Wood lathe Jig

[Cgull]

Have a Shopsmith lathe, looking for suggestions to mount a cutter tool that will cut a 1/8" tenon, 5 inches long in the end of a 1-3/4" dowel. It needs to be some kind of jig that will hold the cutter in place, and travel up to 5 inches moving to the left. I want to avoid paying for an expensive lathe duplicator, just needing some kind of cutter holding device that can traverse a short distance.

Cgull