# ATC ER20 collets not snapping into tool holders **URL:** \ **Category:** General\ **Created:** [June 12, 2025, 11:45pm UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211 "2025-06-12T23:45:41Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Ryks](https://avatars.discourse-cdn.com/v4/letter/r/e9bcb4/32.png) [@Ryks](https://forum.pwncnc.com/u/Ryks)\ **Post date:** [June 12, 2025, 11:45pm UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/1 "2025-06-12T23:45:41Z")
Hello, Forgive me if this is a known issue, but I have not found a similar topic from searching. I use ER collets and tool holders at work, but they are larger than the ER20 tool holders and collets that came with my ATC. The larger collets snap into the tool holders just fine, but I am somehow missing on how to snap the ER20 collets into the tool holders for my ATC…is there a trick to it or do they not snap into the tool holders? Is it the wrench that holds the collet in line in the nut with the axis of the tool holder the key? Thanks, Ryk ---
**Author:** ![Chris](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/chris/32/54_2.png) [@Chris](https://forum.pwncnc.com/u/Chris)\ **Post date:** [June 13, 2025, 12:16am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/2 "2025-06-13T00:16:30Z")
The atc collets don’t snap in. You use the wrenches to snap and unsnap them thru rotation > **[ER Collets - A How-To - PwnCNC](https://support.pwncnc.com/kb/article/253-er-collets-a-how-to/)** ---
**Author:** ![Eriz](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/eriz/32/540_2.png) [@Eriz](https://forum.pwncnc.com/u/Eriz)\ **Post date:** [June 13, 2025, 12:38am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/3 "2025-06-13T00:38:48Z")
@Chris any tips on 1. Determining what is tight enough (not too tight and not too loose). 2. How to remove a collet? My collets never come out, by hand, once I remove the nut. I have to use the wrenches to lever the collet out. ---
**Author:** ![Chris](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/chris/32/54_2.png) [@Chris](https://forum.pwncnc.com/u/Chris)\ **Post date:** [June 13, 2025, 12:45am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/4 "2025-06-13T00:45:12Z")
1. I don’t have torque specs, but i don’t think it can be over tightened by hand unless you’re built like john cena. Don’t try to over do it. You see in the video in the link above when it stops (look at my thumbs), i try more, but its good and doesnt move any more. 2. Put the nut back on and use the wrenches to loosen it. The wrench that is closer to the bit grabs onto the groove in the er20 collets and will pull it out as you loosen it. Just like the traditional nuts (router or spindle), there’s 2 loosening spots when taking it off. The first being the tighten down spot, the second being the collet getting released from the shaft. With atc, the shaft is part of the iso20 tool holder ---
**Author:** ![Aiph5u](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/aiph5u/32/727_2.png) [@Aiph5u](https://forum.pwncnc.com/u/Aiph5u)\ **Post date:** [June 13, 2025, 1:05am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/5 "2025-06-13T01:05:43Z")
Hey Ryks, I don’t know if it’s your first [ER collet](https://forum.onefinitycnc.com/t/metric-collets-for-makita/18428#the-er-collet-1) spindle, but I often heard that some people didn’t know how to mount them correctly. Then they’ll have to know [this (clicking video jumps to the specific explanation inside the video)](https://youtu.be/WKikm6cQKh0?t=778): [![1000000770](https://canada1.discourse-cdn.com/flex011/uploads/pwncnc/original/2X/f/fbcd148c486c9ecce628c5843cf39eb537251ad6.png) ER Collet Essentials. Do You Know? – Haas Automation Tip of the Day - Youtube](https://youtu.be/WKikm6cQKh0?t=778) **[ER collets](https://forum.onefinitycnc.com/t/metric-collets-for-makita/18428#the-er-collet-1) are not mounted the way a trim router collet is mounted.** Most people put the collet into the axle of the spindle and then they put the collet nut over it. **That is definetely wrong!