Broken Tap

Ranchero50 · Mar 14, 2016

cap6888 said:
I suppose worse case scenario is that I could just drill one size up and then put a nut on the inside.

The problem is the tap. You need to remove the tap before trying to drill it out to another size or bad stuff WILL happen. That application, drill a 3/16" hole through a chunk of stock and hold it in a vise. Set the receiver over the stock so the tap is in the hole. Then use a punch to drive the tap through the receiver. If you don't support to receiver wall it will deform when you punch the tap out.

Extractors on that small of a tap are hit or miss, usually miss if the tap was tight when it snapped off. If you have a Dremel, sand or stone to top of the tap smooth and pick the trash out of the tap swarf reliefs. Expect the extractor finger to twist up and don't be afraid to go in if it doesn't want to come out.

clandestine · Mar 14, 2016

If the tap extractor does not work use map gas and head up the broken tap. The tap will heat up faster than the trunnion. Once its cherry red, hit it with a short punch and it will shatter.

Tap extractors rarely work.

cap6888 · Mar 14, 2016

Well I'm hoping for the best with the tap extractor. If that doesn't work and I try the Mapp gas option, will the torch head from a regular propane torch work, or do indeed one specific to Mapp gas?

molonlabe · Mar 14, 2016

I have had luck with tapping it with a punch CCW gently did I say gently (it will back out with patients)until I have enough to grab on to. You need the right size tools.

ezracer · Mar 15, 2016

First, there's some good news!! It's a "thru" hole not a "blind" hole. Also, taps are brittle and your tap is already shattered. Unfortunately, tap extractors rarely work. I would't waste my money.

You need to get an "adjustable" Automatic Center Punch. Start with the punch
set on it's lowest setting and start applying force. Increase pressure if necessary. The tap will start cracking more and will fall out. ( most of it )
Try not to "bung-up" the threads any more than they are.

Next, re-tap for 10-32 using a "Quality" ( sharp ) starter tap. Don't use a junk tap from Home Depot or Lowes. Get a good tap from...www.mscdirect.com

IF this does not provide enough holding strength, then you will need to drill and re-tap ( using a starter tap ) for 12-28. The tap drill size for 12-28 is #14 (.182 ). Again, you MUST use a quality tap ( sharp) and keep the tap perpendicular to the surface. I have found that the best taps are "OSG"
(Japanese). A little lubricant also helps.

Over the years I've used this technique with a modicum of success.
Good Luck.

ps: You CANNOT drill out a broken tap. You could possibly take it to a Machine Shop and have them EDM the tap ($$$$). Heat would be a last resort!!!!

http://www.amazon.com/General-Tools...458047736&sr=8-6&keywords=automatic+pin+punch

StickShaker · Mar 15, 2016

As far as broken taps go that looks like an easier one. Get a very small machinists center punch and small hammer and try to work it back and forth. Use a lot of patience and take your time. Sometimes the tap will also be split in the hole from the initial break and cause it to wedge in there even tighter but it can also make it easier to get out if you tap on it in the right places. Your punch will get dull but it can be resharpened.

PapiBarcelona · Mar 15, 2016

I really don't get the EDM machine comments. Some shop with an EDM hole popper isn't like a drill press sitting in the corner, could be back logged for months

In fact, any good machinist wouldn't even need to use an EDM machine to remove that easy broken one.

ezracer · Mar 15, 2016

PapiBarcelona said:
I really don't get the EDM machine comments. Some shop with an EDM hole popper isn't like a drill press sitting in the corner, could be back logged for months

In fact, any good machinist wouldn't even need to use an EDM machine to remove that easy broken one.

I WAS a good Machinist!!!!!!!!!!! And, the VERY few broken taps I had over 35 years were removed very carefully with a punch ( automatic or manual ). I'm surprised you were concerned with EDM and not concerned about heating the steel to "CHERRY RED"!! Not a good idea! If the part is steel, heating the part to "Cherry Red" (~1500-1700deg F ) and then letting the part air cool will "anneal" the steel and make it soft. If the part is
Aluminum ( which melts at 1100 deg F ) it will become a molten mess. This is "IF" the OP has the equiptment to get the part THAT hot!!!

