# ER Collets: What's the Difference?



## wrmiller

What's the difference between the different numbers on collet sets, e.g. er20, 40, etc.?

Looking at these as a possible upgrade from R8.


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## Terrywerm

As far as I know, the size is determined by the OD of the collet at its largest point. So an ER32 collet will have a 32mm OD.  You get the picture.


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## Ulma Doctor

to add to Terry's comment,
the larger collet system you get the larger tooling you can use here's a link for a chart of different sizes
i have no connection to this manufacturer or it's distributors


http://www.techniksusa.com/metal/cnaerpci.htm


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## darkzero

The size is not actually the OD of the collet at the largest point, more like a nominal size. If you measure one it will be oversize. Perhaps they may measure on point when compressed to their nominal range. ER collets have a clamping range of .039mm/1mm, much wider than R8, 5C, etc.

Ultimately it's the max tool size that will base your decision on which size to buy. I have heard that the larger sizes don't hold smaller sizes too well, ie ER40 won't hold 1/8" shanks well, etc. Not sure of the truth in that but I use ER40 for 3/8" - 1" & ER16 for 3/8" & smaller. I like the ER16 for tighter areas where the ER40 won't fit with a smaller endmill. ER32 (max 3/4") is a good all around size for our size mills.

Technicks make the best quality ER collets you will find for an import & are all I use. Made in Taiwan. Hemly Tool & All Industrial on ebay have the best prices on them. Nemic tools has them cheaper so if buying a few at a time that's the place place to buy. ER collets were designed by Rego Fix & are the most used collet system worldwide. I have heard Glacern ER chucks are made by Rego Fix but I'm not sure of the truth in that. I do know they are very high quality though. For the mill I have an ER16 chuck from Glacern & I have 2 ER40 chucks from Bison/TMX.









And I also use ER40 & ER16 on the lathe.


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## Terrywerm

Thanks for the clarification, Will. I was basing my thought on the dimensions I have for some ER collet chuck plans. On those, the largest diameter of the taper matches the 'series' number (32mm for ER32, 16mm for ER16, etc), and the largest diameter of the compressed collet would then be the same also, or at least very close to that.


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## wrmiller

Thanks for the info guys (and the pics Will, very nice).

For those that do use them, how often do you run into clearance issues when up close to a part/vise/chuck? Reason I ask is I remember setting up tooling for my friends CNC and noticing rub marks (and worse) on some of the collet chucks where they've banged into stuff.

I can see one advantage though: Yesterday when I was doing my first cutting on my new mill I was having to move around quite a bit to see under the head and around the quill stop (or whatever you call that thing). A collet chuck would get the cutter down a bit further from the spindle so I could see it easier. 

I would only worry about being so far from the spindle bearings if I was taking heavy cuts, but then if I have to do that I could buy a regular NT30 tool holder.

Every time I turn around there's more stuff that needs buying...  ondering:


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## drs23

wrmiller19 said:


> What's the difference between the different numbers on collet sets, e.g. er20, 40, etc.?
> 
> *Looking at these as a possible upgrade from R8.*



Why would these be considered an upgrade? I ask because I got a complete set when I bought my mill. I've used them and much prefer the R8s. My brief experience left me unimpressed and wondering what the positive points might be. I found them to be somewhat cumbersome and as you mentioned I was unable to get close enough to my work piece at the time (2 x 3 aluminum angle). I realize I'm really green relative to many here but I've yet to have any issues with the R8s so why is it an "upgrade"?


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## LEEQ

One of the reasons I like them is using one set of collets for a lot of things. I have an r8 chuck, an mt2 chuck and a plate chuck like Dark Zero. I can use one set of collets in my lathe headstock with the ability to pass material/tools through the spindle and chuck,in the lathe tailstock, in my rotary table, and in my mill. That's pretty versatile. They are supposed to have less runout than r8 collets. I believe they have more holding power also. I bought a metric set of er collets that holds anything from it's lowest size to it's highest without any gaps in collets which is nicer than standard inch sizes that have gaps in the sets. I have some metric tooling projects and don't have to buy metric r8 collets that would only be useful in the mill. I can also swap mills/drills ect in the mill without climbing my short rear up on a step stool to fool with the draw bar. Within it's range, I don't have to swap out to a drill chuck to hold drill bits. That's what I can think of right off. I want to get  a little set to complement my er40's, but that has to wait. Edit I forgot, I have no lack of vertical room on my Bridgeport to fight, and my chuck is scarcely bigger than my spindle, so no clearance issues for me. Those with mini mills would lose clearance in the Z using er chucks vs collets that fit inside the spindle.)


