Exactly!
Compound still moving a little, tho not nearly as bad. Needed to broach an internal keyway in a sleeve, don't have a broach.
There's a trick using a parting tool and a lathe. Mount the parting tool sideways, mount the piece in the chuck. With the lathe OFF and the back gear in to lock the spindle in position, use the saddle to drive the cutoff tool through the piece and advance it a couple of thousands after each pass.
Slow...Very, VERY slow...but it works.
It also spurred me to crack open the toy fund and buy a basic set of broaches...