A friend of mine is an engraver for a sign manufacturer. After I recently asked if he had an er11 collet I could look at (thinking of making a little spindle), gave me some food for thought because after showing me both an er11 and er16, he showed me a box of slightly unusual collets in his cupboard. He asked if they might be of use to me and said that I could have them if I wanted.

Naturally I was pretty chuffed at the prospect but I need to figure out if they're are going to be usefull to me or not. They look like this:

Each one has its own closing ring circlipped to the top. From what I can gather they are porter cable collets for use in wood routers. I can see making a little chuck straightforward enough, I may even be able to use one of those soft morse stubs you can buy. One thing that does interest me is the relief (black bit in middle if relief isn't the right word )in the middle if the collet. It's not a double angle type so I don't see what having the gap does. Any suggestions?

So what do people think could I use these for a small mill drill spindle for my lathe?

cheers

martin