The offset is to clip the collet into which will then make it captive in the nut so that when you undo the nut it pulls the collet out of the taper. If you put the nut on loose the offset ring will push the collet side ways and give a wonky cutter, make it hard to extract the collet and may well damage the collet

See here

Edited By JasonB on 14/03/2021 10:10:53

If you mean the flange is inside the nut then Yes it is there for a reason. I think you have just scrapped it. The collet clicks into it to retain the collet

The offset flange is there for a very good purpose.

Examination will show that it is a deliberate design feature and not poor workmanship.

The Collet clips into the offset flange, so that when the nut is slackened, it releases the collet from the taper.

If you have tightened the nut down hard onto the collet, you may have cracked or distorted both, and ruined them!

The Arc Euro catalogue shows how to mount ER collets.

Howard

Oh dear, the good news is the clip flange thingy regularly catches out newcomers to the ER system. You and your neighbour are not alone, though this is the first time someone has gone so far as to removed the lip! Usually not clicking the collet into place just causes poor run-out, and the problem is easily fixed when the secret is revealled. (Incidentally, I've never seen it explained other than in the ArcEuro link Jason provided.)

Word of warning; quite a lot of chaps on the internet set the expectation that everything made in Asia is carp. It's not true. True some stuff is 'cheap and nasty', but most is mid-range, and probably 'good enough'. Give it the benefit of the doubt before jumping to conclusions! To reduce the risk I prefer to buy from the likes of ArcEuro rather than importing from abroad because local firms filter out much of the rubbish and UK consumer protection applies if a total dud gets past them. (They do sometimes.)

Bad news, I doubt the modified ER chuck is 'working perfectly'. As the flange serves to locate and support the collet, it's unlikely the chuck will hold the collet as well as it should, particularly when fully torqued up and used to take deep cuts.

By the by the amount of tightening required is also rarely mentioned. It's far more than I expected! Good news, you can get ball bearing Collet Nuts that are easy to tighten, which will solve both problems. Arc~Euro sell them, other vendors available. (Note there are two types of nut depending on the holder.)

Can you report back on how your modification works?. In theory it's not a good idea, but it might work in practice. Only you can tell us!

Don't be afraid to ask on the forum – chances are someone knows the answer or can point you in the right direction.

These incidents are all part of the fun!

Dave

It's just a pain to get the collet out! If you tighten the nut properly it is surprising just how much torque is needed to release the collet when unscrewing.

When I got my little Novamill which was an ex-school machine it still had a cutter mounted. Clearly the teacher who "looked after" the machine didn't have a clue about how the chucks are supposed to work, so the nut on the ER16 chuck was tightened to the n'th degree to get the tool gripped properly. Getting it loose and removing the collet and too was a nightmare.