Make up a straight bar about 1" diam and 4-5" long with a taper on the back to fit your
tailstock. Then make a sleeve to slide over the straight bar, about 1/8-3/16 wall is good,
and knurl the outside, and thread the front for a drill chuck.
Chuck a tap in the drill chuck. Run the lathe at any speed you like with the sleeve running
on the guide rod in the tailstock with a bit of oil between them. You control the position
and torque with your grip on the knurling. When the tap bottoms, it will spin in your
hand. Stop and reverse the lathe. No need to break a tap this way.
Bill