Here are a few pics of Centerless Pen Turning. I am totally sold on this method and have the bushings for most of the common pens that I make and definately all my high end pens.
I think Frank F. will also say he likes this method.
The old pen mandrel looks more like a crankshaft with the amount of flex you can easily get in the middle.
This method is right on the money. I have not measured runout with this method but I bet it is close to zero.
The bushings fit so perfect that you get a definate pop when you remove them from the tubes. Glue run into your tubes - you better not with these bushings as the fit is perfect.
I do not sell the bushings. I get them from John Gooden. The standard set up is a hard steel set plus a Delrin set turned just a little undersize used for sandind and finishing. Delrin so that CA and/or your finish does not stick to them.
What makes the wood turn with no solid connection? Friction of the 60 degree centers pushing up against the bushings.
Try it sometime - you will like it.
BTW - The wood shown is Morton Bay Fig from T. Edisons house in Ft Myers, FL.
1 st - picture is the wood on a standard mandrel. No need for this to turn this pen Just shown for comparision.
2 nd - Using centerless bushing
3 rd - out of bushings to show the set up
4 th - engraved Edison box
5 th - Set of bushings