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method of mounting tooling on a mill/drill

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  • #16
    Your describing this but with a expanding collet in place of the locking screw. Mine don't repeat great, you still have to crank the length of the pin which isnt much less than the taper anyway, and you can't hold end mills or slot drills with them without a adaptor designed for that purpose which extends below the central collet pin by at least the depth of the shank engagement into the lower holder + a margin, which adds to the stack up height in a machine which is compromised to start with in this aspect.
    I just leave them set up with insert heads on the tapers and swap the tapers still and swap them in for heavy roughing down of slab work.
    http://www.ebay.co.uk/itm/DIN-69871-...-/200627051082

    I did see a tooling system that had the head on dovetails, and you slid the tool insert in and tighted up some screws to retain it in position but that was on a edm electrode holder not subject to much in the way of cutting sideforce.

    What you need is something like qc30, smallish, fat taper so it comes sideways without cranking down very far etc but we know how loved that is round here, although I've never had one drop out yet myself and I've been using a bit of the qc30 tooling that came with the pos bridgeport in a 40 shanked adapter I got off awemason

    Comment


    • #17
      Originally posted by Paul Alciatore View Post
      J, I totally agree with you on the fit and wear factor. My suggestion was for a practical device for use in a small or home shop ("Home Shop Machinist"). The other side is that a taper has little longitudinal repeatability. As it wears it will seat further and further back in the socket. So it will be impossible to get repeatability in that direction.
      You do not NEED repeatability in that direction..... not decade-to-decade, which is more like the time period of the possible wear on a substantial taper....

      What you NEED is short-term repeatability, last week to this week, etc. THAT is trivial to attain with any taper, even with an HRS spindle. It could probably be done with a WOODEN spindle... (not balsa, but you get the point....).
      CNC machines only go through the motions.

      Ideas expressed may be mine, or from anyone else in the universe.
      Not responsible for clerical errors. Or those made by lay people either.
      Number formats and units may be chosen at random depending on what day it is.
      I reserve the right to use a number system with any integer base without prior notice.
      Generalizations are understood to be "often" true, but not true in every case.

      Comment


      • #18
        I appreciate the discussion. I did have some kind of dovetail system in mind- possibly a V where the tool holder would nest and be forced into tightness with it via a surrounding clamp of some kind. Each holder would be mounted, then machined in place for the tool that will be used in it. You'd be using the mill as a lathe for this operation. It would be relatively easy to bore for end mills- might be tricky machining the short taper for the drill chuck to mount to, but still possible.

        The spindle adapter part would take time and care to produce so it basically fits without play, but that's certainly not impossible- I've done it three times now for various tools, mostly boring and trepanning tools which benefit noticeably by having a stiffer mounting method. So far though they all still have the tapered shank, though on two of them I shortened the taper section. I would also make the new adapter complete with a taper shank- the difference being that I wouldn't be dismounting it all that often.
        I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

        Comment


        • #19
          I must be having a particularly dense evening as I can envision a quick change set-up of sorts but I still don't see, baring mattthemuppet's suggestion, how you can possible eliminate or even nearly so the action of cranking something (head or table) up and down.
          I mean even if you do limited operations even just within a common operation, drilling say, doesn't the tool length vary too much to avoid changing a head or table height?

          To me it sounds like motorizing some axis is a "solution".

          Edit: thinking out loud, relating back to you wanting the mill equivalent of a lathe QCTP, if you oriented the dovetail in a vertical fashion (creating a "tool post" on the end of a MT # 3 stub) could you then swap out various blocks and adjust to compensate for differing heights by touching off and then tightening the "wedge" for the dovetail?
          Problem I can instantly see with that is you have all the tooling offset some amount from the vertical spindle axis.
          Its almost like you need a small chuck mounted on a hollow spindle, with enough size for tooling and enough length for same. Like a vertical lathe?

          How far away would a Clarkson or Tru-Loc set up be from what you want?
          Last edited by RussZHC; 08-21-2014, 02:01 AM.