** An ER collet has a groove that goes all the way around near the top of the collet. The corresponding **collet nut** of an ER collet has an excentric extractor ring or offset lip inside. It is absolutely mandatory to fully engage (clip in) the collet inside the nut **before** you tighten it onto the holder, as shown at [this moment of the video “ER Collets | 5 Things to Know for Beginners”](https://www.youtube.com/watch?v=R0tJorTM0BE&t=153s). See also this picture from my spindle manual: ![1000000771](https://canada1.discourse-cdn.com/flex011/uploads/pwncnc/original/2X/8/83c02b400e3d7d0ac88a269f9b5675cf8bd40a80.png) ---
**Author:** ![Chris](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/chris/32/54_2.png) [@Chris](https://forum.pwncnc.com/u/Chris)\ **Post date:** [June 13, 2025, 1:17am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/6 "2025-06-13T01:17:54Z")
This is not how you install them in iso20 tool holders which is what the atc uses. ---
**Author:** ![Aiph5u](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/aiph5u/32/727_2.png) [@Aiph5u](https://forum.pwncnc.com/u/Aiph5u)\ **Post date:** [June 13, 2025, 1:24am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/7 "2025-06-13T01:24:15Z")
Hey Chris, yes I was not sure what the original poster meant. But that my older quoting finds a place here hopefully can do no harm. The spindle I intend to use has more modern [HSK](https://de.wikipedia.org/wiki/Hohlschaftkegel) tool holders, not [ISO](https://de.wikipedia.org/wiki/Steilkegel) tool holders. ![1000001599](https://canada1.discourse-cdn.com/flex011/uploads/pwncnc/original/2X/e/e502ec92eb503b49d0d15ef1fc0ba32c5d3100b3.png) HSK tool holder [Sven Gleich](https://commons.wikimedia.org/wiki/File:DIN_69893_HSK_A63_3drender_1.png), [CC BY-SA 2.5](https://creativecommons.org/licenses/by-sa/2.5), via Wikimedia Commons ![1000001602](https://canada1.discourse-cdn.com/flex011/uploads/pwncnc/original/2X/2/2e3c6a053a175fe38e4a18a592819486ac1d50ba.jpeg) ISO tool holder [Gargoyle888 at the English-language Wikipedia](https://commons.wikimedia.org/wiki/File:1941-G.jpg), [CC BY-SA 3.0](http://creativecommons.org/licenses/by-sa/3.0/), via Wikimedia Commons EDIT: Okay I just had a look at the [the video you linked](https://youtu.be/HOFnpRG19Kk?t=21), so it doesn not seem that the PwnCNC/G-Penny ISO toolholders have [ER collets and nuts](https://forum.onefinitycnc.com/t/metric-collets-for-makita/18428/2#the-er-collet-1). Here I see that it’s also a matter of space. The ISO holders with ER collets are much larger: [![](https://canada1.discourse-cdn.com/flex011/uploads/pwncnc/original/2X/c/cbe483001544988959baa9f1c14dbe49e5a29a0b.jpeg "ER Collet Essentials. Do You Know? – Haas Automation Tip of the Day") ](https://www.youtube.com/watch?v=WKikm6cQKh0&t=38s) ---
**Author:** ![Aiph5u](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/aiph5u/32/727_2.png) [@Aiph5u](https://forum.pwncnc.com/u/Aiph5u)\ **Post date:** [June 13, 2025, 1:59am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/8 "2025-06-13T01:59:43Z")
Hey Ryk, > [@Ryks](#): > > I use ER collets and tool holders at work, but they are larger than the ER20 tool holders and collets that came with my ATC. The larger collets snap into the tool holders just fine, but I am somehow missing on how to snap the ER20 collets into the tool holders for my ATC… So in fact there are not ER collets on these ISO 20 tool holders. ---
