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...let's here yer tricks.

I've tapped thousands of holes in my life, and never, ever, once, have I broken a tap....until Friday...in the bowl when I was cutting 5/16-18 threads for the ride plate saddle. It broke about 1/4" below the surface. I got it out tonight.

I tried a couple different things, but the last one worked.

I tried some carbide tipped glass drill bits...no dice
I tried a 3/8 plug cutter bit (for wood...but aluminum is almost as soft) to try and cut around it...That made it about 1/8" in the hole and then gave up the ghost.

I ended stacking tack welds on top of each other on the tap the weld had reached the surface, then stuck a 7/16 nut on there, and welded the nut to my pile of tack welds. I went through a couple of nuts before I got it right....apply light force back and forth in both directions and it started to move a bit....kept doing this for about 5 minutes and it came right out. I ended up drilling out the hole to 5/8", turned up an aluminum plug (which I drilled and threaded on the lathe) and tig'd it in. A bit of work with a flap wheel and some paint and it looks like new.

any better ways (besides EDM)?

I learned:

When using tap sockets instead of the tap handle, use a stubby ratchet. My 12" snap-on ratchet offered more than twice the leverage of the tap handle and I didn't really think about that when I was running the tap in...took very little pressure to snap the tap.
 

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...let's here yer tricks.

I've tapped thousands of holes in my life, and never, ever, once, have I broken a tap....until Friday...in the bowl when I was cutting 5/16-18 threads for the ride plate saddle. It broke about 1/4" below the surface. I got it out tonight.

I tried a couple different things, but the last one worked.

I tried some carbide tipped glass drill bits...no dice
I tried a 3/8 plug cutter bit (for wood...but aluminum is almost as soft) to try and cut around it...That made it about 1/8" in the hole and then gave up the ghost.

I ended stacking tack welds on top of each other on the tap the weld had reached the surface, then stuck a 7/16 nut on there, and welded the nut to my pile of tack welds. I went through a couple of nuts before I got it right....apply light force back and forth in both directions and it started to move a bit....kept doing this for about 5 minutes and it came right out. I ended up drilling out the hole to 5/8", turned up an aluminum plug (which I drilled and threaded on the lathe) and tig'd it in. A bit of work with a flap wheel and some paint and it looks like new.

any better ways (besides EDM)?

I learned:

When using tap sockets instead of the tap handle, use a stubby ratchet. My 12" snap-on ratchet offered more than twice the leverage of the tap handle and I didn't really think about that when I was running the tap in...took very little pressure to snap the tap.

I have a little set of modified snap ring pliers I made for removing broken taps, only used it once, but it worked, it goes down between the slots of the tap...Never used it on a tap that broke that far below the surface, good job that you got it out...:)devil

I have been using a slow variable speed 18V cordless driver drill for tapping aluminum and cast iron, I set the clutch for about 1/3 the total, works great, just back and forth and keep repeating with some quality cutting oil and never had an issue...
 

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Snap On broken tap removers work great! Has three fingers that slide into the broken tap and same slow process and wala its out.
 

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Ditto to what Glenn and Ted mentioned. I've made a halfass'd tool using pins that would slip down into the hole and inside the flutes of the tap to rock the tap back out. With that said, that has been in steel. Something like aluminum stock might be a whole different animal. Nice job with your approach and getting it out.
 

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...let's here yer tricks.

I've tapped thousands of holes in my life, and never, ever, once, have I broken a tap....until Friday...in the bowl when I was cutting 5/16-18 threads for the ride plate saddle. It broke about 1/4" below the surface. I got it out tonight.

I tried a couple different things, but the last one worked.

I tried some carbide tipped glass drill bits...no dice
I tried a 3/8 plug cutter bit (for wood...but aluminum is almost as soft) to try and cut around it...That made it about 1/8" in the hole and then gave up the ghost.

I ended stacking tack welds on top of each other on the tap the weld had reached the surface, then stuck a 7/16 nut on there, and welded the nut to my pile of tack welds. I went through a couple of nuts before I got it right....apply light force back and forth in both directions and it started to move a bit....kept doing this for about 5 minutes and it came right out. I ended up drilling out the hole to 5/8", turned up an aluminum plug (which I drilled and threaded on the lathe) and tig'd it in. A bit of work with a flap wheel and some paint and it looks like new.

any better ways (besides EDM)?

