Sorry I still can't see it, if I turn any pen with a nib end blank and a clip end blank, I need a bushing in the middle, BUT if I have bushings that somehow go into something in my tailstock and headstock and the middle is unsupported I surely must get inherent hysteresis (Wobble for want of a better word), do you have any pictures or schematics?
Now offer me bushings that don't wear down with sanding and I will be seriously interested. BUT anything that costs lotsa dosh will get Dragon Ops breathing fire....
PG