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          • #20
            While I am convinced you require a taper for any credible mounting of a rotating tool, the taper should not need to be long.... We think of tapers like an MT or the like, but there are chuck mounting tapers that are quite short relative to their diameter, and which work very well indeed.

            The taper also may not be a shallow taper (shallow being closer to parallel with axis). Steeper tapers alleviate the problem of axial location more-or-less in proportion to their steepness.

            With a shallow taper, a slight amount of wear or error makes a very large (in relative terms) change in axial position. The taper changes very little in diameter per thou of length, and ratio may be 10:1 or more.

            A steeper taper reduces that problem. a 45 degree taper reduces it to 1.414 :1, which is likely to be as far as you need to go. And the steeper taper gives more area per unit of length axially, as well, reducing the wear problem, ans well as being easier to clean.

            A steeper taper then would allow a shorter taper to be made without needing ridiculous accuracy to maintain axial position. It may be possible to minimize table or head cranking.

            Since all tools have some length if they are useful, I do not see the idea of avoiding table cranking etc as being realistic. Even if you had a magical slide-in-from-the-side mount with perfect alignment, the tool length is bound to give problems in some setups at least.

            And it is possible in many cases to bring the tool in at an angle and slide it into the socket. That is easier with a steep taper and more "open" socket than with a longer shallower taper.
            CNC machines only go through the motions.

            Ideas expressed may be mine, or from anyone else in the universe.
            Not responsible for clerical errors. Or those made by lay people either.
            Number formats and units may be chosen at random depending on what day it is.
            I reserve the right to use a number system with any integer base without prior notice.
            Generalizations are understood to be "often" true, but not true in every case.

            Comment


            • #21
              Originally posted by J Tiers View Post
              Since all tools have some length if they are useful, I do not see the idea of avoiding table cranking etc as being realistic. Even if you had a magical slide-in-from-the-side mount with perfect alignment, the tool length is bound to give problems in some setups at least.
              What about a different approach. a "magical", slide in from the side work alignment method/device. Clearing the vise or workpiece fixturing from under the spindle might give you enough space to change tooling. It would require a positive way to reposition the work holder on the table within a couple thou. Then you might not have to crank the head up every time to change tooling.

              Comment


              • #22
                You can do that with a tooling plate bolted to the bed. It has tapped holes for bolts and reamed holes for dowel pins, usually in an alternating pattern.
                Kansas City area

                Comment


                • #23
                  Why not make a side loading tool holder, something like this:



                  Too change a tool, remove the socket head screws and the C shaped piece, swap cutters, bolt the C shaped piece back on.
                  Location: Long Island, N.Y.

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                  • #24
                    I'm familiar with fixturing sub-plates The OP needs something "magical" that will overcome the lack of room between top of workpiece (probably in vise) and the spindle. He could use three dowels to locate the vise on the mill table and toggle clamps to hold the vise in position. Unlock the vise, slide it out of the way, change tooling, slide vise back into position and lock it down.

                    Comment


                    • #25
                      Originally posted by RussZHC View Post
                      ...<snip>...

                      To me it sounds like motorizing some axis is a "solution".

                      ...<snip>...
                      Gee, I wonder why they don't do that? Sounds like a "no brainer".



                      Don't look here:

                      http://www.grizzly.com/products/Heav...wer-Feed/G0755
                      Paul A.
                      SE Texas

                      And if you look REAL close at an analog signal,
                      You will find that it has discrete steps.

                      Comment


                      • #26
                        Your comments on the taper in the third paragraph illustrate my thought that you do need better control in the axial direction. This is why lathe collets have stops fitted to them so that multiple parts can be located in the same position on the same day, hour, even minute.

                        The problem with a shallow taper is you start to lose angular accuracy. So, at the taper you may have very good X, Y, Z positional accuracy, but at the tool tip, which is hanging out several inches lower, you can get a lot of run out. The length of a conventional taper controls this, but a shorter taper and especially one at a larger angle, like 45 degrees, will rotate sideways much more easily. That short taper starts to approximate a spherical surface.

