shaft to cool it down and shrink it a thousandth or so = prior to > > inserting into the platter. Removing it would be a nuisance then, > > however. > > > > I'm guessing that the left side of the drawing (the female) will be > > threaded > > on the outside, and a big honkin nut will bind it down to the = subchassis > > as > > in Scheu's design. > > > > Thanks for putting your thoughts to paper Chris - I think these are = the > > ideas we were working towards !! It's not quite time for Igor to = get > > online. I'm really curious about his thoughts. > > > > Cheers, > > Thom > > ----- Original Message ----- From: Mackris, Thom G. Sent: Thursday, January 13, 2000 10:56 AM Subject: RE: Scheu-Bearing & Platter 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 -----Original Message----- From: Schei, Kenneth [mailto:SCHEIKE@asa.org] Sent: Thursday, January 13, 2000 10:56 AM Subject: RE: Scheu-Bearing & Platter I agree that the bearing is the critical part to be fabricated = precisely. Regarding the platter, it was my impression that it also will be CNC = milled for adequate precision. That would also make the rebates for the rim = and label easy. 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 -----Original Message----- From: Steve Zettel [SMTP:zettel@libby.org] Sent: Thursday, January 13, 2000 10:12 AM Subject: Re: Scheu-Bearing & Platter Well, as I see it, this part of the design is key -- I might be able = to fabricate most of the other parts of the turntable, but it is doubtful = that I could do the bearing and spindle at work (and our best machinist = there just retired on a medical retirement). Without a quality bearing, the = whole project is just pretty acrylic sculpture. No matter what we do with dampening, mass loading, vibration isolation, or sand boxes, if we have = a noisy bearing we can't overcome that. So thanks again, Chris. [snip - discussion about how much the bearing will cost ] [back to Steve] I am on a budget with this project, but I would consider paying more = for the bearing (and economizing and doing more DIY elsewhere) than to cheap = out on this part. [Thom] (a) to consider expanding the horizontal disk in to be more of a true = sub platter [Chris B] I thought about this also. My brother indicated that we can have a = spindle diameter of up to 2 inches from a single piece of stainless. Any = bigger than this and it would need to be made from 2 pieces. That would = increase the cost and also reduce the mechanical stability. Thom as you pointed = out making the spindle larger also removes more of the platter creating a different set of problems. From the comments received perhaps the = spindle diameter should be increased a little. Say 1.75 to 2.0 inches, but no more. Also as Steve pointed out the bearing housing needs to be = smaller than the spindle so making the spindle a little bigger would give the bearing some clearance. [Steve] I am not sure, given a certain tolerance, how enlarging the spindle = will give any more accuracy or precision. Granted, 0.001 in 2.0" = mathematically is a smaller error than 0.001 in 1.5" or 1", however when talking about runout or eccentricity, I don't think it makes a material difference. Bottom line, we have to make sure the platter hole for the spindle is = as precisely concentric with the outside platter edge as possible. With = CNC machining, this a trivial matter for the spindle/bearing assembly. For = the platter, the only method that comes to mind is to mill the center hole/bearing hole in the platter and turn the outside edge of the final platter assembly on a lathe or a cutting jig, using the actual bearing assembly as the pivot, or a lathe chuck of equal or better tolerance. Perhaps this has already been addressed and I am getting ahead of = myself. Only other comment, realizing that this is a preliminary drawing, is threading the top of the spindle to accept a thread-on record clamp, a = la Oracle. I will determine the pitch mine uses if desired. [Chris] I was unsure of what to do here since I had no idea of how the various clamps attach. Perhaps we need to provide a threaded hole (with an = agreed upon size an thread pitch) in the top of the spindle that can = accomodate everyones needs. Those not wanting to use a clamp would need to have a short shaft made to screw into the spindle. This would increase cost = but would be a more flexible solution. I had the concept of a spindle with the initial part of the shaft = unthreaded as it exits up through the platter, at least to height that would = account for a small dished washer placed next to the platter and the thickest = label area (MOFI UHQR?) plus a little, then threaded with a *male* thread, = with sharp edges chamfered at the top. This would be less of a fabrication = hassle than internal threads, and though it sounds less elegant than a plain spindle for those who opt not to clamp, in practice, it does not look obtrusive at all. Or, for those not wanted the top threaded, that step = could be eliminated at a slight cost savings. (In all the experiments I have = done I have *always* perferred clamped over unclamped, but YMMV). [Thom] I'm guessing that the left side of the drawing (the female) will be = threaded on the outside, and a big honkin nut will bind it down to the = subchassis as in Scheu's design. [Chris] Exactly! Thanks Thom for pointing that out. [Chris] My brother was confident that the delrin could easily handle any = platter we wanted to throw at it. I have no opinion if 3" would be better than 2" = but Alex's brass puck idea sounds cool. It goes against my "keep it = simple" approach but may have merit. [Steve] 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. But this is turning into a platter discussion, and not bearing final decision. [Chris] Last of all we need to come up with a name for this project. It certai= nly 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. [Steve] Actually, "The Table" makes kind of a nice, proud statement about the project. 8^) ----- Original Message ----- From: Chris Brady Subject: Re: Scheu-Bearing & Platter For the specification of tolerances (fit) we can rely on a machinist. However, we need to be able to describe the kind of fit we at shooting for. I agree with the idea of a tight fit. In my layman terms I would describe tight fit as "tight as we can get and still be able to insert/remove without use of tools". I don't think that temperature will be as much of an issue with the = small diameters we are working with. Steve's description of the fit of the shaft into the bearing is exactly what I have had in mind. I don't know how to spec this, but I am sure that this description will tell a machinist exactly what is needed. Chris [Thom] Well said Steve (Steve's description of the distinction between the = vertical and horizontal locating forces on the bearing/platter interface). I'd also like to go on record for as tight as possible without an interference fit. With respect to "as tight as possible", we briefly covered temperature coefficients of expansion before, but we might want to address this = again prior to spec'ing out the final dimensions (Ken?). I know that my (aluminum) periphery clamping ring on my Merrill feels snug against the acrylic platter in the Summer (say ... 