[RotarySMP]

Good post Geof,

You idea has the makings of a very ellegant solution. Your toggle opens the collet as it moves up the ramp. How do you close it? Maybe replacing the ramp with a cam slot?

I was wondering what the closing force on a 3C needs to be. Could you post the link to this 5C closing force? Do they also list forces for smaller collets?

I got the idea with the spring from the Automatic tool changer for the mini mill, but then again, with a ATC you only need enough force to hold two tapers tightly together, whereas here you need enough force to close the taper and provide sufficient clamping force.

For the sort of parts you can hold with 3C (up to 1/2" diameter) I am not so sure that you couldn't make my idea work. Maybe not with valve springs, but with a stack of Bellville washers.

Jeff you are right, the handle could be disconnected ommiting the bearing. I would think it would all get a little wobbly though.

You need something like ebay 190121671299 or here is a partial one in the states. 120131086073. These Weiler turret lathes are now dirt cheap here in Europe. Even fully loaded with accesories, they rarely fetch over €1000. Weiler is the Mercedes of German Lathes (well one of them - there are lots of excellent german tool companies)