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End mill holders vs ER collet

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  • #46
    Originally posted by DR
    I have noticed that companies such as Boeing generally don't use collets for holding end mills in high production applications.

    They use end mill holders.
    Like Russ and Row say, high-volume production usually uses heat shrink toolholders, which you can argue is a collet and an endmill holder (a collet with no slits, or an endmill holder with no setscrew) But the reason VMC's use don't use conventional collets is because you can't guarantee the tool offset, not because of any perceived issues of the tool pulling out.
    "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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    • #47
      Setting up

      A couple of comments.

      First of all, if a shop has a high volume output and a high number of CNC/NC machines the tools can be accurately pre-set for their actual state or condition with one of these:
      https://www.machineryhouse.com.au/Pr...tockCode=D780#

      Next, a very good accuracy for size and concentricity can be achieved in a small shop with a "passable" tool and cutter grinder by grinding the tool in the holder.

      But back to the main topic - "End mill holders vs ER collet".

      I am surprised that some who use a wood-working router (and have read the manual for it) have not pointed out what just about very router user knows and/or does - push the cutter shank into the collet until it "hits bottom" and then with-draw it ~1/8" (~3mm) and THEN tighten the collet.

      If the cutter shank "bottoms" and the collet grips it tightly enough the "closing" of the collet is resisted very significantly to the extent that the collet may be prevented from adequately closing and gripping the cutter shank. In this case the cutter may very well "work out/forward" in the collet.

      In this case the fault is not with the collet, the cutter or the machine - but with the operator.

      I use ER-32 and ER-16 collets exclusively. I have but don't use C5 collets.

      I just tighten my collets with a final "bump" with the heel of my hand.

      I have never had a correctly installed collet or cutter - particularly an ER collet - "slip".

      If ever anybody bashed or torqued or similarly abused a machine or a collet in any of my machines, like some here seem to do, they would only do it twice - the first and the last time.

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      • #48
        "If ever anybody bashed or torqued or similarly abused a machine or a collet in any of my machines"

        If I could take them with me I'd take better care of them.

        Comment


        • #49
          Originally posted by lazlo
          Like Russ and Row say, high-volume production usually uses heat shrink toolholders, which you can argue is a collet and an endmill holder (a collet with no slits, or an endmill holder with no setscrew) But the reason VMC's use don't use conventional collets is because you can't guarantee the tool offset, not because of any perceived issues of the tool pulling out.

          Nope a collet would pull out and eat a fixture, iv seen it with dual rotatory 4 axis fixtures and the endmill was all the way through the fixture completly destroying it. you dont have a clue.

          they quit using collets , thats for sure.

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          • #50
            Originally posted by lazlo
            Like Russ and Row say, high-volume production usually uses heat shrink toolholders, which you can argue is a collet and an endmill holder (a collet with no slits, or an endmill holder with no setscrew) But the reason VMC's use don't use conventional collets is because you can't guarantee the tool offset, not because of any perceived issues of the tool pulling out.
            Originally posted by tattoomike68
            Nope a collet would pull out and eat a fixture, iv seen it with dual rotatory 4 axis fixtures and the endmill was all the way through the fixture completly destroying it. you dont have a clue.

            they quit using collets , thats for sure.

            Both wrong
            The Mazak FJV-20 in our toolroom uses split collets for everything apart from a couple of dedicated U-drill holders. And we're not cutting soft stuff like Aluminium or Brass - it's all either P20, H13, EN30B, D2, EN57.

            Mind you, we only have 20 Hp and 25,000rpm on the spindle.....

            Peter

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            • #51
              Originally posted by Peter Neill
              Both wrong
              The Mazak FJV-20 in our toolroom uses split collets for everything apart from a couple of dedicated U-drill holders. And we're not cutting soft stuff like Aluminium or Brass - it's all either P20, H13, EN30B, D2, EN57.

              Mind you, we only have 20 Hp and 25,000rpm on the spindle.....

              Peter
              So what? It was hardinge conquest mill with a 10,000 rpm spindle it eats a fixture just about as fast. they did switch to shink fit holders shorty after that. but used real endmill holders for roughing.

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              • #52
                You missed the sarcasm that despite the 20hp and 25Krpm, non shrink-fit collets are perfectly adequate.
                The Mazak is used for Roughing and Finishing on mould tool bolsters, cores, and cavities, and doesn't need weldon type or clarkson type endmill holders.

                Peter

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                • #53
                  For me, Clarkson rules. end of story. Peter
                  The difficult done right away. the impossible takes a little time.

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                  • #54
                    Originally posted by Peter Neill
                    You missed the sarcasm that despite the 20hp and 25Krpm, non shrink-fit collets are perfectly adequate.
                    The Mazak is used for Roughing and Finishing on mould tool bolsters, cores, and cavities, and doesn't need weldon type or clarkson type endmill holders.