80 deg F) and looser in the = Winter (~ 68 deg. F.). Cheers, Thom -----Original Message----- From: Steve Zettel [mailto:zettel@libby.org] Sent: Thursday, January 13, 2000 11:20 AM Subject: Re: Scheu-Bearing & Platter on 1/13/00 10:03, Mackris, Thom G. at tgmackris@vicorpinc.com wrote: The bearing/spindle interface is certainly an area for tweakery & experimentation. Hartmut's substitution of a less-lossy substance = (than the original Scheu rubber), Merrill's use of a thin sheet of lead - which = would tend to validate Hartmut's findings. While I can agree with a more stress-less fit, I'm still struggling = with the idea of platter stability on a disk that's only 1.75 to 2.0 inches in diameter. Someone help me here ... Thom [Steve writes ...] Thom, The platter will be plenty stable, even without a 2" "disk" to rest on. Actually the very slightest of shoulders would be enough to secure the platter rigidly, as long as clearances between the upper bearing = assembly and platter do not get excessive. The platter is not resting balanced = on a 2" disk, it is located both axially and radially by the part of the = bearing that extends up through the platter and ultimately becomes the spindle protruding from the platter's upper surface. The horizontal shoulder, = or 2" disk of the bearing takes care of supporting the platter weight and = locating the platter in the vertical plane. The *vertical* part of the upper = bearing assembly locates the platter side to side and resists tipping. The = longer the vertical surfaces of platter and bearing in contact, *and* the = tighter the fix, the more stable is this location. This quite effectively = resists and "tilting" of the platter on the bearing, as if one were to grab = opposite edges of the platter and lift on side and push down on the other. Additionally, stability of the platter is enhanced by having the = bearing recessed into the platter, both statically by lowering the center of = gravity of the platter, and dynamically by lowering the belt/platter interface = in relation to the bearing, as already identified. The platter "hangs" = from the bearing assembly, rather than resting on top of. I could see how resting the platter on a "washer" of some very uniform, lossy material might add some minimal dampening, but I don't see how we = can line the inside of the hole in the platter with another substance, get = a snug fit, and avoid eccentricity problems. But I could be wrong 8^) Please put me on record (pun intended) for advocating very strongly, = the snuggest fit between platter and bearing assembly, short of an = interference fit. Steve Z ----- Original Message ----- From: Thomas R Martin Sent: Thursday, January 13, 2000 12:59 PM Subject: Re[2]: Scheu-Bearing & Platter Forgive my non-technical minded $.02, but by going with a 3" thick platter, aren't we risking introducing wobble just from that. Or = is an acrylic sheet relatively uniform enough that three 1" thick = disks would be inherently balanced on their respective centers? Or am I just picking at knits here? Thomas ----- Original Message ----- From: Mackris, Thom G. Sent: Thursday, January 13, 2000 1:13 PM Subject: RE: Re[2]: Scheu-Bearing & Platter Thomas, Regarding picking nits (or knitting picks) ... The challenge of laminating two, 1" pieces together uniformly is that = same as that of laminating three pieces together. In both cases, the = platter would be machined *after* lamination and not before. This brings up something I was just discussing with Ken. Ken had = mentioned that it mighb be in our best interest to buy pre-cut (say 12.25" = square) pieces, laminate them ourselves after researching the proper materials, = and ship them off to Chris' brother to have him machine the interface. I = fogot to mention a problem with this to him (in addition to extra shipping = cost) - I believe that Chris's brother set up to work in much smaller = dimensions - like the size of our bearing and *not* with larger pieces of acrylic. Chris' brother could still help us to spec out the dimensions for the interfacing surfaces. We could then have only one platter made locally = (in Colorado), inspect it, either make adjustments, or procede with the remaining 11 or 12 platters. Regarding names for our project ... here are a couple: Saturn ... because it will run rings around other turntables (of = course, this sounds like a cheap car) Jupiter ... because it will be massive I know that we can get more imaginative than this. Thom ----- Original Message ----- From: Schei, Kenneth Sent: Thursday, January 13, 2000 1:53 PM Subject: RE: Re[2]: Scheu-Bearing & Platter If Chris's brother can't machine the platter, there are several = plastics places that I've talked to here in Denver that will do CNC milling of = the acrylic at moderate prices. Ken ----- Original Message ----- From: Igor Kuznetsoff Sent: Friday, January 14, 2000 3:39 AM Subject: RE: Scheu-Bearing & Chuckle And, now that the serious work is done for the evening..... IDLER BEARING THOUGHTS Now we can obsess over lubricants! 8^) Steve Z If I were a rich man ( bubba-dubba-dub-dub, remember that tune ? = )..Now, *if* I were a rich man..I would think about keeping a Hugh Hefner style = pipe rack stocked full of turntable bearings prepped & ready with an = assortment of different lubricants to suit my musical moods. Just like some guy I = read about years ago who kept a pipe rack full of tonearm wands set up with = a variety of cartridges to suit his moods. I don't remember what arm = system it was that allowed the quick changes, but it must have been a nifty = design. Anyway, this would allow me to match the lube to the music. For = instance, I could use suntan oil for Beach Boys surf music. Gear oil for = listening to the Cars. Extra heavy, *heavy* oil for Wagner. Hot pepper oil for = Salsa. Exotic pressed-between-crystals Grape Seed Oil for New Age Music.. = Corn oil for Country. KY for Tchaikovsky or Chopin. Multi-weight for Marsalis. Single-weight (or nothing at all) for Reich. Gun oil for Gangsta = 'rap Music. Notice the proper use of the capital ' (apostrophe) in 'rap = as well as the M in the "Music", without which, we just wouldn't know. Schmaltz for Klezmer. Preparation H (the Inyer Ear Formula) for Heavy = Metal Music. Olive oil for Mediterranean Music. Triple antibiotic ointment = for Madonna . Dry graphite lubricant for Chamber Music. Castor oil for = 78's.. Igor ----- Original Message ----- From: Chris Brady 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: Jeremy Epstein Sent: Friday, January 14, 2000 9:54 AM Subject: Re: Scheu-Bearing & Platter Chris Brady wrote: > > 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: 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: Steve Zettel To: Igor Kuznetsoff ; Chris Brady 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 Sent: Friday, January 14, 2000 12:02 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: Schei, Kenneth Sent: Friday, January 14, 2000 12:27 PM Subject: RE: Scheu-Bearing & Platter The following tips for working with acrylics are from San Diego = Plastics (http://www.sdplastics.com/acrylic.html). Ken Working with acrylic plastic sheet DO Keep masking on as long as possible. Use