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Tapping hard to reach holes

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  • Tapping hard to reach holes

    I needed to tap some holes on my shaper in the yoke drive on the bull gear. They are hard to reach and I really didn't want to take the bull gear out so I made a tap handle extension. It has a small Jacobs chuck on the end to hold the tap. The extension is a custom piece of metal I made to act as a torque enhancer. The spiral four start thread encourages the tap to cut without breaking.



    Here it is in use. I made the extension longer than needed since one never knows when a few inches more might come in handy.

    Free software for calculating bolt circles and similar: Click Here

  • #2
    Very stylish.

    Presumably, picket practice piece?

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    • #3
      At first glance I wondered where you were getting the new and improved taps that didn't break

      Maybe it's just my un-educated eye but I can see where that design might actually be useful for the purpose at hand. Given the direction of the twist with the intended direction of the tap I could visualize less spring and more applied torque. (less spongy feel expected of a long shaft in radial twist) Does it really work that way or is there little differance?
      Last edited by Your Old Dog; 05-31-2007, 05:35 AM.
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      Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

      It is true, there is nothing free about freedom, don't be so quick to give it away.

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      • #4
        Yes, a practice piece. In particular a piece taken to the point where one more twist would break it. And yes, it isn't just stylish. The metal work hardens very noticably when twisted that far cold and becomes much less "spongy" so it really does enhance the feel. When work hardening takes place there is a point just before failure where the resistance to further deformation suddenly skyrockets. That's the point that extension piece is at. It has excellent feel and doesn't even feel like there is an extension.
        Free software for calculating bolt circles and similar: Click Here

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        • #5
          I realise that Evan wanted something straight away and not everyone is close to a store, having to rely on mail order but they do sell these.

          http://www.arceurotrade.co.uk/en-gb/dept_197.html
          Second item down

          There are also ratchet types for when you are in real tight spaces and they also do these in extended format.



          Had these years so don't remember where they came from but they have been handy at times.

          .
          .

          Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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          • #6
            I had to rig my drill extention to get the same thing done, believe me --- nothing to bragg about as the drive mechanizm was a pair of vise grips, did get the job done however...

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            • #7
              Evan, I'm implying that due to the 4 corners of this shank that, at least in theory, there should be some mechanical advantage to reduce the "sponge" feel you speak of. Your answer just address the property of steel to work harden.

              I'm saying that if you had a round rod with the same cross sectional area as the square, that the square rod would be stronger even though both had been twisted to a point of work hardening them. I'm basing this belief off the belief that a triangular shape is stronger than a round shape all factors being equal. It would be easy enough to test, make one with the spiral going in the other direction and try to put sink a tap. I'm betting that work hardening or not that the one with the twist reversed will fail. I've got a headache.
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              Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

              It is true, there is nothing free about freedom, don't be so quick to give it away.

              Comment


              • #8
                Thanks for the link, Sir John.
                Stepper motors and drivers at the right $/Nm ratio
                Just got my head together
                now my body's falling apart

                Comment


                • #9
                  Evan, I'm implying that due to the 4 corners of this shank that, at least in theory, there should be some mechanical advantage to reduce the "sponge" feel you speak of. Your answer just address the property of steel to work harden.
                  Nope, no advantage there. A tube is the strongest shape given a set quantity of material. I was joking, in part.
                  Free software for calculating bolt circles and similar: Click Here

                  Comment


                  • #10
                    How do you keep the chuck from backing off?

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                    • #11
                      I grind three flats on the tap for the chuck to hang on to.
                      Free software for calculating bolt circles and similar: Click Here

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                      • #12
                        Oh, that answers the question.

                        Let me ask another, How do you keep the threaded chuck on the spiral extension?

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                        • #13
                          Originally posted by Swarf&Sparks
                          Thanks for the link, Sir John.
                          Stepper motors and drivers at the right $/Nm ratio
                          Did I miss something? I checked out the link but did not find any reference to steppers.
                          Paul A.

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

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                          • #14
                            Perhaps a liitle off-thread Paul, but if you click the "enter shop" button at the top of page, you'll find all sorts of good stuff.
                            Just got my head together
                            now my body's falling apart

                            Comment


                            • #15
                              I like it, Evan. "Purdy",functional, and made of materials on hand.


                              I'd be lost without my tap sockets. Snap on however many extensions you need and whichever drive tool and go to town.
                              Jon Bohlander
                              My PM Blog

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