Subject: Re: [teres] Motor Pod Date: Sun, 5 Mar 2000 22:18:44 -0700 From: Thom Mackris, Thom Mackris To: teres@aiko.com All, I'm still not certain which way I'll go with the mount at this point. Igor's idea has a certain elegance from an engineering & aesthetic standpoint. It seems as if getting verticality is one challenge. One point / question for the group. I haven't played with my Merrill setup in a year and a half or so, so my memory is a bit fuzzy - help me on this, gang... The Merrill has a convex surface on the pulley, and if I recall, the belt wanders toward either flange when the the pulley is not exactly parallel to the platter. If I my memory is correct, then there is *no* problem knowing when the pulley perfectly is parallel. Getting there may take some fiddling as you incrementally walk one or both points. What I'm having trouble visualizing is whether there are any stability differences between the counterbalanced image that Igor proposes and having the mass firmly seated on tip toes or even a squishy surface. I'm thinking from a perspective of minute excentricities in any part of the pulley, platter, belt system; be it machining or the join of the belt (knot on string, ovelapping tape, etc.). Would more wobble be induced? I'm not sure. In my earlier musings about a sled or tracks, I think you'd want to tighten down the screws when you set the correct tension in order to couple the motor to the mass. A problem with this system is that If there were any stretch in the belt, you wouldn't necessarily know it unless you checked. Our volt meter would of course be helpful here. Confused in Philadelphia (this week only - Philadelphia, not confused), Thom __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Motor Pod Date: Mon, 6 Mar 2000 00:11:33 -0700 From: phclark, phclark To: teres@aiko.com -----Original Message----- From: Thom Mackris To: teres@aiko.com Date: Sunday, March 05, 2000 9:18 PM Subject: Re: [teres] Motor Pod >All, > >I'm still not certain which way I'll go with the mount at this point. >Igor's idea has a certain elegance from an engineering & aesthetic >standpoint. > >It seems as if getting verticality is one challenge. One point / question >for the group. I haven't played with my Merrill setup in a year and a half >or so, so my memory is a bit fuzzy - help me on this, gang... > >The Merrill has a convex surface on the pulley, and if I recall, the belt >wanders toward either flange when the the pulley is not exactly parallel to >the platter. If I my memory is correct, then there is *no* problem knowing >when the pulley perfectly is parallel. Getting there may take some >fiddling as you incrementally walk one or both points. > >What I'm having trouble visualizing is whether there are any stability >differences between the counterbalanced image that Igor proposes and having >the mass firmly seated on tip toes or even a squishy surface. I'm thinking >from a perspective of minute excentricities in any part of the pulley, >platter, belt system; be it machining or the join of the belt (knot on >string, ovelapping tape, etc.). Would more wobble be induced? I'm not >sure. > >In my earlier musings about a sled or tracks, I think you'd want to tighten >down the screws when you set the correct tension in order to couple the >motor to the mass. Spposedly, the mass of the pod (and perhaps other measures) would achieve the desired coupling. If you clamp the pod down, you're back to needing an idler. This is part of the point about a completely passive system. Igor's wouldn't have to be retensioned, or checked once it was set. At the risk of oxymoron, the "passive" system is dynamic in that the weight (tension) is constant, and continuously exerts the moment of the weight, unlike clamping it and trusting that the belt won't stretch. The principal merit in the track idea is that the pod would be free to move under to tensioner's weight, without losing its orientation, a potential problem with the Two Point idea. By clamping, I suspect you would have defeated the idea. >A problem with this system is that If there were any >stretch in the belt, you wouldn't necessarily know it unless you checked Once again, Igor's Magic Idea conceivably might be a little difficult to set up, but barring the belt stretching unduly, it is set and forget. Peter C Subject: RE: [teres] Motor Pod Date: Mon, 6 Mar 2000 09:27:09 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Jon: Good point. However, we can radius the pulley with a radius that will yield a constant geometry as the motor pivots. This will work because we can keep the pivoting to a small range. That way we can still use a flat belt. Cheers, Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: Jon Lane [SMTP:jhlane@email.msn.com] > Sent: Friday, March 03, 2000 11:14 PM > To: teres@aiko.com > Subject: RE: [teres] Motor Pod > > > > > > Peter, > > Does this help? (see below) > > > > Igor > > > Gentlemen, > > Respectfully, the pivoting motor assumes a round belt, > right? The geometry is compounded with this arrangement > making flat belts (magnetic tape) impossible to use. Such > belts will chafe the pulley and run against one or the other > rim depending on motor tilt. > > I've been taking the following as truths: > > 1. A slightly radiused pulley for self centering a flat > belt. > > 2. Solidly fixing the motor against as much mass as > possible. > > 3. Pursuant both of these, orienting the motor shaft > absolutely vertical with respect to the platter rim. > > From there, a variety of tensioning methods can be used from > merely sliding the motor base away from the platter to using > a idler. Investigations into instrumentation drives reveals > the latter is common - I'd intended to use it myself. A > spring-tensioned idler using a quiet rotating pulley would > be simple, cheap and effective. And self-tending. > > But tilting the motor from perfectly vertical eliminates the > flat belt option. Is the pulley design decided on at this > point? > > Jon lane > Subject: RE: [teres] Motor Pod Date: Mon, 6 Mar 2000 09:28:44 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Thom: We want to radius the pulley for centering; if we make the radius the right dimension, it will retain the geometry even if the motor shaft is not perfectly vertical. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: Thom Mackris / Joan Panzella [SMTP:tmackris@earthlink.net] > Sent: Saturday, March 04, 2000 12:09 AM > To: teres@aiko.com > Subject: Re: [teres] Motor Pod > > You were echoing my thoughts, Jon - getting the vertical plane of the > motor > shaft and the platter bearing perfectly parallel appears as if it would be > a > chore. Any thoughts on how this can be accomplished without staying up > late? > > Thom > > > ----- Original Message ----- > From: Jon Lane > To: > Sent: Friday, March 03, 2000 11:14 PM > Subject: RE: [teres] Motor Pod > > > > > Peter, > > Does this help? (see below) > > > > Igor > > > Gentlemen, > > Respectfully, the pivoting motor assumes a round belt, > right? The geometry is compounded with this arrangement > making flat belts (magnetic tape) impossible to use. Such > belts will chafe the pulley and run against one or the other > rim depending on motor tilt. > > I've been taking the following as truths: > > 1. A slightly radiused pulley for self centering a flat > belt. > > 2. Solidly fixing the motor against as much mass as > possible. > > 3. Pursuant both of these, orienting the motor shaft > absolutely vertical with respect to the platter rim. > > >From there, a variety of tensioning methods can be used from > merely sliding the motor base away from the platter to using > a idler. Investigations into instrumentation drives reveals > the latter is common - I'd intended to use it myself. A > spring-tensioned idler using a quiet rotating pulley would > be simple, cheap and effective. And self-tending. > > But tilting the motor from perfectly vertical eliminates the > flat belt option. Is the pulley design decided on at this > point? > > Jon lane > > > Subject: Re: [teres] Motor Pod Date: Mon, 6 Mar 2000 10:03:50 -0700 From: Roscoe Primrose, Roscoe Primrose To: teres@aiko.com "Schei, Kenneth" wrote: > > Jon: > > Good point. However, we can radius the pulley with a radius that > will yield a constant geometry as the motor pivots. This will work because > we can keep the pivoting to a small range. That way we can still use a flat > belt. > But, as Jon mentioned, if the motor is not vertical. even with a radiused pulley you're going to get chaffing because the pulley is rotating off the horizontal. Look at lit like this. Assume the top of the pulley is a little further away from the platter than the bottom. As the belt first contacts the pulley, the pulley surface is rotating at a downward angle to the belt. On the side where the belt is leaving the pulley, the surface is rotating at an upward angle to the belt. The only way the radiused pulley can be used w/o chaffing is if it's vertical. Peace -- Roscoe Primrose -- mailto:roscoe@aiko.com -- http://www.aiko.com/roscoe "Once in a while you get shown the light In the strangest of places if you look at it right." Robert Hunter "640K ought to be enough for anybody" , Bill Gates, 1981 Subject: Re: [teres] Motor Pod Date: Mon, 6 Mar 2000 10:23:44 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com If the suggested bubble level was on the pod, a glance at it would tell you all need to know. It would still be vertical , or not. If the belt stretches enough to need touch up, the level could tell you, or just look to see where the belt is riding on the pulley. Igor --- Thom Mackris wrote: > All, > > I'm still not certain which way I'll go with the > mount at this point. > Igor's idea has a certain elegance from an > engineering & aesthetic > standpoint. > > It seems as if getting verticality is one challenge. > One point / question > for the group. I haven't played with my Merrill > setup in a year and a half > or so, so my memory is a bit fuzzy - help me on > this, gang... > > The Merrill has a convex surface on the pulley, and > if I recall, the belt > wanders toward either flange when the the pulley is > not exactly parallel to > the platter. If I my memory is correct, then there > is *no* problem knowing > when the pulley perfectly is parallel. Getting > there may take some > fiddling as you incrementally walk one or both > points. > > What I'm having trouble visualizing is whether there > are any stability > differences between the counterbalanced image that > Igor proposes and having > the mass firmly seated on tip toes or even a squishy > surface. I'm thinking > from a perspective of minute excentricities in any > part of the pulley, > platter, belt system; be it machining or the join of > the belt (knot on > string, ovelapping tape, etc.). Would more wobble > be induced? I'm not > sure. > > In my earlier musings about a sled or tracks, I > think you'd want to tighten > down the screws when you set the correct tension in > order to couple the > motor to the mass. A problem with this system is > that If there were any > stretch in the belt, you wouldn't necessarily know > it unless you checked. > Our volt meter would of course be helpful here. > > Confused in Philadelphia (this week only - > Philadelphia, not confused), > Thom > > > __________________________________________________ > Do You Yahoo!? > Talk to your friends online with Yahoo! Messenger. > http://im.yahoo.com > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] Motor Pod Date: Mon, 6 Mar 2000 10:31:48 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Perhaps if the cones were mounted with threaded shafts, and maybe a lock nut? Igor --- "Schei, Kenneth" wrote: > Thom: > > We want to radius the pulley for centering; if we > make the radius the right > dimension, it will retain the geometry even if the > motor shaft is not > perfectly vertical. > > Ken > > Ken Schei, P.E. > Project Engineer > Antarctic Support Associates > Email address: scheike@asa.org > Phone: 303-643-0163 > > > > > > -----Original Message----- > > From: Thom Mackris / Joan Panzella > [SMTP:tmackris@earthlink.net] > > Sent: Saturday, March 04, 2000 12:09 AM > > To: teres@aiko.com > > Subject: Re: [teres] Motor Pod > > > > You were echoing my thoughts, Jon - getting the > vertical plane of the > > motor > > shaft and the platter bearing perfectly parallel > appears as if it would be > > a > > chore. Any thoughts on how this can be > accomplished without staying up > > late? > > > > Thom > > > > > > ----- Original Message ----- > > From: Jon Lane > > To: > > Sent: Friday, March 03, 2000 11:14 PM > > Subject: RE: [teres] Motor Pod > > > > > > > > > Peter, > > > Does this help? (see below) > > > > > > Igor > > > > > > Gentlemen, > > > > Respectfully, the pivoting motor assumes a round > belt, > > right? The geometry is compounded with this > arrangement > > making flat belts (magnetic tape) impossible to > use. Such > > belts will chafe the pulley and run against one or > the other > > rim depending on motor tilt. > > > > I've been taking the following as truths: > > > > 1. A slightly radiused pulley for self centering > a flat > > belt. > > > > 2. Solidly fixing the motor against as much mass > as > > possible. > > > > 3. Pursuant both of these, orienting the motor > shaft > > absolutely vertical with respect to the platter > rim. > > > > >From there, a variety of tensioning methods can > be used from > > merely sliding the motor base away from the > platter to using > > a idler. Investigations into instrumentation > drives reveals > > the latter is common - I'd intended to use it > myself. A > > spring-tensioned idler using a quiet rotating > pulley would > > be simple, cheap and effective. And self-tending. > > > > But tilting the motor from perfectly vertical > eliminates the > > flat belt option. Is the pulley design decided on > at this > > point? > > > > Jon lane > > > > > > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Motor Pod Date: Mon, 6 Mar 2000 11:12:19 -0700 From: phclark, phclark To: teres@aiko.com That's how I was planning to do it. Since you have to mount it in some fashion, it may as well be adjustable, even if only once. I have sexy, big speaker cones and lethal little spikes on hand, both have lock nuts. Peter C -----Original Message----- From: Igor Kuznetsoff To: teres@aiko.com Date: Monday, March 06, 2000 9:32 AM Subject: RE: [teres] Motor Pod >Perhaps if the cones were mounted with threaded >shafts, >and maybe a lock nut? > Igor > >--- "Schei, Kenneth" wrote: >> Thom: >> >> We want to radius the pulley for centering; if we >> make the radius the right >> dimension, it will retain the geometry even if the >> motor shaft is not >> perfectly vertical. >> >> Ken >> >> Ken Schei, P.E. >> Project Engineer >> Antarctic Support Associates >> Email address: scheike@asa.org >> Phone: 303-643-0163 >> >> >> >> >> > -----Original Message----- >> > From: Thom Mackris / Joan Panzella >> [SMTP:tmackris@earthlink.net] >> > Sent: Saturday, March 04, 2000 12:09 AM >> > To: teres@aiko.com >> > Subject: Re: [teres] Motor Pod >> > >> > You were echoing my thoughts, Jon - getting the >> vertical plane of the >> > motor >> > shaft and the platter bearing perfectly parallel >> appears as if it would be >> > a >> > chore. Any thoughts on how this can be >> accomplished without staying up >> > late? >> > >> > Thom >> > >> > >> > ----- Original Message ----- >> > From: Jon Lane >> > To: >> > Sent: Friday, March 03, 2000 11:14 PM >> > Subject: RE: [teres] Motor Pod >> > >> > >> > >> > > Peter, >> > > Does this help? (see below) >> > > >> > > Igor >> > >> > >> > Gentlemen, >> > >> > Respectfully, the pivoting motor assumes a round >> belt, >> > right? The geometry is compounded with this >> arrangement >> > making flat belts (magnetic tape) impossible to >> use. Such >> > belts will chafe the pulley and run against one or >> the other >> > rim depending on motor tilt. >> > >> > I've been taking the following as truths: >> > >> > 1. A slightly radiused pulley for self centering >> a flat >> > belt. >> > >> > 2. Solidly fixing the motor against as much mass >> as >> > possible. >> > >> > 3. Pursuant both of these, orienting the motor >> shaft >> > absolutely vertical with respect to the platter >> rim. >> > >> > >From there, a variety of tensioning methods can >> be used from >> > merely sliding the motor base away from the >> platter to using >> > a idler. Investigations into instrumentation >> drives reveals >> > the latter is common - I'd intended to use it >> myself. A >> > spring-tensioned idler using a quiet rotating >> pulley would >> > be simple, cheap and effective. And self-tending. >> > >> > But tilting the motor from perfectly vertical >> eliminates the >> > flat belt option. Is the pulley design decided on >> at this >> > point? >> > >> > Jon lane >> > >> > >> > >> >__________________________________________________ >Do You Yahoo!? >Talk to your friends online with Yahoo! Messenger. >http://im.yahoo.com > Subject: Re: [teres] Motor Pod Date: Mon, 6 Mar 2000 11:14:02 -0700 From: phclark, phclark To: teres@aiko.com Certainly. If the belt's not running true for whatever reason, it will be apparent and then you adjust the pod. It's not as if this will have to be done ever time the table is powered up (I hope/think.) Fundamentally, the belt is either happy 8^), or not. If not, adjust the pod until it is and get on with your life. Peter C -----Original Message----- From: Igor Kuznetsoff To: teres@aiko.com Date: Monday, March 06, 2000 9:24 AM Subject: Re: [teres] Motor Pod >If the suggested bubble level was on the pod, a glance >at it would tell you all need to know. It would still >be vertical , or not. If the belt stretches enough to >need touch up, the level could tell you, or just look >to see where the belt is riding on the pulley. > > Igor > >--- Thom Mackris wrote: >> All, >> >> I'm still not certain which way I'll go with the >> mount at this point. >> Igor's idea has a certain elegance from an >> engineering & aesthetic >> standpoint. >> >> It seems as if getting verticality is one challenge. >> One point / question >> for the group. I haven't played with my Merrill >> setup in a year and a half >> or so, so my memory is a bit fuzzy - help me on >> this, gang... >> >> The Merrill has a convex surface on the pulley, and >> if I recall, the belt >> wanders toward either flange when the the pulley is >> not exactly parallel to >> the platter. If I my memory is correct, then there >> is *no* problem knowing >> when the pulley perfectly is parallel. Getting >> there may take some >> fiddling as you incrementally walk one or both >> points. >> >> What I'm having trouble visualizing is whether there >> are any stability >> differences between the counterbalanced image that >> Igor proposes and having >> the mass firmly seated on tip toes or even a squishy >> surface. I'm thinking >> from a perspective of minute excentricities in any >> part of the pulley, >> platter, belt system; be it machining or the join of >> the belt (knot on >> string, ovelapping tape, etc.). Would more wobble >> be induced? I'm not >> sure. >> >> In my earlier musings about a sled or tracks, I >> think you'd want to tighten >> down the screws when you set the correct tension in >> order to couple the >> motor to the mass. A problem with this system is >> that If there were any >> stretch in the belt, you wouldn't necessarily know >> it unless you checked. >> Our volt meter would of course be helpful here. >> >> Confused in Philadelphia (this week only - >> Philadelphia, not confused), >> Thom >> >> >> __________________________________________________ >> Do You Yahoo!? >> Talk to your friends online with Yahoo! Messenger. >> http://im.yahoo.com >> >> >__________________________________________________ >Do You Yahoo!? >Talk to your friends online with Yahoo! Messenger. >http://im.yahoo.com > Subject: Re: [teres] Motor Pod Date: Mon, 6 Mar 2000 11:22:30 -0700 From: phclark, phclark To: teres@aiko.com We still are talking a matter of only a couple of degrees of pivot, I suspect. The amount of belt tension exacerbates the problem, too. We still don't know how much tension will actually be required, though I suspect someone has an idea of the range. Also, how much slippage will/can be tolerated. This is belt dependent, but I think the range is a knowable quantity. Peter C -----Original Message----- From: Schei, Kenneth To: 'teres@aiko.com' Date: Monday, March 06, 2000 8:27 AM Subject: RE: [teres] Motor Pod > Jon: > > Good point. However, we can radius the pulley with a radius that >will yield a constant geometry as the motor pivots. This will work because >we can keep the pivoting to a small range. That way we can still use a flat >belt. > > Cheers, Ken > > Ken Schei, P.E. > Project Engineer > Antarctic Support Associates > Email address: scheike@asa.org > Phone: 303-643-0163 > > > > >> -----Original Message----- >> From: Jon Lane [SMTP:jhlane@email.msn.com] >> Sent: Friday, March 03, 2000 11:14 PM >> To: teres@aiko.com >> Subject: RE: [teres] Motor Pod >> >> >> >> >> > Peter, >> > Does this help? (see below) >> > >> > Igor >> >> >> Gentlemen, >> >> Respectfully, the pivoting motor assumes a round belt, >> right? The geometry is compounded with this arrangement >> making flat belts (magnetic tape) impossible to use. Such >> belts will chafe the pulley and run against one or the other >> rim depending on motor tilt. >> >> I've been taking the following as truths: >> >> 1. A slightly radiused pulley for self centering a flat >> belt. >> >> 2. Solidly fixing the motor against as much mass as >> possible. >> >> 3. Pursuant both of these, orienting the motor shaft >> absolutely vertical with respect to the platter rim. >> >> From there, a variety of tensioning methods can be used from >> merely sliding the motor base away from the platter to using >> a idler. Investigations into instrumentation drives reveals >> the latter is common - I'd intended to use it myself. A >> spring-tensioned idler using a quiet rotating pulley would >> be simple, cheap and effective. And self-tending. >> >> But tilting the motor from perfectly vertical eliminates the >> flat belt option. Is the pulley design decided on at this >> point? >> >> Jon lane >> > Subject: RE: [teres] Motor Pod Date: Mon, 6 Mar 2000 13:32:06 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > If the suggested bubble level was on the pod, a glance > at it would tell you all need to know. It would still > be vertical , or not. If the belt stretches enough to > need touch up, the level could tell you, or just look > to see where the belt is riding on the pulley. > > Igor Relatively speaking, the bubble level is a low-precision, subjective evaluation of conditions. Machined parts guarantee perfect alignment, on the other hand. Jon Lane Subject: RE: [teres] Motor Pod Date: Mon, 6 Mar 2000 15:25:15 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com; teres@aiko.com Thats' right Igor's idea doesn't insure perfect alignment,but with the right pulley may not have to. Another concern I have is what happens at start up, does the belt slip or will it grab causing the motor to teeter toter back and forth on its pivot and if its get too volent then it might cause the pod to move slightly, which would loosen the belt. Guess we better make the pod (stainless steel) pretty heavy just in case. Guess it depends on the belt and weight used and how much torque the motor has. We have unknowns here. I can see another idea that uses a cam action to keep belt tension. By drilling a offset hole or holes at the bottom of the pod and pivot this on a dowel pin on the platform then using Igor's weight (heavier weight) and string to rotate the pod, the offset (cam action) would move the pod away from the platter tighting the belt. Problem here of course is friction, and the only cheap and easy way I can think of right now is a flat polished surface on the bottom of the pod and have it ride on 3 teflon pads affixed to the platform. I think Igor's idea is still better from a performance stand point, but just another idea. Stan At 12:26 PM 3/6/2000 -0700, Jon Lane wrote: >> If the suggested bubble level was on the pod, a glance >> at it would tell you all need to know. It would still >> be vertical , or not. If the belt stretches enough to >> need touch up, the level could tell you, or just look >> to see where the belt is riding on the pulley. >> >> Igor > > >Relatively speaking, the bubble level is a low-precision, >subjective evaluation of conditions. Machined parts >guarantee perfect alignment, on the other hand. > >Jon Lane > Subject: RE: [teres] Motor Pod Date: Mon, 6 Mar 2000 20:40:31 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com; teres@aiko.com; teres@aiko.com Sorry Guys, I just can't leave this thing alone. You'll need paper & pencil to figure this one. Forget what I said below, after further thoughts it should be possible to use the torque of the motor to tighten the belt automatically. All that is needed is a thust bearing to allow the motor pod to rotate freely. Ok picture this, your looking down the left side of the turntable with motor in the foregound and platter in the background. Now the motor spins clockwise which creates a counter-clockwise torque on the pod. With a offset spindle to the right of center (say 3/8") of the pod. The counter-clockwise force will tighten the belt. Way cool Uh. Now at full speed if the belt starts to slip there will be less torque applied and thus less tension, now you may have tension runaway. So you may need to add a little weight for insurance. Or just reconfigure it where less torque will give more tension by using a string and weight to bias the pod in a clockwise direction, with the spindle to the left of center now. The torque is now opposing the weight and if the belt starts to slip there will be less torque to counter the weight and the weight will tighten the belt. But this config. may have a lot of slippage at startup because of higher friction (thus higher torque fighting the weight) caused by the belt slowly moving. But once up to speed it should work perfect. Happy confusions, Stan At 03:17 PM 3/6/2000 -0600, Stanley Goudge wrote: > Thats' right Igor's idea doesn't insure perfect alignment,but with the right pulley may not have to. >Another concern I have is what happens at start up, does the belt slip or will it grab causing the motor >to teeter toter back and forth on its pivot and if its get too volent then it might cause the pod to move slightly, >which would loosen the belt. Guess we better make the pod (stainless steel) pretty heavy just in case. >Guess it depends on the belt and weight used and how much torque the motor has. We have unknowns here. > > I can see another idea that uses a offset action to keep belt tension. By drilling a offset hole or holes >at the bottom of the pod and pivot this on a dowel pin on the platform then using Igor's weight (heavier weight) >and string to rotate the pod, the offset (cam action) would move the pod away from the platter tighting the belt. >Problem here of course is friction, and the only cheap and easy way I can think of right now is a flat >polished surface on the bottom of the pod and have it ride on 3 teflon pads affixed to the platform. >I think Igor's idea is still better from a performance stand