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Military Firearm Restoration Corner

How Do You "shatter" A Broken Tap.


rdm1962

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The Yugo 24/47 I am building for my Daughter was ready to be D&T. I had all 4 holes drilled. The first 3 holes tapped just fine. I screwed the tap into the 4th hole. Then as I was backing the tap out it broke. I can't really complain that it broke. This is the 5 receiver I tapped with that tap. The tap broke flush with the receiver. Brownells says that these taps can be "shattered" if broken off in the screw hole. I figured I would ask for the best way to get it out first. I thought maybe the receiver could be re installed in the D&T fixture. The tap could be drilled out using the correct bushing. I have a 2nd tap to clean up the threads. Any one have any other ideas on how to get it out. Ralph

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Just use a punch. But most of the time you will need to redrill and tap oversized, either to #8 or to the special oversized size brownells sells. I tap extractor is my first go to before trying to shatter out a tap. Usually then you can just retap the same size. You can get them from brownells or msc. Or pm me your address and I can lend you mine. Note this is why I never use a tap twice on a receiver. I save the used taps for general shop stuff or truck guns. Good custom stuff warrants a new tap.

Don

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Don is correct. Just use a punch and tap it with a hammer. What you might try doing, and I have never tried this yet, is to get some of the canned "air" used for blowing dust and stuff out of computors, and spray the broken tap with the can inverted. That causes the cold, compressed liquid to come out and freeze the tap, and should make it more brittle so that it will break/shatter easier.

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Don is correct. Just use a punch and tap it with a hammer. What you might try doing, and I have never tried this yet, is to get some of the canned "air" used for blowing dust and stuff out of computors, and spray the broken tap with the can inverted. That causes the cold, compressed liquid to come out and freeze the tap, and should make it more brittle so that it will break/shatter easier.

That's a "cool" idea. Could you use something like dry ice too?

 

Along with temperatures, would it be possible to spot-anneal the tap with a torch and a ton of heat paste?

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"tap extractor"

 

The nice thing about this place is that you can learn thing here.

I did not know that there was such a tool.

Bob

I didn't either. The extractor runs about $13 and replacement /fingers are $6 for a bag of 10. I just add them to my wish list and they will be on my next order. Ralph

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  • 2 weeks later...

Drill it with a smaller carbide bit. It will usually shatter after just a bit of pressure. Run a new tap through & see if the hole can be saved. Believe it or not I've put jb weld in a damaged hole like this, let it cure, redrilled & re-tapped. Over half the threads were still metal, but the epoxy took a thread just fine & the mount is solid as a rock.

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  • 3 weeks later...
  • 3 years later...
Guest dwade7551

If the tap is carbon steel it will usually break. HSS sometimes just peens. That's the reason that Brownells sell the smaller taps in carbon steel. Maybe the freezing idea will work. I think the carbide drill idea is best if you have one small enough.

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This thread is a bit aged, but thanks for your input and welcome to the board.

 

Personally, I get a small punch and try to hammer the broken bit in an anti-clockwise direction. Sometimes you can break them loose to the point that you can have something to grab onto and twist out.

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