Circlip grooves

Reading John's post, it looks like 'armature' is a typo for 'amateur', which would match with the comment about there not seeming to be anything appropriate available.

When I needed some internal grooves cut inside a piece of 20mm aluminium tube recently, I used a blank tool steel as I didn't have an old boring bar handy (not been into this lark long enough to have old tools yet). I used a grinding wheel to remove a section of the steel, creating a narrower section in it, then I squared off the sides if the cutting tip with a dremel. It's worked a treat so far.

Regards

G.