Correction of inaccurate information
Hi Carlo,
In my last post I stated a couple of figures regarding my DIY main bearing. I was quoting from memory and got my figures wrong. My bearing dissipates a bit more than I stated at 1.9mW. A sleeved bearing dissipates between 10mW and 50mW depending largely on the mass of the platter with about 25mW being typical. The bearings of super - heavyweight platters can easily exceed 100mW. The energy dissipated is in two forms, vibration and heat. If the bearing dissipates a lot as vibration you have a noisy bearing. A large heat dissipation means that the bearing will heat up during use and can change its performance with time. Totally off topic I know but I don't like to give misleading information.
Niffy
Hi Carlo,
In my last post I stated a couple of figures regarding my DIY main bearing. I was quoting from memory and got my figures wrong. My bearing dissipates a bit more than I stated at 1.9mW. A sleeved bearing dissipates between 10mW and 50mW depending largely on the mass of the platter with about 25mW being typical. The bearings of super - heavyweight platters can easily exceed 100mW. The energy dissipated is in two forms, vibration and heat. If the bearing dissipates a lot as vibration you have a noisy bearing. A large heat dissipation means that the bearing will heat up during use and can change its performance with time. Totally off topic I know but I don't like to give misleading information.
Niffy
off topic reply - sorry
one or two mW, you got remarkable results Niffy, thanks for infos.
Till now i've learned this (experiences related to bronze-silver steel bearing, on my working conditions):
too heavy platters bring just problems; (with my Premotec 4kg are enough, if the weight is on the outer section);
reversed spindle are noisier than regular; larger spindles worse than smaller.
Noise comes from spindle-bushing - spindle-ball matching (audible difference). The vibrations of a small lathe turning at high speed - low advancement engraves resonance pattern that do not disappear with lapping. (till reaching a too loose fit, wich is even worst)
Quite frustrating
carlo
one or two mW, you got remarkable results Niffy, thanks for infos.
Till now i've learned this (experiences related to bronze-silver steel bearing, on my working conditions):
too heavy platters bring just problems; (with my Premotec 4kg are enough, if the weight is on the outer section);
reversed spindle are noisier than regular; larger spindles worse than smaller.
Noise comes from spindle-bushing - spindle-ball matching (audible difference). The vibrations of a small lathe turning at high speed - low advancement engraves resonance pattern that do not disappear with lapping. (till reaching a too loose fit, wich is even worst)
Quite frustrating
carlo
Hi Carlo,
Most of the problems with bearings seem to arise from the sleeve. My solution was to get rid of the sleeve entirely. The bearing is "inverted" with the contact point just below the upper surface of the platter. This contact point is the only point of contact in the bearing resulting in excellent mechanical grounding. It consists of a 2.5mm (1.25mm radius) ball sitting in a shallow 1.5mm radius pit. The contact point is only 0.25mm across with the mass of the platter being just shy of 4kg. This means that the load acting on the bearing occurs only 0.1mm from the from its axis. A sleeved bearing with a 12mm shafts has the load acting at 6mm from the axis (60 times further). Check out Hertz contact geometry for the maths that discribe this. The platter is perfectly balanced. The belt passes around 2 idler wheels as well as the motor pulley in order to balance the belt tension from pulling the platter off level.
With records that are severly off balance I do get a bit of runout but the benefits of this system more than outweighs this small error. The runout is actually still less than I've seen on a top of the line Linn sondek (£25k). I'm currently working on a new set of idler wheel and an experimental belt system that I hope will eliminate this small problem.
Back to topic.
