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ER Collets

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  • ER Collets

    Does anyone on the forum use ER collets in their mill? I have been considering purchasing a set of ER32's for my R8 spindle vertical mill to eliminate jacking with the draw bar so often and it would give greater working distance over the table. Right now I am using a keyless chuck for drills and reamers but it eats up so much working space. Am I correct in assuming that they will securely grip anything ( drills, endmills, reamers) within their capacity.

  • #2
    Yep.. I use an ER40 collet set myself and it was well worth the investment.

    Yep. They will securely grip anything within thier collapsing range and TIR is essentially non existant too.


    • #3
      Just how large of a shank will fit into the largest ER40 and how much hang down is there below the spindle assuming that you have an R8?


      • #4
        You may have trouble finding an ER-40 for an R-8 spindle. They normally are on either straight 2" shanks or NT30+ spindles.

        Tip: make sure the nut you get with the collet holder is a ball bearing type as they can apply far more pressure to the collet -important with carbide. I would also suggest you buy a better name brand collet such as Collis, Lyndex, etc. The reason for this is they are hardened and bored properly and last far longer.

        DO NOT use a boring head with a straight shank in your collet holder, use the proper spindle taper (in your case an R-8) adapter. This will give you far more accurate holes.

        KPT Kaiser makes precision boring heads that fit ER-25 and ER-32 collet holders - these are the exception (less than 3/4" boring capacity) and have an ER-collet shaped shank and nut.


        • #5
          Yes, I have 'em too. Max shank diameter is 25 or 26 mm. R8? IIIiiiiidunnobout that. Like Thrud was onto, they usually live in something sturdier. I have a #50 m'self. Hangdown depends on the machine taper, I suppose you know. On on R8, it would be considerable. If available. Can you step down a bit to ER 32 or 25?

          About their grip...I find that the smaller diameters like 4 or 5 are really not that spend a lot of effort trying to tighten up properly.

          EDIT: Oh fer says right there that you're looking for 32's, not 40's. Well, never mind that shank diameter then. It (the 32) maxes at about 20 mm if I recall. Sorry.

          [This message has been edited by Dr. Rob (edited 10-13-2003).]


          • #6
            Here's an R8 ER40 set on ebay 6 days left @199.00 w/15 collets..damn good price..but not any indication of brand(maybe too good of a price..they usually run around $600 US).

            ER40 maxes out at 1.024"(26.0096mm) and ER32 at 0.787"(19.9898mm)....ER25 at 0.469"(11.9126mm)but specs vary from manufacturer to manufacturer slightly.


            Chuck projection from spindle is 2.56"(+/-0.005") best I can measure on my R-8 ER40 set.

            Hope this helps you in deciding

            [This message has been edited by HPS (edited 10-13-2003).]

            [This message has been edited by HPS (edited 10-13-2003).]


            • #7
              That collet set is obviously an import. Gives accuracy to 0.0001", not accuracy of 0.0001". Bit of a difference.
              You might want to check on guaranteed accuracy and return policy before taking the plunge.
              Current price for ETM 15 piece collet set with R8 holder is $729.00. Projection below holder looks to be on the order of 2 to 2-1/2".
              R8 holders are readily available from several sources around $125-$150.

              [This message has been edited by JCHannum (edited 10-13-2003).]
              Jim H.


              • #8
                For the gripping problems on small diameters, I saw a collet last week at a trade show that fits in the ER collet chuck, but gives better gripping. It's made by Techniks and called the DNA collet. It's basically a shorter ER collet where the nut grips on the grooved shoulder instead of on the top of the collet. They claim this eliminates the slipping problems of small diameter carbides.


                • #9

                  Dunno where you got those capacity figures for the ER25 - mine holds up to 16.0mm diameter.

                  Maximum/Minimum dias spec'd are as follows:-
                  ER8 = 5.0mm / 1.0mm (x 0.5mm steps)
                  ER11 = 7.0mm / 1.0mm (x 0.5mm steps)
                  ER12 = 7.0mm / 1.0mm (x 0.5mm steps 1.0mm to 3.0mm, then 1mm steps from 3mm to 7mm)
                  ER16 = 10.0mm / 1.0mm (all this range and up collets collapse down by 1mm)
                  ER20 = 13.0mm / 1.0mm
                  ER25 = 16.0mm / 1.0mm
                  ER32 = 20.0mm / 3.0mm
                  ER40 = 26.0mm / 4.0mm
                  ER50 = 32.0mm / 12.0mm

                  So if you want to grip small sized cutters use the smaller ER sizes, which can be achieved by getting an ER 32 and using a ER 8 straight shank collet holder (12mm shank diameter)in the ER 32 chuck.

                  Another good brand to look out for is ETM, they also do the ball bearing nuts.



                  • #10
                    J&L carry the ETM brand.
                    They are listing a ER16 0.5mm - 10mm at 46.40 UKP #ETM-90068A
                    A ER32 2.0mm - 20mm at 57.00 UKP # ETM-90001D
                    and a ER40 3.0mm - 26mm at 67.50 UKP # ETM-21855A

                    All these are on R8 shanks.

                    John S.

                    [This message has been edited by John Stevenson (edited 10-13-2003).]

                    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.


                    • #11
                      Sorry double post

                      [This message has been edited by John Stevenson (edited 10-13-2003).]

                      Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.


                      • #12
                        Hey guys,
                        thanks for the great info. My wife was in the shop while I was loosening the draw bar to change to another R8 and she said "that kind of sucks if you have to do that every time, don't they make something where you can do all of that from below. How are you going to reach it when you put the riser thing on your mill?"
                        Sit down honey we really need to talk. I just love it when she solves my problems. The sad part is I have to wait for Christmas.


                        • #13
                          Unless you have a need to hold 1" shanks, I would recommend the ER32 chuck over the ER40. When I upgraded to ER32 (3/4" max) from a smaller (5/8" max) chuck, I was really surprised how much larger it was. ER40 would be even larger. For me, on my small R8 Rockwell mill in a home shop, 3/4" shanks covers a lot of tooling, plus I can hold down to 1/8.