I would have to look up the specific manufacturer but this is what I was told by a manufacturer of oil impregnated bearing liners when I discussed their use with them. The manufacturer specifically stated that their bearings were not suitable for such an application (a turntable bearing) because of the reason given earlier. What I wrote was not a personal theory but a repetition of a statement made to me.
OK, I believe you. I don't know if this is specific to this manufacturer, or to all manufacturers of oil impregnated bearings.
Regardless, jewels seem to be the best for this application.
He also used roller bearings. I've heard that he was the first to do so, anyone else hear that?
John Harrison used Lignum Vitae for his turntable bearings..
H1, H2, and H3.
jn
John Harrison used Lignum Vitae for his turntable bearings..
H1, H2, and H3.
jn
That would be a good solution also. The wood has a high oil content and is very hard. It was historically used for rudder bearings in ships because they didn't rust or rot and they didn't need lubrication.
I never heard that. Just googled roller bearing inventor, wiki had him as the first to use caged roller bearings in H3.
sunovagun. Thanks...
John
Just had a look through this thread and was wondering if anyone has tried using vesconite, as a machinist I have found it to be a viable replacement for bronze bushes in many applications. It would seem the problem experienced with TT bearings is that the surface speed on the spindle is too low to have any real hydrodynamic action in the oils used hence the metal to metal contact we see. The concern that synthetic engine oil might damage a bronze bearing is unfounded, if the bearing was brass on the other hand and the operating temperatures were elevated then there would be a chance of the zinc additives in the oil leeching out the zinc in the brass bush.Vesconite long life low friction bushings
As a manufacturer, I'd prefer to not comment on the quality but rather the solution. It's possible that when they checked the bearing tolerance, the shop temperature was on the cold side, and the clearance was in range.
Your safest solution is to polish the male portion of the bearing with 2000 grit sandpaper. It's a repetitive process of polish/check fit. Polish in a radial motion (not axial) - as if the bearing were chucked up on a drill press. You can do this manually, and with 2000 grit, it will take some time (very little material is removed.
Ideally, when you're done, you'll still feel resistance - that of the air being displaced from between the bearing journals when inserting into the female section. Under no circumstances should there be any audible bearing noise during play, however. It's not incumbent on you to wear in the bearing.
The feel of the bearing tolerance is difficult to describe, but numerically, you're looking at a radial clearance in the range of .0003" (3 ten-thousandths).
I can't speak to the design intention and whether the cross hatching in the female section was intended to either hold oil or to pump it, but in our designs, I've never found this to be necessary. Whether the cross-hatching is a liability according to their design, I can't tell you.
Cheers,
Thom
Hi,
Just read through 90% of this thread.
First of all, is this a 7K platter/bearing assy job? Really?
Sorry, P. but the entire concept is pre-historic and that's being kind.
Boca bearings are the ones we absolutely avoid, mostly cheap imported Chinese crap.
The least a half decent high-end platter/bearing assy should be made of is a top grade ceramic ball (Si3N4) on a Zirconium trust plate.
Even that is primitive (by design principle) as you can still reduce friction by another 30% by introducing a few ceramic balls inside the top of the bushing sleeve.
The only reason you'll want to lube it is not to reduce friction (there'll be virtually none) but to reduce noise.
Sorry for being so harsh but it breaks my heart to see a friend vinyl/valve fan waste money on such a mediocre design.
Reading this should set all the red flags:
The exact opposite is true. It will increase friction, not reduce it.
Anyhow, I hope it will all turn out for the best.
Cheers,
Just read through 90% of this thread.
First of all, is this a 7K platter/bearing assy job? Really?
Sorry, P. but the entire concept is pre-historic and that's being kind.
Boca bearings are the ones we absolutely avoid, mostly cheap imported Chinese crap.
The least a half decent high-end platter/bearing assy should be made of is a top grade ceramic ball (Si3N4) on a Zirconium trust plate.
Even that is primitive (by design principle) as you can still reduce friction by another 30% by introducing a few ceramic balls inside the top of the bushing sleeve.
The only reason you'll want to lube it is not to reduce friction (there'll be virtually none) but to reduce noise.
Sorry for being so harsh but it breaks my heart to see a friend vinyl/valve fan waste money on such a mediocre design.
Reading this should set all the red flags:
The exact opposite is true. It will increase friction, not reduce it.
Anyhow, I hope it will all turn out for the best.
