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method of mounting tooling on a mill/drill

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  • #31
    Originally posted by Paul Alciatore View Post
    That sounds like more trouble than cranking the head up and down. But usable if you are at the limit of vertical travel.
    Three pins/points is a common part locating method for both wood and metal work. Maybe you never used toggle clamps: http://www.destaco.com/horizontal-hold-down-clamps.html They are very quick and hold securely.

    With the vise slid out of the way, tooling could probably be changed without moving the head. A power draw bar would still speed things up.

    Maybe the OP needs to start using stub or screw machine drills instead of jobbers length.
    Last edited by Rosco-P; 08-22-2014, 12:52 PM.

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    • #32
      Originally posted by Rosco-P View Post

      Maybe the OP needs to start using stub or screw machine drills instead of jobbers length.
      that's something I keep coming back to, it would make switching back and forth between milling, drilling and countersinking/ chamfering a lot easier. Just have to save up the pennies, looks like there are 29pc fractional sets for ~$60 which isn't too bad.

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      • #33
        Hey, J, calm down. I was just trying to present a different idea here. Original thinking.

        I was attempting to address the OP's concern. He wanted a way to change tools without cranking up and down. Sure there are other ways to change tools and I as well as most of the folks here who use a vertical mill have done things like cranking the work to the side.

        You say, "I expect it illustrates more clearly my responding to your extreme concern about axial location.... not any actual concern about it on my part......". OK, you are not concerned. That is fine. Perhaps I should not have added this to the original requirement, but it does seem logical. I have observed that tapers have very poor axial positional control. At least shallow ones do. So, as far as my concern being extreme, I doubt it. Wouldn't that be a real plus on a CNC machine? Probably on a manual one when identical parts are being made. Anyway, yes I was concerned about it as I looked at the problem, but hardly extremely concerned.

        Then you say, "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." Well, a very short taper is exactly what I was discussing. If you want to avoid cranking up and down (or cranking the work sideways which can take just as long) then you need a mounting method that does not require a very long axial movement. If you read my post carefully, you will see that a very short, wide diameter taper is exactly what I was talking about. To quote myself, "That short taper starts to approximate a spherical surface." Notice the word "short" in there.

        I know that the CAT type tapers are widely used and they DO work with good positional accuracy in all directions. But I assumed that the OP has an R8 or other small angle taper style spindle and adding a CAT type adapter would be somewhat awkward at best. I would think you are going to lose at least two inches of vertical clearance under the tool to the taper alone. By the time you get down to the tool tip, it will be hanging WAY out there.

        Again, we are not talking about a new spindle, just a method of attaching tools to the existing one. So, your comments about a pin/socket not being easily replaced are not valid. The spindle end of my proposed adapter would change just as easily as a Weldon style holder. It may be a bit more expensive, but it would be easy to change. I have never used one or even held one in my hand, but are Weldon holders, regardless of price and quality level, really accurate to fractional tenths? I mean, do they actually hold a tool that well centered? Wouldn't at least part of that depend on the accuracy of the size of the shank on the tool itself? And there has to be some allowance to allow the tools to be inserted and removed: I would imagine a few tenths, at least. Or do they use an interference fit? Seems that would make inserting them very difficult and removal almost impossible. But, as I said, I have not used them so I don't know.

        I do see your point about a mid length, 45 degree taper. It would have good accuracy in all directions, but you still have that one inch or so of length. Perhaps it would not be much of a problem when changing tools as only a fraction of an inch would be needed for the tool to be rotated out or in, but there is that one inch of lost vertical work envelope. I was looking at a way to keep that down to 1/2 to 1/4 of that amount.
        Paul A.
        SE Texas

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

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        • #34
          This system uses a iso 30 , but it seems to be a quick change toolholerd that also needs a lot les hight to change the tools
          http://www.marktplaats.nl/a/doe-het-...reviousPage=lr

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          • #35
            Originally posted by Paul Alciatore View Post

            I do see your point about a mid length, 45 degree taper. It would have good accuracy in all directions, but you still have that one inch or so of length. Perhaps it would not be much of a problem when changing tools as only a fraction of an inch would be needed for the tool to be rotated out or in, [b]but there is that one inch of lost vertical work envelope. I was looking at a way to keep that down to 1/2 to 1/4 of that amount.[b/]
            If in the spindle, the entire holder could be swallowed up to the top rim.... that would mean ZERO lost to the holder, aside from removal. Of course, removal IS the issue, but in this road of thinking, there are two choices, you decision as to which poison you take.

            1) Have toolholder swallowed in spindle, but then have a need to remove it which means extracting it, presumably axially. That takes a distance which at worst is the full depth of the holder PLUS the length of the tool axially.

            2) Have toolholder slide out sideways somehow. never mind whether it is practical. That requires a depth at worst of the full depth of toolholder, PLUS the length of the tool axially.

            Hey... those are almost exactly the same!

            So....

            Now consider a larger spindle diameter..... toolholder goes down the length of it, on the end of an inside "push bar". The push bar forces it against a taper inside the spindle, trapping the holder in position and securing it.

            ZERO loss of daylight inder the spindle, AND the fairly steep, maybe 45 deg included angle tapers give very accurate positioning.

            Hey... we might have a potential winner here.

            What consideration does it not cover?
            CNC machines only go through the motions.

            Ideas expressed may be mine, or from anyone else in the universe.
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