                        By the way, it is not just the wear that changes the axial position of a taper when tightened. Also the amount of force used in tightening it will make a major change. Even if you use a torque wrench, you will still have variations due to lubrication and contaminants between the surfaces. Oh, and temperature.

                        The added length of some of these schemes has been mentioned. Well, yes they would reduce the tool to table space would be reduced unless you can bury some of the mechanism inside the mill's spindle. I don't see this happening with a R8 taper and will probably be difficult with most of the other tapers currently in common use. If you want a new tool mounting method that does not require so much up-down cranking, then you are going to have to separate this requirement from the requirement for a maximum amount of space under the tool. If you really need the maximum amount of vertical working space, you can just mount each tool in a matching collet, but this brings you back to the cranking problem. Life is a series of compromises.

                        A further thought on the need for using a taper. One of the mostly highly regarded methods of mounting a milling cutter is the fixed hole holder, with a set screw for fixing the milling cutter in place. Personally, I always worry about the buildup of tolerances and allowances in this system. It seems to me that an off axis tool is almost the inevitable result of this system. I mean, that set screw is just constantly forcing it off center, isn't is? And do you always buy a dedicated holder for each and every tool that you own? I suspect that many will be constantly changing holders/tools for many jobs, so what about wear there? Yet, this system is widely used and many swear by it. Oh, all those milling cutters swinging around off center and cutting extra wide swaths with only one of their 4 or 5 flutes.

                        I still feel that a short pin, without any taper, is a workable device. Even with a little clearance (tenths?), if the angular alignment is good (my outer ring surface), then the error at the tool tip will be small. Not a perfect solution, but workable. And, as I showed above, it can be done with only 1/2" or less of extra vertical space for tool changing.

                        As far as different tools having different lengths, yes they do. It is hard to get around that. Live with it.


                        Originally posted by J Tiers View Post
                        While I am convinced you require a taper for any credible mounting of a rotating tool, the taper should not need to be long.... We think of tapers like an MT or the like, but there are chuck mounting tapers that are quite short relative to their diameter, and which work very well indeed.

                        The taper also may not be a shallow taper (shallow being closer to parallel with axis). Steeper tapers alleviate the problem of axial location more-or-less in proportion to their steepness.

                        With a shallow taper, a slight amount of wear or error makes a very large (in relative terms) change in axial position. The taper changes very little in diameter per thou of length, and ratio may be 10:1 or more.

                        A steeper taper reduces that problem. a 45 degree taper reduces it to 1.414 :1, which is likely to be as far as you need to go. And the steeper taper gives more area per unit of length axially, as well, reducing the wear problem, ans well as being easier to clean.

                        A steeper taper then would allow a shorter taper to be made without needing ridiculous accuracy to maintain axial position. It may be possible to minimize table or head cranking.

                        Since all tools have some length if they are useful, I do not see the idea of avoiding table cranking etc as being realistic. Even if you had a magical slide-in-from-the-side mount with perfect alignment, the tool length is bound to give problems in some setups at least.

                        And it is possible in many cases to bring the tool in at an angle and slide it into the socket. That is easier with a steep taper and more "open" socket than with a longer shallower taper.
                        Paul A.
                        SE Texas

                        And if you look REAL close at an analog signal,
                        You will find that it has discrete steps.

                        Comment


                        • #27
                          Looks like you're a big fan of Lincoln.


                          Originally posted by RichR View Post
                          Why not make a side loading tool holder, something like this:



                          Too change a tool, remove the socket head screws and the C shaped piece, swap cutters, bolt the C shaped piece back on.
                          I too save and use those return envelopes. Great for filing things like receipts and, of course, scratch paper. One more reason for not converting to paperless bills.
                          Paul A.
                          SE Texas

                          And if you look REAL close at an analog signal,
                          You will find that it has discrete steps.

                          Comment


                          • #28
                            That sounds like more trouble than cranking the head up and down. But usable if you are at the limit of vertical travel.


