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.0625 hole 3 inches deep in Brass

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  • .0625 hole 3 inches deep in Brass

    I have a .25 diameter 3 inch long brass rod that I need to drill a .0625 hole lengthwise through the center. Tolerance is .0625 to +.005.

    My plan is to peck drill on the lathe against the micrometer stop. My tailstock CL is low, so my plan is to use a drill chuck attached to the QCTP. I'll hold the part in a collet chuck.

    My max RPM is 625 and I'll have to drill the part from both ends and try to accurately meet in the center.


    Other than an accurate setup, what else can you recommend to accomplish this?

  • #2
    That is awfully deep for such a narrow hole. 1/16 inch, right? I imagine that you might need a very still drill bit, possibly carbide?

    Use a spindle mounted collet to minimize any runout? Trying to pick up the same line from the other side within .005 might also require that you use a witness mark so that you can put it in the same orientation to do the second side.

    Dan
    At the end of the project, there is a profound difference between spare parts and extra parts.

    Comment


    • #3
      There are drill bits designed for what you are trying to do( deep hole drilling) : http://www.mscdirect.com/product/85769040 They have better chip removal than standard bits and can probably allow you to drill the entire 3" from one end.

      RWO

      Comment


      • #4
        Originally posted by RWO View Post
        There are drill bits designed for what you are trying to do( deep hole drilling) : http://www.mscdirect.com/product/85769040 They have better chip removal than standard bits and can probably allow you to drill the entire 3" from one end.

        RWO
        It may be hard to drill a 3" deep hole with a 3" long drill

        Do a search for gun drills, you may find one that's the correct diameter and length to do this, if not, then you can make a D-bit that may work. You also may want to start with larger diameter stock and turn it down between centers after drilling the hole.

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        • #5
          Originally posted by elf View Post
          It may be hard to drill a 3" deep hole with a 3" long drill

          Do a search for gun drills, you may find one that's the correct diameter and length to do this, if not, then you can make a D-bit that may work. You also may want to start with larger diameter stock and turn it down between centers after drilling the hole.
          Are you suggesting that to handle any wandering of the drill bit? It seems that turning between centers (using the drilled holes as the centers) ensures that it is centered.

          I looked around and found long 3/32 bits but none over 1-7/8 inch long in the 1/16 size.

          It sounds like a home made gun drill will be needed.

          Dan
          At the end of the project, there is a profound difference between spare parts and extra parts.

          Comment


          • #6
            A few observations for my own enlightenment if you will.

            Why is the hole required to be .0625 all the way through? Could you achieve the same effect by using a tube with a larger bore and plugging and drilling the plugs out to .0625?

            The other point is your maximum speed of 625 RPM... strikes me as slow by an order of magnitude, I would have guessed closer to 6000 than 600.

            paul
            Last edited by ironmonger; 05-05-2013, 04:47 PM.
            paul
            ARS W9PCS

            Esto Vigilans

            Remember, just because you can doesn't mean you should...
            but you may have to

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            • #7
              Indeed, that is a difficult ratio.

              What about CNC and slowwwly pecking it? Walk away and come back in an hour.

              Are there any edm like methods that can work for this (wet or dry)?

              Comment


              • #8
                Originally posted by ironmonger View Post
                A few observations for my own enlightenment if you will.

                Why is the hole required to be .0625 all the way through? Could you achieve the same effect by using a tube with a larger bore and plugging and drilling the plugs out to .0625?

                The other point is your maximum speed of 625 RPM... strikes me as slow by an order of magnitude, I would have guessed closer to 6000 than 600.

                paul
                Or in other words....Do you know what it is the purpose of the hole ?
                I would perhaps use a mill instead, if possible. Set up in a v-block, indicate, spot and drill, perhaps undersize, perhaps not.... but go as deep as you can, at least half way. Follow up with correct size drill.
                Flip , re-indicate and repeat....

                Comment


                • #9
                  I'd really like to know what application requires such a hole. Sounds like an engineer with no shop experience shop designed it.
                  Any products mentioned in my posts have been endorsed by their manufacturer.

                  Comment


                  • #10
                    Find someone with a hole popper edm. There is just no way you are going to do this on a lathe with .005 tolerance.

                    Comment


                    • #11
                      Originally posted by macona View Post
                      Find someone with a hole popper edm. There is just no way you are going to do this on a lathe with .005 tolerance.
                      Perhaps then drill the hole in oversized stock, and turn the stock between centers using the hole just drilled? That would be dead nuts.

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                      • #12
                        I put a 3/32" hole thru a 8" hardened steel shaft. Here is what I did:

                        I mounted the drills in the QCTP and made sure they were both pointing forwards and on center, using a test indicator on the chuck.

                        Start the hole with a ball end mill. (learned this trick from Rich)
                        Then use a stub length drill
                        Then use a jobber length drill
                        Then use an "aircraft" drill

                        If your drill holder is the kind that lets excess drill length stick out the back, then you can skip the stub drill and go right to the aircraft drill, being sure to occasionally advance the drill in the holder.

                        I would use a little bit of cutting oil, mainly to ensure smooth chip flow and no rubbing.

                        Comment


                        • #13
                          Any chance of getting some tubing with a 1/16" bore and maybe 1/8" o.d. and drilling a 1/8" hole and epoxying the smaller tube into it? Or use soft solder. A 3" long 1/8" hole would be no joy either, but it would be better than a 3" long 1/16" hole. (If you could find 1/6" bore tubing with a larger o.d. than 1/8" all the better, of course. Check www.smallparts.com )

                          If I had to drill it, I would do something along the lines of what beanbag describes. Clear chips FREQUENTLY!
                          Last edited by SGW; 05-06-2013, 08:52 AM.
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                          • #14
                            Originally posted by winchman View Post
                            I'd really like to know what application requires such a hole. Sounds like an engineer with no shop experience shop designed it.
                            My first thought also. :-) I can think of no application that would require such
                            a hole.
                            ...lew...

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                            • #15
                              I think it's entirely possible. I would put the part in the spindle, face off the end and use a center drill, spot drill or ball end mill to start the hole on both ends. Use a parabolic flute drill and drill a little over 1/2 way, turn end for end and repeat. Some cutting oil would help as well as clearing chips. The stated RPM will cut fine, just take a little longer than a fast RPM.

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