Subject: Re: [teres] synchronous vs. asynchronous motors Date: Wed, 23 Feb 2000 00:00:18 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Manfred, all, Thank you for an interesting analysis. I would like to take a moment at this time for a short analysis to address the matter of low motor inertia, as I believe that a lot of people are starting to think that only low inertia motors are good for *any kind* of TT use, because that is best for our high mass platter based system. I believe that such an understanding would be misleadingly incomplete. I would like to reduce the physics of the situation to the most basic level to simplify the mystery. Also, I want a reality check of my own understanding of these mechanics, to be sure that I am analyzing this properly, so feel free to shred my statements. It is not low inertia in absolute, but in *relative* terms that is desirable in a motor/platter system. With our high-mass platter, a motor with low moment of inertia is desirable. With a low mass platter, such as in the Kyocera TT system some years ago, the opposite was true. They, for reasons not worth going into at this moment (and I don't endorse their design in general), opted to use a super-hard ceramic platter of extremely light weight. They coupled this to a motor with a *flywheel* on it, for an extremely high moment of inertia, because the platter was very low in inertia. Because the motor turned at 4 times the speed of the platter, the moment was multiplied by 4 in relation to the platter (mass x velocity), amplifying the differential of inertia relative to the platter. This was a legitimate way to effect the same goal we are after, a *differential* in inertial values, not simply low inertia in the motor in all situations. I do consider the high platter mass/inertia - low motor inertia combination we are using to be the superior way to go, obviously, and for additional reasons. Also the more frequently encountered technique for reasons of practicality. What is important, I believe, is the need to understand that it is the *differential* in inertia between the motor and the platter that is desirable. The reason for this is simple enough when reduced to non-technical terms. If you were to link two objects of very dissimilar mass imperfectly (and what is perfect, especially in TT belts?), and swing, spin, or whatever, them about, they would stay together reasonably well. Just imagine a basketball together with a ping-pong ball. Now link two basketballs, or two bricks, or whatever, and try the same thing (carefully, if you use bricks). They tend to want to go separate ways. *It is much harder to get things of similar inertia to track together accurately*. When the inertial values are different enough, the smaller one gets influenced/dragged along with the larger much more easily, and they don't go bobbling about. Regardless of whether it is the motor or platter that enjoys the higher inertia. In a motor /platter system this means reduced harmonic motion, and stabler platter speed. Igor --- Manfred Huber wrote: > Hello Group, > > I have done some mathematical analysis of the > mechanical > system made up from a motor and a rotating mass and > found > some interesting (surprising to me) results: > > sync (ac) motor: > ---------------- > > The system made up from a synchronous motor and the > platter > is able to oscillate! Wether oscillation occurs > depends on > the strength of the motor, the moving mass and the > amount > of frictional force (damping) The best you can > achieve with > a sync. motor is aperiodic damping. This is because > in a sync > motor the torque linearly depends on the angle in > between > the two magnetic fields in the motor. One field is > generated by > the applied electrical power. It is rotating at a > fixed speed > dictated by the frequency of the power supply. The > rotor has permanent > magnets that generate a static field. For the motor > to work properly > the rotor has to rotate at the same speed as the > stator field. > The whole thing behaves exactly like a PLL (phase > locked loop) > > Imagine the platter is too slow and the rotor falls > behind the stator field. > Now the motor tries to get the angle in between the > fields back to its static > value. As the stator field move on at a fixed speed > the rotor has to move > at a speed higher than that of the stator field. > This means that there has to > be some speed overshot no matter how much damping we > have in the system! > > The damping can be influenced by to amount of > voltage that is applied to the motor. > The best case is reached when the voltage is just > sufficient to generate enough torque > to keep the platter going. In this case we have > aperiodic damping. In practice we > need to apply a higher voltage in order to avoid the > motor falling out of sync when > the system is disturbed. This means that the speed > will always ring when > recovering from a disturbance. > > async (dc) motor: > ----------------- > > The system made up from an async motor and platter > is a first order system, it has no resonance i.e. > there > is no oscillation possible no matter how strong the > motor, > how heavy the platter and how much damping is > involved! > > This is because the torque linearly depends on the > angular velocity. Imagine the platter is too slow > and > the motor generates more torque in order to bring > the speed up. > As the speed of the platter rises the torque > decreases thus > lowering the angular acceleration. The speed will > 'creep' > asymptotically to it's end point. There is no > possibility > for oscillaton. Not even a single overshot. > > Note that I do not say that damping does not matter > when using > an async motor. I used a very simple model that did > not include > the following points: > > - interaction of platter and needle > - elastic coupling of platter and motor > - ripple of torque generated by commutation > > I hope I managed to describe what's going on. > > Any takers? > > Regards > Manfred > > > ------------------ > Manfred Huber > MHuber@t-online.de > ------------------ > > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: belt material, was RE: [teres] synchronous vs. asynchronous motors; Date: Wed, 23 Feb 2000 01:03:46 -0700 From: phclark, phclark To: teres@aiko.com ----- Original Message ----- From: "Sellek, Grant (TSA)" To: Sent: Tuesday, February 22, 2000 8:55 PM Subject: belt material, was RE: [teres] synchronous vs. asynchronous motors; > -----Original Message----- > From: phclark [mailto:phclark@uswest.net] > Subject: Re: [teres] synchronous vs. asynchronous motors > > 2. Elastic coupling is inevitable at some level. Non-compliant materials > like magnetic tape would seem to be preferable to, say, string. > =============================================================== > > Peter, I'm not entirely convinced about this >What about leather? > > Grant Works for me. Responding to doubters: I'm not necessarily a proponent of mag tape. Actually, I thought it was a little silly when I first saw reference to it. I still think it would be prone to slippage, though this would be easy to verify on an existing 'table. As others have noted in this portion of the thread, and I agree, a material that has a higher co-efficient of friction might be desirable. Leather might fill that bill. I know that there are glues for leather that probably would solve the joining problem. OTOH, synthetic leather, like the belt I'm wearing right now, is essentially indestructible and to a large extent (??) doesn't stretch. It certainly can be glued. I'd bet that natural leather in a useable thin-ness would continue to stretch throughout its service life and be a bit of a maintenance headache. I think the spring gauge idea has merit, no matter what you use to drive the platter. Additionally, a machine woven synthetic (like dental floss) or monofiliament (like fishing line) might be good as well. My first thought was tape that is used for shipping, using mechanical fasteners. It's *very* strong and flexible, joinable chemically. However, it kind of gets you back to mag tape. A woven product, though, would add the "lossiness" that at first, and second glance, would seem to be desirable. It doesn't stretch meaningfully and has the big advantage that even though it would consume some power with the flexing of the individual fibers (especially at the motor end) damping is provided by this very action while maintaining a relatively high co-efficient of friction. My $0.02. Peter C Subject: Re: belt material, was RE: [teres] synchronous vs. asynchronous motor s; Date: Wed, 23 Feb 2000 01:43:37 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Lossy makes sense, but stiff does not! Perhaps you mean strretchless, not stiff. See the other post, responding to Roscoe's post on the subject for a possible idea using a rubberized cotton cloth. Igor --- "Sellek, Grant (TSA)" wrote: > -----Original Message----- > From: phclark [mailto:phclark@uswest.net] > Subject: Re: [teres] synchronous vs. asynchronous > motors > > 2. Elastic coupling is inevitable at some level. > Non-compliant materials > like magnetic tape would seem to be preferable to, > say, string. > =============================================================== > > Peter, I'm not entirely convinced about this, > especially if we concede that > the motor is not providing effective instantaneous > speed correction. I would > agree with the advantage of non-compliant materials > if there were no > tradeoffs, however I reckon the danger of a mag tape > drive is that it will > efficiently transmit any motor noise to the platter, > either bearing-type or > brush-type noise. We are trying to reduce that noise > at its source with a > good choice of motor, but that doesn't mean we can > ignore the tranmission of > noise through the drivetrain. Like Chris Brady said, > take every possible > measure. > > I don't want an elastic coupling either. Who wants > the platter going boing > boing on the end of a rubber band? I think this is > what Peter and others who > favour mag tape are trying to avoid. > > So I am in favour of a stiff but lossy drivetrain. > Mag tape is stiff but not > lossy. Rubber is slightly lossy but not stiff. The > best candidate that comes > to mind is string, or cotton thread! Does anyone > have a better suggestion > for a stiff, lossy material? What about leather? > > Grant > > Grant Sellek > Adelaide, Australia > grant.sellek@transport.sa.gov.au > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: belt material, was RE: [teres] synchronous vs.asynchronous motors; Date: Wed, 23 Feb 2000 08:45:53 -0700 From: George Munger, George Munger To: teres@aiko.com Hey there. I know not much, but Thom keeps saying to express ourselves so... Isn't there a way(s) we could try to perform some tests to obtain some quantitative data, once a list of possible belt materials is made? A) id the energy transmission levels of various belt materials to an acrylic platter (maybe we don't even need a Teres platter, just an acrylic one). 