Broken tap or drill bit

Discussion in 'The Garage' started by Half Fast, Apr 19, 2013.

  1. Half Fast

    Half Fast Gnarly lurker

    Joined:
    Jan 7, 2007
    Oddometer:
    293
    Location:
    PA
    When drilling or tapping a hole, what are the options for removing a broken drill bit or broken tap that is stuck in the hole?

    I just finished a project that involved lots of new threaded fasteners and each time I held my breath thinking "Man, if I break this tap/bit I'm screwed". All went well but what to do if the worst happens?
    #1
  2. Motomedic

    Motomedic Long timer

    Joined:
    Oct 4, 2004
    Oddometer:
    2,520
    Location:
    Spokane
    An EDM (electrical discharge machining) machine is usually the best tool for the job.
    #2
  3. Half Fast

    Half Fast Gnarly lurker

    Joined:
    Jan 7, 2007
    Oddometer:
    293
    Location:
    PA
    That's what I was thinking. I was curious to ask if there were any other options but EDM was all I could think of.

    Thanks.
    #3
  4. Daryl_Stamp

    Daryl_Stamp Been here awhile

    Joined:
    Oct 7, 2006
    Oddometer:
    809
    Location:
    FL NY
    It's a PITA for sure, EDM is ideal solution but generally out of the reach of backyard or home workshop types.

    A former colleague always had reasonable success by tapping around radially with a punch if anything was sticking out, but the punch usually gets pretty chewed up.

    Another guy that worked with me showed me a trick when we had a tap break off in a mold that was in for a rush job,
    We put pins in between the flutes of the tap and kept wiggling it around until it came out, but it required a lot of expletives and angst to finally get it out. IIRC, it may have been old-school bobby pins, but for sure the tap wasn't jammed too bad, but nothing was sticking out either.

    Also saw a guy weld a nut onto the protruding piece of broken stud or tap, combination of heat cycle and better leverage worked ok on my brothers diesel rig.

    No one size fits all solution though for sure.
    #4
  5. silverbandit1

    silverbandit1 Long timer

    Joined:
    Jun 5, 2004
    Oddometer:
    1,010
    Location:
    NorCal
    I have removed broken HSS Taps with a carbide end mill and I have used a acid product ( available at machine shop supply ) if the tap broke in an aluminum part - otherwise EDM
    #5
  6. Beezer

    Beezer Long timer

    Joined:
    Oct 26, 2004
    Oddometer:
    6,067
    Location:
    Anchorage, formerly Spenard (hub of the universe)
    only other one I can add is the cutting torch. if the tap is broken off in aluminum you can blow it out with the ol fire ax. aluminum transfers heat way better than steel so if you heat the steel really quick you can burn it out of the hole with not too much damage to the aluminum, though you will probably need a helicoil. and yes, I have actually done this.

    best thing is to not need this kind of anguish in the first place. tap with a good lube, turn in a half, maybe 3/4 of a turn, and then out a quarter, keep the chips cleaned out of the flutes.

    as for broken studs... first is a left handed drill, if that doesn't work I try to drill it down the center "on size" , if I screw that up I helicoil it. I really don't even bother with easy outs anymore. a broken ez can be drilled with a cobalt though
    #6
  7. DaymienRules

    DaymienRules Traffic target

    Joined:
    Jul 10, 2008
    Oddometer:
    219
    Location:
    vancouver, bc
    I've successfully used a broken tap extractor tool once before. it looks kind of like a socket with teeth that engage the reliefs in the tap.
    #7
  8. Anorak

    Anorak Woolf Barnato

    Joined:
    Jul 23, 2004
    Oddometer:
    35,180
    Location:
    OAK
    Yes! True relief when it works. Patience is very important.
    [​IMG]
    #8
  9. kantuckid

    kantuckid Long timer

    Joined:
    Nov 29, 2007
    Oddometer:
    3,395
    Location:
    Kentucky-Eastern that is!
    Seriously, anything said is purely hit & miss until you fully describe the situation. We know not if it's a tap or a bit and nothing about the location or materials involved. It can be relatively easy or nearly impossible based on the total situation of factors. Lots of taps & bits get removed with no use of EDM. :ear
    #9
  10. S/W

    S/W Been here awhile

    Joined:
    Oct 21, 2003
    Oddometer:
    412
    Location:
    Massachusetts
    I have used almost all of these methods, except for the EDM and acid, with varying success. I have always had the best results with a carbide end mill. Of course, how many home shops
    have carbide endmills? Probably a small percentage.
    Another method I have used is to shatter the tap with a center punch. This works pretty good if the tap broke because it is brittle or improperly heat treated. The center puch should be a good tool steel for it to work.
    Prevention is the best course of action. Buying cheap taps will get you into trouble, as they aren't as sharp and might be brittle. If they aren't sharp, they will jam and break. Also, backing the tap out until the "chip" breaks off frequently will help keep the tap from jaming, and of course use plenty of taping fluid. Examine your tap for broken or chiped teeth before you start
    #10
  11. Flashmo

    Flashmo Whatever...

    Joined:
    Dec 21, 2008
    Oddometer:
    2,635
    Location:
    Vagabond Hippie
    I have tried that method...it always left a broken tap in a completely f'ed up hole that could no longer be removed with any method other than our portable EDM.