metal cutting saw blades and = drills which are ground for acrylic sheet. Make sure all tools are sharp. Use water or drilling oil as a coolant when cutting sheets over 1/8" = thick or drilling sheets over 3/16" thick. Wet the material before cleaning. DON'T Use saw blades with side-set teeth. Saw teeth ideally should be ground = with 0=B0 of rake and be of uniform height and shape. Cutting Acrylic Plastic Sheet Cutting with a knife or scriber Acrylic sheet up to 3/16" thick may be cut by a method similar to that used to cut glass. Use a scribing knife, a metal scriber, an awl, = or a utility knife to score the sheet. Draw the scriber several times (7 or = 8 times for a 3/16" sheet) along a straight edge held firmly in place. = Then clamp the sheet or hold it rigidly under a straight edge with the = scribe mark hanging just over the edge of a table. Apply a sharp downward = pressure to break the sheet along the scribe line. Scrape the edges to smooth = any sharp corners. This method is not recommended for long breaks or thick material. Cutting with power saws Special blades are available to cut acrylic. Otherwise use blades designed to cut aluminum or copper. Teeth should be fine, of the same height, evenly spaced, with little or no set. Table and circular saws Use hollow ground high speed blades with no set and at least 5 teeth per inch. Carbide tipped blades with a triple chip tooth will give the smoothest cuts. Set the blade height about 1/8" above the height of the material. This will reduce edge chipping. When using a hand held circular saw, clamp the sheet to the work surface and use a length of 1x3 wood to distribute the clamping = pressure and act as a guide for the saw. Feed the work slowly and smoothly. Lubricate the blade with soap or beeswax to minimize gumming from the masking adhesive. Be sure the saw = is up to full speed before beginning the cut. Water cooling the blade is = suggested for thicknesses over 1/4", especially if edge cementing will be = performed. Saber saws Use metal or plastic cutting blades. The blades you use to cut acrylic should never be used for any other material. Cut at high speed = and be sure the saw is at full speed before beginning the cut. Hand saws Good results are possible, but very difficult. Be sure the acrylic is clamped to prevent flexing. Flexing at the cut may cause cracking. Routers and shapers Use single fluted bits for inside circle routing and double fluted bits for edge routing. At the high speeds at which routers operate it = is critical to avoid all vibration. Even small vibrations can cause = crazing and fractures during routing. Drilling For best results, use drill bits designed specifically for acrylic. Regular twist drills can be used, but need modification to keep the = blade from grabbing and fracturing the plastic. Modify the bit by grinding = small flats onto both cutting edges, so the bit cuts with a scraping action. = If the drill is correctly sharpened and operated at the correct speed, two continuous spiral ribbons will emerge from the hole. Finishing Acrylic Plastic Scraping The first step in getting a finished edge is scraping. The back of a hacksaw blade is perfect for scraping. Simply draw the corner of the = square edge of the blade along the edge of the acrylic. Filing A 10 to 12 inch smooth cut file is recommended for filing edges and removing tool marks. File only in one direction. Keep the teeth flat on = the surface, but let the file slide at an angle to avoid putting grooves in = the work. Sanding If necessary, start with 120 grit sandpaper, used dry. Then switch to a 220 grit paper, dry. Finish with a 400 grit wet/dry paper, used = wet. Grits as fine as 600 may be used. Always use a wooden or rubber sanding block. When removing scratches be sure to sand an area larger than the scratch. Sand with a circular motion, and use a light touch and plenty = of water with wet/dry papers. Almost any commercial power sander can be used with acrylic. Use light pressure and slower speeds. Polishing Final polishing will give acrylic a high luster. Power-driven buffing tools are recommended without exception. Buffing wheels are available as attachments for electric drills. A good buffing wheel for acrylic consists of layers of 3/16" carbonized felt, or layers of unbleached muslin laid together to form a wheel. Solidly stitched wheels should be avoided. The wheel should reach a surface speed of at least 1200 feet per minute. Speeds of up to 4000 feet per minute are useful for acrylic. Acrylic should be polished using a commercial buffing compound of the type used for silver or brass, or you can use a non- silicone car = polish that has no cleaning solvents in it. First, however, tallow should be applied to the wheel as a base for the buffing compound. Just touch the tallow stick to the spinning = wheel, and then quickly apply the buffing compound. To polish, move the piece back and forth across the buffing wheel. Be careful not to apply too much pressure. Keep the work constantly = moving to prevent heat buildup. Never begin polishing at the edge of the sheet. The wheel could easily catch the top edge and throw the piece across the room or at = you. ----- Original Message ----- From: Jeremy Epstein Sent: Friday, January 14, 2000 12:37 PM Subject: Re: Scheu-Bearing & Platter "Schei, Kenneth" wrote: > The following tips for working with acrylics are from San Diego = Plastics > (http://www.sdplastics.com/acrylic.html). Thanks, very helpful. I noted that these folks sell acrylic sheet up to 4" thick! -j -- ----- Original Message ----- From: Chris Brady Sent: Friday, January 14, 2000 12:26 PM Subject: Re: Scheu-Bearing & Platter Ken, 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? Plenty strong? Good grief we are talking major over-engineering here. 1/4" would probably be strong enough :). Chris ----- Original Message ----- From: Steve Zettel Sent: Thursday, January 13, 2000 9:10 PM [snip] 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: Thom Mackris / Joan Panzella Sent: Saturday, January 15, 2000 12:15 AM Subject: Re: Scheu-Bearing & Platter 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. The spindle is a total of 3/4" high. The first half (3/8", or 12/32") of the spindle is unthreaded, also = with a taper over the last 1/16" or so. The remaining 3/8" is threaded. My dial indicator measures the diameter of the spindle (the area where = the record passes through) between .280" and .281". It also fits records = snugly but without having to push hard on any records in order to pass them = over it. I'm going to measure Chris' and Ken's Thorens this weekeend. Chris = says he has to push a few records rather firmly in order to get them to pass = over the spindle. I wonder how many more thousandths this ends up being. = We'll then be certain where we need to be. 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: Thom Mackris / Joan Panzella Sent: Saturday, January 15, 2000 10:51 PM Subject: Re: Scheu-Bearing & Platter I'm thinking that accomodating the largest imaginable label is also the = safe bet. 