Looking for an MT2 Milling Chuck.

Which is the best type of milling chuck with an MT2 taper? I am looking at the Chronos, Vertex, Posilock type. I have used the Posilock type before and I rather like them.

The other alternative is one from Arc which takes ER20 collets. I don't know a thing about the ER collets, so I don't know which type hold best.

I want a selection of both Metric and Imperial collets in common sizes. The Vertex chuck has 4 of each. The Arc chuck has only metric collets with another set to "fill the gaps". Can I use imperial size milling cutters in the metric collets, as I understand (perhaps wrongly) that ER collets have a wider gripping range than the posilock type collets.

Any help gladly received.

Andrew.

Hi Andrew,

ER collets will have a wider gripping range than the Posilock type (cutter should fit well in the collet). If you want a Posilock chuck you will need cutters with a thread at the end of the shank, ER collets will grip cutters with or without a thread. I use ER collets not just to hold cutters but also to hold work, and I am very satisfied with the ER chucks I have.

Thor

The ER collets have a good range of squish. Eg: You could hold a 1/4" (6.35mm) endmill in a 7mm collet (works 6-7mm).

Posilock needs a threaded shanked cutter to work. ER can take smooth or threaded shanks which allows carbide tools and cheaper cutters in general.

Also get 1/2 price on arceruo ER vs Chronos Posilock which would give you a good selection of cutters for the difference.

As a last thing you can use ER collets for workholding on the lathe as well.

If you do go down the ER route then I would suggest getting the Imperial size ER collets for the common shank sizes you use, its easier to tighten them with out a third hand and takes less effort than closing a metric one down to the lower end of it's size range.

There are a lot more cutters about with plain or Weldon shanks than there are screwed shanks so it gives you a better choice. Also can be used to hole drills, reamers etc and with thinks like ER blocks you can hold and index work in the mill.

Hm Seems that the posilock gets the thumbs down!

Rainbows where on earth did you get Arc Euro as half the price of the Chronos Vertex chuck? last time I looked the Vertex was priced at £79 with 4 of each of the common Imperial and metric colletts. I think the Arc Eurotrade was 80 odd pound with about 8 to 10 of the metric collets. Am I missing some superdeal here?

Most of my milling cutters are threaded, so the posilock chuck is attractive. If the thread isn't present on the cutter then I assume the posilock system won't hold as well as the ER collets? For the life of me I can't see there being much difference and if the thread is present then the posilock would be much better. Now tell me why I am wrong again!

Andrew.

Do you need a specific milling chuck? In MT2 you won't be holding cutters bigger than 1/2" / 13mm, and probably only in a small range of shank sizes - 1/4, 3/8, 1/2; 5, 6, 8, 10 mm. You could use buy a set of 7 or 8 MT2 drawbar collets for ~£50 - £60 from Arc and gain useful extra daylight under your milling head.

A chuck designed for threaded shank cutters will not work with a plain shank cutter as it relies on the thread to tighten the collet. I suspect the days of the threaded shank cutters are numbered as the ER type are very effective and efficiently hold both types of cutter. A threaded shank is sure to add a premium to the price as time goes on. I have the option of both types but ER is the chuck that I use most. As previously mentioned it is useful for work holding in the lathe and even if you need a different chuck mounting, the collets are interchangeable as long as you use the same series

Mike

Another advantage is ER gives you more daylight. I use ER25 with a full metric (except very tiny sizes) set + 1/4" and 1/2", 3/8" cutters are fine in the 10mm collet.

I also have had an Osborne Titanic II which is polsilock compatible for several years but I hardly use it and still haven't got round to buying metric collets which tells its own story.

Neil

I bought a Posilock type chuck not long after I bought my mill, but now I would buy an ER one, it would hold any cutter threaded or not, where as the Posilock will only hold threaded end cutters. The Posilock chuck is fairly long, reducing the space under it, and that's small enough as it is.

My reason for buying a proper milling chuck, I tried using the Jacobs chuck supplied with the mill, and of course it fell out.

Ian S C

Thanks everyone,

Looks like Arc are going to get my order for the ER20 collet chuck. Thanks everyone for being so helpful!

Regards,

Andrew.

Hello Andrew, I would go for the ER25 if it is not too large, you could then go up to a shank of 16mm. ER20 will restrict you to 13mm.

+1 for Michael's suggestion; I have the ER25 set with collets from 1.5 mm to 16 mm + some imperial collets from 1/8" to 3/8" & a couple of times I'd thought 'could have done with ER32 set for the extra capacity to 20mm but I have a two insert tip cutter which covers up to 19mm so I can make do. so it's ER collets for me.

George.

ER collets can also hold drill bits, so there is no need to change to the Jacobs chuck for drilling.

Brian

I have never had a drill slip in an ER collet, 3 jaw drill chucks are a different matter.

Martin C

Have used ER collets for both work and tool holding. (Milling and turning)

Started many years ago with a set of metric ER25 collets, in a 2MT holder. (ER25 will hold upto 16mm)

The 1mm "squash" range is SO useful.

Now use ER20, ER25 and ER32 for all sorts of jobs; in some cases making my own holders.

As you may gather, ER gets my vote.

Howard

If you're not in a rush have a look at BangGood for collets and chucks. I've been pleased with mine.

But that would mean I would have to learn something for imperial. (Awkward)

So what size would I need for a 10mm cutter? that would seem like a pretty obscure fraction to go to something like 10.20 or so say, to make it easy to use. 3/8" at 9.55 wouldn't cut it.

I probably just don't understand it or used to it. Metric just seems easier to match up to me, even if it means I need 0.5 graduations for some sizes.

Michael W

If you buy 16mm, 1/2", 12mm, 10mm and 1/4" collets, you can accommodate 16mm, 5/8", 1/2", 12mm, 10mm, 3/8", 1/4" and 6mm diameter end-mills and never have to tighten them more than 0.5mm.

Jon

My ER32 collets are laid out in a drawer facing up. I don't even look at the size, just pick one that is the closest fit to the tool.

I must do the same for the ER11 collets for the toolpost grinder.

If you took 3/8" to mean the upper limit of the collet, then a 10mm shank would be bell mouthing a 9.55mm collet.

and then if you took the next size in your list up, 1/2" would be 2.7mm too big.

So if you see what I mean, you've got a sizeable gap there (for imperial sizes).

Edited By Michael-w on 02/10/2017 18:45:06