Polymer bearings as turn table main bearings. - diyAudio
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Old 3rd July 2009, 01:11 PM   #1
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Question Polymer bearings as turn table main bearings.

Hi,

Can we use the new polymer bearings like the one from Igus or Saint Gobain as the turn table main bearing ? Please suggest.

The links are: http://www.igus.com/iglide.asp and http://www.bearings.saint-gobain.com/


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Bins.
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Old 3rd July 2009, 03:32 PM   #2
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IMHO, you'd expect to find polymer bearings on the cheapest of turntables. They usually require greater clearances than metal bearings and unless the shaft is remarkably well polished, are probably noisier than an oil lubricated bearing. We're talking radial bearings here.

For the thrust bearing I've seen polymer bearings and they can work quite well. The loads are high, so a really hard hi-tech plastic like PEEK, using a lubricating filler (graphite/moly/teflon) might be a good choice to keep the contact area small. Expensive but probably even better would be DuPont Vespel with a filler. I still think a hard ball on a hard flat is a better solution.

IMHO again, I think people attribute too much to the tt bearing. Any vibrations in the bearing support (plinth) will get transmitted right through it to the platter. Way more effort should be put into motor isolation and tone arm isolation than is often the case. The tt I own is very well known and has an excellent bearing, but you can put a vibration pickup on the platter and listen to the motor vibration as clear as a sunny day. The design was a failure at the Engineering 101 level.
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Old 3rd July 2009, 11:46 PM   #3
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The other problem with polymer bearings is durability.

Because the bearing material is soft and the primary mechanism by which they keep their low friction at high loads is material shear and transfer, they wear very quickly if loaded heavily.

I replaced the idler bushings in my Garrard 301 with Iglidur G. They wore out very quickly indeed, IIRC I put the original bushings back less than a year later (and the originals are fifty years old).

BTW Conrad I disagree entirely about motor isolation and tonearm isolation. IMO the best tack for dealing with motor noise is to kill it at the motor. Once this is done the motor / platter coupling can be made far less lossy which has huge benefits.
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Old 3rd July 2009, 11:57 PM   #4
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I wouldn't disagree with that, but I don't know how to kill the vibes at the motor to the degree I want- other than by turning off the switch! IMO, an external motor seems like the best answer, but I want the convenience of a self-contained tt. I may next try something like a small iron-less DC motor, rather than the synchronous/stepper motors used by Project and later Thorens.
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Old 4th July 2009, 05:29 AM   #5
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Hi,

IGUS is having a clearance free pre stressed bearing - JVSM. I am planning to try that one with a silver steel shaft. But, I am not sure on the bearing dimension. Will a 10mm or a 12mm diameter enough ?

What type of bearing should be used - Normal one/Flanged one ?

What is the best material for thrust pad ?

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Bins.
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Old 5th July 2009, 03:26 AM   #6
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Can anyone give us some feedback on Bill Firebaugh's teflon bearings in the WellTempered turntables?

For lack of teflon in my junkbox I have my TT running with nylon for both the sleeve on top and a ruby ball on a nylon pad for thrust bearing. both bearings are lightly lubricated with silicone grease. Seems to be a very quiet, low friction, bearing setup. I too wonder about longevity. Guess I will find out someday. Meantime I'm enjoying it. BTW it is very easy to replace.

Bill
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Old 10th July 2009, 08:56 AM   #7
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I totally agree with Mark about killing noise at the motor end instead of motor and tonearm isolation. After switching to a quieter motor, everything sound cleaner and better focus.

I completely disagree with tonearm isolation because I firmly believe the tonearm should be rigidly couple to the same material the bearing is mounted so the platter and tonearm would vibrate in unison. Friends had experience with isolated tonearm mounting pods or blocks and they sound terrible.
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Old 10th July 2009, 09:59 AM   #8
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Hi,

I got the JVSM bearing of diameter 10mm with the polished aluminium shaft from IGUS. Is that diameter enough or do I need to go for a bigger value? (My acrylic platter weight is < 4 Kg).

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Bins.
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Old 18th September 2009, 05:00 AM   #9
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Hi,

What is the best material for bearing thrust pad ? Can we use acrylic / nylon ? My bearings are polymer ones with ceramic balls.

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Bins.
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Old 6th October 2009, 12:17 PM   #10
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Bill,

1. What is the best material for thrust pads ? Can we use acrylic/nylon/delrin ? (Delrin is used by Garrard and also used in some guitar pickups as they are highly resistant to wear)

2. What should be the size and grade for the ruby/sapphire balls ?

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