**Author:** ![Aiph5u](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/aiph5u/32/727_2.png) [@Aiph5u](https://forum.pwncnc.com/u/Aiph5u)\ **Post date:** [June 13, 2025, 2:31am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/9 "2025-06-13T02:31:23Z")
Hey Chris, by the way → [here the HSK tool holder with ER collet](https://m.youtube.com/watch?v=vB_FvkllLPc&t=248s&pp=2AH4AZACAcoFEVNwaW5kbGUgbWVjaGF0cm9u) that I hope to soon be able to afford ([ATC-8022-HSK25](https://www.spindel-shop.de/en/high-frequency-spindles--Professional-Series/automatic-tool-change-spindle-ATC-Series/Water-Cooled-HF-Spindles--HF-Spindle--HF-Spindles--HF-Spindle--HF-Spindles--Motorspindle--Milling-Spindle--Grinding-Spindle-4-53-54-79-480.html), [available here](https://www.sorotec.de/shop/HF-Spindle-Mechatron-2-2-kW---HSK25----30-000-rpm---230-V---ATC-8022-30-HSK25.html)) [![1000001606](https://canada1.discourse-cdn.com/flex011/uploads/pwncnc/original/2X/6/6ed2ec006b1b69cfd1eb5cd04adf4fa3be7a66e0.png)](https://www.spindel-shop.de/en/high-frequency-spindles--Professional-Series/automatic-tool-change-spindle-ATC-Series/Water-Cooled-HF-Spindles--HF-Spindle--HF-Spindles--HF-Spindle--HF-Spindles--Motorspindle--Milling-Spindle--Grinding-Spindle-4-53-54-79-480.html) ---
**Author:** ![Chris](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/chris/32/54_2.png) [@Chris](https://forum.pwncnc.com/u/Chris)\ **Post date:** [June 13, 2025, 2:45am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/10 "2025-06-13T02:45:18Z")
Kind of… Collets are not included with iso20 tool holders, but iso20 tool holders use er20 sized collets to hold the bit ---
**Author:** ![Aiph5u](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/aiph5u/32/727_2.png) [@Aiph5u](https://forum.pwncnc.com/u/Aiph5u)\ **Post date:** [June 13, 2025, 2:47am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/11 "2025-06-13T02:47:18Z")
You mean they fit, interchangeable? ---
**Author:** ![Chris](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/chris/32/54_2.png) [@Chris](https://forum.pwncnc.com/u/Chris)\ **Post date:** [June 13, 2025, 2:56am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/12 "2025-06-13T02:56:10Z")
Yes, the er20 collets are interchangeable. No other size will work though (er11, er16 ect). There’s no off center ring in the iso 20 tool holder, and the wrench that is closer to the bit goes in the groove that snaps into the off center ring on the traditional spindle nut. I took the 1/8" collet from the link posted above out of my traditional spindle nut, and put it in the tool holder. Here’s a few pics using a 1/2" er20 collet, iso20 tool holder and bit: No off center ring ![1000009439](https://canada1.discourse-cdn.com/flex011/uploads/pwncnc/original/2X/3/37f68c991334c4c5d65a31226023e52623906f16.jpeg) Tried to high light the groove in the collet lining up with the slot on the “nut” ![1000009440](https://canada1.discourse-cdn.com/flex011/uploads/pwncnc/original/2X/6/69e92c5f08686a3f1e373cd0b160132694541bd9.jpeg) The wrench fits in the collet ![1000009441](https://canada1.discourse-cdn.com/flex011/uploads/pwncnc/original/2X/0/04bdc56c244e1dcc67affc2cf03f620b14ce769b.jpeg) The collet won’t fall out of the “nut” with the wrench ![1000009442](https://canada1.discourse-cdn.com/flex011/uploads/pwncnc/original/2X/2/22575976e8fb3a33484f0d5deab34bccc5dfc534.jpeg) All together ![1000009443](https://canada1.discourse-cdn.com/flex011/uploads/pwncnc/original/2X/3/3ab5fddce46bb109885abeebee5886e2b212cc37.jpeg) ---
**Author:** ![Aiph5u](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/aiph5u/32/727_2.png) [@Aiph5u](https://forum.pwncnc.com/u/Aiph5u)\ **Post date:** [June 13, 2025, 3:10am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/13 "2025-06-13T03:10:37Z")
Thank you Chris! Very interesting. I assume the original poster has no questions left 🙂 ---
**Author:** ![Eriz](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/eriz/32/540_2.png) [@Eriz](https://forum.pwncnc.com/u/Eriz)\ **Post date:** [June 13, 2025, 4:32am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/14 "2025-06-13T04:32:38Z")
> [@Chris](#): > > The wrench that is closer to the bit grabs onto the groove in the er20 collets and will pull it out as you loosen it. Thanks for that tip @Chris . As soon as I broke the nut free I was removing the wrench and doing the rest by hand. I just tried your suggested technique and it worked perfectly! ---
