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  • end mill holders?

    Do you (maybe the right question should be should you) use endmill holders to hold end mills or are collets sufficient? I've run across a couple of recommendations suggesting that endmills cannot be held well in a collet, and should be only used with a set screw type end mill holder. OTOH, I haven't seen many people using them, it seems like you always see and endmill just stuck in a collet.

    Honestly, I'm not all that experienced a machinist, but I've never had an endmill move in a collet, at least not that I noticed.

  • #2
    End mill holders do not allow slipping which can be good or bad.

    End mill holders need the flats on shanks.

    Also they protrude more than collets.

    I use holders with no problem.

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    • #3
      Originally posted by Teenage_Machinist
      End mill holders need the flats on shanks.
      Not necessarily disagreeing, however, not required for normal cutting, if you will be hogging then that would be highly recommended.
      Before it is over you will have both collet and EM holders. Collet's grip more concentric (that is to say, a good collet and holder) and a set covers a lot of sizes that would require a one for each if using a tool holder.

      Ken

      EDIT:
      Should say that while Collets can run more concentric, for the HSM on average equipment and for the average job it is almost irrelevant.
      Last edited by Ken_Shea; 01-09-2009, 01:01 AM.

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      • #4
        I used to use nothing but collets, 'cause that was all I had... then I turned a perfectly good not yet finished part into scrap because the endmill started climbing into the work while I was hogging... now I have one or two end mill holders for my bigger end mills...

        - Bart
        Bart Smaalders
        http://smaalders.net/barts

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        • #5
          I have both collets and end mill holders. I find I use the end mill holders more just because I have a rack full of them sitting there with end mills already loaded and ready to go. I just grab the one I need and pop it in the mill. It is just quicker for me and since customers are relying on me to be quick that is what works in my shop. I don't have a problem with either collets or holders and would recommend collets to someone just starting out if you have to choose between one or the other. Most beginners are not going to be hogging material so a slipping end mill will never be a problem.
          Mark Hockett

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          • #6
            Originally posted by Teenage_Machinist
            End mill holders do not allow slipping which can be good or bad.
            I could see good, but I'm not sure about why it would be bad.

            All of you seem to agree that endmill holders are needed for hogging, at what point does cutting become hogging?

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            • #7
              Originally posted by Silverback
              I could see good, but I'm not sure about why it would be bad.
              An old machinist told me that's why they're called "Weldon" holders, because when the endmill jams, it Welds On to the set screw
              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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              • #8
                Oim 'oggin' on ma mill Oi am - big deal!!

                Oh dear me.

                Any wood-worker who has ever used a router will give you a good answer for this.

                Put the end-mill etc. "hard into" the collet so that it "bottoms out" then withdraw it about 1/8" (or more - suit yourself) THEN close/clamp the collet. A lot of problems are caused by the end mill shank being clamped by the collet and "hits bottom" before the collet is fully "home" such that when you think the collet is "clamped" it is not fully so due to the interference of the withdrawal of the collet into its socket.

                This is mainly - but not only - a concern with collets in a collet adaptor in a mill spindle.

                A lot of the problem is not "hogging" either but is due to "heavy handedness" with a less than adequately sharp cutter - especially so with compounding it by trying to "hog" and push the machine and the cutter too hard.

                The problem gets worse with the "steeper" angled helixes on some of the "high performance" cutters.

                I hear a lot about cutters cutting but little about using blunt cutters or sharpening them - particularly up the length of the spiral edges. The cutters don't stay sharp for ever.

                Dull cutters and dull(er??) "machinists" seem to go together.

                If I ever made the mistake of letting a "hogger and flogger" use or abuse my machines or tools he'd be out that door pronto - and made known in no uncertain terms that he's not welcome.

                Driving a machine within its limits and without "belting it" is OK if and when NECESSARY - which is very rarely here.

                I have yet to have a need for an end mill holder as I find that my ER collets do a good job.

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                • #9
                  Originally posted by Silverback
                  I could see good, but I'm not sure about why it would be bad.

                  All of you seem to agree that endmill holders are needed for hogging, at what point does cutting become hogging?
                  For me it's a function of vibration - the endmills tend to walk if the load generates much of that.... there's no way I'd trust a collet to hold a 3/4" end mill if I push it much at all... I usually cut pretty slowly on cast iron or steel, but Al brings out the speed demon, and that's when I run into trouble

                  - Bart
                  Bart Smaalders
                  http://smaalders.net/barts

                  Comment


                  • #10
                    Originally posted by barts
                    For me it's a function of vibration - the endmills tend to walk if the load generates much of that.... there's no way I'd trust a collet to hold a 3/4" end mill if I push it much at all...
                    Bart +1: I use collets (a mixture of R8 and ER40) up to 3/4", mostly for the convenience. But if I'm running a 3/4" corncob, I'll go for the endmill holder.

                    ER40 goes well above 3/4", but I've never tried to run a rougher in it.
                    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                    Comment


                    • #11
                      Gone!!!

                      I run a 20mm (~0.800") "roughing" (aka "corn-cob") cutter easily in an ER-32 collet. If it is being "pounded" and you can see or feel it, then its not just the cutter or the job that's getting thrashed - so is just about everything.

                      If you get all glassy-eyed and start to hyper-ventilate, dribble and drool etc. in those self-made situations, perhaps you are beyond help.

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                      • #12
                        Depends on the collet type. I wont trust a R8 for much of anything. But I have never, ever had a ER collet slip. And if you are still paranoid there are ER collets that have a protrusion to grab into the weldon groove.

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                        • #13
                          I was talking about R8 - the standard Bridgeport collet. I don't have a ER collet setup.

                          - Bart
                          Bart Smaalders
                          http://smaalders.net/barts

                          Comment


                          • #14
                            Whew, at least everyone on here seems to acknowledge that a milling cutter should be retained in a collet AT LEAST. The number of posts on other forums that show cutters held in drill chucks with the safety rider "But it's only" are unbelievable. The cutter holders in my toy workshop are mini-Autolock types for screwed shank cutters, but a couple of adaptors I made for 1/4" and 6mm plain shank cutters (Yes, one for each) have allen grubscrews locating on to flats on the shanks. Takes a BIT longer to work safely but WTH, in HSM we don't have to cleave at the speed of light, or do we??

                            Regards Ian.
                            You might not like what I say,but that doesn't mean I'm wrong.

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                            • #15
                              On an older machine or a cheap machine, things are rarely perfect. The extra length of an EM holder on a machine with a less-than-perfect spindle often makes the difference between a lousy finish and an acceptable finish. If the holder does not hold the cutter nicely concentric, it will cut more like a single-point tool than a mill. The more expensive EM holders are ground offset by 5 tenths or a thousandth to keep the cutter centered when locked. The cheap imports are not ground that way. A 3/4 EM holder sticks out a good 2 1/2 inches. That is a much bigger concern for me than the possibility of a collet slipping. If it's a good collet, it won't slip. On a bigger spindle, like 40 or 50 taper, that's a different animal. But on an R8 or MT usually found in a small shop, I go with collets.

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