point, but just another idea. > >Stan > > > >At 12:26 PM 3/6/2000 -0700, Jon Lane wrote: >>> If the suggested bubble level was on the pod, a glance >>> at it would tell you all need to know. It would still >>> be vertical , or not. If the belt stretches enough to >>> need touch up, the level could tell you, or just look >>> to see where the belt is riding on the pulley. >>> >>> Igor >> >> >>Relatively speaking, the bubble level is a low-precision, >>subjective evaluation of conditions. Machined parts >>guarantee perfect alignment, on the other hand. >> >>Jon Lane >> > Subject: RE: [teres] Motor Pod Date: Mon, 6 Mar 2000 21:26:06 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > Sorry Guys, > I just can't leave this thing alone. You'll > need paper & pencil to figure this one. Forget > what I said below, > after further thoughts it should be possible to > use the torque of the motor to tighten the belt > automatically. > All that is needed is a thust bearing to allow > the motor pod to rotate freely. > Ok picture this, your looking down the left side > of the turntable with motor in the foregound and > platter in the background. > Now the motor spins clockwise which creates a > counter-clockwise torque on the pod. With a offset > spindle to the right of center (say 3/8") of the > pod. The counter-clockwise force will tighten the belt. Yes. The motor rotates "into" the drive force and holds tension. I'm liking the eccentric mounting notion more and more. Off the shelf bearing races or lubricated bushing halves could rim the top-plate and allow for quiet, precise rotation. A weight or spring is again an adjustable constant to apply initial and then restorative forces both preceding startup and following stabilizing at final speed. During acceleration, the motor rotation is complimentary and creates more tension than without the cam system. One concern: Choice of belt material will play a predominant role in friction between pulley and belt which will need to go hand in hand with the amount of static tension in the system, unless I miss my guess. I'd guess further that a slick plastic film belt will all but ignore the effect of the rotation driving "into" the torque (at least with a line-contact drive pulley such as our radiused affair) while a very tacky rubber belt may hang up even more than desired. Or at least something to that overall effect. But the weighting of this rotation is indeed an effective means of generating correct tension. Jon Lane Subject: RE: [teres] Motor Pod Date: Mon, 6 Mar 2000 21:26:17 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > I think that the disadvantage of my original > musing - mounting the motor on > sliding rails and tensioning somehow is that you > are not firmly coupling the > motor to the mass in the pod. > Thom Thom, in this scheme, I'd suggest gliding the entire pod, motor securely bolted directly to 20 lbs of metal. A pair of short linear ways and bearing sets are all you'd need. Jon lane Subject: RE: [teres] Motor Orientation Date: Mon, 6 Mar 2000 21:35:12 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > Jon, > > This also has merit. I guess my principal > objection is to the idler, which, > while it will do the job, it also can/will add > variables we are striving > mightily to eliminate. A track system utilizing > passive weight for > tensioning has big possibility, though it is more > complex than Igor's idea. > > Should we decide collectively to go down this > path, it would require, > however, almost as much thought as the rest, plus > a bunch of fabrication. > Perhaps others have given tracks, etc. more thought? > > Peter C Peter, in the interest of developing this idea to the point of making a decision, I wish to point out that the scheme would require only a few basic components: 1. The motor bolted solidly into a block built for the task. I plan aluminum of at least a few inches on a side by a half foot deep to lay alongside the table base. 2. Two off the shelf bearing races installed into milled reliefs in the lower half of this block. 3. Two linear ways to receive the bearings. That's it. The choice of a spring or weight is left up to the individual. The bearing parts may be purchased from bearing houses and the aluminum block could be standard 6061 stock or something, with minimal machining to accept the motor and races. Our planned top plate is even unnecessary. Jon Lane Subject: Re: [teres] Motor Pod Date: Mon, 6 Mar 2000 22:40:57 -0700 From: Thom Mackris, Thom Mackris To: teres@aiko.com Jon, Re-reading your Saturday post, you raise some good points. I missed your recent thoughts on what to sled. Indeed, we all seem to be in agreement with respect to the benefits of keeping the motor firmly coupled to the mass of the pod. I can very easily get behind the concept of the entire motor pod being on a sled. Sledding would certainly be more resistant to the effects of motor cogging than would pivoting (Igor's design, for lack of a better descriptive term) at least in theory. Whether or not this would be audible would have to be determined empirically. For this reason, I think my focus is going to shift to something that is easily convertable from one approach to the other. This ought to be fairly simple to accomplish without sacrificing aesthetics. I honestly don't think that pulley chafing will be an issue in Igor's proposal, but I may be wrong. This is more of an intuitive feel than something I can justify with a geometrical proof as Ken has alluded to. Those of us are who are thinking about adding belt tensioning force prefer using gravity for obvious reasons of energy (non)storage. I now wonder as you do if a spring (rubber or metal) could effectively supply the force. In the "sled" approach, perhaps the mass of the pod is high enough to filter out any spring resonances. In Igor's approach, I think gravity would be necessary (and way cool looking), since the system depends directly on the locating force for it's stability. Cheers, Thom ----- Original Message ----- From: Jon Lane To: Sent: Saturday, March 04, 2000 2:11 PM Subject: RE: [teres] Motor Pod > > And I want to be clear that this idea has its obvious > merits: The belt is under constant tension and with an > adjustable, yet invariable as standard to work from. > Gravity. The notion is VERY attractive provided all of the > designed elements are balanced, IMHO. > > Two impractical sides to this, as I see them in my limited > perspective. > > 1. The belt _will_ chafe if the pulley is in anything other > than perfect upright alignment. Assuming a radiused > pulley - and we are, right? - the pulley surface will scribe > infinite and ever so slight arcs against the driven surface > of the belt when the motor is tipped off axis. Yes, the > belt will center around some portion of this "ball" at the > end of the motor shaft, but intuitively, the drive will be > in a constant state of imperceptible friction. Noise? > Theoretically, yes. How much? Don't know. Audible? Don't > know again. > > 2. With a motor _not_ in firm contact with its independent > chassis, any cogging (Manfred?) that may be present will > work against the compliant mounting. Again perhaps > completely imperceptibly, the motor will shudder constantly > during operation unless it's rigidly fixed. > > Now this, in my mind, raises another point. If the motor > _is_ bolted securely into another twenty pounds of housing, > will any of this theoretical cogging make its way into the > drive, not being able to go anywhere else? Seems to me a > balance needs to be struck. Time to consult the motor > experts in attendance. > > I hasten to add my disclaimer which is that I have always > avoided compliant interfaces in any transducer system. I do > not use rubber mountings for my drivers in spite of their > obvious damping because such resilient interfaces introduce > another resonant mechanism entirely - they may eliminate > say, HF resonance, but they must impart, by nature, a > predominant LF fundamental in it's place. Might the same > happen with a resilient motor mounting? An entire spectrum > of upper harmonics are attenuated to the degree that any > such damped mounting can, but a new and pronounced resonance > (vibration, actually) is introduced where the suspended > weight, cogging speed (if any) and resilient Q all interact. > > If this is correct (correct me; this is speculation!) than > would we be better served by a rigid, dead-vertical motor > environment? > > If so, how do we tension the belt? This major problem > remains. > > Personally, I believe miniature belt tensioners are > perfectly suitable. These have justifiably been brought > into question, however for reasons of being, we assume, > noisy. Okay, I'd suggest "sledding" the entire motor > housing. That is, allowing it to float to and fro in one > plane only against one intentional constant; either a spring > set or Igor's elegant weight. > > What are the benefits I see here? > > 1. Perfect alignment between platter and pulley. > 2. An as-specified environment for the flat, rigid belt to > live in. It will simply seek its own position related only > to the pulley radius and will be driven dead parallel to > it's center line. As before, the platter end will follow > suit. > 3. Thusly, near-zero out-of-alignment condition to create > chafing against the radiused pulley. The "quietest" > possible drive, assuming this is desirable. > 4. While I don't feel belt wear is really a practical > issue, we can take this one step further and reduce the > pulley to a flat design just as is typically done in tape > drives. Or perhaps a really huge radius like a half a foot > or so. This drives the belt uniformly across its entire > surface, or in the case of the large radius option, at least > in the way least destructive to the belt's shape. Mylar and > Kapton hate to stretch. > > > Not really, the act of sliding doesn't tension > > the belt, adjustment of the > > weight does. That's precise. > > But sliding on a design intended for the purpose would be > perhaps the best solution. And one completely unique to > Teres which I really like. No other 'table regardless of > cost or rated excellence to my knowledge uses a movable > motor sled with a tensioning constant like gravity or, to a > lesser degree, a set of springs. Let's hang it out there! > > > Again, I don't have any particular problem with > > idlers. I was intending to > > use one myself before Igor came along. The > > difficulty arises from their > > implementation in the spirit of practicality and > > KISS. As I've often said > > about coupling capacitors, "no mechanical monkey > > motion (or capacitor) is > > better than the best you can buy." > > True, but I'd ask that we isolate the complexity of > performing a simple task from the simplicity of the task > itself. Frankly, excepting the presumed costs involved, I'd > wager that "sledding" the entire motor against a gravity > constant is actually far simpler in _function_ and use than > attempting to orient a motor in a geometrically variable > environment. > > > This is a related but separate subject. I am > > graced with concrete floors > > and certain considerations for other Teres > > listees possibly don't apply to > > my installation. My intent is to try using a > > massive plinth (135# > > machinists' surface plate) only to start, with > > separate subchassis for > > motor, platter and arm. On a concrete floor this > > might prove to be > > sufficient without complexifying. I always have > > the option to add sand > > boxes and inner tubes should the initial > > installation prove unsatisfactory > > With exception to isolating the arm, I'm dead parallel with > you here Peter. Mine and yours are going to have many > resemblances... > > > Unanticipated resonances elsewhere in the system... > > Agreed. Smart variables built in at the right places are a > godsend when it comes time to dial in. The difference > between fabulous sound and transcendent sound is usually > found in those adjustments, IME. > > > Again, I'm not trying to be argumentative. > > Not taken that way, sir. Your passion is why this project > is working! > > > Assuming that the motor is as > > quiet as we can procure, and that the assembly is > > sufficiently massive to > > damp the remaining nasty, utilization of the > > simplest tensioning method > > would seem to be the path to follow. If it > > doesn't work, go to Plan B. > > I'm going to slide my entire motor... Complex, but simple, > if you catch my meaning. > > Jon Lane > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] Motor Pod Date: Tue, 7 Mar 2000 04:38:26 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Gentlemen, Ken, well put. For starters, when a flat belt goes over a radiused surface, some "chafing" or "squirming" has to occur regardless. With proper radiusing, the additional chafing from 1-2 degrees (which should easy enough to stay within) of off-axis alignment won't make an appreciable difference. Finally, Ken's excellent point: ride stability vs. minor chafing. Instability of belt ride position will cause fluctuations of belt tension, which can translate into FM distortion, probably in the "flutter" range. A little chafing (just what problems can we expect from that?) would be a small trade-off for belt stability, a plus to think about. Igor --- "Schei, Kenneth" wrote: > Roscoe: > > In theory you are correct, but in practice my method > is reasonable. The > whole reason for a radius on the pulley is because > we can't be perfectly > accurate. Any imperfection in alignment will cause > the belt to walk off a > "flat" pulley; the radius causes it to find the > equilibrium point and ride > there. We