Rerurn to Romy the Cat's Site
In the Forum: Analog Playback
In the Thread: Copper Mat on a Micro Seiki Gun Metal Platter
Post Subject: Silicon nitridePosted by Wellington on: 11/7/2017
I think that I saw someone offering a silicon nitride thrust plate along with the ball bearing years ago. Jam, your solution of simply flipping the thrust plate upside down makes perfect sense, but I suppose a silicon nitride (or similarly hard) plate might offer the lowest friction/wear and lowest noise solution. The dimple in Measet’s plate looks cavernous, almost enough to have gradually affected VTA 
But I suppose the close-up picture makes it look worse than it is.
That cracked ball bearing is a reminder to us all that brittle ceramic balls, while hard, can’t handle very much shock. This reinforces the importance of VERY GENTLY lowering the platter down onto the spindle using the T-handles. And never try to move the turntable with the platter in place (who would try with that much weight?) Measet, I am not suggesting that you were less than gentle with your platter, but that over the decades and through multiple owners, who knows what that ball had been subjected to? Jam, were either of your original ball bearings cracked? A ball on a fresh thrust plate makes contact on an infinitesimally small point, therefore pressure (which is force divided by area) is enormous at that point. Fortunately silicon nitride is more shock resistant than other ceramics. I have a silicon nitride ball ready if I decide to perform bearing surgery, but so far I have resisted the temptation to open it.
By the way, I put a tiny amount of grease onto the conical spindle surface that mates with the platter. Not enough to ooze out, barely more than a greasy fingerprint. I do this to make it easier to pull the platter the next time.Rerurn to Romy the Cat's Site