[CS900]

Has anyone here ever machined a bore for a 5C (or R8 or any collet really) before? I've made a new spindle for my little CNC lathe that I'm building, and my intent was to machine a seat for a 5C collet right into the new spindle. that said, I've never done anything like this before so I'm not sure what areas need to be held to a tight tolerance. I've gotten the basic 5C dimensions and was planning on just machining a female version of that shape into the spindle but with a bit of extra clearance (in the Z direction) at the back of the collet so it can be pulled back with a drawbar and not bottom out against the spindle. So am I on the right track? Things I should be aware of?

[MattCEng]

Hi, did you ever solve this problem? I'm looking at doing the same thing currently. I was considering reaming the spindle to 1.25" then boring the taper in, but I don't know if it should be a larger hole than the nominal 1.25" of a 5C collet.

[peteeng]

Hi all here - I suspect that the taper has to be ground or lapped. Anyone can help here? as I want to do the same thing!! Peter

[Jim Dawson]

Pretty hard to stuff a 1.250 plug in a 1.250 hole. Maybe 1.251 hole would be better. I would bore the hole at about 1.255 except for the last 1/2 inch or so forward of the threads, that would be bored to 1.251, this allows easy insertion of the collet. Then, past the back of the collet, the bore needs to be larger to clear the OD of the draw tube, unless you want to use the ID threads in the collet for a draw bar. The ID threads in the collet is normally used for a collet stop.

The nose taper should be ground, I have done this with a tool post grinder. But it could be turned and still work.