On Tue, 6 Mar 2012 13:11:26 -0500, Wild_Bill wrote:

[...]

I don't know what would be best for your lathe spindle as far as mounting a
hand crank, but the ones I've used are a split-wedge sort of locking device
which clamps securely inside the hollow spindle. There's a name for this
particular locking part, but I don't recall what it is. They were once a
popular method of installing a bicycle handlebar stem into the fork tube.
Then a crank and handle or handwheel can be mounted for those short
threading jobs.

That's a good idea. Sort of an inside collet, with a sleeve forced
open by a wedge?

Bob