Radius cutting attachment for pen ends

[Amihai]

Hello, question for the kitless makers here:
I have the Proxxon radius cutting attachment for their PD400 lathe.

I want to cut a radius at the end of the pens I turn, to give them less of a "square" and more professional look. However, I don't seem to get the positioning of the tool right.

Is there some sort of formula or method to find out where should I position the tool to get the closest to perfect of half a sphere around the axis of rotation while moving the tool?

Pictued are my setup and the kind of end I want.

Thanks,
Amihai Fishman.

 

[hooked]

I have ground cutting tools to form the radius. I have also tried mounting a radius milling bit in the tool holder. I even bought a micro mark jig to do radius ends. By far, the easiest and quickest way I have found for pens is to move the pen to a wood lathe and do it by hand. If you don't have access to a wood lathe, the homemade radius cutter gave me the best cone-shaped result. The problem with the raius jig is that it is hard to get something other than a "ball end"

This video explains what I mean by making a cutting tool to form the radius. It also shows the operation of a radius cutting jig, but a much larger one.

 

[Chriscb]

Afternoon, I'm with Hooked - I also move the pen onto a wood lathe and form the end using hand tools. Although I have come across this video which shows the use of the tool you mention. I fear that it will only enable you to cut a constant radius, rather than the shape you want. Either way, you'll learn a new skill.

Chriscb

 

[d_bondi]

I'm with Hooked and Chriscb, I do it all on a wood lathe and shape the ends with hand tools.