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 ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Saturday, January 15, 2000 11:33 PM Subject: Re: Scheu-Bearing & Platter All, I just got back from hearing Grant's phenomenal Edgar Horn rig. He's = just getting it dialed in and all I can say is WOW !! I honestly think that = he can stand a bit of room treatment, and perhaps this can be the subject = of a serious geek fest once he gets the opportunity to live with them a = while more. As good as they are, I think a little room fixin' and they'll be = even better. I know that Brian heard them while Grant was still dialing in = the crossover and so his opinion was formed prematurely. One thing fer = shure - it *definitely_does _not_need* digital room correction. I won't make = this a full review, but let me mention that this system moves some *serious* = air, without causing his 3 watt amp to break a sweat. Stevie Ray Vaughn had = me pinned against the wall with effortless dynamics and slam. It does low level stuff equally well. About the only thing that sounds "horny" = about them is the sense of effortless dynamics and low level detail. Now back to our regularly scheduled programming ... Chris & Ken were also at Grant's and we got to chat about the 'table. = Not to steal Chris' thunder, but merely to save him time so that he can = devote himself to the drawings. It appears as if Chris's brother is gung ho = to machine the platters too! The three of us had been silently voicing = the concern over how to make sure that the platters fit the bearing = properly. I had the thought of making up one extra spindle and amortizing the $45 = over the dozen or so 'tables we make up. The idea was to leave it with the plastic shop so that they could test fit it into some sample drillings. = If Chris' brother does all of the work, (a) that won't be necessary and = (b) we'll have his sympathetic, patient ear to make sure that we get what = we want. Grant asked Chris what his brother normally machines & Chris responded = that until recently, most of his work used to be bearings for computer disk drives. Could we have stumbled on someone who had more experience with = what we need? With respect to bonding the acrylic sheets together, Chris' brother indicated that there are glues out there which can bond the acrylic so = well (when clamped properly), that even if the edges were flame polished, = you wouldn't be able to see the seams! I think that this should eradicate = any lingering concerns about the uniformity of the platter with respect to balance. This is also something to keep in mind for those of you who = are thinking about a thick, acrylic subchassis. As far as extra shipping costs, this should be insignificant. I'm = thinking that since we have such a trustworthy contractor here, that we can ship = the parts directly to everyone, so there won't be duplicate shipping = expenses. He is going to work up a delivered price for bearing platter combos = (I'm not sure when). One thing to note is that he mentioned occasionally, the acrylic chips unexpectedly, so we might have some rejects to factor = into the cost. Chris is also going to work with him about scheduling the work. = If he takes on the platters, he'll obviously have to schedule more time. I'm getting more jazzed about this with each new tidbit of information. Cheers, Thom ----- Original Message ----- From: Igor Kuznetsoff Sent: Saturday, January 15, 2000 11:57 PM Subject: Re: Scheu-Bearing & Platter --- Thom Mackris / Joan Panzella wrote: [snip] > With respect to bonding the acrylic sheets together, > Chris' brother > indicated that there are glues out there which can > bond the acrylic so well > (when clamped properly), that even if the edges were > flame polished, you > wouldn't be able to see the seams! I think that > this should eradicate any > lingering concerns about the uniformity of the > platter with respect to > balance. This is also something to keep in mind for > those of you who are > thinking about a thick, acrylic subchassis. 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 ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Sunday, January 16, 2000 10:16 AM Subject: Re: Scheu-Bearing & Platter Now that I'm awake and have some of my faculties ... I'll respond in the body of your text (below). ----- Original Message ----- From: Igor Kuznetsoff Sent: Sunday, January 16, 2000 1:39 AM Subject: Re: Scheu-Bearing & Platter 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 ? ------- Igor said ... 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. Thom says ... Yes, I read the Scheu drawing the way you do --------- Igor said ... 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. Thom says ... I think I can actually visualize this! If the belt pull is at the = middle of the top bearing contact area (say an inch below the plane of the record surface), there's no teeter-totter effect. ----- Igor said ... 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 ? Thom says ... If I can summarize and embellish, it seems as if we one *very* = significant strength in this design: The center of mass of the platter is well below the top contact point = of the bearing, lending inherrent stability to the system. If you visualized = an absurdly long bearing shaft (say, 10' long), it's fairly obvious that = any rocking forces would be lessened compared to an absurdly short bearing = shaft (say 0.5", for example). Anything you might lose (with a long shaft) = by having the pull slightly above the exact midpoint of the bearing shaft, = is more than compensated for by the increase in length of the bearing = shaft. I would vote for as long as $fiscally$ possible -The reason mention = this is that I seem to recall some practical length limit for the stainless = steel stock that the shaft is made from. I'd also think that the bearing = well should not extend down into the area that's threaded for the mounting = nut ... say the last inch of the housing (a guess). ---------- Igor said ... 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. Thom ... Yes, Chris' brother is our key here. --------- ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Sunday, January 16, 2000 10:33 AM Subject: Re: Scheu-Bearing & Platter 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: Steve Zettel Sent: Sunday, January 16, 2000 10:14 AM 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: Igor Kuznetsoff Sent: Sunday, January 16, 2000 11:45 PM Subject: Re: Scheu-Bearing & Platter (Finish) Yup, what they said....The idea of *truing up* the entire top surface / unifying the finish sounds very practical, and less slippery to the record, as well. Wish every response was this easy ! I Good reasoning, Thom. I am cool with machined rather than polished, for all the points you listed. Thanks,Steve --- Thom Mackris / Joan Panzella 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: Steve Zettel > Sent: Sunday, January 16, 2000 10:14 AM > > > 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: Igor Kuznetsoff Sent: Monday, January 17, 2000 12:09 AM Subject: Re: Scheu-Bearing & Platter / Spindle & Balance >... the last inch... "That's what she said...." I agree that there is not enough reason to pay premium costs for length. Whatever doesn't get exorbitant. I also agree that it may be marginally undesirable to go into the threaded area. While I think it not terribly likely, I would not want to risk even possible microscopic deformation of the bearing area from tension applied by the large nut. 