Magnetic Platter bearing replacement - Sapphire and Si3N4

Re: Magnetic Platter bearing replacement - Sapphire and Si3N

Postby DrumTemp » Tue Jan 09, 2018 4:32 pm

Brf wrote:
DrumTemp wrote:Yes, O-ring is factory placed. In addition, as I mentioned above, the thrust pad has changed as well: two different sizes! It appears the bottom (facing the bottom of the holder) is 15.8mm as you said. The top (exposed) part is a little less than that. There is a ridge in the middle of the pad where the size transitions.


Thanks, mine is not tapered, but a stepped thrust pad makes more sense as it will allow an easier alignment within the bearing shaft. Have you installed the sapphire disk yet?


Yes, I centered the 15.8mm crystal as dead on as I could. I then (carefully and slowly) screwed the holder in place, then took it off to take a look at the crystal. All appeared fine except the O-ring was frayed. After replacing the O-ring (1" size), I re-installed the holder. I then put in .7ml of 5-30w synthetic oil and began placing the platters back in place. Once I placed the motor housing up against the platter, I was surprised how much the platter was now raised from before. The platter bearing felt as though it was settled on the thrust plate, so not sure about that. Maybe because the thrust pad was tapered, the oil seeped down and around it? I've been running the platter for about 40 minutes and all seems well!
Avenger Reference, Graham Phantom III, Benz Micro LP S, AI Mod 3B, Pass Labs X250.8, Vandersteen Quatro Wood CT
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Re: Magnetic Platter bearing replacement - Sapphire and Si3N

Postby Brf » Tue Jan 09, 2018 4:50 pm

I should have mentioned that you need to grease to the O-ring. The rim drive should now ride 1mm below the previous platter spot (the thickness of the sapphire disk), therefore, you will need to raise the rim drive unit. FYI, I replaced my rim drive feet with threaded adjustable cone feet for fine alignment and leveling.
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Re: Magnetic Platter bearing replacement - Sapphire and Si3N

Postby DrumTemp » Tue Jan 09, 2018 6:42 pm

Brf wrote:I should have mentioned that you need to grease to the O-ring. The rim drive should now ride 1mm below the previous platter spot (the thickness of the sapphire disk), therefore, you will need to raise the rim drive unit. FYI, I replaced my rim drive feet with threaded adjustable cone feet for fine alignment and leveling.


Well, everything is running smooth and uber quiet. The feet idea is a good one; will have to investigate that.
Thanks for all your help, Brf!!
Avenger Reference, Graham Phantom III, Benz Micro LP S, AI Mod 3B, Pass Labs X250.8, Vandersteen Quatro Wood CT
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Re: Magnetic Platter bearing replacement - Sapphire and Si3N

Postby Brf » Tue Jan 09, 2018 8:55 pm

DrumTemp wrote:
Brf wrote:I should have mentioned that you need to grease to the O-ring. The rim drive should now ride 1mm below the previous platter spot (the thickness of the sapphire disk), therefore, you will need to raise the rim drive unit. FYI, I replaced my rim drive feet with threaded adjustable cone feet for fine alignment and leveling.


Well, everything is running smooth and uber quiet. The feet idea is a good one; will have to investigate that.
Thanks for all your help, Brf!!


You’re welcome.

Don’t forget to adjust your vta now that your platter is a touch higher.
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Re: Magnetic Platter bearing replacement - Sapphire and Si3N

Postby bryanjan » Tue Jan 09, 2018 10:43 pm

Brf wrote:
bryanjan wrote:
I don't intend to get it out, I just want to adhere the sapphire crystal direct to it. My original question is, the PEEK thrust plate already indented by the weight of the platter itself against the bearing ball, will that hemispherical indent create an imperfect flat surface to the sapphire crystal and make it the weakest point and crack?

Bryan


My educated "guess" is that it won't affect the crystal's integrity.


Thank you for the comfort, will report back once I've done. By the way, I will add the sapphire to the motor flywheel too.

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Re: Magnetic Platter bearing replacement - Sapphire and Si3N

Postby DrumTemp » Sun Jan 14, 2018 11:16 pm

Ok, here's some information I hadn't seen before. The first paragraph of Harry's review of the Mag platter (from 2015) contains important info I wish was included in the Avenger Reference manual. No mention about wear on the bearing, though. I thought it worth copying here as these issues were discussed in this thread.

The drive platter is mounted to the shaft which goes through both platters and deep into the bottom of the bearing assembly. The bottom bearing is an oil bath, the thrust disc on the bottom bearing takes the full 30 pounds total of both platters so we made the thrust disc replaceable and will recommend changing it every year so you get a new table sound. We tried levitating the drive platter with opposing ring magnets for less wear but the low end deteriorated as you took off weight. Sorry other table makers, get a set of Everest's and you will hear it too!! Bass requires a good solid footing.

The top platter, or slave platter, is in a super grease inverted bearing with almost zero rotational motion so there is no wear on that thrust disc. The powerful magnets from the drive platter grab the magnets in the slave platter and send it rotating noiselessly with a beautifully damped motion. Wow and flutter levels are exceptionally low but noise level is approaching 100 db down!!!

The Atlas, which has very powerful magnets has no reaction at all to the platter magnets. Neither does the Ortofon A95, the Shure Ultra 500, the Sound-Smith Hyperion, etc.

I am very pleased with the results, have compared many records to 15 ips 1/2 track tape counterparts, and will not shy away from saying it is 95% direct drive sound for a lot less money and a lot easier repair or replacement.

It will be available for upgrades on all tables eventually but the entire platter and bearing needs to be replaced, a credit will be given. I have a feeling a Classic 3 or Signature with this setup will be very, very hard to beat at any where near the price.

HW
Avenger Reference, Graham Phantom III, Benz Micro LP S, AI Mod 3B, Pass Labs X250.8, Vandersteen Quatro Wood CT
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Re: Magnetic Platter bearing replacement - Sapphire and Si3N

Postby bryanjan » Sun Jan 14, 2018 11:23 pm

I replaced the PEEK thrust disc in June last year on both the motor flywheel and platter, yesterday I found the one in the motor flywheel already worn out only after six months. Seems PEEK thrust disc is not sustainable.

Sapphire thrust plate is the way to go.

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