[bojan]

Tube arrived today... I hoped it would have a tad thicker wall, but this should be OK as well.
I can try to glue the tube with silicone rubber...which will fill the gap (~0.1 mm) Or.. I can try with cone spacers (that will force rubber tighter into bearing)

Anyway, I think 1 mm layer of silicone rubber may be OK for damping and also to accommodate tolerances of the metal ring.. (which I intend to grind flat and perpendicular to shaft by mounting angle grinder on the frame. I started this couple of years ago but stopped.. because I needed scope for something. Now it's the time to finish this idea.