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 ----- Original Message ----- From: Igor Kuznetsoff Sent: Monday, January 17, 2000 2:50 AM Subject: RE: Scheu-Bearing & Machining The delay is just fine by me. I really don't think we've quite planned out everything that should go into the machining package yet, such as, perhaps, the idlers, and the motor pulley, just off the top of my head. I --- "Mackris, Thom G." wrote: [snip] > 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 ... [snip] ----- 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: Igor Kuznetsoff Sent: Monday, January 17, 2000 3:06 AM Subject: Re: Fw: Scheu-Bearing & Relief LOVE I IT EVEN MORE !!! And for good reason, and more reasons than just Steve's excellent idea. I've been agonizing all day long , as well as during the ride to and from today's interesting NJAudSoc meeting (Harmonix/Combak Premium-Priced Voodoo and some very interesting 96/24 digital listening. Clue: digital is getting damn good ! More on that, maybe, later.) as to how to break some wet - blanket bearing worries. Worse, having to talk you guys into a fix for the problem I see. I think Steve just talked us more than halfway into the solution I was worrying about having to sell you on. I should have thought more about this when the clues came up about how long it takes for a spindle shaft to settle into a well because of the *air* pocket ! What we are going to have is a well with an *oil* pocket in it. What does this mean ? Ever try to quickly collapse, by hand, a very stiff automotive shock absorber ? Our bearing will be a *heck of a lot tougher* than any bearing you ever encountered before to stick the spindle into. But, at least, we have a massive platter we can put on it, and leave to do its thing for a few hours. What's going to be a *lot* more difficult, should the need arise, will be to *remove* that spindle. How are you going to do it, with a crowbar between the spindle shoulder and bearing well ? What's worse, how are we going to determine exactly how much oil to put in there so the level comes up to the upper contact area ? The only way to tell that you didn't put in too little will be when the oil starts to overflow on to your plinth....We could, I suppose, drill a hole into a scrap piece of wood, mount the bearing temporarily on that, let the oil overflow, dismount, wipe up, and mount the assembled bearing into our subchassis. But that won't solve the problem of practical disassembly, and that means that replacing, say, the break-in oil with fresh will be quite a problem. The real solution is to provide a pressure relief system which will hold oil after the assembly. I thought about a number of awkward ways, the extra machine work I'd have to talk you into,.... The easiest way will be to drill a hole in from the bottom, plus a bypass off-centered around the Delrin thrust washer. The bearing can then be assembled upside-down : hold right-side-up, put a finger over the bottom hole, add oil, put the spindle up to the well, turn over, press in. With no serious back pressure (just some drag at the small Delrin bypass), the spindle will be reasonably easy to seat. The threaded shaft of the tip-toe cone, with some teflon plumbers tape on it, can now seal the hole, and go to work in the function Steve envisioned. The only problem will be reconciling the extra distance from the bottom of the plinth, but cones come in different sizes, and sand is very forgiving of minor differences. Or shims can be added if necessary. The tricky thing will be connecting to the well shaft area, as the ball bearing and, ostensibly, the cone will be both be centered, so the bore cannot just be carried through. The diameter of the bearing housing is not large enough to want to off-center the cone, or, at least, not by enough to do the trick. The solution will probably be to not carry the 1/4" x 20 bore all the way through, instead drilling past the depth needed for the cone by just enough so that everything lines up just right so that a smaller drill will angle through the 1/4" bore and into the edge of the spindle shaft bore, around the edge of the Delrin, where the ball bearing does not need support. The Delrin must be bypassed, or it will act as a one way stop-valve. At least, this is my idea for connecting them up. "Our Machinist" (what *is* Chris's brother's name, anyway ?) may have better ideas about this detail. Comments ? Good thinking, Steve ! Igor --- Thom Mackris / Joan Panzella wrote: > I LOVE it !!! ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Monday, January 17, 2000 9:57 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 ----- Original Message ----- From: Schei, Kenneth 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: Steve Zettel Sent: Monday, January 17, 2000 10:17 AM Subject: Re: Scheu-Bearing & Relief Thanks for the kind words, Igor, about my "wild ass idea". I would however add the following counterpoint to your concerns about = the pneumatic effect of inserting and removing the bearing/platter from the bearing well/subchassis -- In practice I don't think undue difficulty will occur even though our bearing is machined to sub-RCH (engineering term) tolerances, because = it will still be far from airtight. On insertion, some patience will be needed, but the air will ultimately = be displaced, and probably quicker than the several hours you postulated. = I would certainly not let the platter loose until I was sure that it = actually was supported by the pneumatic cushion to avoid having it seat home = with a thud and possibly flat-spotting the delrin or ball-bearing. On removal, a steady gentle upward pressure will allow the air to = migrate back into the bearing housing as the spindle is withdrawn, again fairly rapidly. The analogy is the difference between speed and force = application: Take a sheet of newspaper laid flat on a table top with a yardstick = inserted between the table top and the newspaper. The yardstick has one foot of length projecting out into space past the edge of the table top. The newspaper edge is aligned right up to the edge of the table top and painstakingly smoothed out until it lays flat with few or no air voids between it and the table. If you strike the end of the yardstick in an attempt to "flip" the = paper up in the air rapidly, the yardstick breaks. The paper is effectively = immovable with the mass of the column of air above it, and none below. If = instead, a slow, gentle pressure is applied to the yardstick, the paper can be = lifted from the table with ease. A little clumsy, but you see what I mean. Again, we have an incredibly precise bearing, but *not* airtight. I would prefer to exercise patience, than to see more complicated = machining take place or the integrity of the bearing well compromised. As far as overflowing or underlubricating the sump, given the precise dimensions we have for our components, it is a trivial matter to = calculate the exact volume of lubricant required, and convert the value to CC's. = Given enough time and the use of all my fingers and toes to count on, even I = might be able to do it. But I note we have a PE in the group. 