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Platter thrust plate and bearing replacement - Sapphire and Si3N4
#11
(05-11-2022, 05:20 PM)Brf Wrote: I'm not questioning your measurement accuracy, but when I did a couple of Prime bearing replacements just before Xmas, both spindles had a 3/8' ball.  Perhaps VPI uses more than one size?  Since replacement balls are very inexpensive, I would order both sizes just to be on the safe side

I have attached a picture of the old ball with a measurement and a copy of the replacement Si3N4 ball.

Interesting... I measured it in several different ways... I already ordered the 5/16" ball... Darn it, I should have ordered a 3/8" as well just in case...  Blush

I will wait until the thrust plate arrives (got confirmation from Steve that he shipped those).  Remove the existing ball and validate size then.  That will also give me time to see if I need anything else from McMaster to leverage the shipping costs... 

Thank you for the photos!

Brf, if you do not mind sharing, how do you secure the sapphire disc to the brass? What kind of glue are you using?
Whoa listen to the music...

Wachuko
VPI Scoutmaster Refurbish, Prime Signature Motor (300 rpm), Prime Aluminum (20 lbs) Platter and Bearing, Delrin Record Clamp, JMW 9 3D Arm with Sumiko Blue Point No.2, Upgraded Classic Feet, Periphery Ring Clamp
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#12
Brf may have another technique, but no glue needed, actually: a tiny dab of grease will stick the sapphire plate to the brass.
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#13
(05-11-2022, 07:53 PM)bhjazz Wrote: Brf may have another technique, but no glue needed, actually: a tiny dab of grease will stick the sapphire plate to the brass.

Good to know.  I thought it needed to be secured with some sort of adhesive…
Whoa listen to the music...

Wachuko
VPI Scoutmaster Refurbish, Prime Signature Motor (300 rpm), Prime Aluminum (20 lbs) Platter and Bearing, Delrin Record Clamp, JMW 9 3D Arm with Sumiko Blue Point No.2, Upgraded Classic Feet, Periphery Ring Clamp
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#14
I wish the old forum was still up because BRF had a nice write up on doing this DIY, specs, pencil torches, and all.  Initially, I had Steve @ VAS do the ceramic ball (I think ZrO2 given its white color) and sapphire thrust plate on my Prime.  But I wasn't happy with the speed stability (checking via Adjust+, AnalogMagik, and the SOTA Condor/Total Eclipse).  So I decided to DIY.  I used a 5/16" diameter hot isostatic press Si3N4 grade 5 ball from Boca Bearings and a 10mm diameter λ/4 sapphire thrust plate (actually called a sapphire window) from Edmund Optics.  The λ/4 flatness was probably overkill given how small the thrust plate is, but the combo resulted in better speed stability over longer periods of time.  YMMV



https://www.bocabearings.com/products/be...ductType=0


https://www.edmundoptics.com/p/10mm-dia-...dow/30685/




FWIW, the max diameter of the thrust plate is about 14mm as I recall, but I was trying to find something a bit smaller in case I had to remove the sapphire thrust plate for servicing.  10mm thrust plates are easier to find and work well.
[Image: full]
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#15
(05-14-2022, 04:22 AM)edwyun Wrote: I wish the old forum was still up because BRF had a nice write up on doing this DIY, specs, pencil torches, and all.  Initially, I had Steve @ VAS do the ceramic ball (I think ZrO2 given its white color) and sapphire thrust plate on my Prime.  But I wasn't happy with the speed stability (checking via Adjust+, AnalogMagik, and the SOTA Condor/Total Eclipse).  So I decided to DIY.  I used a 5/16" diameter hot isostatic press Si3N4 grade 5 ball from Boca Bearings and a 10mm diameter λ/4 sapphire thrust plate (actually called a sapphire window) from Edmund Optics.  The λ/4 flatness was probably overkill given how small the thrust plate is, but the combo resulted in better speed stability over longer periods of time.  YMMV



https://www.bocabearings.com/products/be...ductType=0


https://www.edmundoptics.com/p/10mm-dia-...dow/30685/




FWIW, the max diameter of the thrust plate is about 14mm as I recall, but I was trying to find something a bit smaller in case I had to remove the sapphire thrust plate for servicing.  10mm thrust plates are easier to find and work well.

Brf’s thread was the genesis of the whole bearing upgrade trend. Even Steve of VAS Audio credits that thread as his source of motivation to offer his upgrade service. That thread had a lot of details, pictures, etc., and only serves as one example why the the old forum content must be restored.
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#16
No wonder… it was Brf’s thread that I had bookmarked…
Whoa listen to the music...

Wachuko
VPI Scoutmaster Refurbish, Prime Signature Motor (300 rpm), Prime Aluminum (20 lbs) Platter and Bearing, Delrin Record Clamp, JMW 9 3D Arm with Sumiko Blue Point No.2, Upgraded Classic Feet, Periphery Ring Clamp
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#17
Thumbs Up 
Parts arrived... will tackle later today.  Now it is time to sleep.  Good night!

[Image: file.php?id=117540&mode=view]
Whoa listen to the music...

Wachuko
VPI Scoutmaster Refurbish, Prime Signature Motor (300 rpm), Prime Aluminum (20 lbs) Platter and Bearing, Delrin Record Clamp, JMW 9 3D Arm with Sumiko Blue Point No.2, Upgraded Classic Feet, Periphery Ring Clamp
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#18
I can confirm the ball is 5/16” in mine. So looks like VPI used different setups for different platters.

Sapphire thrust plate/disc diameter is 0.47 inch. I will measure thickness and update this post.

Will post photos in a bit.
Whoa listen to the music...

Wachuko
VPI Scoutmaster Refurbish, Prime Signature Motor (300 rpm), Prime Aluminum (20 lbs) Platter and Bearing, Delrin Record Clamp, JMW 9 3D Arm with Sumiko Blue Point No.2, Upgraded Classic Feet, Periphery Ring Clamp
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#19
I removed the spindle from the base... First I tried using a soldering gun to heat the shaft... that did not do squat...

[Image: file.php?id=117589&mode=view]

Then remembered we had a small torch that my daughter uses when making Crème brûlée... used that to heat the shaft and the ball just fell off... nice.

[Image: file.php?id=117586&mode=view]

With the ball removed I could see the stuff used to hold it in place...  all that needed some cleaning before installing the new ball.

[Image: file.php?id=117587&mode=view]

Much better... all clean...

[Image: file.php?id=117588&mode=view]

And Si3N4 ball now in place...

[Image: file.php?id=117590&mode=view]

Some photos of the steel ball... placed it on a magnet to not loose it...

[Image: file.php?id=117591&mode=view]

Close-up

[Image: file.php?id=117593&mode=view]

Okay then... everything back in place... Forgot to take photos installing the sapphire thrust plate... but nothing to it. Just insert it in the plate.  Followed the suggestion to place a tiny bit of grease so it holds in place while I lowered the plate in place. That worked fine.

[Image: file.php?id=117592&mode=view]

Before installing the belt, I gave it a spin and just got tired of waiting for it to stop after the first minute. It just spins forever... not perpetual motion of course   Cool

[Image: file.php?id=117594&mode=view]

Done!
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#20
Nice work!
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