Tapping over 150 holes made power tapping a requirement for my 2000 mill project.
I used 5/8" drill rod for the adapters.
Each blank was 2" long.
Turned a taper on the nose of each blank.
Drilled/reamed the hole for the tap in the tapered end while still in the chuck.
Reversed the partially completed tool in the chuck.
Turned down the shaft to 1/2" for use in my drill press, mill, or portable drill motor.
Moved the part to the mill to drill the set screw hole. Note that while I had it in the mill vise
I drilled the set screw hole all the way through. Now I have an extra hole in case I need a spare set screw threaded hole.
Made one for 10-32 and another for 1/4-20.
Added one blank to be used for whatever in the future.