Source for good quality ER11 collets

I’ve been buying ER-11 collets and tools from Maritool and have been quite pleased w/ the quality.

The Precise Bits folks offer several different precision grades, allowing one to settle in at a price one finds workable:


Love that they list the Tolerance Grade! Sweet. Thanks for the info.


That link is very helpful. I knew that I wanted to spend a little more but I have never looked closely at ER collets. Their collet selection tutorial is very informative.


It’s also worth buying a spare collet nut or two whilst you’re there.

The Aliexpress collet nuts are, shall we say, variable quality, even if you buy from the good vendors. Beware that you need to buy properly balanced nuts, those at precisebits seem to meet the spec. They might seem a little expensive buy the cheap AliExpress ‘balanced’ nuts about 1 in 5 is usable in my experience.


I will note that one thing I’m considering, if I ever get enough metric tooling to make it worthwhile is to use a different sort of nut for the metric collets vice the Imperial ones — it’s rather indulgent, but every little bit helps.

There’s some discussion of this on this thread. Make sure that the nuts are balanced for 24,000 RPM (Precise Bits aren’t).

Would that help? I live in the metric part of the world, and most of my tools are metric. I bought a set of ER11 metric collets from Aliexpress, but I’m using the standard nut supplied with the Nomad. Are nuts for metric and imperial collets different?

BTW, I noticed that the ER11 collets I bought do not support the bits on the rear end, like the collet shipped with the Nomad does. Should I look for better ones?

It would help my OCD and help assuage my concern that I’ll mix them up — that said, ER collets have a pretty wide clamping range, so usually one can use the nearest other size tooling in them, but I’m finally at a point in my life were I don’t have to make too many compromises.

That said, it’s mostly an idle whim since I haven’t found any metric tooling I’m inclined to purchase/use other than 8mm shank.

For the clamping shaft length consideration I’ll yield to folks who are more knowledgeable and experienced (though I have a suspicion).

As a European, I tend to get annoyed whenever I encounter imperial units, but I have to admit that it’s much nicer to have one 1/8" collet and one 1/4" collet rather than the entire metric collection of 14 collets. So much nicer that I started buying metric tools with a 1/4" shank, just to make tool changes quicker.

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Uh, I’m going to just leave this picture here:

(yes, I did buy a complete set of metric endmills for my Carbide Compact Router, and I also got the 3/16" and 5/16" (8mm) as well)

That said, I still haven’t picked up the 3/16" cove radius endmill I’ve been wanting (mostly because I’ve pretty much switched over to ER collets in the awesome ER collet Carbide Compact Router I’ve been testing) — also didn’t get any metric collets for the Mafell aside from the 6mm which was described as 1/4" but isn’t — fortunately, a forum user was kind enough to hook me up, just need to do some test cutting sometime soon so as to settle up. I still wish there was a better variety of 3/16" tooling.

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I just have a few metric collets and a few imperial collets, and I bought a nut for each one, and keep them organized like this:


And the files are up on Thingiverse if you have a 3D printer.


I think I will eventually get a nut for each collet but that’s a little more than I want to spend right now. I like that holder though and will use it when it comes time.

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Thanks for the heads up, I was going to get some from Precise Bits but ended up getting a couple from Techniks.

That’s just nuts.

Not sorry :wink:

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No, no… There’s collects and wrenches too. :grinning:

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You can buy good ones out of China - you just need to know where to shop.

Aliexpress has some good stuff, and a whole lot of crap.

With ER collets, they have three grades, get the AAA ones - like from this link:

There are certainly cheaper ones about - but they’ll have a dubious pedigree.

Search aliexpress for “ER11 collet 0.005” and then try “ER11 collet 0.008” and you’ll see two of the quality levels

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I doubt that you’ll be disappointed, but if you are, Amazon returns are usually free and easy! But, you should make sure that your runout isn’t a result of your spindle mounting.

I never bothered to check anything else. You can see the shaft move in and out of the router body when you push on it. I’m not terribly annoyed since I was always going to switch to a spindle anyway. Now I am just doing it sooner.

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I normally don’t have the time anymore to hang around the forums but this thread came up in our domain notifications and there’s just too many things I want to say to not post.

Quick preface: I work for Think & Tinker (PreciseBits) so I’m biased about everything. I try to keep the information I post brand agnostic and as general use as I can (other than when addressing specifically things about us). But keep that in mind for the below.

Thanks for the link and mentioning us. Wouldn’t have seen this without it.

Thanks. We actually measure at 2 points in the tolerance spec (face and 1”). More details in the tutorial for collet selection.

Be careful if you do this that you are getting the right nuts. There are 3 “standard” designs. They all take the same ER collets but they have different threads and spanners.

ER11 thread M14x0.75
Typically 17mm hex wrench

ER11 thread M13x0.75
Castle or slotted wrench

Never seen this type for ER11

This gets into an issue of empirical vs marketing spec.

Short version:
Anytime you see someone list a balance spec of GX at/for X RPM this is a ISO 1940-1 spec. It doesn’t mean that it’s only balanced for use up to that specific RPM. Balanced to 100KRPM with no other spec means functionally nothing. EVERYTHING can be called balanced to a million RPM at some absurd error level. Well, assuming it stays in one piece I guess…

Long version:
GX at/for X RPM is, as stated earlier from the ISO 1940-1 (although I believe it’s been revised to a new version). As an example if you have G2.5 at 20KRPM this is also ~G6.3 at 70KRPM. This is due to the fact that it is based on the same static with a base permissible residual unbalance in Not going to post it, but a .mil may have put online the entire 1940-1 spec with the table in it if one were to google for it.

What spec you need can’t really be determined by this alone as it also depends on the dynamic load that the bearings can take, tool mass, etc. I can tell you that the G2.5 at 20KRPM is the spec regularly used in Colombo 40K spindles for their collets and toolholders. So that should give you some baseline.

The “official” minimum length by DIN standard is 4x the diameter if I remember correctly.

In most cases the reason you see a counterbore in the back of the collet is to help with manufacturing tolerance. The longer you bore a small hole the more likely it will move off center. So ideally we would have a perfect bore with no counter bore all the way though the collet. But functionally you are picking between more accurate collets or a longer bore.

If you do get a nut for each collet make sure that you take them apart and clean them or at the very least blow them out after changing tools. If you don’t then you may not get the accuracy out of them as debris stuck in either taper (spindle side and nut side) can force it off center. Not to mention grind away at your precision ground surfaces if it’s abrasive.

Not to be pedantic but runout is specifically a rotational error. So you can’t get it from mounting issues. You can get other errors from mounting like movement, orthogonality, etc.

One last thing to watch for if you are specifically looking for high precision collets. Most TIR specs are listed as “typical”. This means that they could have more or less TIR than listed. They are usually done with either an average of a number of the batch (e.g. average TIR of 10 out of a batch of a 100) or AQL (e.g. less than X spec failures in X percentage measured of the batch). I only know of 3 companies that measure the actual collets that you receive Us, Techniks’ UP grade, and REGO-FIX. There are probably more but those are the ones I’m aware of. To make it extra fun we all use different measurement standards. As mentioned, I’m biased so I won’t comment on what ones I think are better.

Hopefully that’s helpful and doesn’t come off as “marketing”, advertising, or defensive. If there’s anything I can help with or answer let me know.


I’m pretty sensitive to people pretending to not be marketing their products, while doing that exact thing, and I did not get that feeling from reading your post. It was good info as far as I am concerned.