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Ancient history: half drilling vee for tailstock. Why??

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  • Ancient history: half drilling vee for tailstock. Why??

    First, I understand the entire tailstock drilling vee thing ( = "crotch center" ), but why make one with half a vee? I can't come up with a reason. picture

  • #2
    It may be shop modified. The only reason I can think of is for clearance of some protrusion on the backside of tube or rod.

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    • #3
      If the "half" were actually not quite half, it would allow one to drill completely through a tube/pipe/rod with a larger diameter than would be the "norm"...or at least I would assume that the width of the "V" of the crotch sort of controls how large a bit can go entirely through before touching the sides of the "V".

      I also agree with CCWKen, might have been for a very specific purpose/reason.

      The other thing I thought of, though I don't know how valid it is, it would give a flat edge to measure from...

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      • #4
        I've never seen a drill pad or "crotch center" before. Could someone give me a short primer on the purpose/operation (or point me towards some good reading)?

        Thanks!

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        • #5
          Originally posted by Fasttrack View Post
          I've never seen a drill pad or "crotch center" before. Could someone give me a short primer on the purpose/operation (or point me towards some good reading)?

          Thanks!
          You put that in tailstock, drill in the chuck and your workpiece (usually round) in that V and advance it against the drill with the tailstock to get a hole in the workpiece.

          Edit: This is easy way to drill on center holes in pipes and small rods.
          Amount of experience is in direct proportion to the value of broken equipment.

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          • #6
            Originally posted by Jaakko Fagerlund View Post
            You put that in tailstock, drill in the chuck and your workpiece (usually round) in that V and advance it against the drill with the tailstock to get a hole in the workpiece.

            Edit: This is easy way to drill on center holes in pipes and small rods.
            Yes, since the head stock and tail stock of a lathe are supposedly accurately aligned, this is a quick and accurate way to drill round stock (rod or tube) through the center without any additional set up as you would need if using a Vee block in a drill press or vertical mill.
            Paul A.

            Make it fit.
            You can't win and there is a penalty for trying!

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            • #7
              If it were me, I would have done it if I needed to repeatedly drill a cross-hole - for example, for a cotter pin - through a turned part, whereby the cross hole is referenced off a shoulder on the part.

              So, you would butt the shoulder on the part up against the ground away face of the V-centre, which gives you the right distance away from the shoulder, and cross drill - to make a a second-op simpler. You could do the same op on a drill press or a vertical mill, but perhaps it was more sensible for the creator to do that op on a small lathe, perhaps with a lever tailstock.
              Last edited by Sun God; 06-05-2013, 05:10 AM.

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              • #8
                Thanks guys!

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                • #9
                  It would seem a little dangerous if the part wasn't supported on both sides of the hole being drilled. A recipe for binding.

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                  • #10
                    That was my thought too, Forestgnome. Sun God's thoughts seem the most practical. At least if there was a shoulder that would aid in supporting the workpiece cross-wise to the vee. Even so, I feel like it still makes no sense, and it is a manufacturer catalogued item:

                    Unfortunately, the catalog provides no more detail. It is called, quite literally, "drilling vee, half." Bizarre.

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