can tolerate a small amount of pivoting > of the motor axis because > of the classic small angle relationship. The sine > of 0 degrees is 0.00000. > That is the perfect alignment we are seeking. > However, the sine of 1 degree > is 0.01745, the sine of 2 degrees is 0.03490, and 3 > degrees is 0.05233. I > think +/- 2 degrees would give us an ample range for > belt tightening, but we > should adjust the initial setting to be as vertical > as we can get it. If > our axis is 2 degrees out of plumb, the lateral or > "walking" force of the > belt will be 0.0349 times the belt tension. As the > belt walks up the slope > of the pulley the centering force of the pulley > increases. The equilibrium > point is where the centering force exactly equals > the "walking" force, or > 0.0349 times the belt tension, and that's where the > belt will ride. It may > well be that a slight canting of the motor axis will > actually make the belt > ride more consistently on the pulley, with less > walking or hunting back and > forth. > > Incidently, the correct radius for the face of the > pulley for this system is > equal to the radius from the pivot point of the > motor mount to the > horizontal centerline of the pulley. > > Cheers, Ken > > Ken Schei, P.E. > Project Engineer > Antarctic Support Associates > Email address: scheike@asa.org > Phone: 303-643-0163 > > > > -----Original Message----- > > From: Roscoe Primrose [SMTP:roscoe@aiko.com] > > Sent: Monday, March 06, 2000 9:05 AM > > To: teres@aiko.com > > Subject: Re: [teres] Motor Pod > > > > "Schei, Kenneth" wrote: > > > > > > Jon: > > > > > > Good point. However, we can radius the > pulley with a radius > > that > > > will yield a constant geometry as the motor > pivots. This will work > > because > > > we can keep the pivoting to a small range. That > way we can still use a > > flat > > > belt. > > > > > > > But, as Jon mentioned, if the motor is not > vertical. even with a > > radiused pulley you're going to get chaffing > because the pulley is > > rotating off the horizontal. Look at lit like > this. Assume the top of > > the pulley is a little further away from the > platter than the bottom. > > As the belt first contacts the pulley, the pulley > surface is rotating > > at a downward angle to the belt. On the side > where the belt is leaving > > the pulley, the surface is rotating at an upward > angle to the belt. > > The only way the radiused pulley can be used w/o > chaffing is if it's > > vertical. > > > > Peace > > -- > > Roscoe Primrose -- mailto:roscoe@aiko.com -- > > http://www.aiko.com/roscoe > > > > "Once in a while you get shown the light > > In the strangest of places if you look at it > right." Robert Hunter > > > > "640K ought to be enough for anybody" , Bill > Gates, 1981 > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] Motor Pod Date: Tue, 7 Mar 2000 08:37:30 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > "flutter" range. A little chafing (just what problems > can we expect from that?) would be a small trade-off > for belt stability, a plus to think about. I've already responded to this but see now that I've missed the inference. Belt chafe _will_, in my opinion, cause FM. That is, since the belt is never perfectly registered on the pulley but is perpetually being driven at some axis to it's rotation about the platter, it will stick/slip minutely, and potentially more so than any LF offset up and down the drive surface itself. Precision instrumentation belts are actually regularly seen perfectly aligned on cylindrical drives assuming polar (or is it axial?) adjustment of the drive pin is enabled. Jon Lane Subject: RE: [teres] Motor Pod Date: Tue, 7 Mar 2000 08:37:32 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > Relatively speaking, Jon, you are far too anxious > to complicate the design. Fortunately, we're in an > individual area here. Having standardized a motor > mounting plate, Everyone can now decide how > impractical they want to be. There is nothing > imprecise about a properly mounted bubble level. Just > use a good level with a higher degree of accuracy as a > reference when gluing / attaching the bubble. This > technique of truing up an inexpensive bubble level has > already been covered in previous discussions. There > is a wealth of information available in the records, > please feel free to use them, we've already done the > work. What machined parts guarantee is additional > expenses & difficulties. Bearings: get 'em just > right, or you're moving backwards. Springs: should be > avoided *anywhere possible* around turntables. > Why are you bucking the elegance of simplicity > **so** hard? Does it offend your sense of mechanical > philosophy to use something so simple that it doesn't > *need* to be complicated to death? You know, if this > doesn't work, or works poorly, your bearings could > still be added to the bottom of the pod, after > removing the cones. > > Igor Igor, given the personal investment you've made in this remarkable project, I'm certainly willing to exit the discussion - I joined late on. My intent is not to disrupt the proceedings, and I'm guessing you want to keep your own Igo out of it also. Mass-coupled, linear motion of the motor is far more simple and elegant, in my opinion, than seeking a way to cause a looser, more geometrically challenged drive to track quietly and properly. Hence, "complicating it to death" was actually the risk I thought I saw us taking with the current scheme and my remarks were intended to address that only. I think I've itemized the pros and cons adequately to allow an informed decision on all fronts. Standing by for the consensus. Jon Lane Subject: RE: [teres] Motor Pod Date: Tue, 7 Mar 2000 08:37:39 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com I asked Barry Instrument Corp to quote us a belt in 2 mil, flat endless Kapton by .175" in width. Assuming a 1/2" drive and 12" driven diameter - but pending a center-to-center dimension - the reply returned was: "Jon: We would produce a belt this long in the 2 mil Kapton @ 27.40/ea for 100/ pieces. Delivery would be 3 to 4 weeks." Searching "Barry Instrument" will bring up the site. Jon Lane > -----Original Message----- > From: owner-teres@aiko.com > [mailto:owner-teres@aiko.com]On Behalf Of > Igor Kuznetsoff > Sent: Tuesday, March 07, 2000 6:25 AM > To: teres@aiko.com > Subject: Re: [teres] Motor Pod > > > >The group can buy endless, precision-made > > instrumentation-grade plastic drive belts for $30 > >each from the instrumentation biz who has a track > >record of millions of these in everything from > >aerospace to the nearest tape drive. Quiet, > >reliable, long-lasting, easily centered, strong. > > Jon, > I'd like to look into these. Could you please > list some suppliers? > > Igor > __________________________________________________ > Do You Yahoo!? > Talk to your friends online with Yahoo! Messenger. > http://im.yahoo.com Subject: RE: [teres] Motor Pod Date: Tue, 7 Mar 2000 08:37:44 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > I missed your recent thoughts on what to sled. > Indeed, we all seem to be in > agreement with respect to the benefits of keeping > the motor firmly coupled > to the mass of the pod. I can very easily get > behind the concept of the > entire motor pod being on a sled. One of the philosophies I think we need to always keep in mind is that of proper machine design - we're making a precise machine here and while our intuitions on lead, MDF, adhesives, levitating platters and tilting motors and other interesting notions are very valid from the perspective of their _intended effect_, thus far we have made a true machine and have observed reasonable convention in it's philosophy and execution. One example: Personally, I will use a pair of 1" plates of pure 6061 alloy laminated together for the base of my platter, not unlike a small machine table to which things attach with high precision and intimate mechanical bonding. This will be (at first) limited resonance-wise by only a thin scrim of sorbothane-like material between it and 2" of granite. From experience, these two constrained layers will quiet the base sufficiently without compromising mechanical coupling. The motor pod will also be a heavy block of aluminum with motor bolted firmly in absolutely vertical alignment. The pod's underside will be machined flat relative the motor alignment and will be held there by the surface of the granite, again, with an intermediate thin damping layer. Sliding bearings are an available option under consideration. Many can argue, and probably successfully, that this isn't "tweak" enough. I'd counter that in fact it will be insofar as it immediately lends itself to evolutionary improvements in tuning. The design tuning only _begins_ at the stage I describe here, as I intend it. However, there simply will be no "non-workmanlike" portions to the design. It will be utterly stable, perfectly aligned, and bulletproof. Or at least I hope it will be ;o) I merely want to observe proper machinist protocol and wish to avoid anything resembling a spit and bailing wire philosophy - not that that's what anyone else has proposed here, I hasten to add. I'm just explaining that my personal philosophy is one of ensuring that all components are fit together precisely and all portions of the design are simple and effective. Unfortunately, I can't yet visualize how to solve the three issues I think I see with the unsecured motor: Belt chafing, motor "roll" or shudder, and lack of mass coupling. While Manfred hasn't commented, I'm betting that the motor won't be capable of driving much energy back into the mountings, making the "open" design less problematic. Anybody? But I'm still betting further, that actually because of this, any vibration that IS present will handily be removed entirely by mass coupling. Second, while belt chafe isn't a serious issue, why court it at all? Igor's insightful comments include a reference to FM noise, and that's exactly, I think, what we should intuitively be aware of. With a line contact pulley, the belt perpetually being driven by, in effect, a constant series of minute arcs across it's underside is, IMHO, something to avoid. > Those of us are who are thinking about adding > belt tensioning force prefer > using gravity for obvious reasons of energy > (non)storage. I now wonder as > you do if a spring (rubber or metal) could > effectively supply the force. In > the "sled" approach, perhaps the mass of the pod > is high enough to filter > out any spring resonances. In Igor's approach, I > think gravity would be > necessary (and way cool looking), since the > system depends directly on the > locating force for it's stability. I think it's clear that weighting the scope of travel is theoretically the superior method, but once again, I ask if it's necessary. That is, in the case of gently separating a pair incredibly massive entities (relative to our needs here) isn't it just as simple as dropping in a couple of soft, large diameter springs between platter base and motor block? Especially in light of what lengths some are presumably going to damp both bases, two small springs simply cannot inject enough energy back into either via their minute resonance to color the sound. But does the weight handily avoid ALL resonance, Jon? Well, yes it probably does unless we go off on a tangent on vibrations climbing the cord to find their way back into... But there we once again become unreasonable, IMHO. Perhaps the hardest thing about making these decisions is first consciously understanding that there is a real difference between unusual, hard to implement, hard to set up design on the one hand, and classic machine thinking, to coin a phrase, on the other. The differences will be with us through the life of the project. But the sonic contrasts are incredibly small, if they exist at all. The weight/spring choice is probably one of the most obvious in that regard. It should be that there will be no sonic difference whatsoever. And the belt chafe issue may actually favor the vertical alignment to the elegant but difficult concept of pivoting the motor, once all variables are taken into account. So, in those cases at least, we may stand to benefit from the more classic approach and should continue building a precise, no-nonsense machine. Jon Lane Subject: RE: [teres] Motor Orientation Date: Tue, 7 Mar 2000 08:37:52 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > You've been putting [commercial bearings] under the ubiquitous "they" > category. Could you please list one or two *specific* > supply houses, And one or two linear bearing part > numbers for our consideration? I, for one, would be > curious about the price of this complication. Of course. Actually I have no time for this but I knew I'd be asked if I brought it up... No problem. > >Our planned top plate is even unnecessary. > > The mounting plate is for the purpose of rotating the > motor for bearing wear, and is very necessary, or are > you planning to rotate your entire motor pod, linear > bearings & all? I'd planned to rotate the motor itself, Igor. But do you suppose Maxor ever intended the motor to be rotated to minimize wear? Jon Lane Subject: RE: [teres] Motor Pod Date: Tue, 7 Mar 2000 08:41:25 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Stan: You propose a very interesting method. However, I respectfully think that using gravity via a counterweight or the weight of the motor pod on an eccentric support would be simpler and better. Using gravity would assure that there was no "hunting," because gravity is constant and non-reacting (at least on the Newtonian level). I don't envision any