ER Collets: What's the Difference?

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.
 
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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