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?
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.
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
ER collets 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” . See also this picture from my spindle manual:
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
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!
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!
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.
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.