problem with motor axis misalignment because the amount of rotation to maintain belt tension would be mininal. Cheers, Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: Stanley Goudge [SMTP:sgoudge@cisco.com] > Sent: Monday, March 06, 2000 7:33 PM > To: teres@aiko.com; teres@aiko.com; teres@aiko.com > Subject: RE: [teres] Motor Pod > > Sorry Guys, > I just can't leave this thing alone. You'll need paper & pencil to > figure this one. Forget what I said below, > after further thoughts it should be possible to use the torque of the > motor to tighten the belt automatically. > All that is needed is a thust bearing to allow the motor pod to rotate > freely. > Ok picture this, your looking down the left side of the turntable with > motor in the foregound and platter in the background. > Now the motor spins clockwise which creates a counter-clockwise torque on > the pod. With a offset > spindle to the right of center (say 3/8") of the pod. The > counter-clockwise force will tighten the belt. > Way cool Uh. Now at full speed if the belt starts to slip there will be > less torque applied and thus less tension, > now you may have tension runaway. So you may need to add a little weight > for insurance. Or just reconfigure > it where less torque will give more tension by using a string and weight > to bias the pod in a clockwise direction, > with the spindle to the left of center now. The torque is now opposing the > weight and if the belt starts to slip > there will be less torque to counter the weight and the weight will > tighten the belt. But this config. may have > a lot of slippage at startup because of higher friction (thus higher > torque fighting the weight) caused by the belt slowly moving. > But once up to speed it should work perfect. > > Happy confusions, > Stan > > > At 03:17 PM 3/6/2000 -0600, Stanley Goudge wrote: > > Thats' right Igor's idea doesn't insure perfect alignment,but with the > right pulley may not have to. > >Another concern I have is what happens at start up, does the belt slip or > will it grab causing the motor > >to teeter toter back and forth on its pivot and if its get too volent > then it might cause the pod to move slightly, > >which would loosen the belt. Guess we better make the pod (stainless > steel) pretty heavy just in case. > >Guess it depends on the belt and weight used and how much torque the > motor has. We have unknowns here. > > > > I can see another idea that uses a offset action to keep belt tension. > By drilling a offset hole or holes > >at the bottom of the pod and pivot this on a dowel pin on the platform > then using Igor's weight (heavier weight) > >and string to rotate the pod, the offset (cam action) would move the pod > away from the platter tighting the belt. > >Problem here of course is friction, and the only cheap and easy way I can > think of right now is a flat > >polished surface on the bottom of the pod and have it ride on 3 teflon > pads affixed to the platform. > >I think Igor's idea is still better from a performance stand point, but > just another idea. > > > >Stan > > > > > > > >At 12:26 PM 3/6/2000 -0700, Jon Lane wrote: > >>> If the suggested bubble level was on the pod, a glance > >>> at it would tell you all need to know. It would still > >>> be vertical , or not. If the belt stretches enough to > >>> need touch up, the level could tell you, or just look > >>> to see where the belt is riding on the pulley. > >>> > >>> Igor > >> > >> > >>Relatively speaking, the bubble level is a low-precision, > >>subjective evaluation of conditions. Machined parts > >>guarantee perfect alignment, on the other hand. > >> > >>Jon Lane > >> > > Subject: RE: [teres] Motor/supply kit - PURCHASE! Date: Tue, 7 Mar 2000 08:53:16 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com; teres@aiko.com Chris, How about a price using stainless steel for the motor mount. But if not a option I'll take alumimun over bass because it has a higher weight to stiffness ratio which can be better damp using constrained layer damping. Higher frequency vibrations are more efficiently damped than lower ones caused by the use of low weight to stiffness ratio materials like bass. Stan At 06:03 AM 3/7/2000 -0800, Peter Boser wrote: >Chris, >Yes, I want one. I also vote for brass, but will live >with the majority choice. >Thanks for your efforts! >Pete Boser > Subject: RE: [teres] Subchassis Design Layout - Isodamp Date: Tue, 7 Mar 2000 08:56:45 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' I agree with Igor. Toughness in a metal doesn't translate into acoustic inertness. In many cases, the opposite is true. Witness that lead is a particularly "untough" metal. I may be mistaken, but I think that many tuning forks are made of SS. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: Igor Kuznetsoff [SMTP:gorkuz@yahoo.com] > Sent: Tuesday, March 07, 2000 5:01 AM > To: teres@aiko.com > Subject: RE: [teres] Subchassis Design Layout - Isodamp > > Stan, > Swedac is not ordinary PVA, and does not seem to > be similar after drying. It forms thicker, more > compliant layers for starters, beyond that, I don't > know the chemistry. > *No* kind of metal beyond lead belongs in any > part of a TT chassis system!! Stainless steel, no > matter how modified is a particularly bad choice, even > if it won't rust. What mega-buck TT's are using steel > as a chassis material? The only 'table that comes to > mind that uses some is the Townshend, and that is one > of the things that I considered to be among its > weakest features, and that TT is "practically priced", > saving money on compromises like that. > There is no point to arranging lead/MDF/MDF, that > is just lead/MDF, for all intents & purposes. The > point of a *constrained* layer is to *constrain*, or > bound by, as in *sandwich*. > > --- Stanley Goudge wrote: > > Igor, > > I'm still not sure, because what I mean by > > structure is the part that contacts the item your > > trying > > to isolate. In this case the turntable or was this a > > subchassis design, in this case the spindle/bearing > > would contact the lead only. Have you tried > > lead/MDF/MDF,where the lead is the top surface. > > Maybe a thick slab of lead say 1/4" with the next > > layers MDF/HDF. > > But I think the ultimate base or subchassis material > > is a stainless steel sandwich SS/CN/SS. > > In fact SS/CN/SS should be first choice, whether it > > be a platter,subchassis, motor mount, > > motor pod, stand and base. Because SS combines high > > stiffness to weight ratio with self damping > > qualities that no other material has. Why do you > > think most mega buck TT that we'll never hear, > > use the hell out it, unfortunately thats why they > > costs mega bucks. Its tough & expensive stuff to > > machine, > > which should tell you something right there about > > its ideal rigid body qualities. > > > > My second choice would be aluminum, because its > > cheap and easy to machine and there are many > > grades like 7075 which is pretty stiff stuff, > > combined with softer aluminums or even SS in a > > sandwich with > > CLD gives an excellent alternative to the mega buck > > SS. > > > > My third choice is anything I can cut or fab on my > > table saw or router, but these materials usually > > just don't cut it. > > > > Have fun, > > Stan > > > > P.S. Swedac I think is PVA, used to damp dome > > tweeters. > > I have both in hand and can't tell the difference > > when dry. > > > > > > > > > > At 06:09 PM 3/3/2000 -0800, Igor Kuznetsoff wrote: > > >Stan, > > > Now you've got it! I consider MDF/lead/MDF > > >bonded with Swedac to be a *five* layer sandwich > > with > > >*three* active layers of damping, one of them, > > lead, > > >being dual purpose-both structure & damping. The > > >Swedac is not simply a glue! I suppose you've > > missed > > >some stuff I wrote about "Zero Passband" tuning > > early > > >on in the project (I'm sure Thom put it in the > > >digests). The idea is to try, as much as is > > >reasonable, to arrange more than one consecutive > > (or > > >serial) damping tuning in a system, in order to > > >approach a situation where the passbands involved > > are > > >different enough that they mutually exclude > > >transmission of *any* frequency. The idea may be > > >Utopian, nothing works that perfectly, but it *can* > > >do a heck of a good job of damping, better than a > > >single passband damping system. > > > > > > Igor > > > > > >--- Stanley Goudge wrote: > > > > > >Igor, > > > As far as I know there are only two ways to > > damp > > >a structure. > > >One is to use extensional damping by means of > > damping > > >material firmly > > >affixed to the structure > > >by glueing, screws or rivets. And functions by the > > >simple flexing of > > >the > > >damping material, which dissipates the > > >vibrations to heat. The other is constained layer > > >damping, which uses > > >damping (sandwinch) material between > > >two structues and has much higher loss due to the > > >shear strain on the > > >damping material when the stucture vibrates > > >or flexes. So in order for CLD to function the > > damping > > >material must be > > >firmly glued to the structure, any shear strain > > (flex) > > >on the glue and it becomes the damping material not > > >the lead in your > > >case. > > >Of course maybe your using the lead > > >as the structure, which is ok and a cool idea. > > > > > >Stan > > > > > >__________________________________________________ > > >Do You Yahoo!? > > >Talk to your friends online with Yahoo! Messenger. > > >http://im.yahoo.com > > > > > > > > __________________________________________________ > Do You Yahoo!? > Talk to your friends online with Yahoo! Messenger. > http://im.yahoo.com Subject: RE: [teres] Motor Orientation Date: Tue, 7 Mar 2000 09:02:05 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com; teres@aiko.com These guys have all the goodies we need, except maybe a suitable belt. Stan http://www.devicelink.com/company98/p/p00158.html At 01:57 AM 3/7/2000 -0800, Igor Kuznetsoff wrote: >Jon, > >>The bearing parts may be purchased from >>bearing houses > >You've been putting this under the ubiquitous "they" >category. Could you please list one or two *specific* >supply houses, And one or two linear bearing part >numbers for our consideration? I, for one, would be >curious about the price of this complication. > >>Our planned top plate is even unnecessary. > >The mounting plate is for the purpose of rotating the >motor for bearing wear, and is very necessary, or are >you planning to rotate your entire motor pod, linear >bearings & all? > >>only a few basic components >>That's it >>minimal machining > >That simple, eh ? > > Igor > >--- Jon Lane wrote: >> > Jon, >> > >> > This also has merit. I guess my principal >> > objection is to the idler, which, >> > while it will do the job, it also can/will add >> > variables we are striving >> > mightily to eliminate. A track system utilizing >> > passive weight for >> > tensioning has big possibility, though it is more >> > complex than Igor's idea. >> > >> > Should we decide collectively to go down this >> > path, it would require, >> > however, almost as much thought as the rest, plus >> > a bunch of fabrication. >> > Perhaps others have given tracks, etc. more >> thought? >> > >> > Peter C >> >> >> Peter, in the interest of developing this idea to >> the point >> of making a decision, I wish to point out that the >> scheme >> would require only a few basic components: >> >> 1. The motor bolted solidly into a block built for >> the >> task. I plan aluminum of at least a few inches on a >> side by >> a half foot deep to lay alongside the table base. >> 2. Two off the shelf bearing races installed into >> milled >> reliefs in the lower half of this block. >> 3. Two linear ways to receive the bearings. >> >> That's it. The choice of a spring or weight is left >> up to >> the individual. The bearing parts may be purchased >> from >> bearing houses and the aluminum block could be >> standard 6061 >> stock or something, with minimal machining to accept >> the >> motor and races. Our planned top plate is even >> unnecessary. >> >> Jon Lane >> >> >> >__________________________________________________ >Do You Yahoo!? >Talk to your friends online with Yahoo! Messenger. >http://im.yahoo.com > Subject: RE: [teres] Motor Pod Date: Tue, 7 Mar 2000 13:53:16 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com > You say that you > prefer a perfectly aligned > pulley so there is no belt chafing, but how will > you center your belt? I > respectfully dispute your contention that it will > be centered on a > flat-faced pulley, by perfection, without lateral > hunting. I've built three designs with the belt riding on cylindrical pulleys. Adjusting a set of three screws through the mounting into the motor are all that's needed to center the belt indefinitely. This seems to be convention in some tape drive systems, also. Flanges are merely a safety precaution. I hasten to add that this is not necessarily recommended since the simple option of a radiused pulley makes the system self-tending. > IMHO, there > needs to be a method of centering the belt; three > methods come to mind: > flanges, a convex-shaped pulley face, or a wide > enough pulley that allows > the belt to wander back and forth without going > off the edge (pun?). All > three add a modulation to the belt motion. Igor > an I accept that reality > and we are trying to think of the best ways to > mitigate it rather than try > to deny it. When you get the chance, try just a straight pulley and fine adjustment... > I also would like to question your use of SS and > granite. Both have been > addressed in prior posts as being