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## LEEQ

darkzero said:


> The size is not actually the OD of the collet at the largest point, more like a nominal size. If you measure one it will be oversize. Perhaps they may measure on point when compressed to their nominal range. ER collets have a clamping range of .039mm/1mm, much wider than R8, 5C, etc.
> 
> Ultimately it's the max tool size that will base your decision on which size to buy. I have heard that the larger sizes don't hold smaller sizes too well, ie ER40 won't hold 1/8" shanks well, etc. Not sure of the truth in that but I use ER40 for 3/8" - 1" & ER16 for 3/8" & smaller. I like the ER16 for tighter areas where the ER40 won't fit with a smaller endmill. ER32 (max 3/4") is a good all around size for our size mills.
> 
> Technicks make the best quality ER collets you will find for an import & are all I use. Made in Taiwan. Hemly Tool & All Industrial on ebay have the best prices on them. Nemic tools has them cheaper so if buying a few at a time that's the place place to buy. ER collets were designed by Rego Fix & are the most used collet system worldwide. I have heard Glacern ER chucks are made by Rego Fix but I'm not sure of the truth in that. I do know they are very high quality though. For the mill I have an ER16 chuck from Glacern & I have 2 ER40 chucks from Bison/TMX.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> And I also use ER40 & ER16 on the lathe.



Holding that little chuck in the big one is just cheating, I like)


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## darkzero

LEEQ said:


> Holding that little chuck in the big one is just cheating, I like)



Haha. Originally I had planned on doing that for small stuff but I don't. I scored that ER16 extension chuck for cheap, it's Lyndex with the Lyndex ball bearing nut (I also use them on my ER40 chucks) so I just couldn't pass it up.

I use DA collets in the chuck when I need to work on small stuff, it's much quicker. I do have the collet chuck for the DAs also but I never use it since I use the collets for work holding & not tool holding. The DA collets clamp just like the ER, across the full range of the collet but I haven't had a problem with gripping short pieces.






This was back on my mini lathe lathe with a 5" Bison but I do the same on my current lathe.


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## darkzero

LEEQ said:


> One of the reasons I like them is using one set of collets for a lot of things. I have an r8 chuck, an mt2 chuck and a plate chuck like Dark Zero. I can use one set of collets in my lathe headstock with the ability to pass material/tools through the spindle and chuck,in the lathe tailstock, in my rotary table, and in my mill. That's pretty versatile. They are supposed to have less runout than r8 collets. I believe they have more holding power also. I bought a metric set of er collets that holds anything from it's lowest size to it's highest without any gaps in collets which is nicer than standard inch sizes that have gaps in the sets. I have some metric tooling projects and don't have to buy metric r8 collets that would only be useful in the mill. I can also swap mills/drills ect in the mill without climbing my short rear up on a step stool to fool with the draw bar. Within it's range, I don't have to swap out to a drill chuck to hold drill bits. That's what I can think of right off. I want to get  a little set to complement my er40's, but that has to wait. Edit I forgot, I have no lack of vertical room on my Bridgeport to fight, and my chuck is scarcely bigger than my spindle, so no clearance issues for me. Those with mini mills would lose clearance in the Z using er chucks vs collets that fit inside the spindle.)



Agreed. 

I use my same ER collets I use on my mill for tool holding to use for workholding in the lathe. ER collets clamp across the full length of the collet where R8 grips only at the front like 5C. The advantage of this is better concentricity & more gripping strength. To give you an idea, ER40 are recommended to be torqued to 130ft/lbs. The disadvantage because they clamp along the full length of the collet, they not as great for gripping short pieces like 5C would but that can be remedied but inserting a piece of stock behind it. They were really intended for tool holding anyway. I really haven't had a problem with this but I sometimes do this to use the stock as a depth stop or to make sure a short piece is nicely squared in the collet. ER collets also have a wider clamping range of .039"/1mm. (I feel dejavu, I've said this recently somewhere...)

Big deal you say, well I would agree to that too. Many of us don't "need" the higher clamping force & don't have run out issues with R8 collets, especially hobbyists like me. I know I sure don't & I know I don't torque my ER40 collets to 130 ft/lbs. And with R8, generally our endmills and other tools' shanks are right on diameter so they fit nicely in R8 collets. But ERs do run more true, every little bit counts.

Like Bill mentioned earlier, I don't like using R8 collets & having to drop my head (I have a square column mill) so low to the work, it makes viewing & measuring the work piece harder. Yes you could always lower the quill but my quill is not as strong as a BP or larger mills. I keep my quill as short as possible when I can. I don't have chatter issues with the extension of an ER chuck either, not for anything I have done yet. I actually like the extension of the chuck. And when I use my super spacer, the ER16 chuck allows me to get up close to the chuck, R8 will give me more interference issues, I could probably work around it but I prefer the setup I use now.

I can also hold 1" shanks with my ER40 chucks. Not need on my size mill but I can, my 1" APKT endmill should be here any day now. Not sure if all ER chucks are like this but with my Bison & Glacern ER chucks, they have a screw on the inside that is used as a depth stop. This makes them "indexable". Break an endmill during an operation, I could swap out the broken one for another exact replacement if on hand & continue milling, no reindicating required.

After using ER collets for a while, I prefer them over R8s. I can't  convince you that they are better than R8 collets, not my intention  & there is nothing wrong with R8 collets. I won't even say they are  an upgrade but I think they are better in more ways & is just my personal preference, just a different tool to use.


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## Brian Hutchings

I've gone over to ER32 collets because I bought an Alexanda T&C grinder and that came with an ER32 holder as will as an R8 but my bench mill also uses ER32's and I have the metric set. I have also bought some inch collets because they sometimes fit stock and tools better.
I've just bought an ER32 holder for my lathe as it was a cheap option but I may upgrade to a spindle nose ER32 fitting as my 3-jaw chuck is getting past it.
Brian


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