Ring/Pen Mandrel

Made this to figure out the measurements for a pen mandrel I wanted to machine. I use it for turning rings. I printed the bushings in tpi or nylon and everything else I machined from metal.
To hold the end of the rod you can use a tail stock chuck if you have one but it would be better to buy a $20 live tailstock pen mandrel with bearings that fits the Morse Taper for your lathes tailstock.

The rod is 6.3mm in diameter, 10" long and goes into the base about 2"
I tapped a setscrew for #8-32 x 1/4" to hold the rod into the base

You need 4 spacers and 2 bushings for each size:
Small 4-7
Med 8-12
Lar 13-14