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Plumbean 07-10-2010 02:07 PM

Help Removing Broken Bit
So now I really need some help. The other day one of the Ideal 18s at my club got hit by lightning. It blew two holes, each about the size of a golf ball, right through the sides of the hull right at the waterline -- one at each chain plate. So this made me decide to go ahead and take care of grounding my mast, and now I've really gotten myself into trouble.

I decided to go ahead and drill and tap the top of a keel bolt to create an attachment point. See prior thread discussing this approach at I drilled out the hole and used a hand tap on it. I tried fitting in the #10 silicon bronze bolt I had for it, and it was a bit stiff. So I went to run the tap into the hole again, and before I knew it I had snapped the tap off. Grrrr. Sometimes I really impress myself with my own stupidity.

I cannot get the stub out. There is nothing to grab, I've tried using my special set of bits made to remove stripped screws and I've tried drilling it out. The thing is high carbon steel and is quite resistant to these efforts. If anyone has any suggestions, I would appreciate it.

Alternatively, if I leave it in there, any thoughts on corrosion issues? Would be very unhappy to have this cause corrosion of my brand new silicon bronze keel bolt.

Thanks in advance.

tommays 07-10-2010 02:50 PM

A #10 is so small you pretty much SOL trying to get it out a dab of epoxy to seal it would be one way

I have had to crack out other larger taps bit by bit when a tap extractor would not work and in the best case its pretty hard on every thing i would not want to be wracking on a keel bolt that much

donradclife 07-10-2010 03:01 PM

If there is enough of the stub showing, I have had success with two hammers driving small screwdrivers SIMULTANEOUSLY on opposing flutes of the tap. Hitting one side at a time just doesn't work.

eherlihy 07-10-2010 03:14 PM carries a product called "Unscrew-ums" that may work for you.
You can learn more about them here.

If you use them, please post a follow up.

Note that I am not affiliated with them in any way. 'Just tryin' to help.

merc2dogs 07-10-2010 03:58 PM

I'm with Tommays, seal it up and forget about it. It's very unlikely to cause problems.
If you absolutely want it out, look for a core drill of slightly larger size than the tap and use it to core the drill out. Drill to the correct dpth, then use a small chisel to pop the core side to side, it will break the core out and you can then lift the core and tap out. Of course, then you have a hole in the end of the bolt which will trap water, so you'd need to fill/seal it anyway so it's just as easy quicker to seal it with the tap in it.


mitiempo 07-10-2010 04:48 PM

And after you either remove the tap remains or seal it the best way to attach a ground is with a ring connector (like a battery cable lug) and an extra nut.

scottyt 07-10-2010 08:12 PM

there is a tool to remove broken taps, they have 4 skinny legs that go down each flute.

Walton Tools 10314 5/16 (8mm) 4-Flute Tap Extractor

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