8^) The drugstores have syringes for pennies a piece that will allow us to measure and dispense the precise amount of lubricant we need. Under lubricating, unless grossly under, should not be a concern as the = capillary action between the two upper bearing surfaces will ensure a thin film = is developed, and the two surfaces can be given a light coating prior to assembly to eliminate any concern in that area. Any surplus oil will = more than likely ooze along the surface of the bearing well and down it's = sides, rather than oiling the underside of the platter. A felt ring placed = over the bearing well prior to inserting it through the subchassis and = tightening the nut would wick up what little surplus might occur. My humble 2 centavos. Steve Z ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Monday, January 17, 2000 10:37 AM Subject: Re: Scheu-Bearing & Relief In fairness to Igor (I really need to re-read your post, Igor), I'd = side with Steve on this one for all of the reasons he states, especially = with respect to reducing complexity. My Merrill bearing takes all of 5-10 minutes to seat itself using only = the gravity of a one to two pound subplatter. Removing it is quite easy. Merrill's test for whether the bearing shaft is fully seated is to lift = the subplatter 1/8" or so and let go! You hear a small click - the ball on = the end of the spindle shaft hitting the bronze thrust plate!! He's = thoroughly confident that this will cause no harm to the bearing and told me that = he's never had to replace a bearing due to damage !! While I don't = necessarily advocate this procedure (on a Delrin thrust plate), I'm mentioning it annecdotaly to describe the process of seating a high tolerance bearing using (approximately 40 weight) a viscuious oil. I usually guarantee that I'm marginally overfilling the bearing as = there's about 3/4" of clearance between the bottom of the subplatter and the subchassis. I wrap a bit of paper towel (forming a collar) around this area. I do the final cleanup with a long Q-tip. Steve's idea of = metering out the oil is something I've always been too lazy to do, but will = obviously work just fine. Cheers, Thom ----- Original Message ----- From: Schei, Kenneth Sent: Monday, January 17, 2000 11:05 AM Subject: RE: Scheu-Bearing & Relief I agree with Steve's analysis. I think that we will be able to insert = and remove the bearing shaft in a reasonable amount of time without = requiring any extra machining. Ken ----- Original Message ----- From: Chris Brady Sent: Monday, January 17, 2000 11:06 AM Subject: Re: Scheu-Bearing & Machining I think that I have identified the remaining issues regarding the bearing design. Please let me know if I have missed anything. I have added my thoughts and have tried to draw some conclusions. In addition I am assigning an open/closed status to each of the items. This may help us get to closure on the design. For the issues I tag as closed I will assume we are in agreement unless I hear from someone. 1) The length of the spindle shaft. I think that Thom already covered this but lets make sure we are on the same page. My brother Bryce (yes he does have a name) indicated that with a .75" bore that a = 2.5" depth is the max depth that can be done with precision. So based on this constraint I propose that we stay with the current 2.5" length. ## CLOSED ## 2) Increasing the relief in the bearing to accomodate more oil sounds good. I am thinking that 1/8 on each side should be plenty and that more than this amount would do no good. I believe that there is consensus on this. ## CLOSED ## 3) The area of the bearing surface and the sump rebate. The issue is friction and I have been assuming that to some extent friction is good so long as it is smooth and uniform. Smooth friction will provide damping of rotational speed beyond the flywheel effect of the heavy platter. This is the idea behind using a thick oil. The larger the contact area in the bearing the greater the friction. In the current design the contact area is 2 x .75" cylinders .625" high. This is a lot more contact area than is required for good mechanical stability, but it should provide "good" friction. The reason for having contact at only the ends of the shaft is not so much for reducing friction but rather to avoid a binding effect from microscopic imperfections in how straight the spindle shaft is. This issue seems to be a compromise between avoiding a minute (and possibly non-existent) binding effect and beneficial friction. With very narrow contact areas the possiblity of binding is reduced but we also lose much of the beneficial friction of the oil. Given the precision that we can expect for the bearing I am inclined to leave the contact area as is or perhaps narrow it from .625" to .5". I would also leave the sump rebate in the bearing since it would slightly increase friction. This issue needs more discussion. ## OPEN ## 4) Insertion of the shaft into the bearing. I have also been musing about this issue. However, I don't think it will end up being a problem. There should be enough clearance in the bearing for oil to migrate past the contact areas. It will take a little while for the shaft to settle in place and also it will take a little effort to pull the shaft out. This is a nuisance but I don't see it as a problem. However, Igor is right about the difficulty of figuring out how much oil to put in and not have overflow. Unfortunately I don't see any option other than experimentation. Perhaps we could count the drops of oil to find to correct amount. Again this is a nuisance but I = don't think it is a problem. It seems that having a hole in the bottom of the bearing would not help much since there would be pockets of air in the bearing. = Trying to insert oil into the bottom of the bearing would not force out the air bubbles and would not fill the sump as we desire. ## OPEN ## 5) Adding a threaded hole in the bottom of the bearing to accomodate a tip-toe. This will add a little to the cost of the bearing and may or may not be useful. But since the cost is low I suggest that we do it. Better to be flexible. ## CLOSED ## ----- Original Message ----- From: Igor Kuznetsoff Sent: Monday, January 17, 2000 1:47 PM Subject: RE: Scheu-Bearing & Relief [note - with respect to spindle being able to displace oil upon = insertion, due to tight bearing tolerances] I hate to be an alarmist, but I considered every one of Steve's points *before* writing what I wrote. You might think about this for a moment. I've worked on race cars and a lot of fancy machinery, and have a disquieting feeling about this. I --- "Schei, Kenneth" wrote: > I agree with Steve's analysis. I think that we will > be able to insert and > remove the bearing shaft in a reasonable amount of > time without requiring > any extra machining. > > Ken > ----- Original Message ----- From: Igor Kuznetsoff Sent: Monday, January 17, 2000 6:32 PM Subject: Re: Scheu-Bearing & Machining --- Chris Brady wrote: > The reason for having contact at only the ends of > the shaft is not > so much for reducing friction but rather to avoid > a binding effect > from microscopic imperfections in how straight > the spindle shaft is. Makes