milling chuck

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milling chuck

This topic has 21 replies, 11 voices, and was last updated 30 July 2025 at 20:18 by bernard towers.

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28 July 2025 at 18:22 #809524
moonman
Participant
@moonman
I have a Chester Champion 16 mill which I’m going over and getting right, I’ve had it while but now I’ve got the basics down I’m trying to iron out inaccuracies where I can.

One such inaccuracy is the chuck, it’s a china special MT2 ER32. I wish to replace this with a better one as the current one had a whopping 0.08mm of runout which is less than ideal. On the spindle I cannot see any runout at all thankfully.

Can anyone recommend a good brand for such a thing? Warco/RDG/Chester all seem out of stock or only sell these things in kit form. I already have a decent set of ER32 collets so I would like to stick with this size if I can.

Or shall I really go with ER25 and step down a size. I’m a bit reluctant to do this as many of the tools I’ve made for this mill were built on 20mm shanks…

Thank you
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28 July 2025 at 20:01 #809531
bernard towers
Participant
@bernardtowers37738
A two piece one may be the way to go as you can adjust it. ER25 goes up to 20mm with oversize collets
28 July 2025 at 22:49 #809546
Huub
Participant
@huub
The runout can come from the ER32 collet. Also check the collet holder for runout.

A burr or some swarf can give a huge runout. Check the boring of the spindle and collet holder.

You probably do know how to install the collet in the chuck. If not, have a look at this video.

My three collet/spindle sets all came from a local (Dutch and German) supplier and are within spec. None of the collet and collet holders I ordered from AliExpress or Amazon where any good, even the expensive ones.

As I use the collets on the lathe, mill and rotary table, I have ER32 for standard. The CNC router uses ER16 and the brush less drill for the lathe ER11.

The oversized ER11 collets I have, can be difficult to remove.
29 July 2025 at 00:14 #809551
moonman
Participant
@moonman
The collets are fine, they run with 0.02mm of runout in my collet chuck on my lathe.

The chuck in my mill was a £15 amazon special to get me going. I do not trust it so I was hoping a better alternative would exist.
29 July 2025 at 05:53 #809560
Diogenes
Participant
@diogenes
https://rdbarrett.co.uk/product/morse-taper-er-collet-chucks-by-bison/
29 July 2025 at 06:55 #809562
David George 1
Participant
@davidgeorge1
I also have a Chester Champion 16 mill. I have no problems with run out on the collets and as my lathe has a MT2 spindle taper the collet set also runns true in there as well. I did have problems once and found that small pieces of swarf had contaminated the spindle taper bore by using some engineers blue on the taper of the collet set. Because the draw bar is retained I found it difficult to clean and check the bore I made a wooden tapered piece which has a hole in the end to allow the screw to go down the middle and have used it to clean out the morse taper to remove any swarfe or bits up there. It is only ocasionaly I have a problem but when I have the foreign body sticks to the wood stick and can be removed easily.

It only takes a moment to clean the bore with the tapered wood piece.

David
29 July 2025 at 07:55 #809566
DC31k
Participant
@dc31k
CTC Tools, based in Hong Kong, sell what might be called ‘curated’ Chinese offerings.
29 July 2025 at 09:01 #809572
bernard towers
Participant
@bernardtowers37738
plus one for that David i do that but its surprising the number of people who do not have one!
29 July 2025 at 11:17 #809578
Howard Lewis
Participant
@howardlewis46836
If you look at the Arc Euro website there is a statement of run out of 0.008 mm.

The run out will be influenced by the torque (Force applied to the tapers) by the clamp nut, improving as the torque increases.

It might be worth checking that all the tapers in chuck and collet are clean, and then measure the run out with maximum torque applied to the clamp nut.

Howard
29 July 2025 at 11:24 #809579
Vic
Participant
@vic
If you know anyone with a 3D printer, these work very well. A guy at one of my clubs sells them for a pound each I think.
29 July 2025 at 11:38 #809583
Vic
Participant
@vic
I forgot to say, I’ve never checked the runout on my chuck so it could well be out? I think I bought it from ARC many years ago so maybe it’s a good one. The collets were pretty cheap so I doubt they’re amazingly accurate. I’ve not noticed any issues though on my Warco VMC. I suppose maybe it cuts over size on things like slots but I generally sneak up on it with a smaller cutter so not noticed it. Anything else I should look out for?
29 July 2025 at 18:10 #809666
moonman
Participant
@moonman
Thanks for the info chaps on cleaning, I do have a 3D printer and will be printing a few of those. What a good idea, as is the wood alternative.

I am 100% confident though that the chuck I have now is the cause of the runout. It is visibly out as soon as you chuck something up in the collets, it was a long 6mm end mill which made me finally check it so it’s getting replaced. No amount of cleaning has altered anything.

I do have another chuck that came with the mill, it’s a Q24 16 collet system but it seems to be some sort of proprietary system so the collets are not available anywhere and there is very big gaps in the sizes so I want to go back to ER. This chuck results in 0.04mm of runout so it seems like a good one.
29 July 2025 at 18:18 #809667
bernard towers
Participant
@bernardtowers37738
Cant you re-turn the taper to make it true. I have made several ER collet holders in the past and some run to zeros but not all of them but they are all closer than that.
29 July 2025 at 18:20 #809668
JasonB
Moderator
@jasonb
I would not have said 0.04mm is particularly good, I can get a lot better than that. SIEG X3 with a Chronos MT3 x ER32 chuck and an ARC collet.
29 July 2025 at 20:49 #809699
moonman
Participant
@moonman
Yes I’m not blown away by 0.04mm either, hence asking for recommendations on a new collet chuck.

I want to replace it, not fix the one I have and it’s not a cleaning issue. It’s just cheap chinese tat.
29 July 2025 at 20:55 #809701
Diogenes
Participant
@diogenes
I like the Bison one I have.
29 July 2025 at 21:05 #809704
Wink Hackman
Participant
@winkhackman25989
Rotagrip have the Bison ER25 chuck.
29 July 2025 at 22:44 #809716
bernard towers
Participant
@bernardtowers37738
seems a shame not try to rectify the problem before spending money.
30 July 2025 at 15:45 #809802
Oily Rag
Participant
@oilyrag
Have you looked at a Rego-Fix collet chuck?
30 July 2025 at 15:53 #809805
moonman
Participant
@moonman
I took advantage of the ARC 40% off deal last night and got a ER25 chuck with some included collets, it advertises at 0.008mm of runout so we shall see although looking at reviews I doubt it will be a problem.

I will be ordering other collets too so I have the full set and an oversized 20mm one for the rest of my ER32 tooling.

I shall report back with thoughts and reviews.

@Bernard Towers – I could have tried to fix it but ultimately this was a £11 bit and I don’t have the tooling to do accurate grinding. If I had the ability to do that I would go and make one as that would be a nice project but I’d rather just get the right gear and crack on with stuff I know I can do.

Right now my grinding jig is a dremel with a 3D printed mount on my lathe. It’s just not going to give the accuracy needed.
30 July 2025 at 19:10 #809839
bernard towers
Participant
@bernardtowers37738
You dont need to grind the ER taper just use a polished insert.
30 July 2025 at 20:18 #809861
bernard towers
Participant
@bernardtowers37738
Just to add your last paragraph says it all dremel for precision grinding??? and 3d printed mount???. Good quality turning is going to beat that every time
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