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ER32 frustration

starting the closing ring thread

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pgk pgk29/06/2020 06:36:53
2031 forum posts
290 photos

OK so it sounds daft but while occasionally the ring just goes on first time there are many more cases where I end up fiddling for ages (a minute or two is a long time when things aren't going right) trying to snag the thread start.

I can see nothing wrong with thread on chuck or ring (either of two rings) and any 'trick' such as starting in left hand turn to feel the start of the thread click, or slightly angling the ring around the circumference, pushing the collet inwards to align things, slow start, faster start - fiddling. None makes a statistical difference to the simple task of getting the closing ring threading.

I can guess that everyone will tell me they get it on first time, every time... but is there a reliable answer (or relaible ring type)?


Kiwi Bloke29/06/2020 06:47:12
503 forum posts
1 photos

Posted by pgk pgk on 29/06/2020 06:36:53:

...pushing the collet inwards to align things, ...

If you can push the collet inwards, relative to the ring, it's not engaged with the retention lip in the ring. Is that possibly the problem? I hesitate to suggest this, because I would assume that you already know how to use the thing. Some posters on this forum, however, seem not to.

JasonB29/06/2020 06:56:32
19591 forum posts
2150 photos
1 articles

I think PGK is talking about getting the nut to start on the holder, I get it occasionally where it just does not seem to want to engage but no obvious reason why.

pgk pgk29/06/2020 06:57:10
2031 forum posts
290 photos

When the collet is seated in the ring it will still swivel within the ring until the ring is tightenened and there is still a degree of slop. On both my rings. And yes I do know how to snap them in (or I thought I did .....?)


not done it yet29/06/2020 07:06:28
5419 forum posts
20 photos

Presumably this occurs while the chuck is mounted to a vertical spindle? I can understand that and quite often it may take a few seconds - not minutes - to get it started.

Simple cure is to fit your cutter with the chuck off the machine. That is the way the real pro’s do it, for changing CNC cutters. That would be those with a tool setter to change cutters and reset the machine for operation. They do it off the machine to ensure correct tightening torque as well.

I can say that I have no problem screwing in the retaining nut while using the ER in the spindle, on the lathe. Can’t be so positive if it was in the tailstock, mind (so easy to eject it from there to change a cutter, if ever needed).

That means it is the operator, not the nut, that is the problem (unless both are nuts🙂🙂 ), I’m afraid. Confirmed, really, by you saying you can see nothing wrong with it.

Howard Lewis29/06/2020 08:55:35
4166 forum posts
3 photos

Occasionally, I have the same problem with a 3MT ER25 chuck, but not with an ER25 2 MT one, (from different suppliers, separated by several years ). So I assume that the problem, if there is one, results from the fit of the nut to the body, maybe the chamfer on the start of the thread in the body.

I just live with it, Can't afford to lose any more hair over such a thing!


pgk pgk29/06/2020 09:23:10
2031 forum posts
290 photos

Indeed the vertical spindle. Knocking the taper out and repacing/snagging the drawbar each time would also be frustrtaing (to me) but when out of the mill and 'upsidedown' I don't have a problem - so I'd concur with the idea that it may be some aspect of lead-in on the ring(s).
When your my 2metre height then holding my body fixed, bent to stabislise me while messing with the ring gives me severe lumbar spasms after not very long such that collet changes can ruin any fun for me.
Can anyone confirm if a particular brand/type of ring is more reliable?

pgk (still quite hirsute)

Alan Jackson29/06/2020 11:42:36
202 forum posts
92 photos

On my Stepperhead lathe the ER32 collet nut has two hardened discs positioned 120 degrees apart to act to remove the collet. I did it this way to avoid making the eccentric ring. This method has advantages in that it is easy to insert the collet and the hardened discs can be machined to a diameter and thickness to ensure they do not interfere with the concentricity of the installed collet.


Hardened discs for removal

pgk pgk29/06/2020 11:55:40
2031 forum posts
290 photos

Alan, nice simple solution. I hve made one chuck as part of a DIY fixture that works well but bought the nut..your method makes nut creation easy. whether it'll end up with better lead-in is another matter. I suppose i couls also fiddle with making a witness mark for thread start.


blowlamp29/06/2020 12:31:26
1473 forum posts
97 photos

Does the nut screw on OK without a collet?


pgk pgk29/06/2020 14:02:04
2031 forum posts
290 photos
Posted by blowlamp on 29/06/2020 12:31:26:

Does the nut screw on OK without a collet?


Same issues (for me)


Swarf Maker29/06/2020 14:20:15
102 forum posts
4 photos

I think that the problem is with local gravity! I have occasional issues just like this with a Clarkson collet ring. I think that what happens is that just at the moment that the thread would engage, your hand lets the ring drop a fraction and thus miss the opportunity.

If it doesn't go first time with one hand I use two fingers (not like that!), one either side of the tool to hold the ring in constant contact with the tool holder body. The other hand does the turning. Usually works within the one turn then.

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