By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Jan 24th

Slipping ER25 collet and best practice

All Topics | Latest Posts

Search for:  in Thread Title in  
andrew lyner10/06/2021 19:12:27
240 forum posts
4 photos

Time to consult the oracles again.

I guess I am doing something wrong here but collets like the ER25 should be extra good at holding (I would have thought) as both inner and outer bits squeeze down on the tool. I have problems with the tool working its way up inside the collet.

I make sure that the holder, collet and nut are all pretty clean and I sock it up pretty tight Do I need to be extra scrupulous a bout the cleaning? I have eyeballed the inside of the nut and the holder and there doesn't seem to be anything amiss. is there a step that I'm missing. Is lubrication a good thing or a bad thing here?

JasonB10/06/2021 19:23:22
21967 forum posts
2531 photos
1 articles

Are you snapping the collet into the nut correctly before inserting tool and doing it up?

Edited By JasonB on 10/06/2021 19:24:19

Journeyman10/06/2021 19:43:34
1107 forum posts
219 photos

The recommended torque for tightening these collets is quite high. See the Rego-Fix table for details.


Vic10/06/2021 19:53:14
3012 forum posts
8 photos

I find the ball bearing nuts easier to use to get a good grip.


old mart10/06/2021 20:19:13
3487 forum posts
213 photos

I don't find that the spanners that you can get for tightening them are long enough. We use er25 and I have a pair of spanners with 10" long handles. As already mentioned, a ball bearing nut helps.

Emgee10/06/2021 20:22:56
2310 forum posts
277 photos


Some chucks have a facility to use an adjustable backstop screw, if yours has you will see a tapped hole below the internal collet taper.


Neil Lickfold10/06/2021 20:29:24
750 forum posts
129 photos

Make sure that the cutter is in the collet to the full length of the collet or the length of the diameter of the cutter. Some collets are counter bored from the back. Some ER holders or spindle adapters also have end stops provided or a thread to make one as well. They are to set the cutter to the same length when changed. Also will stop a cutter moving back into the collet. You almost can not over tighten the ER25 collet assembly with the 2 spanners provided. Their max closing torque is very high.

bernard towers10/06/2021 21:40:00
385 forum posts
102 photos

Not trying to put a damper on the comments above but nobody has mentioned the cutters! ARE THEY SHARP. I have seen people using cutters in the past that are only fit for the bin and they quite happily complain about poor finish and cutters moving.!!

andrew lyner10/06/2021 22:06:02
240 forum posts
4 photos

Wow. Thanks for that long list of things to look for. The "snapping" could be something that I am missing. There is a slight click but nothing very impressive that I can remember. I'll take more care and tighten it until my eyes bulge.

Oldiron10/06/2021 22:48:09
906 forum posts
40 photos

There are some excellent video's on Youtube on the do's & dont's of ER series colletts. Just search for them. Much easier to see than read directions.


Rob Wheatley10/06/2021 23:08:42
37 forum posts
12 photos

Don't forget they only have a small range they will close up on, generally 1mm over 5mm and 0.5mm for sizes under 5mm, if I'm using a 10mm shank end mill I will always use the 9-10mm collet not the 10-11 mm one.

It helps to have a complete set of metric and imperial ones.

Paul Lousick11/06/2021 00:58:54
1896 forum posts
669 photos

I don't use a tension wrench to set the torque but normally remove the collet holder from the mill and clamp it in a vice so that I can tighten the nut with a bit more force. A little oil on the thread is good but keep the bore of the collet dry.


Edited By Paul Lousick on 11/06/2021 01:00:50

Swarf, Mostly!11/06/2021 09:13:41
621 forum posts
66 photos

Posted by Jason 10/6/21

Are you snapping the collet into the nut correctly before inserting tool and doing it up?

Posted by andrew lyner on 10/06/2021 22:06:02:


The "snapping" could be something that I am missing. There is a slight click but nothing very impressive that I can remember.


Reviewing this thread, it seems to me that this important topic is being glossed over!!!!!!!!!!

My understanding is as follows: the collet should be engaged into the nut while both are OFF THE CHUCK.. Then fit the collet/nut combination onto the body of the chuck and then insert the tool and tighten the nut.

I await comment from others.

Best regards,

Swarf, Mostly!

Andrew Johnston11/06/2021 09:38:06
6390 forum posts
682 photos

Posted by Swarf, Mostly! on 11/06/2021 09:13:41:

..............the collet should be engaged into the nut while both are OFF THE CHUCK.

Correct - Andrew

JasonB11/06/2021 09:43:00
21967 forum posts
2531 photos
1 articles

Yes that's what the link I included says though you can insert the tool into the collet once snapped into the nut and then put nut onto chuck body. I find this way best as you don't need to raise the mill head so much. Main thing is collet snapped into nut first, not only does this ensure even contact of the collet's short front taper it also extracts the collet from the long chuck taper when you undo it.

Mr Happy from Haas has quite a good video

Howard Lewis11/06/2021 09:55:05
5733 forum posts
13 photos

I always engage the collet into the nut, before fitting to the arbor. (How else can you do it? )

The collet should be selected to be as close a fit on the cutter as possible.

And as asked, are the cutters sharp?

Remember that if the collet is not tightened sufficiently, the helix on the flutes will try to screw the cutter out of the collet.

Once I had learned to tighten the clamping nut fully, (The ball bearing type help ) I had no more problems with End Mills moving.


Oily Rag11/06/2021 10:27:02
526 forum posts
172 photos

I am surprised that the OP has not noticed bruising of the lower taper on his collets if he has failed to 'snap' the collets into the nut with the nut removed. This is evident where people have failed to follow the correct procedure in fitting the collet to the nut and as a consequence whenever I have seen this the nut and collets are effectively scrapped due to this bruising and distortion of the 'C' snap ring.

I would agree that a quality nut with bearing, such as the Rego-fix Nuts are the best items for use with the ER system. Too many cheap and inaccurate nuts are on the market from 'you know where'!



Vic11/06/2021 12:23:47
3012 forum posts
8 photos

I have never been shown how to fit a collet in the nut. When I first started using them however, just looking at the inside of the nut for the first time made it clear to me that some sort of engagement was required.

Oily Rag11/06/2021 12:38:56
526 forum posts
172 photos


May I suggest that is because you are an 'intuitive' engineer. I think that the first time I came across ER nuts and collets a look at the inside of the nut made it pretty obvious that the collet needed to be seated under the 'C' ring to act as an extractor, no one showed me, I just worked it out - same as you.


andrew lyner12/06/2021 15:52:28
240 forum posts
4 photos

The 'snap' seems to vary from collet to collet and tool to tool.

Tightening the arrangement up with the holder not in the taper means I can sock it all up a lot tighter. I think that was the main cause of my problem. I may invest in a longer handled replacement for the C spanner supplied. AlsoI'll go for a ball bearing version of the Nut - if I can assume compatibility with the two ER25 holders(?).

BTW, I am aware of a fair bit of reaction against the idea of 'liking' posts with a single button press. This is a typical thread where I could well have wanted to give a brief approval to many of the above ideas but that would have involved explicit quotes of nearly all the posts with the resulting ten mile long post which so one would ever bother to read right through.

Sop here's ONE BIG LIKE and I was shouting this!

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Support Our Partners
Eccentric July 5 2018
walker midge
JD Metals
rapid Direct
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest