My Maggie

[InDaGroove]

I haven't been here in a long time. I came back to do some reasearch on vacuum hold-down and found this thread first. I also have been considering adding magnets just as you did, to lighten my platter, which is 30 lbs.
Congrats on a great looking job!

[livemusic]

I can’t see the belt. On which part of the platter do you run it?

The black belt is hardly seen on background of middle portion of the lower platter, painted black. Yes, static builds up on the belt, but it somehow discharges during play (may be through the bearing housing, which is grounded). If I start TT after break, the belt seems to stick to the platter and makes crackling noise during first turn or two (but it is not audible through speakers). No noise/sticking between records though.

[FastEddy]

... consider a Bismuth /Magnesium & Zinc layered platter next time = a superconductor at about 120 degrees K when activated with a small electrostatic charge (according to Los Alamos Nat. labs).

Then it would be really cool ...

[d to the g]

Originally posted by FastEddy
... consider a Bismuth /Magnesium & Zinc layered platter next time = a superconductor at about 120 degrees K when activated with a small electrostatic charge (according to Los Alamos Nat. labs).

Then it would be really cool ...

Talk to a TEM specialist about unwanted vibrations from boiling Nitrogen. It's about the last thing I'd want on my tt.

[livemusic]

I quit the magnetic bearing route eventually.
I struggled to minimize magnetic flux on the platter surface, especially in vicinity of the bearing axle (inner grooves). In spite of the fact that magnetic field seems to have no audible effect on the cart, I was still a bit worried about long term consequences.
The stanless steel shaft which appeared to be ferromagnetic, was replaced to non-magnetic SS alloy with little effect. The only thing left to try was Mu-metal magnetic shielding, means major re-design of the bearing and platter, not to mention money/time expence.
The main driver behind the mag bearing was the scaring weight of my platter: 35 kg total! I though it is impossible to bear such weight with conventional ball-thrust plate design. I was wrong!
Now I end up with 1/2 inch steel ball running on the delrin thrust plate. Large ball increases the contact area and reduces stess. Another essentinal component is the low viscosity Van-den-Hul bearing oil; any other oil I've tried slowed down the platter too much. Following three weeks of spinning, I disassembled the bering. There was a dimple 1 mm deep in the delrin - not a big deal! The most important, sonically I did not noticed any deterioration, comparing to both fully suspended and partially supported by magnets platter. Quite the opposite - with a fully suspended platter I could not get rid of feeling somehow "springy" bass, quick but lack of authority and proper decay. Subjectively, conventional bearing has more relaxed, full-bodied sound, I was always after. So, why bother with magnets?
I want to say my TT in its recent state leaves very little to desire for me, especially after I switched to wonderfull Sumiko Celebration cart, which appeared to be very good match to my linear tracker.

[Jeb-D.]

You are my Idol!