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how to extract a broke carbide drill bit?

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  • how to extract a broke carbide drill bit?

    This sucker is a #43 carbide bit for a 4-40 tap and it broke off flush. Any ideas how I can get it out? Diamond bit maybe?

  • #2
    Diamond is the only thing that will cut it. Run it in Left hand direction it might free the bit faster that way, use water for lubricant.

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    • #3
      Wouldn't one of those EDM devices I have been reading about do it?


      Paul A.
      Paul A.

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

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      • #4
        I did one #53 I think it was,I took a lead pencil and coated the area around the hole with lead,then I took a small brass washer that just fit the top of the bit and laid it flat ontop of the broken bit,silver soldered it in and then gripped it with a sharp pair of visegrip pliers backing it out left hand.The pencil lead keeps the solder from sticking to the work piece.
        I just need one more tool,just one!

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        • #5
          What kind of material is it imbedded in. Some time ago I purchased one of those sets of 1/8" shank diamond burrs sold by Harbor Freight. Kept it around for emergencies and I had one. Sure enough I was able to use-destroy might be a better word-several of those little burrs but I was able to break things up enough to loosen the drill.

          I like the silver solder and the left hand approach. I didn't think of it at the time.
          O

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          • #6
            the bit is stuck in silver. it's flush so the solder a handle idea while great probably wont work. I ordered some diamond bits to see if that will work.

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            • #7
              A question. Why would you use carbide to drill silver? That is asking for trouble.
              Jim H.

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              • #8
                I was tapping a hole and didnt have a HSS bit, only the carbide one that came with the tap.
                I had no idea it would bind up so quick. I was going nice and easy with it and when I was 1/2" in , snap!!!
                This is my first time working with silver. Is HSS the best to work with for silver?

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                • #9
                  Carbide and silver have different expansion rates. Silver isquite high, carbidemuch lower. Heat up the mess to 500 degrees and see if you can get the carbide drill out.

                  Silver chips love to pack and self-weld. You need to clear the drill frequently and use a cutting fluid.

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                  • #10
                    I'm afraid you may have to scrap the part. Silver is almost as bad as copper for work hardening. That bit is well and truly stuck. A 1/2" hole is pretty deep for such a small bit. About the only thing I can think of is, if possible, finish the hole from the other side with another bit and try to drive it back out with a fine punch, at least enough to get a grip on it.
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                    • #11
                      Hi. I'd try using a tap extractor if the flutes are clear enough to get it in there alongside the tap.

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                      • #12
                        My understanding is this is a broken drill bit, a carbide tap drill. Very small, .089"

                        [This message has been edited by Evan (edited 02-10-2004).]
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                        • #13
                          In the past people have stated that alum can be used to disolve steel taps/drills in aluminum and other non-ferrous mat'ls. Anyone know the reaction of silver and carbide in the presence of alum?
                          Lynn (Huntsville, AL)

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                          • #14
                            It might eat the silver but the silicon carbide will still be there when the sun burns out. The only way to even etch SiC with acid is Hydroflouric acid, BAD STUFF, and very slow. Won't work I'm afraid.
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                            • #15
                              I managed to break off a tap flush in an aluminum part and as it was a spiral flute, there was no way to back it out so I made a simple hollow end mill with the hole the diameter of the tap and the OD the diameter of a tap drill. The mill was slowly fed into the work to the depth of the tap section. Then a small punch was used to break off the small amount of material holding the tap. The hole was tapped to the larger size and a short section of new material was threaded into the hole and then drilled and tapped to the former size. The part was saved..

                              JRW

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