ESX25 collet chuck for the Unimat 3.

Recently I've had a couple of jobs on the lathe where a bigger collet chuck than my ER16 one would have come in usefull. Of course I have a 3 jaw chuck, but I much prefer a collet chuck for workholding as collets hold the work truer and don't mark the surface. With this in mind I ordered myself an ESX25 (or if you prefer ER25) chuck from Pro Machine Tools along with a set of collets (from Aim Tools).

This collet set covers 2mm to 16mm. The largest ER16 collet is 10mm.

The first job was to fit the chuck onto the machine and check the concentricity;

Total run-out is .0005". More than good enough for my needs.

Here it is fitted;

Being longer than either my 3 jaw or ER16 chucks it does of course take up more room on the lathe, however that should not be a problem as I tend to make only small parts.

And here it is next to my ER16 collet chuck;

ER25 and ER16 collets together for comparison;

One other advantage for having two collet chucks is that I can use the ESX25 for workholding and the ER16 in the tailstock for drilling, I find that a collet chuck is better for holding small drills (under 1mm) than a Jacobs drill chuck.

Paul.