"Stanley Schaefer" wrote
Classic method(besides Ed's), is to use a collet with a stop in the
lathe and a pivoting tool rest. This last can be just a bar with a
pivot held by some means on the compound rest up to an elaborate gear
driven C-shaped holder in a half-gimble.
Stan

I chucked the top half of the compound in the 3-jaw and marked the
center of rotation, which for my lathe is on the top slide close to
the tee slot with the compound fully back. I can turn a small convex
radius by swiveling the compound, with a bit in a lantern holder.

jsw