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Idea for removing broken tap.

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  • Idea for removing broken tap.

    Well I was finishing up the boring bar and hand tapping the 6-32 screw hole for the insert screw when I snapped the tap off. It was late so I just came home. I could just cut the bar shorter and re-machine everything but tonight I had a crazy idea. At the lab/shop I've got a ventilated hood, sulfuric and hydrochloric acids, and very small eye droppers. Would it be legitimate to disolve the tap out with acid then weld up the hole and re-drill? Or should I just do it the old fashioned way and drill it out with tungsten carbide? I have to admit I'm more than a little curious about how well the acid might work.

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    -Christian D. Sokolowski

  • #2
    Christian,
    Is it a through hole? If it is just beat it through with a hammer and punch. then put a Heli coil in there or go to the next size set screw. Sometimes with carbon taps and a small enough punch you get lucky and they disintegrate when you hit them and do little damage to the threads.
    Mark
    Mark Hockett

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    • #3
      Yup, it's a through hole but I don't have any punches small enough. I suppose I could just go buy one, but I haven't had a whole lotta luck with that method in the past. I'll probably just cut the bar shorter and re-machine it. Didn't take all that long to begin with. I was just curious if anyone else has tried acid in this manner.

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      -Christian D. Sokolowski

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      • #4
        Oh, can't go up a size on the screw. I'm using 3/8" IC carbide inserts, a larger screw won't work.

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        -Christian D. Sokolowski

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        • #5
          I've heard of success stories disolving a tap out of AL, but it you got the right toxic sludge wouldn't also just disolve the end of the boreing bar as well?
          .

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          • #6
            How about drilling from back side if it is a through hole. Hold in v block or vise with v groove, use tap drill to line up. Then use carbide drill.
            Russ H

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            • #7
              Saw a tap remover made with a old arbor press. The drive was a vibrating pen type engraver. It was mounted to the stem, as you lowered the rod into the metal, you dribbled fluid on it and the vibration jiggled the rod enough to keep the arc excited. It would burn through a tap in a few minutes. Being a small arbor press it was portable.

              I need at least one around here. Them lil 6/32's bust so easy.. I have better luck using a battery drill than a handle too.
              Excuse me, I farted.

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              • #8
                I heard about that A LONG TIME AGO BUT NEVER USED ONE. They do work though?

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                Dave da Slave , BFH

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                • #9
                  Mcgyver, yes it will dissolve the boring bar but I suspect only inside the hole since it's a through hole and I'd be applying acid with a fine eye dropper.

                  Russ, carbide is the way I normally do it. I just wanted to try something different.

                  Just for the sake of experimentation I'm gonna try this later today. I want to stress that I have the proper safety equipment for working with chemicals otherwise I wouldn't even think about it. Also acids should be kept away from machine tools, even the vapors can cause rust.

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                  -Christian D. Sokolowski

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                  • #10
                    Hello Christian,
                    Heat up with oxygen and acetalene until red hot then cut off the acetalene and blow out the tap with just oxygen. Try it you will like it.
                    Chuck

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                    • #11
                      Acid didn't work. I'm out of the really strong stuff and only had a weak dilution. I'll try the torch trick just for the heck of it but I'm going to go ahead and re-machine the part. I just felt like experimenting.

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                      -Christian D. Sokolowski

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                      • #12
                        Hello
                        This is a place for a disintegrator or an edm hole popper.
                        Go to google type in "Electro arc" for a lot of information on this subject.
                        re
                        Herm Williams

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                        • #13
                          Ordinary Alum was mentioned a few weeks ago as a solution for broken taps in aluminum. I don't know if it would work well on other materials. Check out the threads. People were amazed.

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                          • #14
                            I used to work at a place that made a lot of fatigue specimens, and they regularly dissolved broken taps out using conc. hydrochloric acid. Once the tap was gone they just started a new tap down the existing threads and carried on. However, they were working on nimonic alloys and other exotica, so I dont know how much damage would be caused to steel threads.
                            Thers no such thing as too many tools

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                            • #15
                              I used to work at a place that made a lot of fatigue specimens, and they regularly dissolved broken taps out using conc. hydrochloric acid. Once the tap was gone they just started a new tap down the existing threads and carried on. However, they were working on nimonic alloys and other exotica, so I dont know how much damage would be caused to steel threads.
                              Thers no such thing as too many tools

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