Cheers,
Hi,
The formula contains the unknown variable µ, the friction coefficient.
Does this coefficient somehow depend on contact surface area, speed and other factors?
If not, then friction should not depend on the contact surface area.
Is lowest friction a desirable state in this application anyway?
It may be debatable if a certain amount of friction could not in fact be better seen from the motor´s view.
jauu
Calvin
The formula for sliding friction tells us Fr = µ x Fn
The formula contains the unknown variable µ, the friction coefficient.
Does this coefficient somehow depend on contact surface area, speed and other factors?
If not, then friction should not depend on the contact surface area.
Is lowest friction a desirable state in this application anyway?
It may be debatable if a certain amount of friction could not in fact be better seen from the motor´s view.
jauu
Calvin
Hi Frank
Sorry about the late response and thanks for the sympathy. My anxiety levels spiked when i first got it but it has long been water under the bridge and all is well now
I know this is an older thread but as a machinist I was appalled at the construction of that spindle bearing setup. Just so many design flaws!
The only spindle bearing I have looked at closely is the one on my Pioneer PL-41D. Comparing the 2 designs will show just how flawed that spindle is.
1) Spindle on the Pioneer is hardened and precision ground steel with a high microinch surface finished, almost looks polished but it's a ground finish. The built in radius on the bottom for the bearing is ground to a perfect finish like a ball bearing.
The spindle shown looks like a piece of soft barstock, I read that it's anti-magnetic, that makes it a stainless alloy. One of the worst alloys for a plain bearing application. Further more the carbide ball bearing is epoxied into the end of the shaft! If the center of the ball is not exactly in the same centerline of the spindle than as it rotates it will cause the shaft to rotate around the center line of the ball or wobble! Drilling a hole or machining a chamfer for the ball to sit into is no easy task. Maintaining concentricity between the ball seat and the shaft outside diameter is best left to an experienced cylindrical grinder operator.
2) The Pioneer bearing is a bronze bushing pressed into an aluminum housing with a screw cap on the bottom. Removing the cap exposes the plastic bearing pad. Best I can tell, the original bearing was nylon, it was disintergrated and I replaced it with a more modern material machined from delrin bar stock.
The bronze bearings were fitted to the spindle shaft by a proccess known as honing. This produces a finish as fine as found on the spindle shaft with a beautiful cross hatch finish that retains oil. Most people know the process as it's used to finish the bores in an engine.
Even after 43 years both the spindle shaft and the bronze bearings looked virtually brand new. After reassembling and lubing the bearing with a light hydraulic oil I tested by spinning the platter without the belt. It took 3 and a half minutes to come to a stop. My platter only weighs 2.2 kg.
I'm still trying to figure out what they were trying to accomplish with that bearing design.
The only spindle bearing I have looked at closely is the one on my Pioneer PL-41D. Comparing the 2 designs will show just how flawed that spindle is.
1) Spindle on the Pioneer is hardened and precision ground steel with a high microinch surface finished, almost looks polished but it's a ground finish. The built in radius on the bottom for the bearing is ground to a perfect finish like a ball bearing.
The spindle shown looks like a piece of soft barstock, I read that it's anti-magnetic, that makes it a stainless alloy. One of the worst alloys for a plain bearing application. Further more the carbide ball bearing is epoxied into the end of the shaft! If the center of the ball is not exactly in the same centerline of the spindle than as it rotates it will cause the shaft to rotate around the center line of the ball or wobble! Drilling a hole or machining a chamfer for the ball to sit into is no easy task. Maintaining concentricity between the ball seat and the shaft outside diameter is best left to an experienced cylindrical grinder operator.
2) The Pioneer bearing is a bronze bushing pressed into an aluminum housing with a screw cap on the bottom. Removing the cap exposes the plastic bearing pad. Best I can tell, the original bearing was nylon, it was disintergrated and I replaced it with a more modern material machined from delrin bar stock.
The bronze bearings were fitted to the spindle shaft by a proccess known as honing. This produces a finish as fine as found on the spindle shaft with a beautiful cross hatch finish that retains oil. Most people know the process as it's used to finish the bores in an engine.
Even after 43 years both the spindle shaft and the bronze bearings looked virtually brand new. After reassembling and lubing the bearing with a light hydraulic oil I tested by spinning the platter without the belt. It took 3 and a half minutes to come to a stop. My platter only weighs 2.2 kg.
I'm still trying to figure out what they were trying to accomplish with that bearing design.
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