how to remove broken tap in reciever

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  • how to remove broken tap in reciever

    Long story short . Broke a 3.5mm tap ontop of my reciever . Any ideas on how to remove ?
    Seems welding or heat transfer works but im no engineer to have access to specialty tools like that.

  • #2
    Originally posted by M77" post=18649
    Long story short . Broke a 3.5mm tap ontop of my reciever . Any ideas on how to remove ?
    Seems welding or heat transfer works but im no engineer to have access to specialty tools like that.
    Was it a HSS tap or one of those cheap nasty ones?

    Nothing like a broken tap to upset the day.

    Blow the hole and spray lube into it ( helps so it don't bind ) when trying to get the tap out.

    Did it break near the top or in the hole, ie is there a bit of the tap to grab with pliers or vgrips.

    Comment


    • El-Skippo
      Skip commented
      Editing a comment
      Tiny taps are a pain in the butt. Bigger taps are a bit easier to get out. In my experience.

  • #3
    Removing a tap is no joke WHAT SIZE HOLE DID YOU DRILL FOR A 3.5 this is probably the fault hole to small number 31 or 32 drill would be the size
    method 1
    IF any of the tap is above the hole DO NoT grab with pliers or try allen key or wire place a nut over it and mig it to the tap gently TIGHTEN 1/8 turn,then undo

    method 2
    if you have access to tool steel grind up a tool that goes into the flutes and gently try to unscrew the slug

    METHOD 3
    IF ALL FAILS TAKE IT TO A GUNSHOP THAT HAS A SPARK ERODER

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    • fawdon
      fawdon commented
      Editing a comment
      you can not drill a tap unless you have a tungsten bit

  • #4
    Although I would not recommend this unless you have access to a mill, you can drill a HSS tap out with a masonry drill bit (carbide tip) this is what we do at work although it is risky but works fine if you have a mill

    Hope it helps, I feel for you

    Regards Byron

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    • El-Skippo
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      Editing a comment
      If goes any more pear shaped then it already has. Go get it burned out by someone that has a EDM ( if you were in Perth a friend of mine has the machine )

  • #5
    One method not yet suggested is a left hand twist drill bit.

    With a left hand twist bit, each time the drill bites into the tap, it will try to wind the brocken tap out of the hole.

    With a right hand twist drill each time thr drill bites it will actaully tighten the tap in you hole, making the problem worse.

    A specialist tool shop should be able to supply a suitable LH twist bit.

    Paul

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    • M77
      M77 commented
      Editing a comment
      I GOT IT! Can of Compressed air, turned the can upside down and sprayed the reciever were it kinda froze a little then used a 2mm punch i bought couple wacks and bang ! fell out . drilled the hole clean and now will buy another 4mm tap . thanks for all the suggestions

  • #6
    glad you got it out mate, i wasn't keen today to add to the advice already given. the issue you've had is an example of the flaw in these add on pic rails, as strong as the rail is (mine is a steel ken farrell) they still rely on the 4 tiny screws to hold them. perhaps the 4mm screw upgrade will become the norm for the harder hitting calibers in the future, or at the least a dowel drilled through the mounted rail

    steve

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    • #7
      For drill holes prior to tapping the old fraction works well.

      Lets say you need a hole for tapping a m5 into and the bolt is 20 tpi then you'd make the hole 1/20 smaller than 5mm or 4.75mm or thereabouts.

      For getting a broken tap out the only way that's ever worked well for me was to center or pin punch it out, then weld up the dud hole and start over.

      Always use sharp good quality taps.

      Totally painful breaking small taps.
      “Two things are infinite: the universe and human stupidity; and I'm not sure about the universe.”

      ― Albert Einstein

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      • Guest's Avatar
        Guest commented
        Editing a comment
        Originally posted by Capn Dazza" post=18949
        For drill holes prior to tapping the old fraction works well.

        Lets say you need a hole for tapping a m5 into and the bolt is 20 tpi then you'd make the hole 1/20 smaller than 5mm or 4.75mm or thereabouts.
        .
        no offence mate but that sounds too much like a guess to me, and a good way to have the thread strip out under torque. please use a tapping drill chart, it's the best and easiest way to attain maximum thread strength, for an M5 screw ( the OP is looking at M4) the drill size is more like 4.4mm (4.2mm course, 4.5mm fine)

        steve


      • Guest's Avatar
        Guest commented
        Editing a comment
        Originally posted by Capn Dazza" post=18949
        For drill holes prior to tapping the old fraction works well.
        Lets say you need a hole for tapping a m5 into and the bolt is 20 tpi then you'd make the hole 1/20 smaller than 5mm or 4.75mm or thereabouts.
        Not sure where you got that but if it works for you, OK

        Technically you are mixing units.
        M5 thread does not have 20TPI.
        It has a Pitch of 0.8mm
        As with ALL metric threads. If you subtract the pitch from the Thread diameter it will give you the Tapping drill size at 75% full thread.

        ie,
        M5 x 0.8 would be 4.2mm Tapping drill.

        Imperial threads (this one will confuse some of you)
        640 divided by TPI gives you the depth of thread per side in thou
        You need to double that figure (two sides), then subtract that from the thread diameter, then convert it to a fraction to get the drill size. (or bore size when screw cutting the female where you then add a few thou for clearance) :lol:

        Mick.

    • #8
      For the non-machinist I taught myself how to tap using these great tutorials and a (turned off!) drill press:
      http://www.youtube.com/watch?v=GCMjCCDKOes

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      • #9
        Job is done ! Success . Tapped the last hole all good . Re drilled the rail to accept new m4 counter sunk stainless screws. Will loctite screws tomorrow . What torque should I do them up to ?
        Heres a couple of pics .

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        • El-Skippo
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          I did mine with 243 blue goop ( loctite) and 40 inch pounds, cos I won't be needing to remove the mount ever again.

          But that was me

          Glad you had success. When I sore you had posted I thought " oh crap not again " haha glad its sorted
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