Need some help destroying a broken tap

Need some help destroying a broken tap

AdmiralSenn
AdmiralSenn

May 18th, 2012, 8:40 pm #1

Hey guys. I'm back again with another stupid shop problem.

I had to tap a hole in a cylinder head for a Heli-Coil (trust me, I'd have avoided it if I could have). Naturally the helicoil tap snapped off inside the head.

I've been slowly attacking the remnant inside the hole with a variety of tools. Including a tap extractor for this tap, which just bent and failed to budge the tap in any way.

I have already tried heating the tap up and then rapidly cooling it in hopes to shatter it, as well as sharp impacts with a strong punch.

My current angle of attack involves a carbide mill/drill and a carbide material removal bur, however these seem to be taking an inordinately long time to do much of anything. Part of that is my impatience (I've been sitting on this project for a month now) but surely it shouldn't take half an hour to get a 1/16" deep divot started?

Because of the nature of the vehicle and the shape of the motor, the only even remotely appropriate tool I can bring to bear on this is a Dremel with a flex shaft.

So far I've been using plenty of oil and going slow. Are there any recommended methods to this? Would going faster harden the steel more?

If I had the resources I'd just pull the head and take it to a professional to have it EDM'd, or just buy a new head, but neither is an option.

Thanks!
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Someone
Someone

May 18th, 2012, 9:03 pm #2

Hahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahha.....

(Remembers 1990 Ford E250 with a broken exhaust manifold stud at the head, and six weeks of working through the wheel well off and on to get it out)

Hahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahhahahahahahahhahaahahahha.

(Collapses, chokes, and passes out from laughing)

You are in soooooooo much trouble! BTDT
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AdmiralSenn
AdmiralSenn

May 18th, 2012, 9:25 pm #3

I've basically resigned myself to parking the car until I can find a decent condition cylinder head. Even if I somehow get the tap pieces out, I'm likely to destroy the aluminum around it (I've already dinged it in lots of alarming places).

Still, I have to try.
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Maker of Toys
Maker of Toys

May 18th, 2012, 10:42 pm #4

Hey guys. I'm back again with another stupid shop problem.

I had to tap a hole in a cylinder head for a Heli-Coil (trust me, I'd have avoided it if I could have). Naturally the helicoil tap snapped off inside the head.

I've been slowly attacking the remnant inside the hole with a variety of tools. Including a tap extractor for this tap, which just bent and failed to budge the tap in any way.

I have already tried heating the tap up and then rapidly cooling it in hopes to shatter it, as well as sharp impacts with a strong punch.

My current angle of attack involves a carbide mill/drill and a carbide material removal bur, however these seem to be taking an inordinately long time to do much of anything. Part of that is my impatience (I've been sitting on this project for a month now) but surely it shouldn't take half an hour to get a 1/16" deep divot started?

Because of the nature of the vehicle and the shape of the motor, the only even remotely appropriate tool I can bring to bear on this is a Dremel with a flex shaft.

So far I've been using plenty of oil and going slow. Are there any recommended methods to this? Would going faster harden the steel more?

If I had the resources I'd just pull the head and take it to a professional to have it EDM'd, or just buy a new head, but neither is an option.

Thanks!
. . . remove engine/head from vehicle.

seriously-- you need some room to work. A stiff carbide drill might get you some purchase on the problem, but unless you get enough access to the hole to get some pressure on the drill point, AND some way to hold everything rigid, you'll likely break or chip the carbide. If there was enough access room, you might manage this with a magnetic drill like Iron workers use. . . assuming an iron block. Depending on how things are laid out, you might be able to rig a hand-drill and some guides, but ACCESS, man, Access.

Another way, again pre-supposing a drill press or the like, is to use a stub of HSS and valve-grinding compound to wear through the offending tap. It takes the better part of an epoch, but it might be the closest thing to EDM that you can manage in the home shop. If you have the patience of St Peter, you might manage this with a hand drill. . . I wouldn't want to try it.


If you had access and the tooling, you could weld a stub of bolt to the tap and try to turn it out that way. BUT, if the entrance of the hole is buggered up with punch marks, weld-spatter, etc, you'll just bust the weld, and then you're that much farther behind the 8-ball.

Last option is to core-drill the offending place, then thread the resulting large hole and put a plug in, redrill and re-tap. But again, access and rigidity are key.
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Bunker_o_matic
Bunker_o_matic

May 19th, 2012, 4:08 am #5

with decent pressure, I'd suggest a carbide left handed drill. In either case take pictures in between swearing and sweating at it so we can see what worked/didnt work for you?
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Nate
Nate

May 19th, 2012, 7:10 am #6

I've basically resigned myself to parking the car until I can find a decent condition cylinder head. Even if I somehow get the tap pieces out, I'm likely to destroy the aluminum around it (I've already dinged it in lots of alarming places).

Still, I have to try.
If you can get your hands on some (it's now a highly controlled substance), it will dissolve the steel significantly faster than the aluminum. It used to be sold in a formula called Tap-out, but the recent craze of tough guys who think they can compete in MMA has made tap-out a horribly ineffective search string on google.

Talk to local chemistry professors.
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ta2maki
ta2maki

May 19th, 2012, 7:44 am #7

Found a similar product in a google search, but 60 bucks for a 4oz kit seems pretty steep.

http://www.chemical-supermarket.com/Tap ... -p574.html
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AdmiralSenn
AdmiralSenn

May 19th, 2012, 10:20 pm #8

If you can get your hands on some (it's now a highly controlled substance), it will dissolve the steel significantly faster than the aluminum. It used to be sold in a formula called Tap-out, but the recent craze of tough guys who think they can compete in MMA has made tap-out a horribly ineffective search string on google.

Talk to local chemistry professors.
nt
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jkeyser14
jkeyser14

May 20th, 2012, 4:21 am #9

Hey guys. I'm back again with another stupid shop problem.

I had to tap a hole in a cylinder head for a Heli-Coil (trust me, I'd have avoided it if I could have). Naturally the helicoil tap snapped off inside the head.

I've been slowly attacking the remnant inside the hole with a variety of tools. Including a tap extractor for this tap, which just bent and failed to budge the tap in any way.

I have already tried heating the tap up and then rapidly cooling it in hopes to shatter it, as well as sharp impacts with a strong punch.

My current angle of attack involves a carbide mill/drill and a carbide material removal bur, however these seem to be taking an inordinately long time to do much of anything. Part of that is my impatience (I've been sitting on this project for a month now) but surely it shouldn't take half an hour to get a 1/16" deep divot started?

Because of the nature of the vehicle and the shape of the motor, the only even remotely appropriate tool I can bring to bear on this is a Dremel with a flex shaft.

So far I've been using plenty of oil and going slow. Are there any recommended methods to this? Would going faster harden the steel more?

If I had the resources I'd just pull the head and take it to a professional to have it EDM'd, or just buy a new head, but neither is an option.

Thanks!
I've removed broken bolts (it should work for steel taps too) by placing a nut over the hole and welding the inside of the nut to the bolt. Then use a wrench on the nut to back it out. It's been a real life saver in the past.
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Pilgrim
Pilgrim

May 20th, 2012, 6:35 am #10

Found a similar product in a google search, but 60 bucks for a 4oz kit seems pretty steep.

http://www.chemical-supermarket.com/Tap ... -p574.html
The last nitric acid I bought about three years ago,here in the most expensive country in the Western world,was $30.00 for 3.2 litres.
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