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Keeping tap square to material?

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  • Keeping tap square to material?

    Does anyone have some advice on how to keep a tap square to the material when tapping holes for a bolt?

    I have aluminum bar 1 1/2" wide but only 1/4" thick. I am tapping a 1/2" hole but I am finding that it is very easy to tap the hole and not have the threads/bolt square to the material (due to the softness and material thickness)

    Any help would be appreciated.

  • #2

    You can mount the tap in a drill press chuck and turn by hand.A lathe or mill will work also.


    • #3
      Or use a hand tapping machine:

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      • #4
        Tool-Makers use a tapping block.

        We have to hand-tap holes sometimes when working (in assembly).

        In a good flat chunk of tool-steel, Mild-steel will work
        but it won't last as long, drill nominal sized holes for each tap size.
        Using a good drill-press.

        To make a nicer one, drill for ream.....instead,
        and ream with 1 thou / over-size reamers.

        Now clamp or hold your tapping-block inplace and it will
        guide the tap in straight.

        Another way is to have your work level, and tap with a hand-drill
        that has a {plumb-bubble} in the heal of the handle.

        Negative people have a problem for every solution


        • #5
          Or the famous "try-angle" method.

          This requires two people that like you and one who doesn't care.

          Have each of the two friends stand @ 90 degrees to each other.
          Each will coach you as to when the tap is truely square.

          The indifferent friend, will settle the dispute, after the work is spoiled.

          Negative people have a problem for every solution


          • #6
            A simple method is to cut an "L" shaped block of wood out of something like a 2X4. Place the inside corner over the hole and make sure the tap touches both sides of the inside corner as you tap the hole. Similar to the 2 buddies method mentioned earlier, but the wooden block won't drink your beer.



            • #7
              Thanks guys, I knew I'd end up with a few good ideas!


              • #8
                Some of the tool company's offer a hand tap handle with a flat base (you hold the base against the item your going to tap) with a hole in the center of it that the tap goes through that will keep you tap handle and threads straight. Enco sells them i think they are about 15 or 20 bucks but if you cant find one the method Vice Grip told you about is the next best way to go. When i was just starting out as a Machinist one of the first projects our shop teacher had us make was a tap block i made mine out o A2 tool steel and had it heat treated and i still have it and use it from time to time.
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                • #9
                  Yeah. Understand there are three types of taps. Taper, plug, and bottoming. Start with taper tap. Keep the tap verticle to the work when starting. All goes well if you pay attention.


                  • #10
                    i am with the guy on starting it with the jacobs chuck on a drill press or mill,start with a plug or starting tap preferably a starting ,chuck your tap in the jacobs chuck turn it buy hand to start it as far as you can then finish with a tap handle . invest in some good tapping fluid a little goes a long ways !watch tapping aluminum it will gauld on you so be sure to use tapping fluid .. good luck chris


                    • #11
                      Tap holders usually have a central indentation on the top. Center and clamp your work on your drill press table, then insert something like a 1/8" drill or a center punch into the chuck of the drill, lower the quill till the tool is inserted in the central indentation of the handle and keep applying light vertical pressure while turning the tap holder handles by your other hand.
                      Last edited by MichaelP; 01-12-2009, 11:21 PM.


                      • #12
                        Take a look at the "t-type" tap wrench on the top right of this page:

                        Something with a pilot guide like that would make it easy to start using a drill press without having to move the quill.

                        --- RJL ----------------------------------------------

                        Ordinarily I'm insane, but I have lucid moments when I'm merely stupid.


                        • #13
                          Here is a pretty simple solution for solving the misaligned tap problem.

                          The article was written by a machinist. So your mileage may vary depending on your skill, tools, and creativity.

                          - BDC
                          Last edited by BillDaCatt; 02-06-2009, 10:00 PM.
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                          • #14
                            I clamp a die of the same size to the base material and thread it (the tap) through the die.