1) determine the various materials transmission values 2) determine if value changes relate to audible changes 3) determine other factors to check if stiff, lossy, available, etc. We then review the results. We could test an existing rubber TT/belt combo as a reference. Then make/obtain each available belt material, mag-tape, dental floss, etc. using ?? instrument(s) to determine quantitative values, then qualitative (listening) results. All other things being equal, we might get something of value here, maybe not... inquiring minds want to know. What to do? GM >>> "Sellek, Grant (TSA)" 02/22 10:55 PM >>> -----Original Message----- From: phclark [mailto:phclark@uswest.net] Subject: Re: [teres] synchronous vs. asynchronous motors 2. Elastic coupling is inevitable at some level. Non-compliant materials like magnetic tape would seem to be preferable to, say, string. =============================================================== Peter, I'm not entirely convinced about this, especially if we concede that the motor is not providing effective instantaneous speed correction. I would agree with the advantage of non-compliant materials if there were no tradeoffs, however I reckon the danger of a mag tape drive is that it will efficiently transmit any motor noise to the platter, either bearing-type or brush-type noise. We are trying to reduce that noise at its source with a good choice of motor, but that doesn't mean we can ignore the tranmission of noise through the drivetrain. Like Chris Brady said, take every possible measure. I don't want an elastic coupling either. Who wants the platter going boing boing on the end of a rubber band? I think this is what Peter and others who favour mag tape are trying to avoid. So I am in favour of a stiff but lossy drivetrain. Mag tape is stiff but not lossy. Rubber is slightly lossy but not stiff. The best candidate that comes to mind is string, or cotton thread! Does anyone have a better suggestion for a stiff, lossy material? What about leather? Grant Grant Sellek Adelaide, Australia grant.sellek@transport.sa.gov.au Subject: RE: [teres] synchronous vs. asynchronous motors Date: Wed, 23 Feb 2000 08:46:42 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Peter: Good insights. I agree that the motor won't be able to react quickly enough to compensate for the varying stylus drag, no matter how "stiff" the coupling belt is. I tend to disagree on using two motors; I think it would be hard to get precise synchronization and they thus would tend to "hunt," with possible audible consequences. Ken Ken Schei, P.E. Project Engineer Antarctic Support Associates Email address: scheike@asa.org Phone: 303-643-0163 > -----Original Message----- > From: phclark [SMTP:phclark@uswest.net] > Sent: Tuesday, February 22, 2000 5:26 PM > To: teres@aiko.com > Subject: Re: [teres] synchronous vs. asynchronous motors > > Very succinct. You've explained in sufficient detail the "folklore" > aspects > of why dc motors in general are preferable for the application. > > Random thoughts: > > 1. The stylus/vinyl interaction is real, intuitively. I wonder out loud > how much compensation for this that can realistically be applied. Drag > varies instantaneously, and with the exception of Baroque or the Telarc > "1812", randomly. I do not envision a feedback system which could react > quickly and powerfully enough without the dreaded "overshoot." > > 2. Elastic coupling is inevitable at some level. Non-compliant materials > like magnetic tape would seem to be preferable to, say, string. Fishing > line might be better, tho' how one would join it would be problematic. > Considering the potential weight of the platter and the motor assembly, > using 1/2" wide mag tape suggests itself with a separately mounted idler > to > maintain tension. You might achieve closer coupling in that manner, > bearing > in mind that the conflicting consideration of isolating the motor is a > design point. > > 3. Without having seen any justification for Verdier using multiple > motors > on his latest oeuvre, mounting two+ motors mechanically out of phase with > each other would tend to minimize the cyclical, momentary torque peaks. > That's just spitballing, but makes sense on a cocktail napkin. > > My $0.02. > > Peter C > > > ----- Original Message ----- > From: "Manfred Huber" > To: > Sent: Tuesday, February 22, 2000 5:23 AM > Subject: [teres] synchronous vs. asynchronous motors > > > > Hello Group, > > > > I have done some mathematical analysis of the mechanical > > system made up from a motor and a rotating mass and found > > some interesting (surprising to me) results: > > > > sync (ac) motor: > > ---------------- > > > > The system made up from a synchronous motor and the platter > > is able to oscillate! Wether oscillation occurs depends on > > the strength of the motor, the moving mass and the amount > > of frictional force (damping) The best you can achieve with > > a sync. motor is aperiodic damping. This is because in a sync > > motor the torque linearly depends on the angle in between > > the two magnetic fields in the motor. One field is generated by > > the applied electrical power. It is rotating at a fixed speed > > dictated by the frequency of the power supply. The rotor has permanent > > magnets that generate a static field. For the motor to work properly > > the rotor has to rotate at the same speed as the stator field. > > The whole thing behaves exactly like a PLL (phase locked loop) > > > > Imagine the platter is too slow and the rotor falls behind the stator > field. > > Now the motor tries to get the angle in between the fields back to its > static > > value. As the stator field move on at a fixed speed the rotor has to > move > > at a speed higher than that of the stator field. This means that there > has > to > > be some speed overshot no matter how much damping we have in the system! > > > > The damping can be influenced by to amount of voltage that is applied to > the motor. > > The best case is reached when the voltage is just sufficient to generate > enough torque > > to keep the platter going. In this case we have aperiodic damping. In > practice we > > need to apply a higher voltage in order to avoid the motor falling out > of > sync when > > the system is disturbed. This means that the speed will always ring when > > recovering from a disturbance. > > > > async (dc) motor: > > ----------------- > > > > The system made up from an async motor and platter > > is a first order system, it has no resonance i.e. there > > is no oscillation possible no matter how strong the motor, > > how heavy the platter and how much damping is involved! > > > > This is because the torque linearly depends on the > > angular velocity. Imagine the platter is too slow and > > the motor generates more torque in order to bring the speed up. > > As the speed of the platter rises the torque decreases thus > > lowering the angular acceleration. The speed will 'creep' > > asymptotically to it's end point. There is no possibility > > for oscillaton. Not even a single overshot. > > > > Note that I do not say that damping does not matter when using > > an async motor. I used a very simple model that did not include > > the following points: > > > > - interaction of platter and needle > > - elastic coupling of platter and motor > > - ripple of torque generated by commutation > > > > I hope I managed to describe what's going on. > > > > Any takers? > > > > Regards > > Manfred > > > > > > ------------------ > > Manfred Huber > > MHuber@t-online.de > > ------------------ > > > > > > Subject: Re: [teres] synchronous vs. asynchronous motors Date: Wed, 23 Feb 2000 09:11:54 -0700 From: phclark, phclark To: teres@aiko.com I think you are probably right about multiple motors. I was basically thinking out loud about Verdier's multi set up. I'm sure there's justification there somewhere, I was speculating that might be it, rather than needlessly complexifying things. While there many ways to skin a cat, usually an elegant solution is best. Peter C ----- Original Message ----- From: "Schei, Kenneth" To: Sent: Wednesday, February 23, 2000 7:48 AM Subject: RE: [teres] synchronous vs. asynchronous motors > Peter: > > Good insights. I agree that the motor won't be able to react quickly enough > to compensate for the varying stylus drag, no matter how "stiff" the > coupling belt is. I tend to disagree on using two motors; I think it would > be hard to get precise synchronization and they thus would tend to "hunt," > with possible audible consequences. > > Ken > > Ken Schei, P.E. > Project Engineer > Antarctic Support Associates > Email address: scheike@asa.org > Phone: 303-643-0163 > > > -----Original Message----- > > From: phclark [SMTP:phclark@uswest.net] > > Sent: Tuesday, February 22, 2000 5:26 PM > > To: teres@aiko.com > > Subject: Re: [teres] synchronous vs. asynchronous motors > > > > Very succinct. You've explained in sufficient detail the "folklore" > > aspects > > of why dc motors in general are preferable for the application. > > > > Random thoughts: > > > > 1. The stylus/vinyl interaction is real, intuitively. I wonder out loud > > how much compensation for this that can realistically be applied. Drag > > varies instantaneously, and with the exception of Baroque or the Telarc > > "1812", randomly. I do not envision a feedback system which could react > > quickly and powerfully enough without the dreaded "overshoot." > > > > 2. Elastic coupling is inevitable at some level. Non-compliant materials > > like magnetic tape would seem to be preferable to, say, string. Fishing > > line might be better, tho' how one would join it would be problematic. > > Considering the potential weight of the platter and the motor assembly, > > using 1/2" wide mag tape suggests itself with a separately mounted idler > > to > > maintain tension. You might achieve closer coupling in that manner, > > bearing > > in mind that the conflicting consideration of isolating the motor is a > > design point. > > > > 3. Without having seen any justification for Verdier using multiple > > motors > > on his latest oeuvre, mounting two+ motors mechanically out of phase with > > each other would tend to minimize the cyclical, momentary torque peaks. > > That's just spitballing, but makes sense on a cocktail napkin. > > > > My $0.02. > > > > Peter C > > > > > > ----- Original Message ----- > > From: "Manfred Huber" > > To: > > Sent: Tuesday, February 22, 2000 5:23 AM > > Subject: [teres] synchronous vs. asynchronous motors > > > > > > > Hello Group, > > > > > > I have done some mathematical analysis of the mechanical > > > system made up from a motor and a rotating mass and found > > > some interesting (surprising to me) results: > > > > > > sync (ac) motor: > > > ---------------- > > > > > > The system made up from a synchronous motor and the platter > > > is able to oscillate! Wether oscillation occurs depends on > > > the strength of the motor, the moving mass and the amount > > > of frictional force (damping) The best you can achieve with > > > a sync. motor is aperiodic damping. This is because in a sync > > > motor the torque linearly depends on the angle in between > > > the two magnetic fields in the motor. One field is generated by > > > the applied electrical power. It is rotating at a fixed speed > > > dictated by the frequency of the power supply. The rotor has permanent > > > magnets that generate a static field. For the motor to work properly > > > the rotor has to rotate at the same speed as the stator field. > > > The whole thing behaves exactly like a PLL (phase locked loop) > > > > > > Imagine the platter is too slow and the rotor falls behind the stator > > field. > > > Now the motor tries to get the angle in between the fields back to its > > static > > > value. As the stator field move on at a fixed speed the rotor has to > > move > > > at a speed higher than that of the stator field. This means that there > > has > > to > > > be some speed overshot no matter how much damping we have in the system! > > > > > > The damping can be influenced by to amount of voltage that is applied to > > the motor. > > > The best case is reached when the voltage is just sufficient to generate > > enough torque > > > to keep the platter going. In this case we have aperiodic damping. In > > practice we > > > need to apply a higher voltage in order to avoid the motor falling out > > of > > sync when > > > the system is disturbed. This means that the speed will always ring when > > > recovering from a disturbance. > > > > > > async (dc) motor: > > > ----------------- > > > > > > The system made up from an async motor and platter > > > is a first order system, it has no resonance i.e. there > > > is no oscillation possible no matter how strong the motor, > > > how heavy the platter and how much damping is involved! > > > > > > This is because the torque linearly depends on the > > > angular velocity. Imagine the platter is too slow and > > > the motor generates more torque in order to bring the speed up. > > > As the speed of the platter rises the torque decreases thus > > > lowering the angular acceleration. The speed will 'creep' > > > asymptotically to it's end point. There is no possibility > > > for oscillaton. Not even a single overshot. > > > > > > Note that I do not say that damping does not matter when using > > > an async motor. I used a very simple model that did not include > > > the following points: > > > > > > - interaction of platter and needle > > > - elastic