Niffy
Most of the problems with bearings seem to arise from the sleeve. My solution was to get rid of the sleeve entirely. The bearing is "inverted" with the contact point just below the upper surface of the platter. This contact point is the only point of contact in the bearing resulting in excellent mechanical grounding. It consists of a 2.5mm (1.25mm radius) ball sitting in a shallow 1.5mm radius pit. The contact point is only 0.25mm across with the mass of the platter being just shy of 4kg. This means that the load acting on the bearing occurs only 0.1mm from the from its axis. A sleeved bearing with a 12mm shafts has the load acting at 6mm from the axis (60 times further). Check out Hertz contact geometry for the maths that discribe this. The platter is perfectly balanced. The belt passes around 2 idler wheels as well as the motor pulley in order to balance the belt tension from pulling the platter off level.
With records that are severly off balance I do get a bit of runout but the benefits of this system more than outweighs this small error. The runout is actually still less than I've seen on a top of the line Linn sondek (£25k). I'm currently working on a new set of idler wheel and an experimental belt system that I hope will eliminate this small problem.
Back to topic.
Niffy
So the platter remains centered on the top ball by the belt between the 3 pulleys, without wobbling? Interesting and surprising, "out of the box" as you say.
I'm thinking of buying a rectified rod (6- 8mm) and a sintered bushing. (some tests already done) The rod rests at the bottom on a ceramic ball on a teflon washer and on top inside the sleeve, cut and adjustable to get the best fit: completely traditional.
If (a small) friction is uniform, it is not a big problem with a proper motor; a belt on a single pulley aligned to the sleeve, brings a side load that reduces resonances, in my experience. The body of the bearing will be great and heavy, to dissipate heat and transmit the residual resonances to the sub-plinth
carlo
but now let's stop this off topic before being thrown out....
I'm thinking of buying a rectified rod (6- 8mm) and a sintered bushing. (some tests already done) The rod rests at the bottom on a ceramic ball on a teflon washer and on top inside the sleeve, cut and adjustable to get the best fit: completely traditional.
If (a small) friction is uniform, it is not a big problem with a proper motor; a belt on a single pulley aligned to the sleeve, brings a side load that reduces resonances, in my experience. The body of the bearing will be great and heavy, to dissipate heat and transmit the residual resonances to the sub-plinth
carlo
but now let's stop this off topic before being thrown out....
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Hi Carlo/Niffy,
Interesting set up- I will,use a liquid bearing for a 3 point pulley/motor set up
There is a “kitchen sink” holding the water/silicone of about 8 cm high (depending on the weight of the platter. The “floater” has 3 layers, acryllic, and 2 layers of hard foam, with the big (300mm) pulley at about 80% height
Carlo-on you calculations of the Lil Casey arm, I am a bit stumped, 57 grams is a lot of force, that somehow is generated by the needle? i am probably missing something here- help
Thx
Coolerooney
In my opinion Teflon is not a good choice for the thrust plate. Although it has a low coefficient of friction it is also very soft. This will cause the ball to inbed into the thrust plate. To support a 4kg platter the contact point would have to be 1.9mm in diameter. The torque on the bearing would act at 0.75mm from the axis. 7.5times as great as with a steel on steel bearing. The coefficient of friction between steel and Teflon is about 4.5 times lower than between lubricated steel on steel. The Teflon bearing would still have 1.67times as much friction. Also the linear velocity of sliding is on average 7.5times higher resulting in greater noise generation. Another important aspect is wear. Under constant load Teflon has a tendency to creep. A Teflon thrust plate will need replacing on a regular basis. I experimented with Teflon when building my bearing and it didn't work anywhere near as well as steel.