a lot of sense, for that aspect. > This issue seems to be a compromise between > avoiding a minute (and > possibly non-existent) binding effect and > beneficial friction. > With very narrow contact areas the possiblity of > binding is reduced > but we also lose much of the beneficial friction > of the oil. Given > the precision that we can expect for the bearing > I am inclined to > leave the contact area as is or perhaps narrow it > from .625" to .5". > I would also leave the sump rebate in the bearing > since it would > slightly increase friction. This issue needs more > discussion. > ## OPEN ## I would suggest going to the smaller size, pending Brother Bryce's benediction, as I prefer to depend on mass and the oil's viscosity, rather than friction for stability, as discussed in some of today's other posts. > > 4) Insertion of the shaft into the bearing. I have > also been musing > about this issue. However, I don't think it will > end up being a > problem. There should be enough clearance in the > bearing for oil > to migrate past the contact areas. It will take > a little while for > the shaft to settle in place and also it will > take a little effort > to pull the shaft out. This is a nuisance but I > don't see it as a > problem. 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 !!! > > However, Igor is right about the difficulty of > figuring out how much > oil to put in and not have overflow. > Unfortunately I don't see any > option other than experimentation. Perhaps we > could count the drops > of oil to find to correct amount. Again this is > a nuisance but I don't > think it is a problem. > > It seems that having a hole in the bottom of the > bearing would not > help much since there would be pockets of air in > the bearing. Trying > to insert oil into the bottom of the bearing > would not force out the > air bubbles and would not fill the sump as we > desire. > ## OPEN ## If the procedure I outlined is followed, the oil will settle to the bottom, the air to the top (while holding all upside down), and pushing the spindle in from underneath will work just like getting the air out of a syringe. The oil gets poured in from the top, before turning the assembly over, and inserting the spindle. Igor ----- Original Message ----- From: Alex Mitaru Sent: Monday, January 17, 2000 6:33 PM Subject: Re: Scheu-Bearing & Machining [with respect to bearing displacing oil ] guys, I strongly agree with Igor on this one...alex ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Monday, January 17, 2000 6:53 PM Subject: Re: Scheu-Bearing & Platter 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 =3D 11- 7/8" =3D 11.875" Lead-in groove "lump" =3D 3/32, or in terms of diameter - 2 x 3/32 =3D = 3/16" =3D .1875" Diameter to clear the "lump" =3D 11.875 - .1875 =3D 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 =3D 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 =3D=3D> 11.625 12.080 =3D=3D> 12.025 (this would maintain a 45 degree bevel with a = 0.2" drop). 12.280 =3D=3D> 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 ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Monday, January 17, 2000 7:33 PM Subject: Re: Scheu-Bearing & Machining All, I got lost with all of the imbedded comments in all of the e-mails in = this thread. Could we do some judicious snipping? I realize that we are trying to solicit all questions and open issues = in order to reach closure on this phase of the project, but at the same = time, I fear that this particular discussion is degenerating into an "angels on = the head of a pin" discussion. I had the day off today in compensation for working New Year's weekend. I'm heading back to what promises to be a vicious week and will probably back out of most discussions on the = project at least with respect to lengthy responses. Related to this subject and the way things have temporarily stalled, = Joan is throwing her suggestion for a name into the ring - The Odessey. = Actually, we both like the name Teres and feel comfortable going on record with = this name. Back to the subject at hand ... How about doing something so revolutionary as to resolve this bearing = hole issue empirically? I'll pick up some STP and try it in my Merrill. I'd obviously be happy = to donate thimble or two to Chris & Ken to do the same with their Thorens. Steve can have a go with his Oracle. If inserting and removing the = spindle proves to be no problem (as I suspect), can we assume that Merrill's, Oracle's and Thoren's machinists are about as competent as Bryce is and = that we can specify a bearing for use with 20-40 weight oil (which is what = my Merrill oil appears to be)? Critical to this of course is where we want to end up. Do I still hear advocates for machining with a clearance which requires a thin oil = (i.e. finer tolerances)? If this is the case, then there's no way that we = can use heavy oil anyway so jamming STP in there is a non-question, hole or no = hole (I think ). I am however, under the impression that a thicker oil & the resultant bearing clearance is the way we're heading. I personally advocate this = & don't ask me to explain why. The only thing I can think of to justify = this "feeling" is better vibration damping. I personally also think that = this viscuous damping (*not* friction) can only be beneficial. If we do = adopt a 20-40 weight oil bearing clearance, then our STP research on our = existing bearings should have some validity and transfer well to our bearing. What say yee? Thom ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Monday, January 17, 2000 8:06 PM Subject: Re: Scheu-Bearing & Machining O.K. folks. As much as I love this project, I'm also trying to live = the other part of my life. Here's my take on the issues list which Chris thankfully put together. 1) Length of Spindle Shaft - ## CLOSED ##. 2) Relief in bearing - whether or not to have any. The answer is yes. Issue #3 was spawned in order to resolve the particulars. ## CLOSED = ##. 3a) The area of the bearing surface (how tall) 3b) Where to place the sump rebate (by slimming down the shaft or = grinding the bearing housing). ## OPEN ## I suggest that we follow Bryce's advice on this and CLOSE this issue = out!! We're splitting hairs again. 4) Insertion of the shaft into the bearing. To be determined = empirically via experimentation with STP on our existing 'tables in the next 5 days = (see my e-mail on this). Still ##OPEN##. 