I gave up on pen mills about 5 years ago when it hit me I was going to need a bunch of different sized shafts for each tube type or turn a barrel to fit my slim shaft and each tube type, plus having to sharpen the mill which I never had much luck at. I took a small thin parting tool I had made with old planer blades and ground the tip to an angle a little less than 60 deg. I cut the blank close to the brass tube then using my turn between center bushings I turn the blank round and a little larger than final size. I then take it out of the bushings and mount it between my 60 deg. live and dead centers. Working on the assumption that the tubes are cut square and the dead center will come to rest on the inside of the tube slightly before the blank is cut even with the tube I take the parting tool I made and place it flat side up on the tool rest and trim the blank slowly to get it square and even with the end of the tube. I trim at the headstock end using a carbide tipped dead center then turn the blank around and trim the other end. While trimming I adjust the tailstock to keep the blank tight against the dead center in the headstock. This has worked well for me through 2 or 3 hundred pens since I started it and since I trim at about 1200 rpm I get nice clean cuts on wood, acrylics and truestone.
Rick
I support the Pens for Canadian Peacekeepers project