Is this what you mean? I bought some of these because they are from UK and I needed cutters fast. http://www.ebay.co.uk/itm/291185073866

I'll be using delrin at first because I've got some and it seems to be the easiest to machine. Then I'll try nylon.

I've got a bunch of 2 flute endmills coming, mostly 3.175 and 6mm diameter.

I haven't worked out an RPM, speed, DOC, overstep etc yet to start with. Any ideas for dia 3.175 2 flute ?