coupling of platter and motor > > > - ripple of torque generated by commutation > > > > > > I hope I managed to describe what's going on. > > > > > > Any takers? > > > > > > Regards > > > Manfred > > > > > > > > > ------------------ > > > Manfred Huber > > > MHuber@t-online.de > > > ------------------ > > > > > > > > > > Subject: RE: [teres] synchronous vs. asynchronous motors Date: Wed, 23 Feb 2000 09:36:42 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'teres@aiko.com' Agreed. Personally, I'm a devout discipline of the KISS principle. Ken > -----Original Message----- > From: phclark [SMTP:phclark@uswest.net] > Sent: Wednesday, February 23, 2000 8:04 AM > To: teres@aiko.com > Subject: Re: [teres] synchronous vs. asynchronous motors > > I think you are probably right about multiple motors. I was basically > thinking out loud about Verdier's multi set up. I'm sure there's > justification there somewhere, I was speculating that might be it, rather > than needlessly complexifying things. While there many ways to skin a > cat, > usually an elegant solution is best. > > Peter C > > > ----- Original Message ----- > From: "Schei, Kenneth" > To: > Sent: Wednesday, February 23, 2000 7:48 AM > Subject: RE: [teres] synchronous vs. asynchronous motors > > > > Peter: > > > > Good insights. I agree that the motor won't be able to react quickly > enough > > to compensate for the varying stylus drag, no matter how "stiff" the > > coupling belt is. I tend to disagree on using two motors; I think it > would > > be hard to get precise synchronization and they thus would tend to > "hunt," > > with possible audible consequences. > > > > Ken > > > > Ken Schei, P.E. > > Project Engineer > > Antarctic Support Associates > > Email address: scheike@asa.org > > Phone: 303-643-0163 > > > > > -----Original Message----- > > > From: phclark [SMTP:phclark@uswest.net] > > > Sent: Tuesday, February 22, 2000 5:26 PM > > > To: teres@aiko.com > > > Subject: Re: [teres] synchronous vs. asynchronous motors > > > > > > Very succinct. You've explained in sufficient detail the "folklore" > > > aspects > > > of why dc motors in general are preferable for the application. > > > > > > Random thoughts: > > > > > > 1. The stylus/vinyl interaction is real, intuitively. I wonder out > loud > > > how much compensation for this that can realistically be applied. > Drag > > > varies instantaneously, and with the exception of Baroque or the > Telarc > > > "1812", randomly. I do not envision a feedback system which could > react > > > quickly and powerfully enough without the dreaded "overshoot." > > > > > > 2. Elastic coupling is inevitable at some level. Non-compliant > materials > > > like magnetic tape would seem to be preferable to, say, string. > Fishing > > > line might be better, tho' how one would join it would be problematic. > > > Considering the potential weight of the platter and the motor > assembly, > > > using 1/2" wide mag tape suggests itself with a separately mounted > idler > > > to > > > maintain tension. You might achieve closer coupling in that manner, > > > bearing > > > in mind that the conflicting consideration of isolating the motor is a > > > design point. > > > > > > 3. Without having seen any justification for Verdier using multiple > > > motors > > > on his latest oeuvre, mounting two+ motors mechanically out of phase > with > > > each other would tend to minimize the cyclical, momentary torque > peaks. > > > That's just spitballing, but makes sense on a cocktail napkin. > > > > > > My $0.02. > > > > > > Peter C > > > > > > > > > ----- Original Message ----- > > > From: "Manfred Huber" > > > To: > > > Sent: Tuesday, February 22, 2000 5:23 AM > > > Subject: [teres] synchronous vs. asynchronous motors > > > > > > > > > > Hello Group, > > > > > > > > I have done some mathematical analysis of the mechanical > > > > system made up from a motor and a rotating mass and found > > > > some interesting (surprising to me) results: > > > > > > > > sync (ac) motor: > > > > ---------------- > > > > > > > > The system made up from a synchronous motor and the platter > > > > is able to oscillate! Wether oscillation occurs depends on > > > > the strength of the motor, the moving mass and the amount > > > > of frictional force (damping) The best you can achieve with > > > > a sync. motor is aperiodic damping. This is because in a sync > > > > motor the torque linearly depends on the angle in between > > > > the two magnetic fields in the motor. One field is generated by > > > > the applied electrical power. It is rotating at a fixed speed > > > > dictated by the frequency of the power supply. The rotor has > permanent > > > > magnets that generate a static field. For the motor to work properly > > > > the rotor has to rotate at the same speed as the stator field. > > > > The whole thing behaves exactly like a PLL (phase locked loop) > > > > > > > > Imagine the platter is too slow and the rotor falls behind the > stator > > > field. > > > > Now the motor tries to get the angle in between the fields back to > its > > > static > > > > value. As the stator field move on at a fixed speed the rotor has to > > > move > > > > at a speed higher than that of the stator field. This means that > there > > > has > > > to > > > > be some speed overshot no matter how much damping we have in the > system! > > > > > > > > The damping can be influenced by to amount of voltage that is > applied > to > > > the motor. > > > > The best case is reached when the voltage is just sufficient to > generate > > > enough torque > > > > to keep the platter going. In this case we have aperiodic damping. > In > > > practice we > > > > need to apply a higher voltage in order to avoid the motor falling > out > > > of > > > sync when > > > > the system is disturbed. This means that the speed will always ring > when > > > > recovering from a disturbance. > > > > > > > > async (dc) motor: > > > > ----------------- > > > > > > > > The system made up from an async motor and platter > > > > is a first order system, it has no resonance i.e. there > > > > is no oscillation possible no matter how strong the motor, > > > > how heavy the platter and how much damping is involved! > > > > > > > > This is because the torque linearly depends on the > > > > angular velocity. Imagine the platter is too slow and > > > > the motor generates more torque in order to bring the speed up. > > > > As the speed of the platter rises the torque decreases thus > > > > lowering the angular acceleration. The speed will 'creep' > > > > asymptotically to it's end point. There is no possibility > > > > for oscillaton. Not even a single overshot. > > > > > > > > Note that I do not say that damping does not matter when using > > > > an async motor. I used a very simple model that did not include > > > > the following points: > > > > > > > > - interaction of platter and needle > > > > - elastic coupling of platter and motor > > > > - ripple of torque generated by commutation > > > > > > > > I hope I managed to describe what's going on. > > > > > > > > Any takers? > > > > > > > > Regards > > > > Manfred > > > > > > > > > > > > ------------------ > > > > Manfred Huber > > > > MHuber@t-online.de > > > > ------------------ > > > > > > > > > > > > > > Subject: Re: [teres] synchronous vs. asynchronous motors Date: Wed, 23 Feb 2000 14:21:52 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com I noticed the multiple motors, as well. I agree with Ken about that. Could it simply be that he discovered that less just wouldn't drive the huge carousel of a platter ? Igor --- phclark wrote: > I think you are probably right about multiple > motors. I was basically > thinking out loud about Verdier's multi set up. I'm > sure there's > justification there somewhere, I was speculating > that might be it, rather > than needlessly complexifying things. While there > many ways to skin a cat, > usually an elegant solution is best. > > Peter C > > > ----- Original Message ----- > From: "Schei, Kenneth" > To: > Sent: Wednesday, February 23, 2000 7:48 AM > Subject: RE: [teres] synchronous vs. asynchronous > motors > > > > Peter: > > > > Good insights. I agree that the motor won't be > able to react quickly > enough > > to compensate for the varying stylus drag, no > matter how "stiff" the > > coupling belt is. I tend to disagree on using two > motors; I think it > would > > be hard to get precise synchronization and they > thus would tend to "hunt," > > with possible audible consequences. > > > > Ken > > > > Ken Schei, P.E. > > Project Engineer > > Antarctic Support Associates > > Email address: scheike@asa.org > > Phone: 303-643-0163 > > > > > -----Original Message----- > > > From: phclark [SMTP:phclark@uswest.net] > > > Sent: Tuesday, February 22, 2000 5:26 PM > > > To: teres@aiko.com > > > Subject: Re: [teres] synchronous vs. > asynchronous motors > > > > > > Very succinct. You've explained in sufficient > detail the "folklore" > > > aspects > > > of why dc motors in general are preferable for > the application. > > > > > > Random thoughts: > > > > > > 1. The stylus/vinyl interaction is real, > intuitively. I wonder out > loud > > > how much compensation for this that can > realistically be applied. Drag > > > varies instantaneously, and with the exception > of Baroque or the Telarc > > > "1812", randomly. I do not envision a feedback > system which could react > > > quickly and powerfully enough without the > dreaded "overshoot." > > > > > > 2. Elastic coupling is inevitable at some > level. Non-compliant > materials > > > like magnetic tape would seem to be preferable > to, say, string. Fishing > > > line might be better, tho' how one would join it > would be problematic. > > > Considering the potential weight of the platter > and the motor assembly, > > > using 1/2" wide mag tape suggests itself with a > separately mounted idler > > > to > > > maintain tension. You might achieve closer > coupling in that manner, > > > bearing > > > in mind that the conflicting consideration of > isolating the motor is a > > > design point. > > > > > > 3. Without having seen any justification for > Verdier using multiple > > > motors > > > on his latest oeuvre, mounting two+ motors > mechanically out of phase > with > > > each other would tend to minimize the cyclical, > momentary torque peaks. > > > That's just spitballing, but makes sense on a > cocktail napkin. > > > > > > My $0.02. > > > > > > Peter C > > > > > > > > > ----- Original Message ----- > > > From: "Manfred Huber" > > > To: > > > Sent: Tuesday, February 22, 2000 5:23 AM > > > Subject: [teres] synchronous vs. asynchronous > motors > > > > > > > > > > Hello Group, > > > > > > > > I have done some mathematical analysis of the > mechanical > > > > system made up from a motor and a rotating > mass and found > > > > some interesting (surprising to me) results: > > > > > > > > sync (ac) motor: > > > > ---------------- > > > > > > > > The system made up from a synchronous motor > and the platter > > > > is able to oscillate! Wether oscillation > occurs depends on > > > > the strength of the motor, the moving mass and > the amount > > > > of frictional force (damping) The best you can > achieve with > > > > a sync. motor is aperiodic damping. This is > because in a sync > > > > motor the torque linearly depends on the angle > in between > > > > the two magnetic fields in the motor. One > field is generated by > > > > the applied electrical power. It is rotating > at a fixed speed > > > > dictated by the frequency of the power supply. > The rotor has permanent > > > > magnets that generate a static field. For the > motor to work properly > > > > the rotor has to rotate at the same speed as > the stator field. > > > > The whole thing behaves exactly like a PLL > (phase locked loop) > > > > > > > > Imagine the platter is too slow and the rotor > falls behind the stator > > > field. > > > > Now the motor tries to get the angle in > between the fields back to its > > > static > > > > value. As the stator field move on at a fixed > speed the rotor has to > > > move > > > > at a speed higher than that of the stator > field. This means that there > > > has > > > to > > > > be some speed overshot no matter how much > damping we have in the > system! > > > > > > > > The damping can