    I could see it working in thin plate where you only need to break a couple threads of the tap to get it to come out the other side. It has not worked for me in heavier materials.

    To me, it is not even a viable option any more...YMMV.
    #11
  12. S/W

    S/W Been here awhile

    Joined:
    Oct 21, 2003
    Oddometer:
    412
    Location:
    Massachusetts


    Sorry it hasn't worked for you,I have done it a bunch of times.
    #12
  13. ohgood

    ohgood Long timer

    Joined:
    Sep 21, 2010
    Oddometer:
    3,315
    Location:
    alabama
    drill the back side of the hole if possible, then whoop the drill bit of tap from there.

    once its out, drill and tap next size (or two) up and chinese knurl the back side of the tapped hole.

    then heat all thread and force it through, all the way with a little hanging out.

    hack off the all thread, both ends.

    center punch around the all thread, and the edge of the all thread. a lot.

    peen the all thread flat.

    file flat ( the edge cuts best and planes )

    drill and tap the new hole, mo carefully.

    most folks can't spot the repair. ;-)
    #13
  14. Stan_R80/7

    Stan_R80/7 Beastly Gnarly

    Joined:
    May 12, 2012
    Oddometer:
    1,685
    Location:
    VA
    The broken tap problem lead to the Tapmatic:

    http://www.use-enco.com/CGI/INSRIT?PMAKA=317-0726&cm_mmc=Didit-_-SEM-_-GglProd-_-GglProd&003=18299132&010=317-0726&{copy:002}&{copy:004}&{copy:005}&10=317-0726&gclid=CK2G1Zis3rYCFYMWMgodNWAAjg

    Which is a wonderful tool if you are tapping many holes (but a bit pricey for the HSM). I have always tapped holes by hand using a guide or adapting a mill for the purpose - with plenty of cutting fluid and judging by hand force taps don't bread - but it is slow.

    I think the job would decide how to remove the broken tap. Generally, work is done for profit and time is money so the quicker the tap is removed and threads formed the better. Machine shop forums are a better place to ask this question if you are looking for experience and ideas. YMMV.
    #14
  15. ttpete

    ttpete Rectum Non Bustibus

    Joined:
    May 13, 2009
    Oddometer:
    6,260
    Location:
    Dearborn, MI
    A few things about taps:

    Always buy and use high speed steel taps. They're ground shiny all over and marked HSS. They're tough and strong. Carbon steel taps are cheaper, but they are hard as glass and brittle and break easily.

    Taps do get dull after some use. When this occurs, don't use that tap to cut new threads, especially in aluminum or brass. You can use it to clean gasket sealer and dirt out of a threaded hole. Don't do this with a sharp tap if you want it to remain sharp.

    Always use a tapping fluid. Kerosene works well for aluminum. I like Rapid-Tap for ferrous metals. Stainless steel needs a different lube. I've used Anchorlube for many years. It comes in a squeeze bottle and looks like green snot.

    Always use a proper tap wrench so no side loading is placed on the tap. Back the tap up every rotation to break the chips off.
    #15
  16. Half Fast

    Half Fast Gnarly lurker

    Joined:
    Jan 7, 2007
    Oddometer:
    293
    Location:
    PA
    This is all great info, thanks. I don't have a specific issue at present. I just wanted a better understanding of what options are available.

    This last project involved drilling and tapping in tight spots on a bronze plaque. Some areas there was barely enough room to start and turn the tap. Also lots of odd angles so the risk of breaking a tap or drill was higher than normal.

    Here the fastener was under the brim of a hat. I could not access the back of the piece.

    [​IMG]

    (That's a missing canteen strap being replaced on a military monument. Yes, I know it's a simple tig job but if pins were originally used I drill out the old pins and do it the same way.)

    I forgot about those tap removal tools. I'm sure, just like screw extractors, they work "sometimes". Still, it's another option to have on hand.

    Again, thanks for the ideas- I knew this was the place to ask!
    #16
  17. GreaseMonkey

    GreaseMonkey Preshrunk & Cottony

    Joined:
    Jun 16, 2006
    Oddometer:
    5,437
    Location:
    The only county in Illinois with no train tracks
    For that job illustrated I strongly recommend an "extended tap wrench". Not only does the extra length really help, the longer handle makes it a lot easier to keep it in line.
    [​IMG]
    #17
  18. Half Fast

    Half Fast Gnarly lurker

    Joined:
    Jan 7, 2007
    Oddometer:
    293
    Location:
    PA
    I like.

    Gonna add one to the tool kit.

    :nod
    #18
  19. ttpete

    ttpete Rectum Non Bustibus

    Joined:
    May 13, 2009
    Oddometer:
    6,260
    Location:
    Dearborn, MI
    There are also tap sockets available. They have an internal o-ring to hold the tap in. Handy for inaccessible locations.
    #19
  20. Ironwood

    Ironwood Friday Harbor, WA

    Joined:
    Apr 10, 2008
    Oddometer:
    806
    I sometimes chuck the tap in a cordless drill with just snugging the chuck. It allows you to get steady pressure and a good angle on the tap. If it gets too tight it will slip in the chuck. And it is much faster as well.
    #20