**Author:** ![Chris](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/chris/32/54_2.png) [@Chris](https://forum.pwncnc.com/u/Chris)\ **Post date:** [June 13, 2025, 4:41am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/15 "2025-06-13T04:41:46Z")
Youre not the only one. It was a tidbit i had to discover on my own, because i would do the same ---
**Author:** ![Ryks](https://avatars.discourse-cdn.com/v4/letter/r/e9bcb4/32.png) [@Ryks](https://forum.pwncnc.com/u/Ryks)\ **Post date:** [June 13, 2025, 5:22pm UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/16 "2025-06-13T17:22:32Z")
Thanks for all of the information! I feel safer now knowing that this is how they are intended to work. I had worried because one of the first things I learned was how to properly install the collets and it wasn’t working with the ATC collet nuts. I also apparently missed this line on the ER collets video page “If you have an ATC spindle, this does not apply to you, and the video below it does.” Nor did I scroll down to see the second video…Thank you Chris! ---
**Author:** ![QCDvacuum](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/qcdvacuum/32/338_2.png) [@QCDvacuum](https://forum.pwncnc.com/u/QCDvacuum)\ **Post date:** [June 14, 2025, 12:00am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/17 "2025-06-14T00:00:49Z")
> [@Chris](#): > > I don’t have torque specs I use the REGO-FIX Ultra Precision (UP) collets and a castellated REGO-FIX clamping nut on my PwnCNC 2.2kw air-cooled spindle. It is different from the ATC toolholder, which I believe is an ISO20 toolholder. REGO-FIX produced this ER collet system in the 1970s, so I expect that, because they are the originating Swiss Engineers, they have excellent knowledge. Their UP collets demonstrate a TIR value of 5 μm (0.000197"). I have used their torque recommendations, which may be found on pages 163 and 164 of the attached catalogue. ISO 20 collet-holders are mentioned on page 68 of the attached document. They refer back to page 163 for the ft/lbs values and page 164 for the Nm values. Hope this helps. [https://www.dropbox.com/t/9wbSemQvLfdGWMXp](https://www.dropbox.com/t/9wbSemQvLfdGWMXp) ---
**Author:** ![Aiph5u](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/aiph5u/32/727_2.png) [@Aiph5u](https://forum.pwncnc.com/u/Aiph5u)\ **Post date:** [June 14, 2025, 3:12am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/18 "2025-06-14T03:12:46Z")
Hey all, no need for a gated community 🙂, it’s in the [www](https://en.m.wikipedia.org/wiki/World_Wide_Web): > **[ER\_Flyer\_ENG.pdf](https://de.rego-fix.com/system/files/docs/2024-08/ER_Flyer_ENG.pdf)** > > 2.18 MB > **[REGO-FIX\_Main\_Catalogue.pdf](https://de.rego-fix.com/system/files/docs/2020-08/REGO-FIX_Main_Catalogue.pdf)** > > 172.16 KB - [REGO-FIX\_Main\_Catalogue.pdf](https://www.yumpu.com/en/document/download/63820363/f0055-ce19f-046ae-ef85f-48731-04eeb-66a3e-c4a12) (ENGLISH) > **[Download all relevant information now | REGO-FIX](https://de.rego-fix.com/en/media-center/downloads)** ---
**Author:** ![QCDvacuum](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/qcdvacuum/32/338_2.png) [@QCDvacuum](https://forum.pwncnc.com/u/QCDvacuum)\ **Post date:** [June 14, 2025, 11:34am UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/19 "2025-06-14T11:34:01Z")
> [@Aiph5u](#): > > no need for a gated community I could not post a .pdf file. I was unable to do anything with my OCR’d file to make the text searchable. ∴ my Dropbox account was all I could find at the time. 😄 ---
**Author:** ![Aiph5u](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.pwncnc.com/aiph5u/32/727_2.png) [@Aiph5u](https://forum.pwncnc.com/u/Aiph5u)\ **Post date:** [June 14, 2025, 1:52pm UTC](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211/20 "2025-06-14T13:52:13Z")
Sorry, it was not meant as criticism! Rather a joke 🙂 The PDFs are searchable full text, aren’t they? On the phone i use the firefox pdf plugin, on the desktop atril or xpdf [Next page](https://forum.pwncnc.com/t/atc-er20-collets-not-snapping-into-tool-holders/3211.md?page=2)