Being parallel to the axis of rotation - I don't think Knurling myself.

I think crimping wheels - put a wiggle edge on metal to splice and solder
or just make stronger.

I have a large set - 4" wide and 2-3" in diameter.

Martin

Michael Koblic wrote:
http://www.flickr.com/photos/27683124@N07/3614881435/

and the next two pictures.

I suspect they are knurling wheels of some sort. Seeing how one was mounted
presumably you just press them against a rotating part?