Niffy
Niffy
You're right Coolerooney, certainly not, directly. On the drawing is reported the formula of the wedge: the small curvature of the guides gave an angle of around 15 °. N is how much the weight of the trolley could be multiplied when the stylus drag (2-300 milligr) pushes the balls against the curvature: in practice seems like a servo, or a brake: a small side push can generate a relevant friction. But this is only my doubt, to be verified in practice; but if this is not the case (balls not stuck into the wedge) it would be worse: the less the curvature the less the self centering, because the small curvature becomes a very advantageous lever to overcome the weight force, and so the carriage could derail, rubbing against the inner channel
Niffy: long ago i've tested a copper washer, with a scratchy noise: maybe the point contact pressure brings lubing away (metal to metal); Teflon performed silently, but must be changed sometimes, i know. Due my TT project story i'm more obsessed from noise than frictions
carlo
teflon is soft (too soft) to cut or machine, not under pressure - boat small winches with teflon bushing face easily heavy loads
Niffy: long ago i've tested a copper washer, with a scratchy noise: maybe the point contact pressure brings lubing away (metal to metal); Teflon performed silently, but must be changed sometimes, i know. Due my TT project story i'm more obsessed from noise than frictions
carlo
teflon is soft (too soft) to cut or machine, not under pressure - boat small winches with teflon bushing face easily heavy loads
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Hi Niffy
The may be more suitable
https://www.igus.com/igubal/polymer-spherical-bearing?sort=3&fc=300805&inch=false
They also have flat bars
(No I have no shares or work with Igus)
Best
Coolerooney
"teflon is soft (too soft) to cut or machine, not under pressure - boat small winches with teflon bushing face easily heavy loads".
In a turntable bearing the material of the thrust pad tends to be used near its load limit in order to keep the diameter of the contact point as small as possible. With a boat winch the Teflon bushing are used way below their load limit so deformation and creep will not be problematic.
The igus products might well offer a more robust alternative to straight Teflon. I've had a good trawl through their website and can't find the any material specifications, modulus, compressive strength, poisson's ratio, friction coefficients etc. These would be kind of useful.
One further advantage that I believe holds true for both the turntable bearing and the bearings of the LINEAR TRACKING TONEARM is that harder materials seem to offer a better mechanical ground. Ah ha, I managed to get it back on topic.
Niffy
In a turntable bearing the material of the thrust pad tends to be used near its load limit in order to keep the diameter of the contact point as small as possible. With a boat winch the Teflon bushing are used way below their load limit so deformation and creep will not be problematic.
The igus products might well offer a more robust alternative to straight Teflon. I've had a good trawl through their website and can't find the any material specifications, modulus, compressive strength, poisson's ratio, friction coefficients etc. These would be kind of useful.
One further advantage that I believe holds true for both the turntable bearing and the bearings of the LINEAR TRACKING TONEARM is that harder materials seem to offer a better mechanical ground. Ah ha, I managed to get it back on topic.
Niffy
Hi Niffy,
Yes you’re right, the UK website is a bit more sparse
https://www.igus.nl/info/plain-bearings-plain-bearing-general-informations
Its in German though
Better:
ask for their paper catalog, all 1500 pages of them-has all the tech data there (I checked)
Use the calculation wizards on the site
Kindly ask Igus for sample boxes, my friendly local sales rep was generous in the past- there are several different ones- and he knows my business is and will be small, if not microscopic
Best
Coolerooney
Yes you’re right, the UK website is a bit more sparse
https://www.igus.nl/info/plain-bearings-plain-bearing-general-informations
Its in German though
Better:
ask for their paper catalog, all 1500 pages of them-has all the tech data there (I checked)
Use the calculation wizards on the site
Kindly ask Igus for sample boxes, my friendly local sales rep was generous in the past- there are several different ones- and he knows my business is and will be small, if not microscopic
Best
Coolerooney
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Hi Coolerooney,
Thanks for the link. The German site is more comprehensive though Google translate seems to think it's in Dutch. I'm not actually looking for any new bearing materials myself but like to keep my eye on what is available. It's also helpful to have accurate specs if I'm trying to advise anyone else on their application.
All the resent discussion about arm bearings (and the off topic main spindle bearings) has galvanised me into finally making a new set of idler wheel and bearings. This is the one aspect of my deck that I am least pleased with. The new bearings are based on the work I carried out whilst developing the pin bearings for my arm. I won't be going the full jeweled route with these (not yet anyway). These will be the same as the bearings I made from sewing pins and grub screws. If these work as intended I have a further plan for the way the drive belt is run that should eliminate any problems with off balance records.
