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Collet Choice

what to and what not to buy

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iain hale 106/01/2022 15:37:37
14 forum posts

Hello there

I have a new AMAVM25L MT3 Mill. I am looking for hep and advice on collet choice.

Currently my thoughts are to go with ER 32 size. with a collect chuck or would the morse taper 3 collets be a better option to (a) save some money not having to buy a chuck.

Or (b) but loose flexibility in changing different size collets

Any advice welcome please



Dave Halford06/01/2022 15:58:17
2006 forum posts
23 photos

Milling cutters come in standard sizes, your machine only needs 4 or 8 (16mm is the largest) if you go both metric and imperial. However they put the head right down on the job and it's hard to see whats going on.

Journeyman06/01/2022 16:02:26
1147 forum posts
230 photos

An ER32 chuck and full set of collets would be ideal offering maximum flexibility but of course can be a bet expensive to get a decent set all in one go. Some suppliers will sell the chuck alone and then you can add individual sizes of collet as needed. On my smaller mill I use ER 25 and leave the chuck pretty well permanently in situ. I use the collet chuck for drilling as well as milling.

Advantage of the MT3 collets is that they don't use any headroom but you will be limited to size choice. That said you can get away with just four for the common shank size cutters 4,6,8 & 10mm. More restrictive if you need larger sizes. Same applies you don't have to buy them all in one go.

MT collets have a very limited range of opening basically just the nominal size. ER collets have a wider opening range .5mm for the smaller sizes and 1mm for the larger this range enables holding tooling with odd size shanks and indeed drills as necessary.


Brian H06/01/2022 16:03:51
2312 forum posts
112 photos

Hello Iain, my recommendation would be the ER32 as you can have every metric size up to 20 mm and a selection of Imperial ones to hold standard end and slot drills.

Just ensure that the holder does not reduce the daylight on your mill by too much


 I was too slow typing so a couple of answers appeared first!

Edited By Brian H on 06/01/2022 16:05:33

Martin Connelly06/01/2022 16:17:37
2123 forum posts
222 photos

Some thoughts.

I have not used morse taper collets but they have a bad press regarding removing them from some types of machine. Ideally if you use morse taper tooling you would want either a slot to allow use of a taper drift or a drawbar that was able to eject the morse taper from the spindle. The bad press is that without the mechanisms for easy removal they can be overtightened in the socket by too much drawbar tension and then they require a lot of effort to remove.

They do allow for more space under the spindle than an ER chuck and may be cheaper if you only use a small number of cutter shank diameters.

If you get a morse taper ER collet chuck it would be easy to put it in the spindle and leave it there then some point in the future find it is very hard to remove as it has not been disturbed for some time.

There is nothing to stop you from using ER32 for most work and having a few morse taper collets in common sizes for when you want a bit move space under the spindle.

Large diameter cutters or fly cutters can have a lot of reaction force on them. The shorter stick out when used with a morse taper collet would probably be better than the longer stick out that would result from using an ER collet. The more rigid a set up the better when making swarf. So if sweeping a large surface with a fly cutter is likely use a morse taper collet, using a Ø5 milling cutter in a morse collet may be hard to see if the spindle nose is over the workpiece.

Martin C

clogs06/01/2022 16:24:37
626 forum posts
12 photos

I bought the ER collet, set ER42?...

they are so useful in both mills and the bigger well spent I'd say.....

Vic06/01/2022 16:53:48
3060 forum posts
8 photos

I bought an ER32 chuck for my lathe. I then bought a chuck for the mill as well. I’ve also got ER32 collet blocks and a Spin indexer so it’s all proved very useful. I did start with a few finger collets for my first mill though as I was short of cash at the time.

MikeK06/01/2022 17:32:53
226 forum posts
17 photos

I have 3MT collets for my 7x mini-lathe. I have used them, but I don't like them. I can't run long stock through them. ER collets with a collet chuck (and not a collet holder) is much better. While my 3MT collets do allow me to get up close to the spindle I don't see that as an advantage and a ER collet chuck would project out no different than my 3- or 4-jaw chucks. And, yes, I have had trouble removing the 3MT collets from the spindle. PITA! I want an ER32 setup like Gadgetbuilder:


John Haine06/01/2022 17:39:18
4623 forum posts
273 photos

It's worth noting that the mill is also available with an R8 taper - some searching here would have suggested that this is a better choice than MT3.

Howard Lewis06/01/2022 18:09:01
6013 forum posts
14 photos

I use ER25 and ER 32 collets in my MT3 mill (Having bought a set of ER25 collets many years prior to the few ER32 ones )

Occasionally, I use MT collets, where headroom is tight, (And I do not wish to move the mill head ) but nearly all the time use the ER collets.

BUT a MT collet can only accommodate one size without risking damage, so to cover Metric and Imperial sizes, you would probably need more than than the number of ER collets that cover the same range..

ER collets have the advantage that one collet can clamp Metric or Imperial tooling of that size (ie a 12, - 13 mm collet will hold 12 mm, 13 mm or 1/2"End Mills / Slot Drills ).,

MT collets can be released from the spindle by slackening the drawbar half a turn to one turn and tapping the drawbar with a mallet. (Or you can do what i did and make an extractor to push the drawarbar so that there is no shock load to the bearings ).

Both systems have their advantages. Forced to choose only one system, ER would be my choice.


MikeK06/01/2022 19:22:21
226 forum posts
17 photos

Sorry, I missed that the OP has a mill, not a lathe.

Richard Millington06/01/2022 19:52:26
61 forum posts
4 photos

I have an ER32 collet set, a Clarkson type chuck and MT collets with my mill.

ER32 - most versatile, can be used with any type of cutter or drill bit (threaded shank or plain).

Clarkson type - most secure tool holding but you need screwed shank cutters in either metric or imperial to suit your collets.

MT collets - best for height, but are not as flexible on sizing as ER collets. i.e. the shank needs to be suited for the collet size.

If you want to take heavy cuts get the Clarkson type, if you want flexibility get the ER, personally unless you have height issues I wouldn't bother with the MT collets.

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