Broken Tap

cap6888 · Mar 14, 2016

So I finally got my stamp for my M85, and I WAS in the process of drilling and tapping the holes for the hinge mount. I also drilled and tapped the top cover for a picatinny rail. Wouldn't you know it, as I'm on the last hole in the rear trunnion, I broke off the tap. Any suggestions or help on how to remove it would be much appreciated. Thanks.

iH8DemLibz · Mar 14, 2016

But a set of tap extractors.

They're gadgets with little fingers/protrusions that go between the hole and the flutes.

Then you turn the extractor to remove the broken tap.

Number of flutes on tap is important. 3 or 4?

You may be able to get buy with two small drill bits and a pair of vise grips.

gwchem · Mar 14, 2016

If it's a big enough tap, and near the surface, you can weld a rod to the end. I've done that, but be careful you don't weld to the receiver.

kalister1 · Mar 14, 2016

Taps are hard to the point of being brittle. I have seen where you can "Shatter" the tap with a punch and remove piece by piece.

Atlasarmory · Mar 14, 2016

You may need to find a company with an EDM machine if you cant remove it mechanical. I have not had much luck with tap extractors in the past. But it is definitely worth a shot. Generally if the tap was tight enough to snap off then the fingers of the tap extractor usually end up trying to twist up before the tape fragment breaks free. Shattering the tap is definitely an option but you have to be sure you remove all of it before you try to retap it. any remaining fragments will cause the new tap to bind up again and possibly break.

cap6888 · Mar 14, 2016

Any idea where to get tap extractors? And what size would i need for a 10/32 tap?

Matlack · Mar 14, 2016

You can try an easy out. I have had luck with them in the past. I like the alden prograbits.

cap6888 · Mar 14, 2016

Matlack said:
You can try an easy out. I have had luck with them in the past. I like the alden prograbits.

Not enough to grab it.

cap6888 · Mar 14, 2016

Anyone have a tap extractor for a 10/32 tap i can borrow?

PapiBarcelona · Mar 14, 2016

You don't need an EDM machine lol. All you need if you go the professional Route is someone with a capable 5000rpm spindle on something and a old carbide endmill smaller diameter than the tapdrill size.

I've broke hand taps in real hard stainless alloys and removed them that way above.

Ranchero50 · Mar 14, 2016

Ditto, post up a pic of what you have to deal with. Is it a through hole or blind? Did it bind and snap off or did you bend it off? Did you use lube? 10-32 is too small for more extractors to bring out. Broken small taps suck to extract.

Depending on what's left, carbide mill the broken tap flat and then punch through it.

cap6888 · Mar 14, 2016

Hopefully this shows what I'm dealing with. It's a through hole. The tap broke off. Would drilling it out work? What type of drill would work on a tap? my experience with bits that small is that they are usually pretty flimsy. I'd be worried about snapping the drill bit and having that stuck.

iH8DemLibz · Mar 14, 2016

Please tell me you weren't drilling and tapping with all the working parts still inside the receiver.

I see the trigger and lots of pins.

Can you remove the receiver cover and access the tap from the inside?

And are you using any lubricant/cutting fluid? Looks dry.

cap6888 · Mar 14, 2016

I put it back together and grabbed it out of the safe to snap the picture. I used tons of cutting oil. My only guess is that since it was the fourth hole I was tapping, maybe the tap crapped out. For every quarter turn in, I backed out 3/4 to a full turn to clear the chips. The tip of the tap is maybe only an 1/8 inch through the other side, not enough for me to grab.

iH8DemLibz · Mar 14, 2016

cap6888 said:
I put it back together and grabbed it out of the safe to snap the picture. I used tons of cutting oil. My only guess is that since it was the fourth hole I was tapping, maybe the tap crapped out. For every quarter turn in, I backed out 3/4 to a full turn to clear the chips. The tip of the tap is maybe only an 1/8 inch through the other side, not enough for me to grab.

Water under the bridge now, but with only 1/8" inside the receiver, it sounds like you weren't using a "Starting" tap. Which has a very long lead until full threads are produced.

Personally, I would anneal the tap and drill it out. Maybe a Gunsmith is in order if you're not comfortable doing it.

If the hole gets buggered, can you step up in size?

sgt23preston · Mar 14, 2016

http://www.mscdirect.com/browse/tn/Threading/Tapping-Tools-Tapping-Accessories/Tapping-Tools/Tap-Extractors/?008=-99&pcrid=95098036264&007=Search&006=95098036264&005=450197563&004=5290742344&002=2167139&mkwid=segm3Dspq|dc&cid=ppc-google-Product+-+Threading+--+P_segm3Dspq_tap+extractor_p_95098036264_c_S&026=-99&025=c&navid=12106011

Order the #10 size Tap Extractor...

Does you tap have 3 or 4 flutes..?

Ranchero50 · Mar 14, 2016

cap6888 said:
View attachment 173572

Hopefully this shows what I'm dealing with. It's a through hole. The tap broke off. Would drilling it out work? What type of drill would work on a tap? my experience with bits that small is that they are usually pretty flimsy. I'd be worried about snapping the drill bit and having that stuck.

Gonna be a PITA to remove. Part doesn't look mill friendly so if I couldn't hold it in the mill I'd make a drill guide fixture and use that to guide the carbide drill or end mill through the broken tap. Typically I would press a brass oil lite bushing onto the tap so it's threads don't cut through the fixture while plunging through the tap. I've done this on industrial equipment a couple times with great results.

Projects like this only need to work once so take the time to make sure the first attempt works.

cap6888 · Mar 14, 2016

I suppose worse case scenario is that I could just drill one size up and then put a nut on the inside.

cap6888 · Mar 14, 2016

I order d a tap extractor. Fingers crossed that will work. Plan B will be to try and drill it out. Thanks for the suggestions guys. Wish me luck.

2ndltsdad · Mar 14, 2016

some time a left hand drill bit will spin it out but it still hard to drill that stuff. stve

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