I purchased a couple of nuts with 3/4-16 NF thread. These particlar nuts are fairly thin and required no additional milling. I drilled a hole in the center of each face which is just big enough to take one of the tommy bars used on the Sherline equipment. Bigger...

Here we can see the nut installed. Remove the drawbar, and unscrew the nut to pull the taper out. If you forget to install the nut before putting the drill chuck on, you can unscrew the drill chuck from the taper, screw the the nut on, put the chuck back on, and unscrew the nut. Bigger...