5) Adding a threaded hole in the bottom of the bearing to accomodate a tip-toe. ## CLOSED ## Let's all stay focussed, while at the same time not being shy about our ideas. Lastly, let's not let fear of success keep us from putting this project to bed. Remember guyz, as it stands now, we've got a superior bearing to Scheu's (on paper - it ain't real until it's playing = records). Scheu's is equal to or better than the Verdier. I can live with this! Cheers, Thom ----- Original Message ----- From: Steve Zettel To: Chris Brady ; Igor Kuznetsoff Sent: Monday, January 17, 2000 9:02 PM Subject: Re: Scheu-Bearing & Machining My "votes" below: > I think that I have identified the remaining issues regarding the > bearing design. Please let me know if I have missed anything. > I have added my thoughts and have tried to draw some conclusions. > In addition I am assigning an open/closed status to each of the = items. > This may help us get to closure on the design. For the issues I > tag as closed I will assume we are in agreement unless I hear from > someone. Good summation and plan, Chris. > > 1) The length of the spindle shaft. I think that Thom already = covered > this but lets make sure we are on the same page. My brother Bryce > (yes he does have a name) indicated that with a .75" bore that a 2.5" > depth is the max depth that can be done with precision. So based > on this constraint I propose that we stay with the current 2.5" > length. ## CLOSED ## Concur. > > 2) Increasing the relief in the bearing to accomodate more oil sounds > good. I am thinking that 1/8 on each side should be plenty and > that more than this amount would do no good. I believe that there > is consensus on this. ## CLOSED ## The only question I see as open is which part of the bearing the relief = will be on, the well or the spindle. Good cases for either one. Ken makes = the point that removing material from the spindle lowers drag. Some feel = the drag is beneficial. > > 3) The area of the bearing surface and the sump rebate. The issue is > friction and I have been assuming that to some extent friction is > good so long as it is smooth and uniform. Smooth friction will > provide damping of rotational speed beyond the flywheel effect > of the heavy platter. This is the idea behind using a thick oil. > The larger the contact area in the bearing the greater the friction. > In the current design the contact area is 2 x .75" cylinders .625" > high. This is a lot more contact area than is required for good > mechanical stability, but it should provide "good" friction. Again, good summation. I really don't know which is more advantageous = for our purposes, minimizing friction or maximizing friction. Given the = massive size of the platter, and the small size of our motors, I tend to agree = with Ken about minimizing friction with light oil, and making the bearing = rebate on the shaft. >The reason for having contact at only the ends of the shaft is not > so much for reducing friction but rather to avoid a binding effect > from microscopic imperfections in how straight the spindle shaft is. > > This issue seems to be a compromise between avoiding a minute (and > possibly non-existent) binding effect and beneficial friction. > With very narrow contact areas the possiblity of binding is reduced > but we also lose much of the beneficial friction of the oil. Given > the precision that we can expect for the bearing I am inclined to > leave the contact area as is or perhaps narrow it from .625" to .5". > I would also leave the sump rebate in the bearing since it would > slightly increase friction. This issue needs more discussion. > ## OPEN ## As above, it boils down to do we want to maximize friction, or minimize friction. This drives the decisions for bearing contact area, and where = the rebate is located. > > 4) Insertion of the shaft into the bearing. I have also been musing > about this issue. However, I don't think it will end up being a > problem. There should be enough clearance in the bearing for oil > to migrate past the contact areas. It will take a little while for > the shaft to settle in place and also it will take a little effort > to pull the shaft out. This is a nuisance but I don't see it as a > problem. > > However, Igor is right about the difficulty of figuring out how much > oil to put in and not have overflow. Unfortunately I don't see any > option other than experimentation. Perhaps we could count the drops > of oil to find to correct amount. Again this is a nuisance but I = don't > think it is a problem. I think this is a easily calculatable volume, but could also be = determined experentially. > > It seems that having a hole in the bottom of the bearing would not > help much since there would be pockets of air in the bearing. Trying > to insert oil into the bottom of the bearing would not force out the > air bubbles and would not fill the sump as we desire. > ## OPEN ## I have qualms about drilling a hole into the bottom of the bearing = well. Though I don't want to add anymore complexity, I think it would be = easier if we *have* to drill a relief passage that it be done from the top. This avoids having to invert the subchassis or having a low-point leak (that might go undetected for awhile in the sand. Though I might have the = platter off and on a couple of times, I hope that I don't have to pull the subchassis up out of the sand too many times, and have to reposition = and re-level and rebalance air bladders too many times! > > 5) Adding a threaded hole in the bottom of the bearing to accomodate = a > tip-toe. This will add a little to the cost of the bearing and may > or may not be useful. But since the cost is low I suggest that we > do it. Better to be flexible. > ## CLOSED ## Thank you, concur. ----- Original Message ----- From: Steve Zettel To: Igor Kuznetsoff ; Chris Brady Sent: Monday, January 17, 2000 9:45 PM Subject: Re: Scheu-Bearing & Machining on 1/17/00 18:32, Igor Kuznetsoff at gorkuz@yahoo.com 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 ----- Original Message ----- From: Steve Zettel Sent: Monday, January 17, 2000 9:59 PM Subject: Re: Scheu-Bearing & Machining on 1/17/00 19:33, Thom Mackris / Joan Panzella at = tmackris@earthlink.net wrote: My feeling is that closer tolerances (clearances) and lighter lube are = the way to go, and that heavy oil is just a bandaid to take the slop out of = less finely machined bearings (more slop =3D more vibration =3D more need = for vibration damping heavy oil). In support of this I offer the direction Oracle has taken with their = latest MK V Delphi -- "zero" clearance between spindle and well, accomplished = by nylon or delrin tipped bearing surface pads that are lightly run into = the spindle (on threaded inserts, I believe). Their claim is that it dramatically reduces the microvibrations present in other bearings, including their earlier ones. Critical evaluation by audio reviewers suggests *something* is good is = going on because they feel the MK V is the best Oracle yet. Also, commercial turntables are built to price (except for cost no = object "statement" turntables like the Clearaudio or Goldmunds) and extremely = tight tolerance bearings are usually more $$$ than not. Steve ----- Original Message ----- From: Thom Mackris / Joan Panzella Sent: Monday, January 17, 2000 10:13 PM Subject: Re: Scheu-Bearing & Machining Gosh, Maybe you (and Oracle) are on to something here Steve (with respect to = light oil and tight tolerances). I'm now teetering and tottering toward = light oil and the tightest possible tolerances. Help !! 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 ----- Original Message ----- From: Chris Brady Sent: Monday, January 17, 2000 10:51 PM Subject: Re: Scheu-Bearing & Platter 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: > 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 big mistake > 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. 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 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