Hex Collet for a mill?

[WobblyHand]

The inside of the nut should look like this. This is an ER32, but the eccentric ledge at the bottom is integral to the ER collet design. You push the collet groove towards the small ID, on the left, and snap the collet in. Then place in the spindle (with or without the tool). The nut will tighten easily once you line up the threads.

What does your collet nut interior look like?

 

[C-Bag]

I shouldn’t have said I had a set like RJSakowski, my set was under $120. I also don’t work to NASA spec and my old RF30 is well used(read:worn out) so buying expensive collets for it is like buying a diamond necklace for a pig.

I know what it’s like to be on a budget of zero. Swapping out collets is a pain but I try not to think about it. I also don’t work under a time clock and don’t do work for hire. So it seems we are talking apples and oranges. I didn’t mean to second guess your process. I also know the frustration of knowing what would fit with what I’m doing and nobody makes it. I did find a place that had square ID R8 collets. But I don’t remember seeing hex. Seems that stuff is reserved for 5c.

 

[WobblyHand]

One last reference on ER collets. It doesn't solve your problem, but it fully describes ER collets and how how they are used. Hope this works, first time linking video. This is from Haas Automation. I think 13:00 is when he shows/describes inserting collets into the nut. Learned quite a bit watching this.

 

[WobblyHand]

My ER32 collet set was cheap, about $80 from Amazon. Surprisingly good TIR for the money. Most are under 0.0005". 1/16" - 13/16", by 32nds. 25 pieces. Industrial grade, nope, but good enough for me.

Maybe you can find something similar? Please check your ER40 nut, it may be damaged. Replacement flush style collet nuts are not too expensive.

 

[lesrhorer]

Yeah, OK, there is. I've never come across one that is this hard to snap in, however. I have to push with all my might to get this to snap. Strike one issue, but I am still going to give it a try. 'Not much to lose.

 

[WobblyHand]

Yeah, OK, there is. I've never come across one that is this hard to snap in, however. I have to push with all my might to get this to snap. Strike one issue, but I am still going to give it a try. 'Not much to lose.

As you said, if you are just hogging out a hole, it doesn't matter that much. But your tool life will be lower and maybe the spindle bearing life.

Still think your nut (or collets) may be damaged. Is it just one collet that is giving you trouble, or a lot of them?