be influenced by to amount of > voltage that is applied > to > > > the motor. > > > > The best case is reached when the voltage is > just sufficient to > generate > > > enough torque > > > > to keep the platter going. In this case we > have aperiodic damping. In > > > practice we > > > > need to apply a higher voltage in order to > avoid the motor falling out > > > of > > > sync when > > > > the system is disturbed. This means that the > speed will always ring > when > > > > recovering from a disturbance. > > > > > > > > async (dc) motor: > > > > ----------------- > > > > > > > > The system made up from an async motor and > platter > > > > is a first order system, it has no resonance > i.e. there > > > > is no oscillation possible no matter how > strong the motor, > > > > how heavy the platter and how much damping is > involved! > > > > > > > > This is because the torque linearly depends on > the > > > > angular velocity. Imagine the platter is too > slow === message truncated === __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] synchronous vs. asynchronous motors Date: Fri, 25 Feb 2000 09:44:00 -0700 From: Schei, Kenneth, Schei, Kenneth To: 'Thom Mackris / Joan Panzella'; Schei, Kenneth; Igor Kuznetsoff Technically he's not correct. The inertia of an object is independent of any velocity. It is related to the mass of the body and the gravitational force and is constant regardless of velocity. The moment of inertia of an object is the sum of the products obtained by multiplying the mass of each elementary particle by the square of its distance from the the axis. That's why flywheels and often TT platters have most of their mass near the perimeter - to get the highest moment of inertia per mass. Moment of inertia is also independent of velocity. The momentum (not moment) of an object is equal to the mass times velocity. The thing that is proportional to the square of velocity is energy, which yields the classic equation E = 1/2MV^2. Manfred must be wanting to relate the energy of motion of the two objects and incorrectly stated it. I think Manfred is quite knowledgable about motors and controllers, but when he starts to analyze the harmonics of the motor-controller-drive belt-platter-bearing system, he seems to be venturing into unfamiliar waters. Such systems harmonics analyses are extremely complicated and probably beyond the scope of our undertakings. These systems tend to be chaotic, which in the technical sense means that they are extremely non-linear and defy accurate analysis by normal mathematical equations. Analysis of chaotic systems was made famous by the "Butterfly Theory," and is held as an example of why weather forecasters consistently fail. I really think that the "chaotic systems" phenomenon is one reason why classical measuring techniques completely fail to predict how good or bad an audio component will sound. It is also a reason why I try to keep everything as simple as possible. I will accept certain relationships if they have been empirically demonstrated to work, but when someone argues for an arcane or exotic technical phenomenon but cannot describe it with technical accuracy, I hesitate before taking it as doctrine. My position is that we should design a motor and controller that will produce and maintain the required rpm with accuracy, and design a platter/bearing system that will have the moment of inertia and bearing drag that will minimize fluctuations. If there are certain techniques that have been tried and proven, then we should consider them. 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: Thursday, February 24, 2000 6:57 PM > To: Ken Schei (w); Igor Kuznetsoff > Subject: Re: [teres] synchronous vs. asynchronous motors > > Ken, > > It's been a while since high school & college physics. Was Manfred > correct > in his comment that inertia is proportional to the square of the velocity > (i.e. a motor spinning at 24 x the platter speed will should have it's > moment of inertia multiplied by 24^2). > > Thom > > ----- Original Message ----- > From: Igor Kuznetsoff > To: Thom Mackris / Joan Panzella > Sent: Thursday, February 24, 2000 2:42 AM > Subject: Re: [teres] synchronous vs. asynchronous motors > > > You could be right, I don't remember either. Manfred > hasn't commented one way or the other as of yet. It > doesn't change the gist of what is said, fortunately, > but it would be nice to correct this. Would Ken know > the correct answer? > I > > --- Thom Mackris / Joan Panzella > wrote: > > Igor, Sent off list ... > > > > I forget my high school & college physics & so I'm > > not sure if Manfred is > > correct, but he stated that the inertia is > > proportional to the *square* of > > the velocity. In the example below, the moment of > > inertia of the high mass > > pulley is multiplied by 4^2 = 16. > > > > I'll leave it to you to send out the correction if > > you agree. As I said, > > high school & college were a long time ago :-(( > > > > Cheers (off to beddy bye now), > > Thom > > > > ----- Original Message ----- > > From: Igor Kuznetsoff > > To: > > Sent: Tuesday, February 22, 2000 10:58 PM > > Subject: Re: [teres] synchronous vs. asynchronous > > motors > > > > > > Manfred, all, > > Thank you for an interesting analysis. > > I > > would like to take a moment at this time for a short > > analysis to address the matter of low motor inertia, > > as I believe that a lot of people are starting to > > think that only low inertia motors are good for *any > > kind* of TT use, because that is best for our high > > mass platter based system. I believe that such an > > understanding would be misleadingly incomplete. I > > would like to reduce the physics of the situation to > > the most basic level to simplify the mystery. Also, > > I > > want a reality check of my own understanding of > > these > > mechanics, to be sure that I am analyzing this > > properly, so feel free to shred my statements. > > It is not low inertia in absolute, but in > > *relative* terms that is desirable in a > > motor/platter > > system. With our high-mass platter, a motor with > > low > > moment of inertia is desirable. With a low mass > > platter, such as in the Kyocera TT system some years > > ago, the opposite was true. They, for reasons not > > worth going into at this moment (and I don't endorse > > their design in general), opted to use a super-hard > > ceramic platter of extremely light weight. They > > coupled this to a motor with a *flywheel* on it, for > > an extremely high moment of inertia, because the > > platter was very low in inertia. Because the motor > > turned at 4 times the speed of the platter, the > > moment > > was multiplied by 4 in relation to the platter (mass > > x > > velocity), amplifying the differential of inertia > > relative to the platter. This was a legitimate way > > to > > effect the same goal we are after, a *differential* > > in > > inertial values, not simply low inertia in the motor > > in all situations. I do consider the high platter > > mass/inertia - low motor inertia combination we are > > using to be the superior way to go, obviously, and > > for > > additional reasons. Also the more frequently > > encountered technique for reasons of practicality. > > What is important, I believe, is the need to > > understand that it is the *differential* in inertia > > between the motor and the platter that is desirable. > > The reason for this is simple enough when > > reduced to non-technical terms. If you were to link > > two objects of very dissimilar mass imperfectly (and > > what is perfect, especially in TT belts?), and > > swing, > > spin, or whatever, them about, they would stay > > together reasonably well. Just imagine a basketball > > together with a ping-pong ball. Now link two > > basketballs, or two bricks, or whatever, and try the > > same thing (carefully, if you use bricks). They > > tend > > to want to go separate ways. *It is much harder to > > get things of similar inertia to track together > > accurately*. When the inertial > > values are different enough, the smaller one gets > > influenced/dragged along with the larger much more > > easily, and they don't go bobbling about. > > Regardless > > of whether it is the motor or platter that enjoys > > the > > higher inertia. In a motor /platter system this > > means > > reduced harmonic motion, and stabler platter speed. > > > > Igor > > > > --- Manfred Huber wrote: > > > Hello Group, > > > > > > I have done some mathematical analysis of the > > > mechanical > > > system made up from a motor and a rotating mass > > and > > > found > > > some interesting (surprising to me) results: > > > > > > sync (ac) motor: > > > ---------------- > > > > > > The system made up from a synchronous motor and > > the > > > platter > > > is able to oscillate! Wether oscillation occurs > > > depends on > > > the strength of the motor, the moving mass and the > > > amount > > > of frictional force (damping) The best you can > > > achieve with > > > a sync. motor is aperiodic damping. This is > > because > > > in a sync > > > motor the torque linearly depends on the angle in > > > between > > > the two magnetic fields in the motor. One field is > > > generated by > > > the applied electrical power. It is rotating at a > > > fixed speed > > > dictated by the frequency of the power supply. The > > > rotor has permanent > > > magnets that generate a static field. For the > > motor > > > to work properly > > > the rotor has to rotate at the same speed as the > > > stator field. > > > The whole thing behaves exactly like a PLL (phase > > > locked loop) > > > > > > Imagine the platter is too slow and the rotor > > falls > > > behind the stator field. > > > Now the motor tries to get the angle in between > > the > > > fields back to its static > > > value. As the stator field move on at a fixed > > speed > > > the rotor has to move > > > at a speed higher than that of the stator field. > > > This means that there has to > > > be some speed overshot no matter how much damping > > we > > > have in the system! > > > > > > The damping can be influenced by to amount of > > > voltage that is applied to the motor. > > > The best case is reached when the voltage is just > > > sufficient to generate enough torque > > > to keep the platter going. In this case we have > > > aperiodic damping. In practice we > > > need to apply a higher voltage in order to avoid > > the > > > motor falling out of sync when > > > the system is disturbed. This means that the speed > > > will always ring when > > > recovering from a disturbance. > > > > > > async (dc) motor: > > > ----------------- > > > > > > The system made up from an async motor and platter > > > is a first order system, it has no resonance i.e. > > > there > > > is no oscillation possible no matter how strong > > the > > > motor, > > > how heavy the platter and how much damping is > > > involved! > > > > > > This is because the torque linearly depends on the > > > angular velocity. Imagine the platter is too slow > > > and > > > the motor generates more torque in order to bring > > > the speed up. > > > As the speed of the platter rises the torque > > > decreases thus > > > lowering the angular acceleration. The speed will > > > 'creep' > > > asymptotically to it's end point. There is no > > > possibility > > > for oscillaton. Not even a single overshot. > > > > > > Note that I do not say that damping does not > > matter > > > when using > > > an async motor. I used a very simple model that > > did > > > not include > > > === message truncated === > __________________________________________________ > Do You Yahoo!? > Talk to your friends online with Yahoo! Messenger. > http://im.yahoo.com > Subject: Re: [teres] Motor & Controller Date: Sun, 27 Feb 2000 00:56:13 -0700 From: Chris Brady, Chris Brady To: teres@aiko.com Work on the motor & controller kits is progressing. Manfred has provided an updated schematic for his controller. Ron Welborn and I will start looking for sources for the parts. It seems that Manfreds initial motor recommendation of the Maxon 110189 is the best choice. I have not seen any comments to the contrary so unless someone speaks up we will plan on using this motor for the kit. We need to hammer out a design for the motor pulley. I believe that the requirements are high precision (concentric) with a friction fit onto the motor shaft. Also Manfred suggests using 0.5" diameter pulley. There has been a lot of discussion about possible belts so I figure that we will want to accommodate both round and flat belts. Using these guidelines I came up with the attached draft design for the pulley. Take a look and feel free to suggest changes. As before any ideas are welcome but lets try to work toward finalizing a design. For the pulley material I am thinking aluminum or acrylic. Chris --------------------------------------------------------------------- Name: pulley.gif pulley.gif Type: GIF Image (image/gif) Encoding: base64 Subject: Re: [teres] Motor & Controller Date: Sun, 27 Feb 2000 01:15:00 -0700 From: Roscoe Primrose, Roscoe Primrose To: teres@aiko.com Chris Brady wrote: > We need to hammer out a design for the motor pulley. > I believe that the requirements are high precision > (concentric) with a friction fit onto the motor shaft. > Also Manfred suggests using 0.5" diameter pulley. > There has been a lot of discussion about possible belts > so I figure that we will want to accommodate both round > and flat belts. Using these guidelines I came up with > the attached draft design for the pulley. Take a look and > feel free to suggest changes. As before any ideas are > welcome but lets try to work toward finalizing a design. > In general, a flat belt will be happier on a slightly convex profile than it will on a cylindrical profile as you have drawn... > For the pulley material I am thinking aluminum or acrylic. > Either of those is probably good, what about brass of carbon fiber? Carbon fiber ought to make those who feel the motor should have low intertia happy... 