Niffy
Thanks for the link. The German site is more comprehensive though Google translate seems to think it's in Dutch. I'm not actually looking for any new bearing materials myself but like to keep my eye on what is available. It's also helpful to have accurate specs if I'm trying to advise anyone else on their application.
All the resent discussion about arm bearings (and the off topic main spindle bearings) has galvanised me into finally making a new set of idler wheel and bearings. This is the one aspect of my deck that I am least pleased with. The new bearings are based on the work I carried out whilst developing the pin bearings for my arm. I won't be going the full jeweled route with these (not yet anyway). These will be the same as the bearings I made from sewing pins and grub screws. If these work as intended I have a further plan for the way the drive belt is run that should eliminate any problems with off balance records.
Niffy
The Best "space age" polyimide for thrust pads / turntable bearings is VESPEL, some grades are graphite or moly disulfide loaded but $$$$$$$$$ followed by TORLON $$$$. Best to look on ebay for small pieces, just make sure you are sitting down when you see the price !!!! I made my turntable bearing ( inverted ) using polished ultra micrograin carbide 5/8" diameter 5" long. The sleeve is made from 1" diameter Vespel 3" long. The platte is 6061 aluminum and weighs about 55 lbs. I cannot detect ANY noise, much quieter then any of the 3 bronze alloys tried, it wasn't even a contest.
Carbide Rod – Centennial Carbide: Carbide Blanks, Rod and End Mills
Carbide Rod – Centennial Carbide: Carbide Blanks, Rod and End Mills
Hi Joe,
You weren't kidding about the cost of vespel©. The properties that I've seen so far look excellent. Teflon like friction in a much more robust package. Your recommendation of tungsten carbide was spot on so I'd definitely trust your recommendation for vespel. My arm now has tungsten carbide wheels running on the rods you gave me. The bearings are tungsten carbide pivots running in sapphire jewels.
I have toyed with the idea of replacing the main bearing of the deck with tungsten carbide. The question is how to make a perfectly spherical indentation (1.5mm radius, 0.6mm deep) in the end of a short rod. The hardened steel version I'm currently using offers very low friction and is silent so there probably wouldn't be any great difference. Having said that, going from steel to carbide in the arm made a big difference so it might in the main bearing as well.
55lb platter!!! That must be a solid billet over 5"thick. Are there any benefits to going that massive? The load on the bearing is going to push the friction and noise inevitably higher than for a more modest platter. The increase in inertia will be offset by the increased bearing load so speed stability probably won't improve with the increased mass. The benefit I can see is that there is more mass to sink the energy from the stylus into. What are your thoughts on the advantages of higher mass?
Niffy
You weren't kidding about the cost of vespel©. The properties that I've seen so far look excellent. Teflon like friction in a much more robust package. Your recommendation of tungsten carbide was spot on so I'd definitely trust your recommendation for vespel. My arm now has tungsten carbide wheels running on the rods you gave me. The bearings are tungsten carbide pivots running in sapphire jewels.
I have toyed with the idea of replacing the main bearing of the deck with tungsten carbide. The question is how to make a perfectly spherical indentation (1.5mm radius, 0.6mm deep) in the end of a short rod. The hardened steel version I'm currently using offers very low friction and is silent so there probably wouldn't be any great difference. Having said that, going from steel to carbide in the arm made a big difference so it might in the main bearing as well.
55lb platter!!! That must be a solid billet over 5"thick. Are there any benefits to going that massive? The load on the bearing is going to push the friction and noise inevitably higher than for a more modest platter. The increase in inertia will be offset by the increased bearing load so speed stability probably won't improve with the increased mass. The benefit I can see is that there is more mass to sink the energy from the stylus into. What are your thoughts on the advantages of higher mass?
