VPI TNT Bearing question

Please allow to offer some clarification. The MkV mechanical coupling is vastly superior to that of the 3 bolt coupling. VPI also changed to this type/method of coupling the newer JMW Memorial tone arm bearing; it is basically a mini MKV setup.

My only concern with modifying an older TNT bearing to utilize a single bolt coupling method as deployed in the MkV is that the older bearings are aluminum and I am not sure if your could get the appropriate torque without stripping the soft aluminum threads. If you are interested in my back up MkV bearing, send me a pm.

I am not sure if your could get the appropriate torque without stripping the soft aluminum threads

Does VPI give a torque spec for any of their bearings? If you were to strip aluminum threads tightening any component on a turntable you are applying way to much force.

Whatever VPI has done with subsequent iterations of the platter bearing to improve coupling between the bearing housing and the plinth, my point is that massive brass coupling of the metal bearing housing to the platform below will surpass the acrylic plinth in dissipating parasitic vibration from the system. This is based on several modifications to TNT spindle bearing and suspension I've performed that substitute brass for plastic. If you have access to a machine shop, try it you'll see. The construct can be extended to a brass pedestal that extends from the tonearm pedestal through the plinth to the platform. I've done it and it works. After enough of this the acrylic plinth becomes little more than a means of locating the spindle and tonearm in the horizontal plane.

On my custom HW-19 acrylic Plinth, the entire MK-IV Bearing Well (with the 3 screw mounting arrangement) is a tight slip fit.

Ny Spindle-Pivot distance on the Plinth is at +- .003".'

Probably the condition of the Bearing, and well itself is more important than what version bearing well.

I could've had a local machinist I know fabricate me a bearing that would've looked like it came of a military 2-1/2 ton truck. With his knowledge, and inspection of my stock MK-IV bearing, and the Platter, his words were "this is fine".

Yes, the 1/2" bearing shaft looks sort of "spindly" IMO.
Reckon the issues at hand are, how much load is on the bearing? There is no heat to speak of. Tolerances, ans smoothness are probably some of the most important factors.

A local machinist who is worth his salt shpuld be able to do anything you want. Tney'll usually charge you a flat rate charge for labor, and then materials acquired-used.

Very interesting and thought provoking responses.

I am not worried about aluminum threads stripping and suspect you could shear of the top collar of the bearing housing if you apply enough torque (consider the amount of material engaged in the threads compared to the amount of material in the flange).

Dgarretson has done some very nice mods. As I read more about turntables I had begun to wonder if more mass on the bearing housing would be beneficial and I think he is saying it is.

The feet are pretty slick also. Do I understand that the flex provided by the fingers of the cup which holds the ceramic balls is enough to give a bit of vertical compliance as the four balls on the bottom move in and out allowing the top ball to move up and down? Some more details on the foot construction would be nice.

Your AC supply for the turntable bears some research as I have been looking for something that would do that.

As to machinist, while I am not a pro I do have pretty good skills and a very well equipped shop in my garage so I can fabricate a lot of this sort of stuff.

Lots of food for thought...