undesirable for > a TT base because they > ring. Untreated or unconstrained, they ring like crazy. > Marble and Corian are much better than > granite if you want a > stone-like material. "Lowly" MDF is an excellent > material that can be > finished beautifully with veneer and solid wood > trim, with little more than > hand tools. I like the idea of cherry-veneered > and trimmed MDF alternating > with corian laminations for my base. And don't > get me started again on > Ennemoser's theories and C37! I've laminated a pair of alloy plates, which deadens both tremendously, and will damp them further by constraining a thin layer of stuff between their considerable mass and solid stone. The granite will also benefit from a to-be-determined layer of underdamping on it also. And the entire affair could be sand-boxed. A hard metallic chassis is perhaps the closest thing to perfect mechanical grounding - you're only left with damping it. OTOH, losses built into the chassis through the use of the materials you mentioned, excepting to a degree marble, while certainly "quieter", could loose information through the interruption of this coupling. This loss is not recoverable. Lossy chassis seem to blur the signal and loose the fine detail so prized by advocates of permalloy, triodes, and sensitive cones, IMHO. Perhaps this occurs by the minute internal bending of lossy materials - I'm certainly no official expert in the subject. The best case of this I can recall is in the contrast of the sound of the big three: The LP12, the Oracle, and the SOTA. Of these, the Linn uses a reasonable effort to couple but does so with a minimalist subchassis made of fairly rigid sheet metal and thick hardboard. By contrast, the Oracle is virtually rigid, with only that acrylic armboard to interrupt the metallic loop between stylus and record (excepting your choice of mat). The SOTA chassis is a heavy layered MDF affair, the lossiest of the three. Of these, and only by contrast to the others, the Linn has reasonable detail and dynamics but at the expense of loosing control in the upper bass and having no real deep bass. I take this as indication of good coupling in the highs and reactive coupling (flexure) in the lows. No real deep bass suggests a lack of mass throughout. The Oracle, IMHO, perhaps has the best overall detail and most spacious soundstaging, but again, lacks the bass of a heavier design. Only the SOTA has the combo of deep bass, real slam, and rhythmic drive (perhaps just beating the Linn in the latter) but still sounds dark. Of the three, the SOTA, to my ears, misses the mark only in that it cannot retrieve the finest details. Could this be based on a lossier subchassis than the others, at least in the upper registers? Comments? I'll follow my own suggestion to go with the ultra rigid chassis only to ensure that I get all the stuff out of the groove that I can. From _there_, the task is clearly to damp this chassis to critical. But I fear that losing the sonic goods, so to speak, by excessively decoupling is to risk irretrievable loss of information. Jon Lane Subject: RE: [teres] Sub chassis- large tube idea Date: Tue, 7 Mar 2000 13:56:45 -0700 From: Jon Lane, Jon Lane To: teres@aiko.com They use only three O-rings - one around each of the "legs", if I recall. May indicate the relative merits of rigidity, mass-coupling, and controlled damping over just extreme decoupling and isolation...who knows? Jon Lane > -----Original Message----- > From: owner-teres@aiko.com > [mailto:owner-teres@aiko.com]On Behalf Of > Fritz Moore > Sent: Tuesday, March 07, 2000 12:36 PM > To: teres@aiko.com > Subject: RE: [teres] Sub chassis- large tube idea > > > I think Ive seen [the Kuzma] but as I > recall it had no suspension? Do you > know if it is filled with anything? > > Thanks, > > Fritz Subject: Re: [teres] Motor Orientation Date: Tue, 7 Mar 2000 16:01:16 -0700 From: Jeremy Epstein, Jeremy Epstein To: teres@aiko.com Igor Kuznetsoff wrote: > > Jon, > > >The bearing parts may be purchased from > >bearing houses > > You've been putting this under the ubiquitous "they" > category. Could you please list one or two *specific* > supply houses, And one or two linear bearing part > numbers for our consideration? I, for one, would be > curious about the price of this complication. I can dig up a catalog with some linear bearings in it - I think Reid Tool Supply is the name, I have a catalog at home. However I like the drunk-on-crutches, two-point balance idea a whole heck of a lot. Very elegant. I believe that the range of motion needed for tensioning will be extremely small (remember, we are dealing with a stretchless belt) and therefore the geometry will not be sufficiently sloppy to cause significant misalignment from vertical once all is setup. The tension will be supplied by action of the weight, not the motion of the pulley, I think. But I've been wrong before. -j -- ========================================= Jeremy Epstein .........jepstein@shwd.com ========================================= Subject: RE: [teres] Motor Pod Date: Wed, 8 Mar 2000 02:10:58 -0700 From: Manfred Huber, Manfred Huber To: teres@aiko.com Jon, >Perhaps best summed up this way: If holding a running >Maxon, do you feel anything other than gyroscopic effects? Of course you can feel some vibration and if you put the running motor right at your ear you can hear the brushes. >Will mass coupling it to a sizable block damp all apparent >vibration without transmitting anything into the drive? One >assumes the answer is no... I agree. Some noise has to find it's way to the stylus. The question is how much it is and if it is audible. My setup looks like this: Both the TT and the motor are standing on a sand filled plate made from plywood. The TT uses a chassis made from a 1" sheet of constructional steel. No subchassis. The housing of the Motor unit is made from wood. Both TT and drive unit are coupled to the base plate by steel spikes sitting on small ceramic disks. The rigid coupling of drive unit and platter sounded best *to me*, especially when using the magnetic tape. When I remove the belt, put the stylus on the platter and let the motor spin I can hear no motor noise coming from the speakers. But I have to say that I use a tube RIAA amp that has some residual noise. Maybe this is masking some motor noise. Regards Manfred ------------------ Manfred Huber MHuber@t-online.de ------------------ Subject: Re: [teres] Motor Pod Date: Wed, 8 Mar 2000 04:37:50 -0700 From: Ivan Anderson, Ivan Anderson To: teres@aiko.com > A hard metallic chassis is perhaps the closest thing to > perfect mechanical grounding - you're only left with damping > it. OTOH, losses built into the chassis through the use of > the materials you mentioned, excepting to a degree marble, > while certainly "quieter", could loose information through > the interruption of this coupling. This loss is not > recoverable. Lossy chassis seem to blur the signal and > loose the fine detail so prized by advocates of permalloy, > triodes, and sensitive cones, IMHO. Perhaps this occurs by > the minute internal bending of lossy materials - I'm > certainly no official expert in the subject. This aggrees with my own experience, when I had a business designing and fabricating high end supports, tables, and shelves. I found that in order to control vibration, a system must first accept it... and therfore will ring 'alarmingly' until grounded in some way. Any vibration presented to, but not found in the damping system, must be reflected back into the turntable, where it interferes with the information we wish to retreive, cancelling, adding to and smearing it. The best supports and vibration control sytems IMO show a trace on a scope, as presented by an accelerometer (following a short pink noise pulse), which has a large amplitude and fast decay. The systems which present as a low amplitude trace (also tend to have longer decay) smear and veil the information retrieved. Such systems based on Corrian or mdf etc. as the primary layer display this characteristic. I have found that a light and rigid primary layer coupled to a massive secondary layer to provide good control, with minimal information loss. The rigid layer needs to be able to vibrate in order to damp this vibration, or pass it on to further dampening layers. I acheived this in different ways, thin wall steel tube welded to heavy wall large cross section steel, formica - pvc foam - granite slabs and so on. I am undecided how to construct my table, but I am leaning towards a chassis made from say, 50 x 20 x 2mm rectangular steel or s/steel tube welded on the flat, coupled to some massive platform. BTW I found in my experiments, that filling the tube with dampening material negated, to varying degrees, the dissipation abilities of the plain tube. ... > I'll follow my own suggestion to go with the ultra rigid > chassis only to ensure that I get all the stuff out of the > groove that I can. From _there_, the task is clearly to > damp this chassis to critical. But I fear that losing the > sonic goods, so to speak, by excessively decoupling is to > risk irretrievable loss of information. Yes, I think this to be a 'sound' approach. Ivan Subject: Re: [teres] Motor Pod Date: Wed, 8 Mar 2000 10:28:31 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com; teres@aiko.com Your right on Ivan, you've been echoing my thoughts on rigidity vs. lossy. The way I look at, an ultra rigid design has a higher Q and frequency resonance. Higher Q means a narrow range of frequency (high freq in this case) vibrations that will excite the structure into resonance vs low Q (lossy) wide range of frequency excitations and longer decay. Now you have to ask yourself why this important. Because low frequency vibrations are impossible to stop, they travel though anything in nature with very little attenuation. Think of the world as a gigantic low pass filter, where low frequencies rule and become an audiophiles worst enemy. Our only weapon against this insidious onslaught is to design ultra rigid structures that resist this low frequency bomb. Now that we have this shield of rigidity we need to damp it by means of CLD (constrained layer damping). Its easy to damp a high Q system, look at a tuning fork, simply by blowing on it the resonance can change. Try that with a lead tuning fork, although you can't hear it ring, but it does so at low freq. with long wavelenghts that are not coupled to the air because of it small size. However you will not be able to stop this resonance, because of its high mass and low freq. resonance without hugh amounts of material. And just because we can't hear a primary resonance doen't mean it won't travel though (like shi.. though a goose) our equipment raping and pillaging evey beloved sonic detail. Stan At 11:30 PM 3/8/2000 +1300, Ivan Anderson wrote: >> A hard metallic chassis is perhaps the closest thing to >> perfect mechanical grounding - you're only left with damping >> it. OTOH, losses built into the chassis through the use of >> the materials you mentioned, excepting to a degree marble, >> while certainly "quieter", could loose information through >> the interruption of this coupling. This loss is not >> recoverable. Lossy chassis seem to blur the signal and >> loose the fine detail so prized by advocates of permalloy, >> triodes, and sensitive cones, IMHO. Perhaps this occurs by >> the minute internal bending of lossy materials - I'm >> certainly no official expert in the subject. > >This aggrees with my own experience, when I had a business designing >and fabricating high end supports, tables, and shelves. > >I found that in order to control vibration, a system must first accept >it... and therfore will ring 'alarmingly' until grounded in some way. >Any vibration presented to, but not found in the damping system, must >be reflected back into the turntable, where it interferes with the >information we wish to retreive, cancelling, adding to and smearing >it. > >The best supports and vibration control sytems IMO show a trace on a >scope, as presented by an accelerometer (following a short pink noise >pulse), which has a large amplitude and fast decay. The systems which >present as a low amplitude trace (also tend to have longer decay) >smear and veil the information retrieved. Such systems based on >Corrian or mdf etc. as the primary layer display this characteristic. > >I have found that a light and rigid primary layer coupled to a massive >secondary layer to provide good control, with minimal information >loss. > >The rigid layer needs to be able to vibrate in order to damp this >vibration, or pass it on to further dampening layers. I acheived this >in different ways, thin wall steel tube welded to heavy wall large >cross section steel, formica - pvc foam - granite slabs and so on. > >I am undecided how to construct my table, but I am leaning towards a >chassis made from say, 50 x 20 x 2mm rectangular steel or s/steel tube >welded on the flat, coupled to some massive platform. > >BTW I found in my experiments, that filling the tube with dampening >material negated, to varying degrees, the dissipation abilities of the >plain tube. > >... >> I'll follow my own suggestion to go with the ultra rigid >> chassis only to ensure that I get all the stuff out of the >> groove that I can. From _there_, the task is clearly to >> damp this chassis to critical. But I fear that losing the >> sonic goods, so to speak, by excessively decoupling is to >> risk irretrievable loss of information. > >Yes, I think this to be a 'sound' approach. > >Ivan > Subject: Re: [teres] Motor Orientation Date: Wed, 8 Mar 2000 10:43:48 -0700 From: Jeremy Epstein, Jeremy Epstein To: teres@aiko.com Igor Kuznetsoff wrote: > Could you please list one or two *specific* > supply houses, And one or two linear bearing part > numbers for our consideration? Igor, I have a catalog from Reid Tool Supply, 800 253 0421, www.reidtool.com, that I suggest you send for if you are interested : they have four+ pages of linear motion items, most seem pretty big for our application and seem more suited for industrial machinery, but there are some smaller items that look like a ball-bearing equipped dovetail slide (not quite exactly, but that'll give you the idea) which might come in handy given the simplicity I envision of installing them. Precision Ball Slide Assembly, Catalog no. DT-11 is the smallest and cheapest @ 63.00, load capacity 1.5 lbs., travel .5 in. There are "Crossed Roller Slide Tables" that run $200 and up but they are a bit of overkill for our application, they are for 100-lb.