Sandbox-style isolation

Thom, Segmented top plates sharing a single sandbox, each segment with an alumimum angle or aluminum heat sink anchored deep into the sand. Heavy mass-loaded plinth with heavy outboard motor. Do you really believe that the top plate segments will move relative to each other enough to cause even tiny shifts in geometry of drive train?

I can tell you from my own experience the single aluminum plate using the vibration sinks, per Thom's instructions, is superior to the segmented top plates I've tried. More refinement, resolution, more slam, solidity, greater dynamics. Now, I've thought about segmenting the aluminum plate, Thom's argument makes sense, I will not segment.

Do you really believe that the top plate segments will move relative to each other enough to cause even tiny shifts in geometry of drive train

Yes.

Based on the argument that these two pieces won't move independently, one could argue that isolation of any sort wouldn't help because all of this movement is so minute.

Ultimately we are all patently mad and arguing over small things, but as long as we're having fun with it, let the debate rage on.

Cheers,
Thom @ Galibier

Assuming that significant mass loading has been applied to minimize shifts of the segmented top plates in the horizontal plane, the heart of the matter would seem to be that vibration is conducted through dense adjacent solids--in this case, mechanical energy moving in the vertical plane from plinth to footer to wood plate to sand. In a related twist, tonight I modified the suspension of my modified thread-drive VPI TNT to incorporate DIY Stillpoints inside the elephant feet (which are otherwise unsprung.) The mod consists of a pyramid of ceramic balls, supported by spring steel petals that dissipate vibration of the bottom tier of balls into the horizontal plane as mechanical energy. The result was a rather amazing improvement in coherence and general sonics. The operation of the ball/spring combo would seem analogous to grains of sand beneath the sandbox plates, but in the horizontal rather than vertical plane. Now I will bet my eye teeth that those balls & petals in the Stillpoints are by design moving more in the horizontal than the segmented plates in the sandbox-- and yet sound is significantly improved. You would have to put up a pretty strong argument that the improvement in sound represents a compromise between improved resonance control and degraded speed stability.

Dave, the sand should move in both the vertical and horizontal plane as well,

It still seems to me a mass loaded design should sit on the most stable platform you can provide, seems some non-sympathetic vibrations would be induced by more compliant platforms. Therefore, vibrations of different parts of the tt are moving asynchronous to each other, inducing confusing movement to the entire mechanism. Sitting on segmented plinths should only increase this confused movement.