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Help! Broke a drill bit inside my rafter. How to get it out?

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  • Help! Broke a drill bit inside my rafter. How to get it out?

    Hey all, I was up working on my roof today, putting my mounts in, and I managed to break a bit off inside my rafter. Most of the bit is in the hole (prob 2 1/2" worth), and it broke beneath the surface. I believe the top of the bit is probably in the OSB sheeting, rather than actually inside the rafter.

    Any suggestions on how to get it out and still be able to use the hole? It's one of my last mounts, so changing my pattern is not an option at this point.


  • #2
    There may be, and probably are lots of ways I don't know about, so, I called a very old friend from Scotland who's a retired tool & die maker and truly, IMO, and that of a lot of others, one of the smartest technical and common sense people on this planet. Millions of tricks, all probably learned the hard way. His advice: Unless you can get at the broken part of the bit from the other side of the piece (the rafter) by drilling, it'll be next to impossible to get it out. You may be able to drill all the way through the rafter to the broken bit from the backside, but that will require knowing where the bit is pretty much dead nuts. If you can do that successfully (??) through bolt it with nuts/lockwashers, I'd add, maybe a strongback (wood bolted to either side of the rafter) to add some strength to the rafter to replace the strength lost from material removed by any the extra drilling, but that might be overkill.

    I suppose, there are a lot of ways around the situation. Not a recommendation necessarily, but I once had to use U bolts to affix an antenna base to a roof. I drilled 2 holes from the inside, one on either side of the rafter, and bolted a piece of 2 x 2 angle to the ends of the U bolt that stuck through the roof exterior. Flashed it and called it done. Did the same w/3 guy wire anchor points.

    Good luck.

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    • #3
      Excavate around the bit until you have enough exposed to get a pair of needle nose pliers or vise grips on the bit and back it out. You probably hit a knot.
      Good luck they can be a real PIA to get out.

      Comment


      • #4
        If it went all the way through, drive it out with a punch and punch it through. . Otherwise if room, drill another hole in the bracket, and make a new hole. Or use some good Empoxy to seal the hole and glue that bracket to the roof with roof cement.
        MSEE, PE

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        • #5
          Originally posted by Sunking View Post
          If it went all the way through, drive it out with a punch and punch it through. . Otherwise if room, drill another hole in the bracket, and make a new hole. Or use some good Empoxy to seal the hole and glue that bracket to the roof with roof cement.
          I'm not quite sure I understand. Are you suggesting roof cement will serve as a fastener ?

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          • #6
            Originally posted by LucMan View Post
            Excavate around the bit until you have enough exposed to get a pair of needle nose pliers or vise grips on the bit and back it out. You probably hit a knot.
            Good luck they can be a real PIA to get out.
            This is currently my plan. Since I'm pretty sure the top of the bit is in the OSB layer, I can dremel a little bit of material out without impacting the rafter and pull the bit (I hope). I figured before I tackle that project, I might as well make a post to see if someone has a better method I had never heard of.

            Now I just need to find a better 7/32 bit that's long enough. I broke this one and spun two others out today. I'm using harbor freight bits because neither Home Depot or Lowes sells anything that's long enough for my lag bolts. Time to find a specialty tool shop.

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            • #7
              Harbor freight drill bits may not be the worst but are definitely bottom of the barrel. Go with name brand bit. Irwin Tools are generally good to great quality.

              Pardon me for a rant but a general comment is Harbor Freight tools may be functional but pretty much across the board the consumables they sell like drill bits, cut off wheels, grinder disks, saw blades, sandpaper are all subpar. I run into a lot of folks who don't realize how much extra work they are doing to accomplish a task due to crappy consumables.

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              • #8
                Leave the old bit in the hole. Drill a new hole at a slight angle in such a way as to leave the head of the fastener in the proper position but with a slight tilt. Just make sure everything is sealed properly.

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                • #9
                  Or you can just use the Timberlok screws from Lowe's without pre drilling.

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                  • #10
                    Originally posted by peakbagger View Post
                    Harbor freight drill bits may not be the worst but are definitely bottom of the barrel. Go with name brand bit. Irwin Tools are generally good to great quality.

                    Pardon me for a rant but a general comment is Harbor Freight tools may be functional but pretty much across the board the consumables they sell like drill bits, cut off wheels, grinder disks, saw blades, sandpaper are all subpar. I run into a lot of folks who don't realize how much extra work they are doing to accomplish a task due to crappy consumables.
                    Totally agreed. I have a lot of Harbor freight stuff, but it's typically only used on projects where I can account for their potential issues. Unfortunately, I couldn't find a more reputable 7/32 bit that was longer than about 3". I need to be able to penetrate 4" with the lag bolts for my Quickmount PV mounts.

                    Today's project is finding a better bit that's long enough. It's too windy to get on the roof, so retrieving/dealing with the old bit will wait till tomorrow.

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                    • #11
                      Get a 1" or so hole saw. Cut out a hole in just the OSB sheathing so that it encompasses the broken off bit. Remove the plug and you should have good access to the top of the broken bit. Take a pair of vice grips and clamp on the thing and back it out. If you have trouble trying to twist it out, take a dremel tool with a grinder stone and grind a flat spot on one side of the shank. That will give the vice grip jaws a better grip. Once removed, glue the plug back down on the rafter and continue on.

                      But, as LucMan said, Timberloks don't require a pilot hole. They are supposed to be an acceptable substitute for lag bolts.

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                      • #12
                        Originally posted by NorthRick View Post
                        Get a 1" or so hole saw. Cut out a hole in just the OSB sheathing so that it encompasses the broken off bit.
                        That seems like it'd just be a lot worse for the roof - making a big hole where there was a small one.
                        I guess it would all be covered by flashing, but...

                        I'd go with the other advice of not removing it.
                        At this point I don't see anything to be gained by removing it. Yes it's a chunk of metal in the rafter and (maybe) in the sheathing.
                        There's lots of nails like that too.
                        Drill a new hole slightly higher (or lower) than the broken bit. Look at how things are going to line up and figure out whether higher or lower will be easier to adjust the feet to get everything to line up. There normally is some adjustment room in the feet, so if every other foot can be as far one way as possible (or close), and this one as far the other as possible, probably you have enough room to be next to the existing hole (and bit).

                        IF your system has 2 mounting holes instead of one, I'd probably check and see if both have to be used or if just one is sufficient.

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                        • #13
                          One more alternative option - Seal up the hole, put flashing over that hole, and use the adjacent rafters.

                          If needle-nose vise-grips work to get it out, go ahead with those. But I'm guessing they won't.

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                          • #14
                            If you have access to the attic, I think the best thing to do is just sister a piece of 2x6 to the rafter. Then simply attach your mount to the new sistered piece. Anything you do to get the bit out is going to do significant damage to the roof. A new 2x6 is like $5, plus a hand full of nails or screws.
                            If you are using flashing, it will cover the other hole just fine, but a dab of sealant wouldn't hurt.

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                            • #15
                              Lose that drill bit. Quit using lag bolts and quit predrilling mounting holes. Use engineered screws by Simpson or Spax that are quality steel, have published specs, and don't need predrilling.
                              BSEE, R11, NABCEP, >1200kW installed

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