I've actually had pretty good retun on a cheap import drill press and a regular pencil (eraser side down ) and use valve grinding compound.
worked pretty dang well IMHO. Only downside was where I got out of pattern since I was doing it by hand/eyeball w/o a compound table.
PS It helped to have a "feel" for the Z handle, try to use the exact same "feel" or pressure each time you pull it down.
Good luck and TAKE PICS... wait, I mean POST PICS