I learned:

When using tap sockets instead of the tap handle, use a stubby ratchet. My 12" snap-on ratchet offered more than twice the leverage of the tap handle and I didn't really think about that when I was running the tap in...took very little pressure to snap the tap.
Oh me stupid...i didn't read your full post till i had written instructions for exactly what you did...i have been doing broken bolts, taps and drill bits that way for 30 years...at least 200 times, with an almost perfect record.

A couple things that might help ya out...i get the nut FRICKEN hot...the heat migrates to the rest of the material...and just as the glow goes away i give the nut a good shot of wd 40..that cools the nut and the broke part down..shrinking it a little....and i always use vice grips on the nut..it helps cool it down a little more and the vice grips make it easier to to feel when it starts to move and helps avoid any rolling motion that a wrench might put on the nut.....

And i have repaired blasted out holes the same way too....and a couple times when i had a blasted hole in cast iron i have drilled out the hole and taped it 1/4 pipe...screwed a brass quick disconnect air fitting in the hole,
cut it off flush and re-taped the hole back to size....

15 years working on old jap bikes helps......I actually like fixing broken bolts...customers always seemed impressed when i charge them $25, solve a problem that had wrecked their world and have it done in 15 min.
 

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I am a machinist at an EDM shop and we do this almost daily. Bolts, taps, drills, etc. Mostly for harleys. We can normally make it like nothing ever happened. The only downside is its kinda spendy at 50 bucks a hole.
 

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...let's here yer tricks.

I've tapped thousands of holes in my life, and never, ever, once, have I broken a tap....until Friday...in the bowl when I was cutting 5/16-18 threads for the ride plate saddle. It broke about 1/4" below the surface. I got it out tonight.

I tried a couple different things, but the last one worked.

I tried some carbide tipped glass drill bits...no dice
I tried a 3/8 plug cutter bit (for wood...but aluminum is almost as soft) to try and cut around it...That made it about 1/8" in the hole and then gave up the ghost.

I ended stacking tack welds on top of each other on the tap the weld had reached the surface, then stuck a 7/16 nut on there, and welded the nut to my pile of tack welds. I went through a couple of nuts before I got it right....apply light force back and forth in both directions and it started to move a bit....kept doing this for about 5 minutes and it came right out. I ended up drilling out the hole to 5/8", turned up an aluminum plug (which I drilled and threaded on the lathe) and tig'd it in. A bit of work with a flap wheel and some paint and it looks like new.

any better ways (besides EDM)?

I learned:

When using tap sockets instead of the tap handle, use a stubby ratchet. My 12" snap-on ratchet offered more than twice the leverage of the tap handle and I didn't really think about that when I was running the tap in...took very little pressure to snap the tap.
Thats how I have been doing it for years. No need to waste nuts, just use vise grips. Same method for broken studs and bolts. Some time the taps and bolts come right out or sometimes you have to:(:( with the damn thing until it's out. The heat and a hammer is the best method, WD is the bomb until you have to go in a second time
 

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Best way EDM

I am a machinist at an EDM shop and we do this almost daily. Bolts, taps, drills, etc. Mostly for harleys. We can normally make it like nothing ever happened. The only downside is its kinda spendy at 50 bucks a hole.

This is by far the best way IF the part is small enough to transport and mount on the EDM table. I learned about EDMing broken stuff out on some Glenwood wet logs. The "snail" studs were all broken off flush. After the EDM, the holes looked brand new. As far as broken bolts, they are no where nearly as hard as a tap or "easyout" and I use LEFT hand drills. A good center punched hole in the center and drill with the LH drill. The drills usually "bite" and unscrew the bolt right out....Yes, an good EDM shop can diffidently save your bacon without messing up the expensive part you're trying to save.....$50. a hole seems quite high to me. It WAS 25 years ago, but I seem to recall $35 bucks for 8 holes!!!!......Ray
 
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