+ loads. -j -- ========================================= Jeremy Epstein .........jepstein@shwd.com ========================================= Subject: Re: [teres] Motor Orientation Date: Wed, 8 Mar 2000 12:14:55 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com All, Thanks, Jeremy, I'll have to look into this as soon as I can find the time. Right now, I can't even find the time to go through all the mail, much less answer much of this deluge. Don't you guys have lives to live outside of Teres? Most *jobs* have days off. This has been 7 days a week since it started, and I am *extremely* burned out!!! This has been going on a long time!!! I would suggest to everyone that some of us, at least need some time off from this, but that is impossible unless *everyone* takes some timer off together, otherwise it is impossible to catch up. How about shutting this shindig down for a long weekend, say Fri.-Mon., *inclusive*? I mean EVERYONE stops sending for 4 days. I know that Thom would no doubt breathe easier, too, if he could rest up a bit, and enjoy the Noise, as I would like to (I also have a NJAudio Society meeting on Sun., as well), without finding the mailbox out of control. Right Now I have over 60 messages backed up that I don't have time for, and that is after deleting all the inconsequental and pre-embedded ones! Finally, I have glanced at the linear bearing site Jon put up, and see some things I both do & don't like, starting with 2 x $63 for the cheapest (your mention), which is *far* more than I would want to spend, until I see how my simpler system works. The simpler, the better, when something works that way, and I still haven't seen anything (unless it's in a post I haven't gotten to at all) to justify the complexity & cost inherent in using the slides, even if they have merit (yes, Jon, I think they do, I just don't find them justifiable). Igor --- Jeremy Epstein wrote: > Igor Kuznetsoff wrote: > > Could you please list one or two *specific* > > supply houses, And one or two linear bearing part > > numbers for our consideration? > > Igor, I have a catalog from Reid Tool Supply, 800 > 253 0421, > www.reidtool.com, that I suggest you send for if you > are interested : > they have four+ pages of linear motion items, most > seem pretty big for > our application and seem more suited for industrial > machinery, but there > are some smaller items that look like a ball-bearing > equipped dovetail > slide (not quite exactly, but that'll give you the > idea) which might > come in handy given the simplicity I envision of > installing them. > > Precision Ball Slide Assembly, Catalog no. DT-11 is > the smallest and > cheapest @ 63.00, load capacity 1.5 lbs., travel .5 > in. There are > "Crossed Roller Slide Tables" that run $200 and up > but they are a bit of > overkill for our application, they are for 100-lb.+ > loads. > > -j > -- > ========================================= > Jeremy Epstein .........jepstein@shwd.com > ========================================= > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Motor Orientation (linear bearings) Date: Wed, 8 Mar 2000 14:25:48 -0700 From: phclark, phclark To: teres@aiko.com Besides, If I read the specs correctly on the DT-11, even @ 2 x , this slide wouldn't accommodate a 20# + motor pod. Peter C -----Original Message----- From: Jeremy Epstein To: teres@aiko.com Date: Wednesday, March 08, 2000 11:33 AM Subject: Re: [teres] Motor Orientation (linear bearings) >Igor Kuznetsoff wrote: >> >> All, >> >> Thanks, Jeremy, I'll have to look into this as soon as >> I can find the time. Right now, I can't even find the >> time to go through all the mail, much less answer much >> of this deluge. > >It is quite the avalanche. I'm chipping away at it today and hence some >late replies. > >> Finally, I have glanced at the linear bearing site Jon >> put up, and see some things I both do & don't like, >> starting with 2 x $63 for the cheapest (your mention), >> which is *far* more than I would want to spend > >Not arguing with you but I think these slides would be self-squaring and >so you might get away with just the one. I plan on trying your >drunk-on-crutches approach before plunking down that much cash too. > >-j >-- >========================================= >Jeremy Epstein .........jepstein@shwd.com > Subject: RE: [teres] Motor Pod Date: Wed, 8 Mar 2000 14:42:14 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Axial. Given an either-or, I expect belt stability to be much more important, and at a more audible frequency & volume. The chafing could cause the same, but on an entirely different scale, I expect. The chosen material of the belt will also play a role in this. As for perfect alignment-as in perfect on the level required for what you describe-in a turntable with separate sections-this is a Utopian wish, I suspect. Igor --- Jon Lane wrote: > > "flutter" range. A little chafing (just what > problems > > can we expect from that?) would be a small > trade-off > > for belt stability, a plus to think about. > > I've already responded to this but see now that I've > missed > the inference. Belt chafe _will_, in my opinion, > cause FM. > That is, since the belt is never perfectly > registered on the > pulley but is perpetually being driven at some axis > to it's > rotation about the platter, it will stick/slip > minutely, and > potentially more so than any LF offset up and down > the drive > surface itself. Precision instrumentation belts are > actually regularly seen perfectly aligned on > cylindrical > drives assuming polar (or is it axial?) adjustment > of the > drive pin is enabled. > > Jon Lane > > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] Motor Orientation Date: Wed, 8 Mar 2000 14:45:07 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com I doubt that this was their main concern. They are in the business of selling motors, after all. Igor --- Jon Lane wrote: > > I'd planned to rotate the motor itself, Igor. But > do you > suppose Maxor ever intended the motor to be rotated > to > minimize wear? > > Jon Lane > > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Motor Orientation (linear bearings) Date: Wed, 8 Mar 2000 15:26:25 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com I'm sure there are others that can, but the prices... And I'm sure that it would have trouble torsionally with any weight to speak of on it, were only one used, as Jeremy suggested. I would be leery of using just one, as that would be inviting harmonic motion in the cross-axis, which could cause "wow" , or at least flutter, depending on the resonances struck. I'll need to find some time to look for more than a few moments at the specs. Igor --- phclark wrote: > Besides, If I read the specs correctly on the DT-11, > even @ 2 x , this slide > wouldn't accommodate a 20# + motor pod. > > Peter C > > > -----Original Message----- > From: Jeremy Epstein > To: teres@aiko.com > Date: Wednesday, March 08, 2000 11:33 AM > Subject: Re: [teres] Motor Orientation (linear > bearings) > > > >Igor Kuznetsoff wrote: > >> > >> All, > >> > >> Thanks, Jeremy, I'll have to look into this as > soon as > >> I can find the time. Right now, I can't even > find the > >> time to go through all the mail, much less answer > much > >> of this deluge. > > > >It is quite the avalanche. I'm chipping away at it > today and hence some > >late replies. > > > >> Finally, I have glanced at the linear bearing > site Jon > >> put up, and see some things I both do & don't > like, > >> starting with 2 x $63 for the cheapest (your > mention), > >> which is *far* more than I would want to spend > > > >Not arguing with you but I think these slides would > be self-squaring and > >so you might get away with just the one. I plan on > trying your > >drunk-on-crutches approach before plunking down > that much cash too. > > > >-j > >-- > >========================================= > >Jeremy Epstein .........jepstein@shwd.com > > > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Motor Orientation (linear bearings) Date: Wed, 8 Mar 2000 15:49:22 -0700 From: phclark, phclark To: teres@aiko.com Actually, I noticed that there were others perhaps more suited. I was mostly reacting to the cost, which would approximate that of the bearing/platter without giving commensurate precision. Again, Jon's ideas I intend to use as Plan B. I'm still more attracted to the now formally described: Drunk on Crutches. It's simpler, cheaper and affords more flexibility than any of the other, more complex, approaches. And again, if it doesn't work, try something else. I'm not a huge believer in received wisdom in this game, anyway. I have too many applications in my setups that weren't supposed to even work, much less sound good, to not be prepared to try something novel that looks as if it has chance of success... Peter C -----Original Message----- From: Igor Kuznetsoff To: teres@aiko.com Date: Wednesday, March 08, 2000 2:26 PM Subject: Re: [teres] Motor Orientation (linear bearings) >I'm sure there are others that can, but the prices... >And I'm sure that it would have trouble torsionally >with any weight to speak of on it, were only one used, >as Jeremy suggested. I would be leery of using just >one, as that would be inviting harmonic motion in the >cross-axis, which could cause "wow" , or at least >flutter, depending on the resonances struck. I'll >need to find some time to look for more than a few >moments at the specs. > > Igor > >--- phclark wrote: >> Besides, If I read the specs correctly on the DT-11, >> even @ 2 x , this slide >> wouldn't accommodate a 20# + motor pod. >> >> Peter C >> >> >> -----Original Message----- >> From: Jeremy Epstein >> To: teres@aiko.com >> Date: Wednesday, March 08, 2000 11:33 AM >> Subject: Re: [teres] Motor Orientation (linear >> bearings) >> >> >> >Igor Kuznetsoff wrote: >> >> >> >> All, >> >> >> >> Thanks, Jeremy, I'll have to look into this as >> soon as >> >> I can find the time. Right now, I can't even >> find the >> >> time to go through all the mail, much less answer >> much >> >> of this deluge. >> > >> >It is quite the avalanche. I'm chipping away at it >> today and hence some >> >late replies. >> > >> >> Finally, I have glanced at the linear bearing >> site Jon >> >> put up, and see some things I both do & don't >> like, >> >> starting with 2 x $63 for the cheapest (your >> mention), >> >> which is *far* more than I would want to spend >> > >> >Not arguing with you but I think these slides would >> be self-squaring and >> >so you might get away with just the one. I plan on >> trying your >> >drunk-on-crutches approach before plunking down >> that much cash too. >> > >> >-j >> >-- >> >========================================= >> >Jeremy Epstein .........jepstein@shwd.com >> > >> >> >__________________________________________________ >Do You Yahoo!? >Talk to your friends online with Yahoo! Messenger. >http://im.yahoo.com > Subject: Re: [teres] Motor Orientation Date: Wed, 8 Mar 2000 16:23:27 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com Thom, The words "teflon slide" gave me a vision of a wedge shaped (SS) piece bolted to the bottom of the motor pod which would slide down the end of a sloped subchassis. The slope and wedge angles would be the same so that it would look like one piece. Of course it would slide down (away from the platter) on teflon pads. The wedge would have numerous mounting holes to find the right ride height for the motor. And maybe needs to ride between two sides with teflon pads to kept motor torque from moving the wedge. Stan At 01:20 PM 3/8/2000 -0800, you wrote: >Aw, come on Igor - you can measure a real man by the >size of his inbox :-)) > >Seriously, these topics have a way of ebbing and >flowing and there's really no need to check in on a >daily basis - it's just that you and I are posessed by >this project and we've been on it since early >December. > >Let's just let the recent entrants grind away, stand >in the background and benefit from the fact that they >started the race later than we did. No need to >babysit. > >My take which I believe I've mentioned (jet lag >prevails) is twofold: > >(a) Igor's drunk on crutches (thanks Jeremy) apporach > >and > >(b) a teflon slide version of Jon's. I like the idea >of less than perfect friction with teflon as opposed >to bearings... maybe I'm all wet here but I think a >bit of friction would be helpful in swamping the >effects of both any motor imprfections as well as >runnout in the pulley as I noted previously. > >I still haven't had time to ponder Stan's description. > >Certainly (a) and (b) can be accomplished from the >same motor pod without any aesthetic or structural >compromises. I'm moving back to implementing this in >a rectangular box like Chris' first drawing which >conincidentally is the Amazon Reference's >architecture. This ought to furnish a lot of mass. > >Cheers, >Thom > > >--- Igor Kuznetsoff wrote: >> >> All, >> >> Thanks, Jeremy, I'll have to look into this as soon >> as >> I can find the time. Right now, I can't even find >> the >> time to go through all the mail, much less answer >> much >> of this deluge. Don't you guys have lives to live >> outside of Teres? Most *jobs* have days off. This >> has been 7 days a week since it started, and I am >> *extremely* burned out!!! This has been going on a >> long time!!! >> >> I would suggest to everyone that some of us, at >> least need some time off from this, but that is >> impossible unless *everyone* takes some timer off >> together, otherwise it is impossible to catch up. >> How >> about shutting this shindig down for a long weekend, >> say Fri.