Niffy
Hi, Niffy
I kept my platter bearing fairly simple, .625" diameter carbide shaft with a .625 " radius on top using 1" diameter Vespel as the bushing and thrust pad. I made thrust pads of Nylatron, Vesconite, and Torlon with Vespel being the clear winner after spinning the platter for several days on each material. Torlon was a close second. I got a deal on 3 pieces of 6061 aluminum 12.5" diameter and 5.250" thick so that is what I used. That is my "scientific" answer for using that size platter, why make unnecessary chips !!!! My platter also has a mag-lev option that uses a pair of 4"OD x 3" ID x 1/2" thick N48 neo ring magnets which can pull 130lbs. I bought the 3 motor unit / controller from my friend who is a TW acoustic dealer here in N.Y.C. This is the same motor / controller used on their Black Knight turntable. My platter is a light weight compared to my friend in Las Vegas who is a Triangle Arts dealer and has their 750 lb.Reference turntable with a 135lb. Platter !!! Last month we spent 5+ hours at his house listening to the big reference turntable against the "smaller" reference turntable (250lbs with 50lb+platter) using the same tonearm / cartridge / phono stage / electronics on his horn system. It's hard to believe, but the bigger turntable sounded better every time, with all 4 people in 100% agreement. There was a little more of a solid image, more overall weight and presence, not by a great amount but easy to hear. I will not even speculate how this was possible, but there it was. This was an experience I will not forget !!!
I must confess, I "clipped" your carbide ring / axle (size 5 for me) / jewel bearing wheel idea because it is the best design possible for the purpose. My carriage will ride on 3/16" polished carbide rods. The carriage will be more conventional, 4.5" long and made of magnesium with a 7" long precision 7075 aluminum .420" diameter arrow shaft. I listened to the 250K Clearaudio reference turntable at audio shows with their 25K linear arm and it had excellent sound so my arm will be as good or better / lighter / less friction then theirs.
Niffy, thanks again for you precious input and time making this the best DIY linear tracking arm thread on the planet !!! I will be watching, learning, and contributing when possible.
I kept my platter bearing fairly simple, .625" diameter carbide shaft with a .625 " radius on top using 1" diameter Vespel as the bushing and thrust pad. I made thrust pads of Nylatron, Vesconite, and Torlon with Vespel being the clear winner after spinning the platter for several days on each material. Torlon was a close second. I got a deal on 3 pieces of 6061 aluminum 12.5" diameter and 5.250" thick so that is what I used. That is my "scientific" answer for using that size platter, why make unnecessary chips !!!! My platter also has a mag-lev option that uses a pair of 4"OD x 3" ID x 1/2" thick N48 neo ring magnets which can pull 130lbs. I bought the 3 motor unit / controller from my friend who is a TW acoustic dealer here in N.Y.C. This is the same motor / controller used on their Black Knight turntable. My platter is a light weight compared to my friend in Las Vegas who is a Triangle Arts dealer and has their 750 lb.Reference turntable with a 135lb. Platter !!! Last month we spent 5+ hours at his house listening to the big reference turntable against the "smaller" reference turntable (250lbs with 50lb+platter) using the same tonearm / cartridge / phono stage / electronics on his horn system. It's hard to believe, but the bigger turntable sounded better every time, with all 4 people in 100% agreement. There was a little more of a solid image, more overall weight and presence, not by a great amount but easy to hear. I will not even speculate how this was possible, but there it was. This was an experience I will not forget !!!
I must confess, I "clipped" your carbide ring / axle (size 5 for me) / jewel bearing wheel idea because it is the best design possible for the purpose. My carriage will ride on 3/16" polished carbide rods. The carriage will be more conventional, 4.5" long and made of magnesium with a 7" long precision 7075 aluminum .420" diameter arrow shaft. I listened to the 250K Clearaudio reference turntable at audio shows with their 25K linear arm and it had excellent sound so my arm will be as good or better / lighter / less friction then theirs.