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 Subject: Re: [teres] Re: Sure Looks Like a Scheu to Me Date: Sun, 27 Feb 2000 01:18:12 -0700 From: Ron Welborne, Ron Welborne To: teres@aiko.com Wow! Looks like our design will be at least comparable to the Euro Premier Kit and should come in at a fraction of the cost too!!! I was thinking the other day that another option for the belt would be fly-line "backing". FYI this is a dacron line approximately .05" diameter that is typically attached between the fly fishing reel and the fly line. Basically this is used to extend the length of the flyfishing line without having to pay a lot of money for 300 feet (for those really big fish) of expensive fly line. This line is smaller in diameter and has some "give" to it and you don't have to worry about tapers and that sort of thing. Cheap too. Ron Welborne Labs wlabs@ix.netcom.com ph: 303.470.6585 fax: 303.791.5783 website --------------- www.welbornelabs.com ----------------- ----- Original Message ----- From: Thom Mackris / Joan Panzella To: Teres_List Sent: Saturday, February 26, 2000 5:39 PM Subject: [teres] Re: Sure Looks Like a Scheu to Me > When I sent the first link out (below), I didn't realize that they have > three distinct lines of 'tables: > > (1) Euro-Kits > (2) Amazon > (3) Verdier > > The Amazon reference at $11K bears a striking resemblence to the "simple" > drawing on Chris' website. Note that the motor controller incorporates a > suggestion I made, to include a voltmeter. Obviously, they too are of the > Dr. Wilimzig school that the correct belt (string) tension is the one which > maintains platter speed at the lowest voltage. This would certainly make > setup simpler and easily repeatbable. > > This is all coming together! > > Thom > > ----- Original Message ----- > From: Thom Mackris / Joan Panzella > To: Teres_List > Sent: Saturday, February 26, 2000 5:24 PM > Subject: Sure Looks Like a Scheu to Me > > > The audioadvancements 'tables sure resemble a Scheu to me. > > http://www.audioadvancements.com/ > > Thom > > Subject: Re: [teres] Motor & Controller Date: Sun, 27 Feb 2000 01:22:30 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Chris, I realize that the drawing may look as it does for simplicity, but should mention that the larger flat section (.344") should be convex for belt centering. As drawn there would also be a difference in effective working diameter, ditto the simplicity thing. I am also used to seeing small end flanges at top and bottom of convex pulleys, but these may only be a convenience for keeping the pulley from slipping off during tension adjustment. As per Ken's analysis of some time ago, acrylic may be the material of choice to cover thermal expansion considerations. Igor --- Chris Brady wrote: > Work on the motor & controller kits is progressing. > Manfred has provided an updated schematic for his > controller. Ron Welborn and I will start looking > for sources for the parts. > > It seems that Manfreds initial motor recommendation > of the > Maxon 110189 is the best choice. I have not seen > any > comments to the contrary so unless someone speaks up > we > will plan on using this motor for the kit. > > We need to hammer out a design for the motor pulley. > I believe that the requirements are high precision > (concentric) with a friction fit onto the motor > shaft. > Also Manfred suggests using 0.5" diameter pulley. > There has been a lot of discussion about possible > belts > so I figure that we will want to accommodate both > round > and flat belts. Using these guidelines I came up > with > the attached draft design for the pulley. Take a > look and > feel free to suggest changes. As before any ideas > are > welcome but lets try to work toward finalizing a > design. > > For the pulley material I am thinking aluminum or > acrylic. > > Chris > ATTACHMENT part 2 image/gif name=pulley.gif __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Motor & Controller Date: Sun, 27 Feb 2000 05:23:03 -0700 From: Manfred Huber, Manfred Huber To: teres@aiko.com Chris, >As before any ideas are >welcome but lets try to work toward finalizing a design. As has been pointed out before, a convex shape and small flanges on both ends are good ideas. The flanges are a great help during the adjustment of the belt tension. The notch (right word?) for the string should be V shaped with a small flat floor \_/ and not round IMHO. This provides better friction. >For the pulley material I am thinking aluminum or acrylic. My pulley is made from high grade hard aluminium like the stuff used in airplane construction. There is much belt slipping during the acceleration phase and you need to use a hard material for the pulley or else it will wear and loose it's perfectly round shape. A kind of magnesium alloy may mee a good idea (?) and it sure looks sexy. Regards Manfred ------------------ Manfred Huber MHuber@t-online.de ------------------ Subject: Re: [teres] Re: belt material Date: Sun, 27 Feb 2000 05:31:53 -0700 From: Manfred Huber, Manfred Huber To: teres@aiko.com Igor, >I wonder how hard (as in the shaft material) it would >be to thread the motor shaft so that we could just >screw the pulley on... Not possible IMHO as it is not possible to disassemble this motor and you can not cut the thread without disassembling it. Please also take care of fine metal grins entering the bearing. I have lost one motor and think this was the reason! Regards Manfred ------------------ Manfred Huber MHuber@t-online.de ------------------ Subject: Re: [teres] Re: belt material Date: Sun, 27 Feb 2000 10:50:56 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com I agree, it was a very low probability musing, let's scrap that one. P.S.- What does the mounting flange/surface area look like- vis-a-vis the previous threads concerning motor rotation for even bearing wear & my concept of setting up a calibrateable belt tensioning scheme? Igor --- Manfred Huber wrote: > Igor, > > >I wonder how hard (as in the shaft material) it > would > >be to thread the motor shaft so that we could just > >screw the pulley on... > > Not possible IMHO as it is not possible to > disassemble this motor > and you can not cut the thread without disassembling > it. > > Please also take care of fine metal grins entering > the bearing. > I have lost one motor and think this was the reason! > > Regards > Manfred > > > ------------------ > Manfred Huber > MHuber@t-online.de > ------------------ > > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: Re: [teres] Re: belt material Date: Sun, 27 Feb 2000 11:18:02 -0700 From: Manfred Huber, Manfred Huber To: teres@aiko.com Igor, >P.S.- What does the mounting flange/surface area look >like- vis-a-vis the previous threads concerning motor >rotation for even bearing wear & my concept of setting >up a calibrateable belt tensioning scheme? I have scanned the data sheet of the motor: http://home.t-online.de/home/mhuber/amaxdata.gif I'm sorry, but I have only the german version of the catalogue. Regards Manfred ------------------ Manfred Huber MHuber@t-online.de ------------------ Subject: Re: [teres] Motor & Controller Date: Sun, 27 Feb 2000 11:53:16 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Probably much like plastic would stand up to a wire saw. Let's go with Manfred's suggestion of using metal. Igor --- StepHydro@aol.com wrote: > In a message dated 02/27/2000 2: Eastern Standard , cbrady@sgi.com writes: > > For the pulley material I am thinking aluminum or > acrylic. > > For the string-drive guys, there might be a wear > problem. How might acrylic > stand up to string slippage? > > Cheers/Carron > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] Teres-Motor&Supply Date: Mon, 28 Feb 2000 14:43:26 -0700 From: Stanley Goudge, Stanley Goudge To: teres@aiko.com Put me down for one motor and controller. Stan At 02:03 PM 2/14/2000 -0800, you wrote: >I would be interested in the motor controller group package > > > Fritz > >-----Original Message----- >From: owner-teres@aiko.com [mailto:owner-teres@aiko.com]On Behalf Of >Chris Brady >Sent: Monday, February 14, 2000 2:00 PM >To: teres@aiko.com; mikeinchandler@home.com; audiodir@gte.net; >MHuber@t-online.de >Subject: [teres] Teres-Motor&Supply > > >I am really jazzed about using Manfreds excellent controller >design with the Teres so I have been digging up some info. > >I called the US Maxxon rep and got prices for the 110189 motor: > > 1-4 $83.45 > 5-19 $66.25 > 20-49 $57.80 > >These prices seem reasonable, especially if we do a group >purchase. I a have faxed copy of the spec's for this motor and >it looks like an excellent choice. I also have a catalogue on it's >way so that other choices from Maxxon can be considered. Perhaps >I can scan some of the relevant pages and put them on the web page. > >I confirmed that the $29 programmer kit works with the at89c2051 >so we have an inexpensive way to program the chips here in the US. > >I also downloaded and experimented with the free C compiler that >Manfred pointed me to. I have the C code ported and I am working >on porting the assembler. It looks like the free compiler will >be suitable, but the documentation is poor. > >If there is enough interest I would be willing to put together >motor/controller kits for the group. I envision that the kit >would include: > > - A Maxxon 110189 motor > - A precision machined pulley (from Bryce) > > - A printed circuit board (from Ron Wellborn) > - A pre-programmed at89c2051 (code supplied by Manfred, > programed by me) > - All of the other electronic parts (caps, IC's resistors, etc) > - Basic instructions > - An AC transformer > >By doing a group purchase we would save big time on the pulley and >circuit boards. There would also be a savings of 10-15% for the other >components if we are doing 20+ kits. This would also help with >the shipping costs and minimum order problems when you have to source >parts from 4 - 5 different vendors. > >I am generous but not crazy so I would expect to make a little on >each kit to cover some of my time investment. But even with my charge >the kit price would be less than the cost of doing an individual >purchase. I also feel that Manfred should receive some compensation >for his generous sharing of the controller design. Perhaps some extra >circuit boards? > >How many would be interested? Comments? > >Chris > Subject: [teres] Motor/supply kit Date: Tue, 29 Feb 2000 11:31:00 -0700 From: Chris Brady, Chris Brady To: teres@aiko.com I am wondering if there would be interest in including a