                            Originally posted by Rosco-P View Post
                            I'm familiar with fixturing sub-plates The OP needs something "magical" that will overcome the lack of room between top of workpiece (probably in vise) and the spindle. He could use three dowels to locate the vise on the mill table and toggle clamps to hold the vise in position. Unlock the vise, slide it out of the way, change tooling, slide vise back into position and lock it down.
                            Paul A.
                            SE Texas

                            And if you look REAL close at an analog signal,
                            You will find that it has discrete steps.

                            Comment


                            • #29
                              if the tool can be pulled out of the work enough to crank the work sideways out of the way, I don't suppose there would be much problem changing tools. That's most often possible, and seems a lot simpler than some sort of magic 2-way dovetail or the like.

                              But, a smaller taper length than typical with MT or B&S is obviously going to be much nicer to work with than the typical tapers on older machines. At least those NOT using CAT type tapers.


                              Originally posted by Paul Alciatore View Post
                              Your comments on the taper in the third paragraph illustrate my thought that you do need better control in the axial direction. This is why lathe collets have stops fitted to them so that multiple parts can be located in the same position on the same day, hour, even minute.

                              The problem with a shallow taper is you start to lose angular accuracy.
                              I expect it illustrates more clearly my responding to your extreme concern about axial location.... not any actual concern about it on my part......

                              I see a lot of "may have", and "could" type concerns, what might be characterized as "theoretical" concerns.... But as a practical matter, the CAT series tapers, which are pretty steep as tapers go, are sufficiently good that they have become a standard.

                              A shallow taper with a lot of wedging action has much more response to axial tension than a steeper taper. "One up" for steeper tapers, I'd say.... They do not let the tension wedge the socket open.

                              Then also, "approximating a sphere" is not really applicable.... You need to have a very large ratio of diameter to length to cause that to be a serious problem if any care is taken to align the tapers. I suppose a 3" diameter, with a 1/4" length might be getting to a "spherical section".... but that's rather extreme. You can mis-align nearly anything if you try hard enough, but again, the CAT tapers work well, without troubles.

                              Vertical turret mill tooling, most of which is 0.5" or smaller, would work fine with a diameter of say 1.25" and a taper of 45 deg included angle, taper being an inch long axially. I don't suppose anyone would have problems with spherical sections at that taper, and there would be almost a half inch end for drawbars.

                              It would be about as easy as can be to pop in even if it had to be canted a bit to get past the workpiece.

                              And I strongly doubt any serious issue with axial location would come up.


                              Some of your other comments relate to weldon holders. And there is some point to it..... but if a fractional tenth of axial misalignment is a concern for you, then you are already not considering any weldon type holder, both from an axial location point of view, plus due to what you would consider an unacceptable centering.

                              Alternates, such as collets, suffer from other issues, and *still* have basic concentricity issues. A new collet in the $200 class will be quite accurate... Ones in the $5 a pop class are just "pretty decent for the price". Errors of a thou or more are to be expected in the $5 class, which is likely to exceed whatever concentricity issues the weldon holder may have, without considering errors due to off-center drawtubes, etc. The weldon holder is aligned by the typical MT taper shank, and is not as easily canted off-axis by a drawbar, nor does it have the long flexible and misalignable "fingers" of the collet.

                              Now, it is also VERY important to note here that there is a *big difference* between a weldon holder, which can be easily scrapped and replaced if worn, and a machine spindle, which needs a robust tooling recess, since the spindle is not intended to be regularly scrapped and replaced....

                              What can be tolerated for a replaceable holder is quite unacceptable for a more permanent spindle feature. I think attention should be paid to the difference when making these sorts of comparisons............
                              Last edited by J Tiers; 08-21-2014, 08:39 PM.
                              CNC machines only go through the motions.

                              Ideas expressed may be mine, or from anyone else in the universe.
                              Not responsible for clerical errors. Or those made by lay people either.
                              Number formats and units may be chosen at random depending on what day it is.
                              I reserve the right to use a number system with any integer base without prior notice.
                              Generalizations are understood to be "often" true, but not true in every case.

                              Comment


                              • #30
                                In the "tips and tricks" book, it mentions cutting toolholder shanks down to save cranking the knee as far for toolchanges when its appropriate, ie drill chucks, smaller mills etc.

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