Tables That Feature Bearing Friction

Ah, yes!

a = (2*f*sin(x))/mass

Thanks for the trig review. ;-)

So this futzing-about with various types of belt media and such . . . I take it that this is pretty much "de rigueur" to get the best from any turntable that uses the thread-drive approach? What did i.e. Micro Seiki originally intend for the RX/RY-5000 system?

Syntax, In that third photo, is the platter on the right driving the platter on the left, as it appears? This is in keeping with some of Mark Kelly's teachings on "belt creep" and how to prevent it. Anyone interested in this topic should search on the Vinyl Asylum archives for Mark's ideas. He is a brilliant guy who applied math and physics to belt drive and who compared the different qualities of idler-, direct-, and belt-drive to each other, also on a math and physics level. Far be it from me to speak for him, but based on my understanding of his findings, a very long thread between a very narrow diameter pulley and a distant platter is not a good idea, likely to result in significant belt creep compared to other arrangements, such as using one platter to drive another, using capstan type devices to force the driving string to conform to as much of the circumference of the driven platter as possible, etc.

Micro Seiki has a kind of tape (SF-1 Series) with an enormous grip, it is very sought after these days. It was in my comparison among the best. (After 25 years a quite impressing result)

There are more options with the Seiki units out there.

Seiki "Shot Gun 1"

Seiki "Shot Gun 2"

I was influenced from the original Micro Seikii HS-Inertia unit

Seiki Inertia

Anyway, the way I do it works quite well and there are differences in sonics with/without. A good "tool" for comparisons. But depressing.
For the others.

I went through Mark Kelly's extensive teachings. Good research and explanations, but he is not focussing upon the center point.

Some people will hate me for this, but I want to postulate a short and clear statement ( and I ask everybody to give it some deep thought before telling me I am wrong....) regarding ANY principle in turntable drive (idler, dd or belt):

The motor of a turntable has ONLY 2 jobs to handle.
1.) bringing the platter on speed
2.) preventing the platter to slow down once it has reached that constant speed

There is nothing else the motor / drive has to do.
Physics and logic will result in a huge inertia ( = huge mass of platter) providing an extremely constant speed by its own rotation. It will too result in a coupling which does allow some slip at BOTH ends of the drive system - platter AND motor (such that little variations in speed generated by the motor itself will NOT make it onto the coupling device (string, belt - whatever). A say 35 -50 lbs platter on 33 1/3 rpm rotation has a VERY constant speed (much better in its constant speed stability than almost all motors in use in todays high-end turntables).

It is not about control between motor and platter.
The platter will not get any "faster" once it has reached its determined speed.
It gets slower due to air resistance, stylus drag etc. But those are constants in real world application.
So - all the motor and its coupling device have to do is preventing the platter from getting slower.

This automatically does lead us to a definite slip coupling and a huge inertia.
The way to get ultra constant speed and practically zero derivation in as much inertia as possible (in real world application).

Give it a deep though before jumping to the keyboard telling me a stupid, narrow-minded fundamentalist.

Its all about masses in motion.
Again - its all physics.

The trade-off is a long time to arrive at stabilized (2-4 minutes) speed.