motor mounting plate in the motor/controller kit. I expect that there will be a lot of different shapes and sizes of motor pods, but perhaps we can agree on a single mounting plate design and benefit from a quantity discount. I am thinking that a round mounting plate, say 4" in diameter with mounting holes around the edge would work for either a round or rectangular motor pod. We could each make our own but with enough units they could be precision made on a NC mill at a reasonable cost. If made from fairly thin aluminum (1/16 - 1/8") it would be inexpensive. However, we could also opt for a more expensive design made from 1/4 - 3/8" aluminum with nice recessed holes for cap screws and an anodized finish. The thicker plate may not work any better but it would sure look sweet. Chris Subject: Re: [teres] Motor/supply kit Date: Tue, 29 Feb 2000 11:59:57 -0700 From: Alex Mitaru, Alex Mitaru To: teres@aiko.com At 10:28 AM 2/29/00 -0700, you wrote: >I am thinking that a round mounting plate, say 4" in diameter >with mounting holes around the edge would work for either a >round or rectangular motor pod. We could each make our own >but with enough units they could be precision made on a NC >mill at a reasonable cost. If made from fairly thin aluminum >(1/16 - 1/8") it would be inexpensive. However, we could >also opt for a more expensive design made from 1/4 - 3/8" >aluminum with nice recessed holes for cap screws and an >anodized finish. The thicker plate may not work any better >but it would sure look sweet. yes, I would go for it...but why not make it out of brass or copper... brass would look very nice...and the material costs for such a small piece, even if 1/4" would be rather low... alex Subject: RE: [teres] Motor/supply kit Date: Tue, 29 Feb 2000 12:52:13 -0700 From: Mackris, Thom G., Mackris, Thom G. To: 'teres@aiko.com' Although I am gravitating toward a big honkin' rectangular motor/controller "block" much like Chris' first POV ray drawing and the Amazon Reference 'table, I can see a real benefit to a circular plate. A circular plate would facilitate periodic rotation to facilitate equal wear on the motor bushing. If the holes (8 to 12) were drilled via CNC, we'd be guraranteed that they were symetrical and could be mounted in more than one orientation. The idea of 1/4" thickness or greater is appealing from a rigidity standpoint. I'll bet we're talking about only $15 per unit in the quantities we'd be ordering (a guess). Cheers, Thom -----Original Message----- From: Chris Brady [mailto:cbrady@sgi.com] Sent: Tuesday, February 29, 2000 10:29 AM To: teres@aiko.com Subject: [teres] Motor/supply kit I am wondering if there would be interest in including a motor mounting plate in the motor/controller kit. I expect that there will be a lot of different shapes and sizes of motor pods, but perhaps we can agree on a single mounting plate design and benefit from a quantity discount. I am thinking that a round mounting plate, say 4" in diameter with mounting holes around the edge would work for either a round or rectangular motor pod. We could each make our own but with enough units they could be precision made on a NC mill at a reasonable cost. If made from fairly thin aluminum (1/16 - 1/8") it would be inexpensive. However, we could also opt for a more expensive design made from 1/4 - 3/8" aluminum with nice recessed holes for cap screws and an anodized finish. The thicker plate may not work any better but it would sure look sweet. Chris Subject: Re: [teres] Motor/supply kit/Mounting Plate Date: Tue, 29 Feb 2000 12:53:38 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Excellent idea, Chris. This would allow rotating the motor within any shape pod, and a belt tensioning device, the orientation of which which would be unaffected by motor rotation (for bearing wear). This is the very reason I asked Manfred about motor dimensions the other day. I would suggest enough holes around the perimeter to allow small turn increments, as something like, say, four for only 90 degree increments would not be adequate. More holes can be drilled than used at any time for adequate attachment, though vibration transfer would improve with extra screws. I would warn against the use of thin stock for this purpose, as it may act as a resonant drumhead for motor vibration. The thicker the stock, the better it will transfer any existing motor vibration to the pod, which would ostensibly be designed to sink that very thing. Additionally, a small point, I believe that brass or copper, besides being attractive in their own right, are more amenable to gold plating, should anyone want to get *really* ritzed up. This could be done easily (access wise) at most auto dealerships, where badges & metal trim routinely get gold plated nowadays. Anyone wihing to *really* get over the top could even get the plate engraved first..... :-) Igor > yes, I would go for it...but why not make it out of >brass or >copper... > brass would look very nice...and the material costs >for such a small > piece, even if 1/4" would be rather low... > > alex --- Chris Brady wrote: > I am wondering if there would be interest in > including > a motor mounting plate in the motor/controller kit. > I expect that there will be a lot of different > shapes and > sizes of motor pods, but perhaps we can agree on a > single > mounting plate design and benefit from a quantity > discount. > > I am thinking that a round mounting plate, say 4" in > diameter > with mounting holes around the edge would work for > either a > round or rectangular motor pod. We could each make > our own > but with enough units they could be precision made > on a NC > mill at a reasonable cost. If made from fairly thin > aluminum > (1/16 - 1/8") it would be inexpensive. However, we > could > also opt for a more expensive design made from 1/4 - > 3/8" > aluminum with nice recessed holes for cap screws and > an > anodized finish. The thicker plate may not work any > better > but it would sure look sweet. > > Chris > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] Motor/supply kit Date: Tue, 29 Feb 2000 13:35:33 -0700 From: Mackris, Thom G., Mackris, Thom G. To: 'Teres_List' A silly thought ... Six holes in the mounting plate would suffice. There could be 12 holes underneath (hidden from view). Once a month you could rotate :-) Old trick from photography days ... change your camera batteries once a year on your birthday. Thom -----Original Message----- From: Mackris, Thom G. Sent: Tuesday, February 29, 2000 11:36 AM To: 'teres@aiko.com' Subject: RE: [teres] Motor/supply kit Although I am gravitating toward a big honkin' rectangular motor/controller "block" much like Chris' first POV ray drawing and the Amazon Reference 'table, I can see a real benefit to a circular plate. A circular plate would facilitate periodic rotation to facilitate equal wear on the motor bushing. If the holes (8 to 12) were drilled via CNC, we'd be guraranteed that they were symetrical and could be mounted in more than one orientation. The idea of 1/4" thickness or greater is appealing from a rigidity standpoint. I'll bet we're talking about only $15 per unit in the quantities we'd be ordering (a guess). Cheers, Thom -----Original Message----- From: Chris Brady [mailto:cbrady@sgi.com] Sent: Tuesday, February 29, 2000 10:29 AM To: teres@aiko.com Subject: [teres] Motor/supply kit I am wondering if there would be interest in including a motor mounting plate in the motor/controller kit. I expect that there will be a lot of different shapes and sizes of motor pods, but perhaps we can agree on a single mounting plate design and benefit from a quantity discount. I am thinking that a round mounting plate, say 4" in diameter with mounting holes around the edge would work for either a round or rectangular motor pod. We could each make our own but with enough units they could be precision made on a NC mill at a reasonable cost. If made from fairly thin aluminum (1/16 - 1/8") it would be inexpensive. However, we could also opt for a more expensive design made from 1/4 - 3/8" aluminum with nice recessed holes for cap screws and an anodized finish. The thicker plate may not work any better but it would sure look sweet. Chris Subject: Re: [teres] Motor/supply kit/Mounting Plate Date: Tue, 29 Feb 2000 14:31:20 -0700 From: Daus Studenberg, Daus Studenberg To: teres@aiko.com I think the plate would look really great! It would give that really professional look! HOWEVER, I hate to say that it may cause some minor problems. The resonance issue is really not an issue because plenty of modeling clay will take care of any resonance on a thick aluminum plate and is actually better than wood because of the increased stiffness and high dampening. My concern is with magnetic fields. I have the typical Grado Blue/unshielded motor combo on my modified AR turntable. Before I had the acrylic platter, I found that the aluminum platter contributed to add a SIGNIFICANT amount of motor and AC hum (try this out with an AR turntable, you will see what I am talking about). I found out a turntable design that has less metal is better or at least less aluminum. Speaking of which, have we talked about shielding the motor or is it shielded?? Part of the reason that I am going for the separate motor mounting configuration is that I have had a lot of problems with motor noise from its stray magnetic fields. I may be using Mu-metal around my motor housing for shielding. I would be interested in a group purchase of mu-metal. Perhaps we could use a phenolic board painted black or a 1" thick block of acrylic?? Of course, I plan on using the Shure V15MX-VR (anyone like this cartridge??) so hopefully hum will not be that much of a problem! :) Daus > --- Chris Brady wrote: > > I am wondering if there would be interest in > > including > > a motor mounting plate in the motor/controller kit. > > I expect that there will be a lot of different > > shapes and > > sizes of motor pods, but perhaps we can agree on a > > single > > mounting plate design and benefit from a quantity > > discount. > > > > I am thinking that a round mounting plate, say 4" in > > diameter > > with mounting holes around the edge would work for > > either a > > round or rectangular motor pod. We could each make > > our own > > but with enough units they could be precision made > > on a NC > > mill at a reasonable cost. If made from fairly thin > > aluminum > > (1/16 - 1/8") it would be inexpensive. However, we > > could > > also opt for a more expensive design made from 1/4 - > > 3/8" > > aluminum with nice recessed holes for cap screws and > > an > > anodized finish. The thicker plate may not work any > > better > > but it would sure look sweet. > > > > Chris Subject: Re: [teres] Motor/supply kit/Mounting Plate Date: Tue, 29 Feb 2000 15:21:25 -0700 From: Igor Kuznetsoff, Igor Kuznetsoff To: teres@aiko.com Yes, Daus, the subject of shielding has been beaten to death only recently. Mu-metal was discussed as well. Manfred has mentioned that this *DC* motor (yes, DC motors are not absolutely quiet either) is very good that way *and* good with *his* Grado. Your AR uses an AC motor. Under the wrong circumstrances, and depending on relative sizes (tuning), a metal plate can act as a sending antenna. Did you try grounding the plate you mentioned? This can sometimes work. Or not. it's tricky. I use a modified predecessor to your cartridge, the type 5 (last & best of the old series) if I remember correctly. I like it a bit more than the new series, but like both. There is a very simple mod that you can perform for less than $0.02 and five minutes of your time, tightening up your transients & bass. E-mail me if interested. I mentioned it in the Townshend/Dual article. Haven't you read it? I had trouble getting the majordomo system to accept the post. Also, there are a number of materials better than modeling clay for damping. Spend some time with the digests, there is a wealth of good info there. Igor --- Daus Studenberg wrote: > I think the plate would look really great! It would > give that really > professional look! HOWEVER, I hate to say that it > may cause some minor > problems. The resonance issue is really not an > issue because plenty of > modeling clay will take care of any resonance on a > thick