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Anyone Here Experienced With Thread Forming Taps?

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  • Anyone Here Experienced With Thread Forming Taps?

    I didn't realize forming taps came in taper, bottoming, etc. I mistakenly purchased a 6-32 OSG bottoming style thread forming tap, with a 1.5 thread taper. I've got a bunch of holes to tap in 1½ X 1½ X 1/8 extruded 6063 alloy aluminum angle. I've got a Bridgeport with a reversing power tapping head. Am I likely to succeed with this tap, or will it just bind & break?

    I'm building an open computer "case" for a scrypt mining rig. Don't really want to wait for another tap...


    Thanks
    Ed

  • #2
    No problem in that material, not used to the numbered UN series as they are virtually unheard of outside the US but do make sur you have the correct dril size.
    Kerosene or WD 40 takes a good tapping fluid.
    .

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



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    • #3
      Thank you, Sir John! I'm now looking forward to receiving my tap on Monday


      Ed

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      • #4
        Use lots of kerosine

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        • #5
          Make sure to use the right drill also.
          Form threads require larger drill sizes.
          Here's a chart:
          Forming Tap drill chart

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          • #6
            If I were hanging everything one one tap, I would certainly try it out on a scrap. As has been mentioned, use the right sized hole and lube/coolant. I like WD-40 or kerosene for aluminum. Bob.

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            • #7
              I have zero experience with thread forming taps so I must ask. Is WD-40 or kerosene really the best cutting fluid for them, even in aluminum? I do know that WD works well for cutting aluminum and I use it all the time. It would seem to me that lubrication properties would be a lot more important than cooling. I would think/guess that a high pressure grease or oil would be better. Or would it?
              Paul A.

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

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              • #8
                Originally posted by Paul Alciatore View Post
                I have zero experience with thread forming taps so I must ask. Is WD-40 or kerosene really the best cutting fluid for them, even in aluminum? I do know that WD works well for cutting aluminum and I use it all the time. It would seem to me that lubrication properties would be a lot more important than cooling. I would think/guess that a high pressure grease or oil would be better. Or would it?
                The WD or Kerosene are both thin, this is key.

                What you want is a thin fluid that will "soak" the tap in non ferrous metals. That's why the original "tap free" was so good. It had Trichloroethane included. This a truly magical cutting fluid for Aluminum.

                I would get a few more taps though.

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                • #9
                  [QUOTE=Paul Alciatore;895779]I have zero experience with thread forming taps so I must ask. Is WD-40 or kerosene really the best cutting fluid for them, even in aluminum? I do know that WD works well for cutting aluminum and I use it all the time. It would seem to me that lubrication properties would be a lot more important than cooling. I would think/guess that a high pressure grease or oil would be better. Or would it?[/QUOTE

                  As you might realize, the term "cutting" is a bit of a misnomer here.

                  And as has been said before in other contexts, "any oil is better than no oil" and that applies here also. I have form tapped thousands of holes in some long forgotten alloys of aluminum castings and used various fluid facilitation, but mostly just a strong solution of some soluble oil or water based coolant in some type of mist system. The majority of the holes were 4-40 and the tapping rpm was in excess of what you could run a geared tapping head at, or in excess of 2000-2500 rpm. The friction clutch style of tapping head (Procunier) has a much longer life at these speeds.

                  As has been said, hole size is of the utmost importance, also as has been said, the bottoming style tap should produce no problems. Nevertheless I am a bit concerned when you say that you are waiting for you "tap" to arrive. I would have preferred to hear the plural, tapS.

                  Dave

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                  • #10
                    I still use trike for tapping. 75% trike and 25% ATF to give it a bit of body and prevent it evaporating quickly.
                    Works better than anything else I have found.
                    .

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



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                    • #11
                      This is a time when Tap Magic for Aluminum would work really well.

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                      • #12
                        We use thread forming taps whenever possible. Aluminum taping is a good use.

                        6-32 major diameter is about .136, that tap shouldn't be a problem in 1/8" thick material. But, tapping using a spindle reverse on a mill isn't the most ideal method with a tap that small and easily broken (not saying you can't do it, it does require some eye-hand coordination, you're requiring the lead of the tap to start pushing the quill back up). You should have an axial float holder or a tapping head.


                        A little trick with thread forming taps is to regrind the end if it isn't what you need. They appear to be made with no radial relief so simply and carefully spinning the tap against a grinding wheel will allow you to change the taper amount. We have done this dozens of times when the tip breaks off a tap and we don't have or want to use a new one.

                        Tap drill size is only critical on deep holes, tapping sheet metal is possible with a much smaller than recommended tap drill. The tapped hole then extrudes the excess material out the back side giving a longer length of usable thread engagement. If you need the back side of the hole to be smooth, no extrusion, on soft materials like aluminum sometimes you have to countersink it slightly.

                        As far as lubrication, yes, you should have something. I'm not a big fan of home remedies. There are lots of products specifically made for tapping so why not use them?


                        Something you very seldom see is that forming taps wear on the end. After many, many tapped holes the tap will get smaller. I have seen 10-32"s used in high production (several thousand holes in steel) that got so small on the first few turns of the profile the tapped holes came out under sized.
                        Last edited by DR; 01-05-2014, 02:58 PM.

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                        • #13
                          The effectiveness of thread forming taps depends on the base material, lubrication and depth of thread. I have used them in cast iron, cast and wrought aluminum, 1018 cold roll steel, A36 hot roll steel, 4140 and 86L20.

                          First, they don't work well in cast iron, unless it is very well annealed. It works very well in ductile iron, aluminums and steels.

                          The tap drill size is critical and an undersized hole of any depth will fill up with cold formed material, sieze and snap off the tap. In very thin material, the cold formed material can push out ahead of the tap, so success is possible. In production we experimented with tap drill sizes in each material. If the tap drill is too large, you see the thread crest as having a groove. As the tap drill size is reduced, the groove in the thread crest gets narrower and the thread crest begins to show a radius on the cold formed material. The ideal tap drill size will give some indication of radius on the thread crest, but will still show a lap line right at the thread crest. Usually the tap drill size will be at or just above the pitch diameter of the thread.

                          In aluminum, ductile iron and steel, we used cimcool or soluble oil in a flood as the coolant. WD40 or kerosene also work well in aluminum. On the radial drill, regular sulfonated cutting oil worked well. In regular cast iron we used a spiral point cutting tap and didn't mess around with thread forming taps.

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                          • #14
                            Originally posted by DR View Post
                            A little trick with thread forming taps is to regrind the end if it isn't what you need. They appear to be made with no radial relief so simply and carefully spinning the tap against a grinding wheel will allow you to change the taper amount. We have done this dozens of times when the tip breaks off a tap and we don't have or want to use a new one.
                            This makes me think that single-pointing my own thread forming tap from tool steel and then hardening it is feasible... what say ye?

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                            • #15
                              Thread forming taps are not round. The cross section over the length is lobed with either three or four lobes. The tips of the lobes form the thread and the clearance between the lobe tips reduce surface friction and provice space for lubricant to get between the forming lobe tips. A purely round tool will be hard to drive and prone to galling due to lack of lubrication.
                              Last edited by Jpfalt; 01-08-2014, 11:07 PM. Reason: spelling

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