-Mon., *inclusive*? I mean EVERYONE stops >> sending for 4 days. I know that Thom would no doubt >> breathe easier, too, if he could rest up a bit, and >> enjoy the Noise, as I would like to (I also have a >> NJAudio Society meeting on Sun., as well), without >> finding the mailbox out of control. Right Now I >> have >> over 60 messages backed up that I don't have time >> for, >> and that is after deleting all the inconsequental >> and >> pre-embedded ones! >> >> Finally, I have glanced at the linear bearing site >> Jon >> put up, and see some things I both do & don't like, >> starting with 2 x $63 for the cheapest (your >> mention), >> which is *far* more than I would want to spend, >> until >> I see how my simpler system works. The simpler, the >> better, when something works that way, and I still >> haven't seen anything (unless it's in a post I >> haven't >> gotten to at all) to justify the complexity & cost >> inherent in using the slides, even if they have >> merit >> (yes, Jon, I think they do, I just don't find them >> justifiable). >> >> Igor >> > >__________________________________________________ >Do You Yahoo!? >Talk to your friends online with Yahoo! Messenger. >http://im.yahoo.com > Subject: [teres] Armboard Date: Wed, 8 Mar 2000 19:11:03 -0700 From: steve brooks, steve brooks To: teres@aiko.com Has anyone given thought to building an armboard out of one of the hardwoods that have a reputation for good sound...is it Gabon Ebony? Steve Brooks Subject: Re: [teres] HeavyWeight for RB300 Date: Wed, 8 Mar 2000 19:11:36 -0700 From: steve brooks, steve brooks To: teres@aiko.com That was me David..I won't get to it till this weekend probably..I'm moving the arm from the just departed VPI jr to a Mk4...I'll let you know....BTW for you potential Rega 250 buyers, Express is also selling a replacement stainless end stub..similiar to OL? Don't know how it attatches. Price $34.95. Steve Brooks > Someone recently mentioned on this list that he had received the new > tonearm counterweight for the RB300 from Express Machining. > > Can you give us a report? Subject: Re: [teres] Motor Pod Date: Wed, 8 Mar 2000 20:12:16 -0700 From: Thom Mackris, Thom Mackris To: teres@aiko.com Duh ... that was a typo on my part Jon. I'm darned near disfunctional typing on a laptop keyboard. What I was attempting to say was that teflon is *more* frictional than a bearing. Like yourself, I am concerned with the stick/slip issue. My thoughts are that perhaps the teflon is slick enough from the perspective of a 4-12 ounce (a guess) tensioning force, the stick/slip will be inconsequential. At the same time, the stick will be high enough to swamp any residual effects of either an out of round pulley or tiny motor vibrations. How many angels are on the head of that pin :-) What do y'all think about that? Cheers, Thom ----- Original Message ----- From: Jon Lane To: Sent: Tuesday, March 07, 2000 6:08 PM Subject: RE: [teres] Motor Pod > Thom said, > > > With respect to sliding the motor pod ... > > > > I wonder if something less frictional than a > > bearing (like teflon) might not > > be superior to bearings. > > Modern bearings (like these slides) have imperceptable > stick/slip - less than teflon, I think. > > JL > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Motor Orientation Date: Wed, 8 Mar 2000 20:12:33 -0700 From: Thom Mackris, Thom Mackris To: teres@aiko.com Brilliant Stan! ----- Original Message ----- From: Stanley Goudge To: Sent: Wednesday, March 08, 2000 3:15 PM Subject: Re: [teres] Motor Orientation > Thom, > The words "teflon slide" gave me a vision of a wedge shaped (SS) piece bolted > to the bottom of the motor pod which would slide down the end of a sloped subchassis. > The slope and wedge angles would be the same so that it would look like one piece. > Of course it would slide down (away from the platter) on teflon pads. The wedge would > have numerous mounting holes to find the right ride height for the motor. And maybe needs > to ride between two sides with teflon pads to kept motor torque from moving the wedge. > > Stan > > > At 01:20 PM 3/8/2000 -0800, you wrote: > >Aw, come on Igor - you can measure a real man by the > >size of his inbox :-)) > > > >Seriously, these topics have a way of ebbing and > >flowing and there's really no need to check in on a > >daily basis - it's just that you and I are posessed by > >this project and we've been on it since early > >December. > > > >Let's just let the recent entrants grind away, stand > >in the background and benefit from the fact that they > >started the race later than we did. No need to > >babysit. > > > >My take which I believe I've mentioned (jet lag > >prevails) is twofold: > > > >(a) Igor's drunk on crutches (thanks Jeremy) apporach > > > >and > > > >(b) a teflon slide version of Jon's. I like the idea > >of less than perfect friction with teflon as opposed > >to bearings... maybe I'm all wet here but I think a > >bit of friction would be helpful in swamping the > >effects of both any motor imprfections as well as > >runnout in the pulley as I noted previously. > > > >I still haven't had time to ponder Stan's description. > > > >Certainly (a) and (b) can be accomplished from the > >same motor pod without any aesthetic or structural > >compromises. I'm moving back to implementing this in > >a rectangular box like Chris' first drawing which > >conincidentally is the Amazon Reference's > >architecture. This ought to furnish a lot of mass. > > > >Cheers, > >Thom > > > > > >--- Igor Kuznetsoff wrote: > >> > >> All, > >> > >> Thanks, Jeremy, I'll have to look into this as soon > >> as > >> I can find the time. Right now, I can't even find > >> the > >> time to go through all the mail, much less answer > >> much > >> of this deluge. Don't you guys have lives to live > >> outside of Teres? Most *jobs* have days off. This > >> has been 7 days a week since it started, and I am > >> *extremely* burned out!!! This has been going on a > >> long time!!! > >> > >> I would suggest to everyone that some of us, at > >> least need some time off from this, but that is > >> impossible unless *everyone* takes some timer off > >> together, otherwise it is impossible to catch up. > >> How > >> about shutting this shindig down for a long weekend, > >> say Fri.-Mon., *inclusive*? I mean EVERYONE stops > >> sending for 4 days. I know that Thom would no doubt > >> breathe easier, too, if he could rest up a bit, and > >> enjoy the Noise, as I would like to (I also have a > >> NJAudio Society meeting on Sun., as well), without > >> finding the mailbox out of control. Right Now I > >> have > >> over 60 messages backed up that I don't have time > >> for, > >> and that is after deleting all the inconsequental > >> and > >> pre-embedded ones! > >> > >> Finally, I have glanced at the linear bearing site > >> Jon > >> put up, and see some things I both do & don't like, > >> starting with 2 x $63 for the cheapest (your > >> mention), > >> which is *far* more than I would want to spend, > >> until > >> I see how my simpler system works. The simpler, the > >> better, when something works that way, and I still > >> haven't seen anything (unless it's in a post I > >> haven't > >> gotten to at all) to justify the complexity & cost > >> inherent in using the slides, even if they have > >> merit > >> (yes, Jon, I think they do, I just don't find them > >> justifiable). > >> > >> Igor > >> > > > >__________________________________________________ > >Do You Yahoo!? > >Talk to your friends online with Yahoo! Messenger. > >http://im.yahoo.com > > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Motor Pod Date: Wed, 8 Mar 2000 20:37:53 -0700 From: Thom Mackris, Thom Mackris To: teres@aiko.com Ah yes! This is trangely reminiscent of the Roxan Xerxes if I am understanding you correctly. If I recall, the Roxan motor assembly was on some kind of leash. The design challenge seems to be a bearing that is stable and supports our 10 lb. or heavier pod. This would definitely take some work to optimize. It sounds more and more like a basic pod has to be built in order to be spinning discs before Christmas :-) Cheers, Thom ----- Original Message ----- From: Stanley Goudge To: ; ; Sent: Monday, March 06, 2000 7:33 PM Subject: RE: [teres] Motor Pod > Sorry Guys, > I just can't leave this thing alone. You'll need paper & pencil to figure this one. Forget what I said below, > after further thoughts it should be possible to use the torque of the motor to tighten the belt automatically. > All that is needed is a thust bearing to allow the motor pod to rotate freely. > Ok picture this, your looking down the left side of the turntable with motor in the foregound and platter in the background. > Now the motor spins clockwise which creates a counter-clockwise torque on the pod. With a offset > spindle to the right of center (say 3/8") of the pod. The counter-clockwise force will tighten the belt. > Way cool Uh. Now at full speed if the belt starts to slip there will be less torque applied and thus less tension, > now you may have tension runaway. So you may need to add a little weight for insurance. Or just reconfigure > it where less torque will give more tension by using a string and weight to bias the pod in a clockwise direction, > with the spindle to the left of center now. The torque is now opposing the weight and if the belt starts to slip > there will be less torque to counter the weight and the weight will tighten the belt. But this config. may have > a lot of slippage at startup because of higher friction (thus higher torque fighting the weight) caused by the belt slowly moving. > But once up to speed it should work perfect. > > Happy confusions, > Stan __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Armboard Date: Wed, 8 Mar 2000 21:31:57 -0700 From: Thom Mackris, Thom Mackris To: teres@aiko.com Hi Steve, A while back there was a question about the benefits of a completely detached pod / armboard. At the time, I expressed concern that this might be a problem because the separate pod would most likely resonate differently from the turntable base. The relationship between the arm and the bearing would be compromised. I think this reasoning is correct, and following this line of thought, I *think* we'd want the basic structure of the armboard to be the same as that of the base. Notice the word "think" in the prior sentence :-) My current philosophy for chassis/arm board is rigid first, damp later. Jon L & Chris B are also advocates of this approach, but then again, we may all be full of it. Cheers, Thom ----- Original Message ----- From: steve brooks To: Sent: Wednesday, March 08, 2000 9:07 PM Subject: [teres] Armboard > > Has anyone given thought to building an armboard out of one of the hardwoods > that have a reputation for good sound...is it Gabon Ebony? > Steve Brooks __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Motor Orientation Date: Wed, 8 Mar 2000 22:52:30 -0700 From: Thom Mackris, Thom Mackris To: teres@aiko.com Stan, You made me time travel back to college physics. Assuming no friction on an inclined plane, the force along an inclined plane is given by the equation: f = mg cosine theta where: mg - is the weight of the object in question (our motor pod) theta - is the angle between vertical and the inclined plane So: Cosine theta = f/mg And theta in degrees = Arc Cosine f/mg I put together a small spreadsheet which does not take the coefficient of friction into account. Ken probably has the coefficients of friction of teflon. Column A is the desired belt tension in pounds (from 4 ounces to 8 ounces) Column B is the mass of the motor pod - I assumed 20 lbs. Column C is the quotient of A divided by B Column D is angle theta Column E is the angle from horizontal in degrees (from .7 to 1.4 degrees) (Column E is the one we're concerned with). Obviously, the coefficient of friction of teflon against teflon would increase these angles, but you can see, we're looking at fairly small angles to start with. Cheers, Thom ----- Original Message ----- From: Stanley Goudge To: Sent: Wednesday, March 08, 2000 3:15 PM Subject: Re: [teres] Motor Orientation > Thom, > The words "teflon slide" gave me a vision of a wedge shaped (SS) piece bolted > to the bottom of the motor pod which would slide down the end of a sloped subchassis. > The slope and wedge angles would be the same so that it would look like one piece. > Of course it would slide down (away from the platter) on teflon pads. The wedge would > have numerous mounting holes to find the right ride height for the motor. And maybe needs > to ride between two sides with teflon pads to kept motor torque from moving the wedge. > > Stan --------------------------------------------------------------------- Name: Belt_ten.xls Belt_ten.xls Type: Microsoft Excel Worksheet (application/vnd.ms-excel) Encoding: base64