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Home Model Engine Machinist > Building Them > Mistakes, Blunders and Boo Boos > Stuck drill fragment -HELP!

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Old 08-09-2015, 11:07 PM   #1
kvom
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Default Stuck drill fragment -HELP!



1/8" cobalt twist drill broken in through hole in CI. There's only about 1/8" of the drill still stuck, but it's resisted pressing out with vise and arbor press. Also broke a carbide EM trying to drill it out. Heated with a torch a bit but probably not enough. Could resort to 20-ton shop press.

Any ideas. I have a day's work already in the piece and would prefer not to have to make another. :headscratch:


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Old 08-10-2015, 01:34 AM   #2
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Somewhere else I posted a similar situation where I broke off a drill trying to remove a broken exhaust stud from my old 440cu in cylinder head. My Father was still alive then and he got it out by using a burning torch.

He started by slowly heating the piece until it just started to bubble and sparkle like the puddle does when gas welding. He then gave the oxygen lever a quick "pop" (maybe one second or so). The offending drill blew through into the water jacket, and the remaining stud was still intact. It screwed right out after it cooled and the threads in the hole were still good.

My Dad was in his eighties then.

Good luck.

Rich


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Old 08-10-2015, 02:25 AM   #3
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Dremel tool with small grinding tip or small carbide burr. Proceed with caution and try to bore down through the centre web of the drill with your Dremel.

Also, you might have better luck using a small, good quality, hardened pin punch rather than a press to remove the drill remnants. Sometimes the shock of hammer and punch will do more than the steady pressure of a press. I would try knocking it back out the direction it came in from.
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Old 08-10-2015, 06:35 AM   #4
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Not quite sure where it from the picture,but i have had success by drilling from other side and pin punching it out the way it went in,then plug the redundant hole
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Old 08-10-2015, 08:41 AM   #5
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There are several answers. The first is to crack one of the flutes left in. The second is to use a similar drill but the middle is ground out to leve two drivers/lugs. The third is chemically and the choice of concentrated nitric or sulphuric acid or alum . You make a modelling clay dam to hold the acid. Me, I'd use a welding rod to either burn the broken bit or make a joint and then unscrew.

Presently, I'm in a bit of a pickle because the retaining screw in my glasses has unscrewed. No, I haven't got the right size screw driver and obviously, if I had, the tapping must be worn. Not as bad as a ship's engineer mate of mine with a dent in his saxophone- and cannot get to dent. I've suggested freezing water which expand 9%. on freezing and will push the dent out.

Now that is a problem

Cheers

Norman
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Old 08-10-2015, 10:28 AM   #6
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Default Broken Drill Bit.

Hi,

Use the yellow pages to see if there is a local engineering firm with an EDM machine and get them to burn it out.

Martin
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Old 08-10-2015, 01:16 PM   #7
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Got it out by pressing in the vise in the reverse direction. Bar of steel through the opening and against the broken tip; two other bars on each side against vise jaws, and bob's your uncle.
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Old 08-10-2015, 02:08 PM   #8
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I have seen on the shop "How it's Made" how they take out dents from musical instruments. They used a pair of highly magnetized ball bearings, worked well, might look into that.
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Old 08-10-2015, 03:49 PM   #9
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Quote:
Originally Posted by mcostello View Post
I have seen on the shop "How it's Made" how they take out dents from musical instruments. They used a pair of highly magnetized ball bearings, worked well, might look into that.
Yes,we've both 'been there'. One trouble is narrow bores combined with key holes. The trouble is that this is a horn that was never worth much when it was new.

But thanks for your help


Norman


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