General rule with collets is that the parallel, gripping, part inside the collet must be filled for proper, stable, grip.

In the absence of measurements its usually OK to assume that so long as the workpiece goes in a bit further than teh depth of the outer, large, taper things will work correctly on unambitious jobs.

Trying to hold a very short piece and ramping up the pressure to get things to hold is a quick way of messing up a collet. They are not as robust as they look at first sight. There don't seem to be any official figures but I imagine 20 ft lb would be as high as I could sensibly manage with the hand wheel closer on my lathes and the shoe C spanner with my collet block. What I actually use is less.

Clive

Jason

With only 1/32" held how the devil did you get the job running true?

Nearest I ever came to that was with an 3/32" long spigot on an asymmetric and non circular flange that needed the hole in the middle enlarged. I blessed the original maker for putting a teeny undercut at the junction so it sat flat against the face of the collet.

A job for one of the "gash" set of Harding 5C collets I bought for "£ not very much" in the days before I learned proper E-Bay caution. Clearly retired from production duties, probably from a Tier 3 shop, most have lost their spring and don't open properly, maybe half have internal taper in greater or lesser degree and some are so badly distorted that there is visible error in the angle between the main shank and the taper. Lord knows what they were tightening the things up with. Surprisingly concentricity was still very good but the various errors and tapers vastly compromised grip. Which I found out they hard way after a job that needed to be real nice spun! Concentricity great, I checked first, grip crap. Fortunately most of the 1/64 th s are still pretty good.

Clive

Hi colin,

Have a look at Joe Pie's latest model canon video on You Tube.