aluminum plate and > is actually better than wood because of the > increased stiffness and high > dampening. My concern is with magnetic fields. I > have the typical Grado > Blue/unshielded motor combo on my modified AR > turntable. Before I had the > acrylic platter, I found that the aluminum platter > contributed to add a > SIGNIFICANT amount of motor and AC hum (try this out > with an AR turntable, > you will see what I am talking about). I found out > a turntable design that > has less metal is better or at least less aluminum. > Speaking of which, have > we talked about shielding the motor or is it > shielded?? Part of the reason > that I am going for the separate motor mounting > configuration is that I have > had a lot of problems with motor noise from its > stray magnetic fields. I > may be using Mu-metal around my motor housing for > shielding. I would be > interested in a group purchase of mu-metal. > Perhaps we could use a > phenolic board painted black or a 1" thick block of > acrylic?? Of course, I > plan on using the Shure V15MX-VR (anyone like this > cartridge??) so hopefully > hum will not be that much of a problem! :) Daus > > > > > > --- Chris Brady wrote: > > > I am wondering if there would be interest in > > > including > > > a motor mounting plate in the motor/controller > kit. > > > I expect that there will be a lot of different > > > shapes and > > > sizes of motor pods, but perhaps we can agree on > a > > > single > > > mounting plate design and benefit from a > quantity > > > discount. > > > > > > I am thinking that a round mounting plate, say > 4" in > > > diameter > > > with mounting holes around the edge would work > for > > > either a > > > round or rectangular motor pod. We could each > make > > > our own > > > but with enough units they could be precision > made > > > on a NC > > > mill at a reasonable cost. If made from fairly > thin > > > aluminum > > > (1/16 - 1/8") it would be inexpensive. However, > we > > > could > > > also opt for a more expensive design made from > 1/4 - > > > 3/8" > > > aluminum with nice recessed holes for cap screws > and > > > an > > > anodized finish. The thicker plate may not work > any > > > better > > > but it would sure look sweet. > > > > > > Chris > > > __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com Subject: RE: [teres] Motor/supply kit/Mounting Plate Date: Tue, 29 Feb 2000 15:34:45 -0700 From: Mackris, Thom G., Mackris, Thom G. To: 'teres@aiko.com' Daus, No time to reply in detail at the moment, but one item. The motor is DC, and apart from some spurious effects at the brushes, you won't have the shielding issues inherrent in an AC motor like your modded AR or my Merrill. Interesting comments about the aluminum carrying the "hum" to the cartridge. I would have only expected ferrous metals to do this. Mu metal had been mentioned early on, although at the time there was not a much interest - the thinking at the time, I suppose was that there was time to address this later on. It's getting close to "later on". Yes, modeling clay! Igor had turned me on to some black gooey stuff that's used to seal automobile windshields - enough of this black tarry ribbon to go around a windshield sells for ~ $10.00 in an auto parts store. It never hardens and will not flow and make a mess, at least up to temperatures experienced in an automobile in the Summer in Arizona :-)) Cheers, Thom -----Original Message----- From: Daus Studenberg [mailto:daus@ufl.edu] Sent: Tuesday, February 29, 2000 4:37 PM To: teres@aiko.com Subject: Re: [teres] Motor/supply kit/Mounting Plate I think the plate would look really great! It would give that really professional look! HOWEVER, I hate to say that it may cause some minor problems. The resonance issue is really not an issue because plenty of modeling clay will take care of any resonance on a thick aluminum plate and is actually better than wood because of the increased stiffness and high dampening. My concern is with magnetic fields. I have the typical Grado Blue/unshielded motor combo on my modified AR turntable. Before I had the acrylic platter, I found that the aluminum platter contributed to add a SIGNIFICANT amount of motor and AC hum (try this out with an AR turntable, you will see what I am talking about). I found out a turntable design that has less metal is better or at least less aluminum. Speaking of which, have we talked about shielding the motor or is it shielded?? Part of the reason that I am going for the separate motor mounting configuration is that I have had a lot of problems with motor noise from its stray magnetic fields. I may be using Mu-metal around my motor housing for shielding. I would be interested in a group purchase of mu-metal. Perhaps we could use a phenolic board painted black or a 1" thick block of acrylic?? Of course, I plan on using the Shure V15MX-VR (anyone like this cartridge??) so hopefully hum will not be that much of a problem! :) Daus > --- Chris Brady wrote: > > I am wondering if there would be interest in > > including > > a motor mounting plate in the motor/controller kit. > > I expect that there will be a lot of different > > shapes and > > sizes of motor pods, but perhaps we can agree on a > > single > > mounting plate design and benefit from a quantity > > discount. > > > > I am thinking that a round mounting plate, say 4" in > > diameter > > with mounting holes around the edge would work for > > either a > > round or rectangular motor pod. We could each make > > our own > > but with enough units they could be precision made > > on a NC > > mill at a reasonable cost. If made from fairly thin > > aluminum > > (1/16 - 1/8") it would be inexpensive. However, we > > could > > also opt for a more expensive design made from 1/4 - > > 3/8" > > aluminum with nice recessed holes for cap screws and > > an > > anodized finish. The thicker plate may not work any > > better > > but it would sure look sweet. > > > > Chris Subject: Re: [teres] Motor/supply kit Date: Tue, 29 Feb 2000 17:13:05 -0700 From: Chris and Susan Beck, Chris and Susan Beck To: teres@aiko.com I sure like that idea. Any items that we can get a group purchase on (and agree on) is like money in the bank. I doubt many of us have access to either a Bridgeport or a CNC milling center. Chris Beck Chris Brady wrote: > I am wondering if there would be interest in including > a motor mounting plate in the motor/controller kit. > I expect that there will be a lot of different shapes and > sizes of motor pods, but perhaps we can agree on a single > mounting plate design and benefit from a quantity discount. > > I am thinking that a round mounting plate, say 4" in diameter > with mounting holes around the edge would work for either a > round or rectangular motor pod. We could each make our own > but with enough units they could be precision made on a NC > mill at a reasonable cost. If made from fairly thin aluminum > (1/16 - 1/8") it would be inexpensive. However, we could > also opt for a more expensive design made from 1/4 - 3/8" > aluminum with nice recessed holes for cap screws and an > anodized finish. The thicker plate may not work any better > but it would sure look sweet. > > Chris Subject: Re: [teres] Motor/supply kit Date: Tue, 29 Feb 2000 17:13:12 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 2/29/00 10:28, Chris Brady at cbrady@sgi.com wrote: > I am wondering if there would be interest in including > a motor mounting plate in the motor/controller kit. > I expect that there will be a lot of different shapes and > sizes of motor pods, but perhaps we can agree on a single > mounting plate design and benefit from a quantity discount. > > I am thinking that a round mounting plate, say 4" in diameter > with mounting holes around the edge would work for either a > round or rectangular motor pod. We could each make our own > but with enough units they could be precision made on a NC > mill at a reasonable cost. If made from fairly thin aluminum > (1/16 - 1/8") it would be inexpensive. However, we could > also opt for a more expensive design made from 1/4 - 3/8" > aluminum with nice recessed holes for cap screws and an > anodized finish. The thicker plate may not work any better > but it would sure look sweet. > > Chris > I like the idea, especially of the thicker plate. But would willingly buy either. One less piece that I would have to cobble together. Steve Z Subject: Re: [teres] Motor/supply kit Date: Tue, 29 Feb 2000 17:32:46 -0700 From: Steve Zettel, Steve Zettel To: teres@aiko.com on 2/29/00 11:36, Mackris, Thom G. at tgmackris@vicorpinc.com wrote: > Although I am gravitating toward a big honkin' rectangular motor/controller > "block" much like Chris' first POV ray drawing and the Amazon Reference > 'table, I can see a real benefit to a circular plate. > > A circular plate would facilitate periodic rotation to facilitate equal wear > on the motor bushing. If the holes (8 to 12) were drilled via CNC, we'd be > guraranteed that they were symetrical and could be mounted in more than one > orientation. The idea of 1/4" thickness or greater is appealing from a > rigidity standpoint. I'll bet we're talking about only $15 per unit in the > quantities we'd be ordering (a guess). > > Cheers, > Thom > Ditto, on all counts! Steve Z Subject: Re: [teres] Motor/supply kit Date: Tue, 29 Feb 2000 17:59:56 -0700 From: Ron Welborne, Ron Welborne To: teres@aiko.com Chris, I think that is a good idea. Ron Welborne Labs wlabs@ix.netcom.com ph: 303.470.6585 fax: 303.791.5783 website --------------- www.welbornelabs.com ----------------- ----- Original Message ----- From: Chris Brady To: Sent: Tuesday, February 29, 2000 10:28 AM Subject: [teres] Motor/supply kit > I am wondering if there would be interest in including > a motor mounting plate in the motor/controller kit. > I expect that there will be a lot of different shapes and > sizes of motor pods, but perhaps we can agree on a single > mounting plate design and benefit from a quantity discount. > > I am thinking that a round mounting plate, say 4" in diameter > with mounting holes around the edge would work for either a > round or rectangular motor pod. We could each make our own > but with enough units they could be precision made on a NC > mill at a reasonable cost. If made from fairly thin aluminum > (1/16 - 1/8") it would be inexpensive. However, we could > also opt for a more expensive design made from 1/4 - 3/8" > aluminum with nice recessed holes for cap screws and an > anodized finish. The thicker plate may not work any better > but it would sure look sweet. > > Chris Subject: Re: [teres] Motor/supply kit Date: Tue, 29 Feb 2000 19:29:23 -0700 From: phclark, phclark To: teres@aiko.com I think *this* is a good idea. I'd be willing to work around a good stout plate, even if weren't my ideal. Count me in. Peter C ----- Original Message ----- From: "Mackris, Thom G." To: Sent: Tuesday, February 29, 2000 11:36 AM Subject: RE: [teres] Motor/supply kit > Although I am gravitating toward a big honkin' rectangular motor/controller > "block" much like Chris' first POV ray drawing and the Amazon Reference > 'table, I can see a real benefit to a circular plate. > > A circular plate would facilitate periodic rotation to facilitate equal wear > on the motor bushing. If the holes (8 to 12) were drilled via CNC, we'd be > guraranteed that they were symetrical and could be mounted in more than one > orientation. The idea of 1/4" thickness or greater is appealing from a > rigidity standpoint. I'll bet we're talking about only $15 per unit in the > quantities we'd be ordering (a guess). > > Cheers, > Thom > > -----Original Message----- > From: Chris Brady [mailto:cbrady@sgi.com] > Sent: Tuesday, February 29, 2000 10:29 AM > To: teres@aiko.com > Subject: [teres] Motor/supply kit > > > I am wondering if there would be interest in including > a motor mounting plate in the motor/controller kit. > I expect that there will be a lot of different shapes and > sizes of motor pods, but perhaps we can agree on a single > mounting plate design and benefit from a quantity discount. > > I am thinking that a round mounting plate, say 4" in diameter > with mounting holes around the edge would work for either a > round or rectangular motor pod. We could each make our own > but with enough units they could be precision made on a NC > mill at a reasonable cost. If made from fairly thin aluminum > (1/16 - 1/8") it would be inexpensive. However, we could > also opt for a more expensive design made from 1/4 - 3/8" > aluminum with nice recessed holes for cap screws and an > anodized finish. The thicker plate may not work any better > but it would sure look sweet. > > Chris > Subject: Re: [teres] Motor Pod Date: Tue, 29 Feb 2000 19:31:39 -0700 From: phclark, phclark To: teres@aiko.com This has some merit, though I confess it sounds a little Heath Robinson. Perhaps you could flesh this out with some drawings? Peter C ----- Original Message ----- From: "Igor Kuznetsoff" To: Sent: Tuesday, February 29, 2000 2:01 PM Subject: Re: [teres] Motor Pod > All, > Following the various factors & solutions > discussed pertaining to motor pod design & > implementation, I had yet another thought for > consideration. I suppose some of you wish I would run > out of them by now, but I can't help it. This > concerns the underpinnings of the pod. While I am > sure that we will end up with a variety of techniques > employed, I would like to suggest a novel > configuration which would probably not normally be > considered. > What I have in mind is pursuant to my previous > suggestion that there should be enough compliance in > the motor/platter axis to allow a belt tensioning > scheme to do its thing unhindered, so that it can be > repeatably calibrateable. My suggestion today is to > place the motor pod on two, yes two, not three (much > less four) cones. > [Double your pleasure/Double your fun/with two cones, > yes *two* cones on one.