Collet Nut - Any Update?

Is there any update on when we can buy extra collet nuts for the XCP?

Reading the forums it is pretty clear the nut labeled ER16A is not the same as all the nuts available on Amazon. (The threads are not the same.)

Its this one… the standard er16a collet nut is m19 thread size which is why i had reccomended the wrong size to start on that other thread (its now updated with all the bad links removed and my first reply edited to clarify the issue and the correct size btw) …

BUT it turns out the spindle used on the XCP uses a m22x1.5 thread for some odd reason…

Heres a link to the proper nut, i didnt see any m22x1.5 er16a on amazon…

Where ever you do buy it from, make sure its described as m22x1.5 thread…

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I revised my search term over on Amazon and found one listing with only one left in stock for a little cheaper… and it specifies the m22x1.5 threads

I think those (M22-1.5) are pretty standard. On the original thread :joy:, the threads for the XCP spindle looked to be more fine (M19-1?)
Did Inventables confirm the thread spec?

The whole thing is pretty frustrating. I followed your link and Amazon says I already bought that nut. The nut I got only says ER16 and it is definitely too big. My spindle measures 18.9 mm across the threads.

Is it possible there are two kinds of spindles being supplied?

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Look for M19-1, but did support get back to you?

EDIT: Well, it says right on the thing! That picture would’ve helped. :wink:
I’d check ebay or aliexpress


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. But keep that in mind for the below.

Thought I’d try to clear up some of the confusion here (key word being TRY).

There are 3 main ER nut types that I’m aware of (not including through coolant versions):

These are normally used on spindles and have a standard hex wrench.
For ER16:
OD: ~28mm
Thread M22x1.5

Used in some spindles but mostly for toolholders and use a castle or slotted wrench.
For ER16:
OD: ~22mm
Thread M19x1

E/Slotted (yes again)
There are typically only used for larger systems and I’ve never seen one for ER16.

The above are the correct specs (OD variable) for the different types. While I have seen some hex style with “M” threading they aren’t really standard in the industry.

If you want to go back to the source you can look at REGO-FIX (the R in ER collet). Though I don’t believe they sell anything with a hex style anymore, you can see the nut and thread types (Landing, Standard nut, Mini nut)

One other thing to be aware of when looking for these. Make sure that you are getting balanced nuts. A lot of the cheaper ones either aren’t or are very poorly balanced and can cause issues with the spindle bearings over time. You will typically see 2 types of balancing given. Either balanced to X RPM or balanced to GX for/at X RPM. Balanced to X RPM is basically saying that the company selling it to you thinks it good to that RPM. GX at/for is a ISO spec for that much error at that RPM.

If there’s anything I can help with let me know.

I was finally able to get an ER-16m nut (yes it is castle style) with the 19x1 thread pitch off of Amazon.

Not sure if this link will work for everyone, but here’s what I bought:

Too bad the wrench I bought is completely the wrong size. Doh!


I bought these and they fit just fine.

I ordered these, and they turned out to be 22x1.5, not 19x1. They did not work with my XCP. I’m waiting on a direct-from-china nut that had 19x1 stamped in the photo.

It’s important to be clear, because apparently Inventables is shipping two different sized spindles.

I bought those too, but what they sent was wrong, so I let them know the description didn’t match the product. I’m glad they got things sorted out for you.

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