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  • holding endmills

    which do you guys use for holding end mills? r8 collets or r8 end mill holders with the set screw?
    san jose, ca. usa

  • #2
    depends on the size and how aggressively you're going to work them, small = collet, large = endmill holder. Whats large? dividing line is probably 5/8's for me
    in Toronto Ontario - where are you?

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    • #3
      Originally posted by gambler View Post
      which do you guys use for holding endmills? r8 collets or r8 end mill holders with the set screw?
      Depends on size, collets are fine for most situations. Large diameter and/or long endmills with heavy cuts result in stronger down forces (from the helix) causing the mill to pull out of the collet. That's when you need a holder with set-screw. I'm a bit baffled by endmill holders under 1/2" dia., but I suppose there are situations where they might be needed.
      It's all mind over matter.
      If you don't mind, it don't matter.

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      • #4
        Let your work dictate your toolholding. Sometimes the extra reach is nice with EM holders, sometimes the collet shines for reduced stickout. It's very handy to have both available. If your budget says one or the other, get a good set of collets. They're just more versatile.

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        • #5
          I always use colletts, but I don't hog aggressively. I have a few end mill holders and never liked them because they tend to load the cutter to one side when the set screw is tightened. For roughing I suppose it's OK. Lighter cuts and finish dimensions I prefer colletts.

          JL.................

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          • #6
            When I first got my new R8 spindle mill I tested the grip of the R8 collets. One of the end mills in my assortment is a 1" six flute cutter with a 3/4" shank. I figured that was a good "worst case scenario". Installed in the 3/4" collet and given a good pinch on the drawbar without going mondo crazy. If I had to estimate the torque I'd call it somewhere between 15 to 20 foot-lbs. I tend to err on the side of things that results in a torque that only needs a firm tap of a lump of lead to break the collet free instead of a heavy blow that is death to the spindle bearings over the long haul.

            I started making nearly full diameter cuts with this older and used but not abused end mill. A felt pen witness mark between the end mill and the collet was added to see if there was any slip. I quit when I got to about 1/8 x nearly the full 1" of cut with a fairly aggressive but still happy sound coming from the cutter and chips. You guys know that sound. A crisp hissing sound but without the sort of growl and somewhat ripping sound that comes from pushing up to too high a chip load. At that point I figured that was as much as I'd ever need.

            Sometimes the friction thing doesn't work on smaller cutters. So I repeated the same test for 1/2" and 3/8" cutters. I used the 9/16"x 1/2" for the half inch collet and the 7/16 x 3/8 for the 3/8" collet just so it was the worst case situation in all cases. None of them slipped at all that I could see.

            Since then I've used just the collets with confidence.

            It's different for something like a flycutter or large face mill. For those I stick to full R8 shanks.

            My old mill/drill had an MT3 spindle. The MT3 collets that came with the mill did not generate a lot of friction on the end mill shanks. So I bought or made up screw style holders. Bought in a couple of cases where the overhang was very low and made for the sizes where the overhang was very high in the commercial versions.

            In all of this the main idea is to limit the overhang and thus the flexing that can increase chatter and flexing. If collets will give you the friction you need so they don't slip then you're not going to reduce the overhang by any more than that.
            Chilliwack BC, Canada

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            • #7
              thanks again, I'll get some collets. do I need to worry about the .0006 tir ones, or are standard ones ok?
              san jose, ca. usa

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              • #8
                I use a Clarkson AutoLoc with threaded end end mills, and the R8 setscrew type...... Weldon shank.

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                • #9
                  Originally posted by gambler View Post
                  thanks again, I'll get some collets. do I need to worry about the .0006 tir ones, or are standard ones ok?
                  like .0006 is supposed to be good? what are the "standard" ones?

                  1/2 a thou run out is not going to matter aggressively cutting with say a 1/2 endmill, things get loaded and cutters flex....but it seems a lot of run out for a collet. If using very small endmills it would be too much imo
                  Last edited by Mcgyver; 03-14-2018, 03:33 PM.
                  in Toronto Ontario - where are you?

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                  • #10
                    Hi,

                    R8 Collets are just fine for anything up to Bridgeport sized machines. Properly tightened, these machines it's nearly impossible to push a collet hard enough to slip.

                    You only really need a 6 piece set, 1/8" to 3/4" by 1/8's for end mills, (maybe a 5/16" if you want to use carbide). Yay for standard sized shanks!!!! Which ones to buy? Honestly, everybody who makes collets has sold me at least one bad one. From no names to Hardinge. R8 collets are a commodity item and tends to manufactured to commodity price points. My advise is to open wallet, see how much you are willing to spend, then spend that much. But don't be surprised if one or two doesn't meet your expectations........ I look for .0005" or less. I don't think I've ever seen over .001" even in no-name collets. More runout will create shorter tool life in larger tools, and may even cause tool breakage for tiny tools. Like 1/16" of smaller. If you don't use a steady diet of small tools, not much to worry about.
                    If you think you understand what is going on, you haven't been paying attention.

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                    • #11
                      Originally posted by dalee100 View Post
                      Hi,

                      R8 Collets are just fine for anything up to Bridgeport sized machines. Properly tightened, these machines it's nearly impossible to push a collet hard enough to slip.

                      .
                      not true. With a 3/4 or 7/8 endmill in a collet on a 1 - 1.5 hp machine you can definitely move the cutter. Its not that it slips like a drill bit can slip, its starts pulling out of the collet so your DOC changes.
                      in Toronto Ontario - where are you?

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                      • #12
                        I suggest you never trust a collet to securely hold on to a dovetail cutter. I got away with it until I didn't.

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                        • #13
                          I use mostly er25 collets, then threaded to fit Clarkson Autolock, Osborn Titanic and Acramill holders and sometimes R8 collets. As the mill is not used to take heavy cuts, I have never had a cutter move.
                          If you run a machine within an inch of its life, you deserve all you get, this is a "home shop forum" after all.

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                          • #14
                            Originally posted by Mcgyver View Post
                            depends on the size and how aggressively you're going to work them, small = collet, large = endmill holder. Whats large? dividing line is probably 5/8's for me
                            X2.

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                            • #15
                              Originally posted by gambler View Post
                              which do you guys use for holding end mills? r8 collets or r8 end mill holders with the set screw?
                              Neither.

                              Sometimes I use NMTB 40 end mill holders. Sometimes I use TG100 collets in an NMTB 40 collet chuck. Even better than the TG100 collets are the TG100NP collets, which have a plug that fits the Weldon flat. Sometimes DA or WW collets, sometimes LB or 00 collets, sometimes Morse taper end mill holders. Rarely, depending on circumstances, in a drill chuck. Depends on the machine and the end mill size.

                              With quality end mill holders and quality end mills, I've never felt that the end mill was loose enough in the holder that a set screw would drive it off center - at least not enough to matter. To me. And I'd prefer it to be slightly off center against the risk of it pulling out of a collet. Unless it's a "no pull" collet, but I don't know if they make them in R8.
                              Last edited by JohnMartin; 03-15-2018, 12:24 AM. Reason: "quality collets" should have been "quality end mills"

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