Keith, I did have another idea¡ What I¡¯m trying to do is essentially cut an internal semi-circular (ball) shape but there is obviously no room to swing a cutter on a pivot at the edges (it would be on a ridiculously small scale anyway).
I wondered if a cutter held vertically with a simple lever to rotate it would work. Something like a cut-down, ground-down and re-shaped small boring bar (3/16 shank)?
The cutting surface would be greatly reduced, as would load on the drive train. A ¡®proper¡¯ cutter shape could be used to suit the material Arranging it could be quite simple, dropped through a block of half inch square stuff bolted into the top of the tool holder. Disc type stop with a grub screw against a flat. The issue I think would be killing excess wobble (and therefore chatter) while still allowing it to be rotated.
Feasible?