Another option ( probably not for the OP ) is to weld the hole closed and re-drill and tap.... IF the original hole has been mangled!!

EDM ( last resort ) would be mostly used for a DEEP blind hole in a very expensive part that cannot be reproduced. I'm just providing options.
I will reiterate...tap extractors suck!!

ps: OP's broken tap is a relatively easy tap to get out. Been there, done that!!!!!!!!!!!!!!!! 'Nuff said!

clandestine · Mar 15, 2016

ezracer said:
I WAS a good Machinist!!!!!!!!!!! And, the VERY few broken taps I had over 30 years were removed very carefully with a punch ( automatic or manual ). I'm surprised you were concerned with EDM and not concerned about heating the steel to "CHERRY RED"!! Not a good idea!

Another option ( probably not for the OP ) is to weld the hole closed and re-drill and tap.... IF the original hole has been mangled!!

EDM ( last resort ) would be mostly used for a DEEP blind hole in a very expensive part that cannot be reproduced. I'm just providing options.

ps: OP's broken tap is a relatively easy tap to get out. Been there, done that!!!!!!!!!!!!!!!! 'Nuff said!

The tap gets cherry red, the steel around it does not. The strength of the steel on an AK there is not a problem if heated.

ezracer · Mar 15, 2016

With care, that tap should come out using a punch. Heat probably won't be needed!!

PapiBarcelona · Mar 15, 2016

I was just commenting on the thought of taking an AK receiver to an actual job shop, having it sit on the shop foreman's desk for 6 months and pay a few hundred dollars for the guy on the shipping table to use a few hand tools to unscrew whats left of the tap. lol

smdub · Mar 15, 2016

PapiBarcelona said:
I really don't get the EDM machine comments.

I don't think anyone is suggesting they use a full-on cnc sinker edm. Most shops (even auto repair places) have a 'tap burner'. A little portable manual sinker to do quick and dirty work like this.

That said, that is so shallow you should be able to get it out w/ a punch.

StickShaker · Mar 15, 2016

smdub said:
I don't think anyone is suggesting they use a full-on cnc sinker edm. Most shops (even auto repair places) have a 'tap burner'. A little portable manual sinker to do quick and dirty work like this.

That said, that is so shallow you should be able to get it out w/ a punch.

Yeah, set up like a drill press so you can peck at it. Carbon rod with high current low voltage like a welder. Makes it go away.

PapiBarcelona · Mar 15, 2016

Oh right, the little portable guy on the magnetic base. I never think about those

5.56blaster · Mar 15, 2016

Don't forget Tap Magic when using a tap. It works really well. Good luck.

StickShaker · Mar 15, 2016

5.56blaster said:
Don't forget Tap Magic when using a tap. It works really well. Good luck.

Have you ever used the REAL tapping fluids like "Tapmatic" before they banned the 111 Trichlorobadchit? Nothing produced now even comes close to it. :mad54:

RoadDawg · Mar 16, 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.

If you disassemble the receiver... can you get to the tap piece from the inside? Is it a "through" hole in the receiver? Is there a portion of the tap protruding into the inside of the receiver?

If so... Can you try to use a small punch and light hammer to turn the piece in reverse direction. Light taps on it may cause it to break free and turn back out of the hole.

billymx48 · Mar 17, 2016

Use a punch after you support the piece and knock it out. I would just drill and tap both holes bigger for 12-32 screw then so they match.

PapiBarcelona · Mar 17, 2016

Its really easy to avoid being a blacksmith in this scenario, beat it out? It's a perfectly fine hole with a small fine pitch tap that can be easily removed.

What if he breaks the next size up tap? No offense OP. A little due diligence and care, you can remove that tap without destroying anything.

cap6888 · Mar 18, 2016

And problem solved. Finally. Thanks for all of the suggestions. Not that I didn't doubt you guys, but I had already ordered the tap extractor. As you all said, it didn't work. I tried the punches for a while to no avail. Finally, I used one of my smaller dremel bits to grind away some of the tap. After removing some of the material, I was able to knock it out with the punch.

Wouldn't you know it when I ran a new tap through, I was only about 2-3 turns from finishing the hole. Thanks again for all of your help guys!

Broken Tap

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