ER32 Collet Chuck advise please.

I can’t find a reply from you regarding checking the internal taper of the chuck...don’t be fooled into thinking that if the external body runout is ok, that the rest will be ok too...not so....I’m having the same problem with a MT4-ER32 chuck on my Warco lathe...measuring the morse taper of the chuck where it sticks out from the lathe spindle it’s fine, but measuring the internal chuck taper it’s 3 thou out...and the rest of the body is too..

considering collet chucks are designed for accurate work, you’d think they’ve made with some sort of accuracy in the first place...

if you’re not getting a good reading at the chuck taper there’s no point checking the nut or collets, as it can only get worse not better..you need to work forwards from the beginning, starting at the lathe spindle, ...backplate face...etc....Good luck

Collet holder tolerance I think I posted this link before, this gives all the tolerances for the ER collet system parts.

It would be worth taking the collet plate off the backplate and check the running of the backplate.

Thanks guys, I will go back and revisit these points raised.

I did have a good reading inside the taper, but always getting a poor reading on a ground bar in the collets.

I turned the backplate to dimension on this lathe, so would have assumed some degree of accuracy. I'll take the collet chuck off and dti the back plate first.