I made this quick project to use my Geometric Die Head in the Tailstock of my lathe. Otherwise I had to put it in the Turret and setup. I used a 5/8" #2 MT Shank, broken drill bit. The Die Head also had a 5/8" straight shank, which worked out perfect. So I used a 4" piece of 1" Dia. CRS 1018 for an adapter and 4 ea 5/16-18 set screws. You can see me make this on You Tube, "Geometric Die Head Arbor", "Randy Richard". Link http://YouTu.be/jBRca7vSl5k.