                    Peter
                    Yeah, but they don't have near the coolness factor of shink fit. Those things are REALLY slick. As I recall, it went something like this (from memory, been a while). It uses induction heating to heat the holder in about 10(?) seconds or less. The EM/tool held in a fixture with stop to control height and align for quick seating, pull a lever that fully seats against the stop in about a 10th of a second, and 2 seconds later it might as well be welded in place with amazingly near zero run out and accurate depth setting to (I'm told, less than a thou). They run those machines at (to me) just amazing rates of removal. And so I was told, there has never yet been a slip (at their location). Not sure the HP on that machine, but it's HUGE...
                    Russ
                    Master Floor Sweeper

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                    • #55
                      Oh, and my friend, a carrier machinist who just retired as Shop Forman in this place, runs collets almost exclusively in R8 machines of his personal shop. Now obviously that's not the case on the 40 and 50 taper machines, but for R8 machines, there's just no really need for EM holders unless you need repeatable tool offsets between tool changes. Those were his words to me when first setting up my little 2J, and so far, I've seen nothing to contradict his statement. This includes his shop, mine, and several of his friends and acquaintances that I've met and spent time in their shops. With the exception of the CNC machines, or where 3/4 axis DROs are used to do semi-production work, nobody uses EM holders unless it's just due to shared tooling.

                      Oh, and back on topic, those where I've seen EM holders on R8 machines fall into the same category. Mostly just on machines where consistent/repeat offsets are used.

                      At least that's my impression. Most of this is based on my impressions from observation and conversation, I'm well out of my depth at that end of things.
                      Russ
                      Master Floor Sweeper

                      Comment


                      • #56
                        Originally posted by oldtiffie
                        A couple of comments.

                        I have but don't use C5 collets.
                        Now If they need some work I know of a very good home for them

                        Comment


                        • #57
                          Originally posted by lazlo

                          .................................................. ..................

                          But the reason VMC's use don't use conventional collets is because you can't guarantee the tool offset, not because of any perceived issues of the tool pulling out.

                          No, tool offsets are pre-set on bench mounted setters or with touch-off setters on the machine. The offset procedure is the same whether for collets, end mill holders or shrink fits.

                          Determining offsets is not an issue. For heavy production milling the issue is tool movement in it's mount while in the cut.

                          Comment


                          • #58
                            Originally posted by Peter Neill
                            Both wrong
                            The Mazak FJV-20 in our toolroom uses split collets for everything apart from a couple of dedicated U-drill holders.
                            Peter, what kind of collet does your Mazak use? Every Mazak I've seen over here has BT40 or BT50 endmill holders with a hydraulic pull-stud.

                            No, tool offsets are pre-set on bench mounted setters or with touch-off setters on the machine. The offset procedure is the same whether for collets, end mill holders or shrink fits.
                            So how do you pre-set a system where the spindle nose cap closes the collet?

                            On an ER collet chuck, because of the double-angle clamping, the collet aggressive pulls the stock inward until the nose cap is completely locked down. That's a big advantage 5C collets have over ER's, especially on a lathe -- if you use a drawbar closer, the stock offset doesn't change when you close 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


                            • #59
                              Robert, I can't remember if they are TG or ER (hence I mentioned 'split' collets), but I'm back over in the Toolroom on Wednesday so I'll check and take a few pictures of the toolholders all set up for it.

                              Peter

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                              • #60
                                Originally posted by lazlo

                                .................................................. .......

                                So how do you pre-set a system where the spindle nose cap closes the collet?

                                On an ER collet chuck, because of the double-angle clamping, the collet aggressive pulls the stock inward until the nose cap is completely locked down. That's a big advantage 5C collets have over ER's, especially on a lathe -- if you use a drawbar closer, the stock offset doesn't change when you close it.
                                A VMC wouldn't have a nose cap, but if it did you could set with a touch-off point mounted on the table. An inexpensive one would be like I have, (<$100) simply a 2" height device that lights up when the tool tip touches it. The offset is then entered manually via keyboard.

                                Some VMC's have integrated touch-off devices. Touch the device semi-automatically and it enters the offset into the tool table.


                                As to 5C collets, they're notorious for pulling the stock back as they close. A slight difference in stock diameter causes a magnified difference in pullback of the stock.

                                The pull back difference can be a nightmare on precision second op work. For instance, you have a batch of parts turned with a .005"+/- diameter. A precision second operation has to done on the back side of the part while holding the turned diameter in a 5C. If the turned diameter varies to the upper and lower tolerance limits you can't hold any precision because of the pullback.

                                To get around the 5C pullback problem, Hardinge has dead length collet assemblies.


                                There are common dead length type collets for lathes. The type used in B&S screw machines is one. With these type the drawbar pushes the collet rather than pulling it.

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