(axis) (viz. : Pretty twins > holding two motor pods) ] > Wouldn't this just fall over? Well, yes, if you tried > to stand this up by itself. To this end , something > like slightly shorter "training wheel" feet of some > sort could be added on the cross-axis, for convenience > during setup, or disuse. If, however, in use, this > was balanced (adding a simple, inexpensive bubble > level to the top of the pod would be a good idea), and > the belt slipped on, and the belt tensioning set, this > rig will stand up nicely, and, this being the > important thing, *belt tension will now be dependent > only on the tensioner setting*. Additionally, > concentrating the weight upon just two cone points, > not three or more, couples the pod to the surface it > sits on even better. Should you not want this tight > coupling to implement your personal technical > philosophy, or layout combinations, just use something > compliant instead of the two cones. Finding the > balance points for placing the cones is simple enough. > If your pod is symmetrical, this is obvious, just use > the centerline. If it is not , due to the layout of > switches, power supply, whatever, just set the > completed pod, minus the balancing weight (if you go > that route, which I suspect would be the most popular > for its simple neatness, not mention the adaptability > of old tonearms & their weights) on a dowel or > something like that along the expected balance axis. > play with it until it balances neatly, mark the > location, & mount the cones, or whatever, on that > line. I would suggest exiting the wiring on the > centerline somewhere to maintain balance. > To sum up what could be the ideal pod setup: > The scheme outlined above, a belt tensioner rig, a > voltmeter for setting the actual tension, a rotateable > motor mounting plate, a massive pod designed to > dissipate vibration, and a lightweight metal pulley > with dual profiles. The belt, if flat, should have a > half twist. Feel free to add anything I've left out. > A thought about using the voltmeter might be > worthwhile at this point. As the idea has been > running so far, it is assumed that the lowest voltage > reading would correlate to the lowest tension useable, > and that would be the ideal setting for belt tension. > I disagree with that. I suspect that at that lowest > tension we would be running at the onset of slippage, > which would be very difficult to determine, quantify, > or even pin down sonically by ear, and this would be > an unwise condition. I posit that it would be a > better regimen to find that lowest point, and increase > tension bias to just a bit above that to guarantee the > smoothest power transfer. > > Igor > > > __________________________________________________ > Do You Yahoo!? > Talk to your friends online with Yahoo! Messenger. > http://im.yahoo.com > Subject: Re: [teres] Motor/supply kit/Mounting Plate Date: Tue, 29 Feb 2000 20:39:21 -0700 From: Daus Studenberg, Daus Studenberg To: teres@aiko.com Yeah, I too would have expected only ferrous metals to cause EMI problems but my observations have indicated that alluminum is suceptable as well. I have grounded the platter (not running of course!) to see if their was a change and there was not. Perhaps the platter was not fuly alluminum on the AR turntable. In fact, now I think about it, the platter is quite heavy for alluminum. Perhaps it is an alloy with ferrous material in it. I definately think the mounting plate would be VERY cool looking and a GREAT performer! :) Besides, if the hum from the DC motor is not signifigant or noticable at all (I too suspect the AC design causing the bulk of the problems), I say lets get that plate made! > Daus, > > No time to reply in detail at the moment, but one item. The motor is DC, > and apart from some spurious effects at the brushes, you won't have the > shielding issues inherrent in an AC motor like your modded AR or my Merrill. > Interesting comments about the aluminum carrying the "hum" to the cartridge. > I would have only expected ferrous metals to do this. > Subject: RE: [teres] Motor/supply kit Date: Tue, 29 Feb 2000 22:14:11 -0700 From: Paul Croft, Paul Croft To: teres@aiko.com This sounds great, Chris! Let's go for the more expensive one. What the heck, in for a nickel, in for a dime. Cheers, Paul > -----Original Message----- > From: owner-teres@aiko.com [mailto:owner-teres@aiko.com]On Behalf Of > Chris Brady > Sent: Tuesday, February 29, 2000 12:29 PM > To: teres@aiko.com > Subject: [teres] Motor/supply kit > > > I am wondering if there would be interest in including > a motor mounting plate in the motor/controller kit. (snip...) However, we could > also opt for a more expensive design made from 1/4 - 3/8" > aluminum with nice recessed holes for cap screws and an > anodized finish. The thicker plate may not work any better > but it would sure look sweet. > > Chris > Subject: Re: [teres] Motor/supply kit Date: Tue, 29 Feb 2000 23:10:05 -0700 From: Chris Brady, Chris Brady To: teres@aiko.com Oops, I forgot to attach the drawing. Chris Brady wrote: > > There seems to be a consensus that the motor/controller kit > should include a deluxe (thick) motor mounting plate. > Attached is a draft design for the motor mounting plate. > Not all of the dimensions are there yet but it is enough > to get an idea of what it will look like. > > I am working on sourcing parts for the controller and have a few > questions for the group. > > 1) Power xfmr - Should this be a wall wart or a small xfmr that > can be mounted inside the motor pod? Or should we not include > an xfmr in the kit so that everyone can do their own thing? > I am leaning toward a wall wart. > > 2) Switch and LED's - The controller uses a single pushbutton > switch and two LED's. There's tons of styles and types. > Should I just choose what I think everyone would like or > leave them out of the kit. > > Chris --------------------------------------------------------------------- Name: mount.gif mount.gif Type: GIF Image (image/gif) Encoding: base64 Subject: Re: [teres] Motor/supply kit Date: Tue, 29 Feb 2000 23:19:23 -0700 From: phclark, phclark To: teres@aiko.com ----- Original Message ----- From: "Chris Brady" To: Sent: Tuesday, February 29, 2000 10:01 PM Subject: Re: [teres] Motor/supply kit > There seems to be a consensus that the motor/controller kit > should include a deluxe (thick) motor mounting plate. > Attached is a draft design for the motor mounting plate. > Not all of the dimensions are there yet but it is enough > to get an idea of what it will look like. > > I am working on sourcing parts for the controller and have a few > questions for the group. > > 1) Power xfmr - Should this be a wall wart or a small xfmr that > can be mounted inside the motor pod? Or should we not include > an xfmr in the kit so that everyone can do their own thing? > I am leaning toward a wall wart. Cost is a consideration to some extent. My personal leaning is a transformer. I somehow feel I would jave more control over the results. > 2) Switch and LED's - The controller uses a single pushbutton > switch and two LED's. There's tons of styles and types. > Should I just choose what I think everyone would like or > leave them out of the kit. We will. be guided by your judgement. I caution against an error I made a few years ago with Radio Shack DPDT switches, thought. I thought the thread on the shafts was benign (I was threading the chassis on a preamp.) Turns out it was an unusual metric size with an even more unusal pitch. Pain in the derriere to get a tap. Peter C > Chris > Subject: [teres] RE: [tere supply kit& remnant aluminum Date: Wed, 1 Mar 2000 00:12:00 -0700 From: Fritz Moore, Fritz Moore To: teres@aiko.com Would a battery power source with a transformer trickle charger offer any advantage? I have no idea how voltage sensitive the controller is but I think most areas have brown outs and voltage fluctuations. Is the controller able to keep time on a varrying voltage? If it does offer an advantage could we make it so that it can run directly off the transformer or directly from the battery. Seems like the wall wart wood keep the dreaded AC further away even though the wall wart may not be the aesthetic high point of this project. A metal surplus that I frequent has 4.5" OD aluminum tubing it is .395 wall and they have about 20 2-3' lengths. It sells for $2.35/pound. I was going to use this for my motor case. If there is enough interest in this I could buy several lengths and send it to Oregon for machining. It is thick enough that it would take a oring groove and bolt holes at the top. the oring might have some dampening effect? Also we could make two lids one without the motor mount and use it for a bottom then one could fill the motor thing half full with lead shot and oil or just lead shot. They have tons of plate I can check to see if they have the 3/8" it would also be 2.35/pound. If my memory serves me the price on tubing is the deal of the century, generally if you go to have 4" cut off a new odd size tube youll get reamed. Certainly if we could group plan this it would be a money saver. I cant imagine a machinist charging less than 1 hr to do an odd ball operation like drilling and tapping a pipe wall to receive this lid. Add this to a short cut charge and I think we'd be way ahead by trying to make a group run using remnant. I like Chris's lid design if it was adapted to this tube size wed have another problem solved. Id also vote to have Chris source switches and LEDs it will save money and probably cost so little that if someone doesnt like them they can save them for another project. Fritz -----Original Message----- From: owner-teres@aiko.com [mailto:owner-teres@aiko.com]On Behalf Of Chris Brady Sent: Tuesday, February 29, 2000 9:01 PM To: teres@aiko.com Subject: Re: [teres] Motor/supply kit There seems to be a consensus that the motor/controller kit should include a deluxe (thick) motor mounting plate. Attached is a draft design for the motor mounting plate. Not all of the dimensions are there yet but it is enough to get an idea of what it will look like. I am working on sourcing parts for the controller and have a few questions for the group. 1) Power xfmr - Should this be a wall wart or a small xfmr that can be mounted inside the motor pod? Or should we not include an xfmr in the kit so that everyone can do their own thing? I am leaning toward a wall wart. 2) Switch and LED's - The controller uses a single pushbutton switch and two LED's. There's tons of styles and types. Should I just choose what I think everyone would like or leave them out of the kit. Chris