Niffy, thanks again for you precious input and time making this the best DIY linear tracking arm thread on the planet !!! I will be watching, learning, and contributing when possible.
Hi Joe,
Sounds like you've been having fun. My limited experience with heavyweight platters, though nothing as heavy as yours, is that there is a definite advantage in the lower octaves but they seem to loose a bit of delicacy in the higher frequencies. With a short listening session the bigger bottom stands out though with a more extended listen the short comings higher up become more obvious. I haven't had any experience of super heavy megabucks tables. My platter is just shy of 4kg with record and clamp fitted, seemed like a good compromise to me. My entire deck weighs in at 30kg so is no lightweight.
Are you currently using the maglev on your deck? And do you have any materials specs for vespel? I was specifically looking for Youngs modulus and poissons ratio. The website has the coefficients of friction with load variation.
I'm glad you have found my work on bearings useful. My purpose in posting is to share the knowledge and hopefully help others to build a better tonearm. You will definitely get a better bearing than the clearaudio ballrace on glass design. The friction should be between a third and a quarter of their design. I think the biggest advantages are the elimination of chatter and much superior mechanical grounding. Please let me, and everyone else, see what you build and your opinion on the sound.
Niffy
Sounds like you've been having fun. My limited experience with heavyweight platters, though nothing as heavy as yours, is that there is a definite advantage in the lower octaves but they seem to loose a bit of delicacy in the higher frequencies. With a short listening session the bigger bottom stands out though with a more extended listen the short comings higher up become more obvious. I haven't had any experience of super heavy megabucks tables. My platter is just shy of 4kg with record and clamp fitted, seemed like a good compromise to me. My entire deck weighs in at 30kg so is no lightweight.
Are you currently using the maglev on your deck? And do you have any materials specs for vespel? I was specifically looking for Youngs modulus and poissons ratio. The website has the coefficients of friction with load variation.
I'm glad you have found my work on bearings useful. My purpose in posting is to share the knowledge and hopefully help others to build a better tonearm. You will definitely get a better bearing than the clearaudio ballrace on glass design. The friction should be between a third and a quarter of their design. I think the biggest advantages are the elimination of chatter and much superior mechanical grounding. Please let me, and everyone else, see what you build and your opinion on the sound.
Niffy
I will love to see some photos or drawings of your table. It sounds like a very nice table.
My ideal table is air bearing table. Please see the drawing. I have all the air bearings, but since the project involves too much with mechanic parts and additional air supply, etc. I think it is beyond my capacity.
Attachments
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Niffy,
A bit off topic but for a complete review of my Vegas listening session, I left out that we also listened to a highly modified, custom, Technics SP10 MK 2 turntable / electronics with the same arm and cartridge. The turntable was absolutely stunning, with a very large cocobolo base. However, sound wise it was a distant 3rd place. To be fair, the Technics table was about 18K IIRC. The overall sound was a bit thin, less presence, less relaxed sound, almost as if the entire sonic presentation was on a diet !!! In all fairness, if we did not have direct comparisons to the 2 other monster belt drive tables, anybody else would be perfectly happy with the sound of the Technics table.
The Vespel I used was grade SP22. I caught a break on ebay for two 1' x 1" diameter lengths for $310 about 2 yrs. ago. I am not using the turntable at the moment as I think about a final finish (or not) for the platter. I was thinking about anodizing or powder coating but have reservations on both. The platter has a 6" x 1" well machined in the bottom to fit a ring containing the ring magnet with stainless screws. The bottom bearing assembly has the same type ring for the opposing magnet. I can raise and lower the spindle shaft to change the contact weight on the thrust pad. I can install the magnetics in 10 minutes and it works very well. The platter can completely float but I want a constant zero point and a few pound of weight on the thrust pad for energy drain. I even made provisions to add some mu-metal in the magnet well if needed. The plinth is made from a 3" thick x 18" x 20" piece of gray granite with 1/2" stainless steel plate epoxied to the bottom. One of the club members son works for a high end granite company that has a water jet machine who cut the plinth and 5 holes for me, one 2" for the bearing assembly and four 1.250" for the foot assemblies. The plinth is set up to use up to 4 tonearms. The naked plinth weighs 138 lbs. !!! Each foot / arm stanchion assembly weighs 11.5 lbs ( copper / bronze with Nylatron for foot). The bottom line is I got the plinth for free !!!! Of course, I gave a few hundred dollars for the favor.
