Pin-Turning Jig
This type of problem can be solved with a pin-turning jig. This sort of thing is not sold anymore that I know of, at least for any reasonable amount of money, but you can make one as follows:
A pin turning jig can be used to turn pins either on a lathe, mill or drill press. On a lathe the arm of the pin turning jig should be sized to mount on whatever rest you have. On a mill or drill press, the arm of the pin turning jig is clamped to the table.
The parts needed are the:
- the frame of the jig cut from 0.5" plate
- 0.5" bushing
- 3/16" cutter
- a small toe clamp
- (2) 1/8" x 1/2" steel pins
- 3/16"-32 7/8" cap screw
- (2) 6-32 1/4" set screws
[Frame] Cut out the frame. A plasma cutter could be used or even a hacksaw. Grind and finish the edges to be straight and smooth. Drill and ream the hole for the bushing.
[Bushing] Ideally, the bushing should be turned from D2 tool steel and hardened. A bevel can be added to the back of the bushing to make it easier to feed the work into it. A hacksaw/file or a mill can be used to cut the notches out from the bushing to form its tongue. You could alternatively use a milling attachment on a lathe.
Insert the bushing, tongue up, into the frame and scribe a line across it and the frame. This can be used later to make adjustments.
The set screws can be used to rotate the bushing and adjust the depth of cut.