super10018,
Unfortunately, my computer skills are not good as far as CAD, drawing programs go. I make simple sketches of what I need and measure as I go. My projects are "one of" but I make others without much trouble. I will have one of the computer guys from the audio club show me how to upload the pictures I have. Your air bearing arm and turntable are works of industrial art and I very much admire your skills and out of the box thinking.
A bit off topic but for a complete review of my Vegas listening session, I left out that we also listened to a highly modified, custom, Technics SP10 MK 2 turntable / electronics with the same arm and cartridge. The turntable was absolutely stunning, with a very large cocobolo base. However, sound wise it was a distant 3rd place. To be fair, the Technics table was about 18K IIRC. The overall sound was a bit thin, less presence, less relaxed sound, almost as if the entire sonic presentation was on a diet !!! In all fairness, if we did not have direct comparisons to the 2 other monster belt drive tables, anybody else would be perfectly happy with the sound of the Technics table.
The Vespel I used was grade SP22. I caught a break on ebay for two 1' x 1" diameter lengths for $310 about 2 yrs. ago. I am not using the turntable at the moment as I think about a final finish (or not) for the platter. I was thinking about anodizing or powder coating but have reservations on both. The platter has a 6" x 1" well machined in the bottom to fit a ring containing the ring magnet with stainless screws. The bottom bearing assembly has the same type ring for the opposing magnet. I can raise and lower the spindle shaft to change the contact weight on the thrust pad. I can install the magnetics in 10 minutes and it works very well. The platter can completely float but I want a constant zero point and a few pound of weight on the thrust pad for energy drain. I even made provisions to add some mu-metal in the magnet well if needed. The plinth is made from a 3" thick x 18" x 20" piece of gray granite with 1/2" stainless steel plate epoxied to the bottom. One of the club members son works for a high end granite company that has a water jet machine who cut the plinth and 5 holes for me, one 2" for the bearing assembly and four 1.250" for the foot assemblies. The plinth is set up to use up to 4 tonearms. The naked plinth weighs 138 lbs. !!! Each foot / arm stanchion assembly weighs 11.5 lbs ( copper / bronze with Nylatron for foot). The bottom line is I got the plinth for free !!!! Of course, I gave a few hundred dollars for the favor.
super10018,
Unfortunately, my computer skills are not good as far as CAD, drawing programs go. I make simple sketches of what I need and measure as I go. My projects are "one of" but I make others without much trouble. I will have one of the computer guys from the audio club show me how to upload the pictures I have. Your air bearing arm and turntable are works of industrial art and I very much admire your skills and out of the box thinking.
Welcome in the air bearing TT club.
Good idea.
I wish you perseverance in realizing your musical dream ....
Music on a heavenly cloud ... super.
My experience ... I like (& build) TT air bearing (& TA)
Karel
Hottatoo, I think what everyone here will be glad to see some photos of your turntable here. As to heavy platters, I do have my own experience of upgrading several vintage belt drive turntables by installing heavyweight platters (from 4 to 10 kilogram), and sonic results are always huge improvements, with no exceptions.. My last project will be a complete DIY turntable with DIY linear arm and DIY MC cartridge (halfway through for now). Will post it here.
My contribution to off-topic
My contribution to off-topic