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MG TD TF 1500 - Broken tap- I shoulda gone to church

Best way to get a tap out ? I've never broken one after hundreds of times, this one, a Snap-on just gave up the ghost, no big handle, 6 full threads, no hard spots GRRRRRRRRRR! It happened on the exhaust manifold studs. It could be wire EDM'ed I guess, was hoping to just do it myself. Could it be center punched out with a 2 LB sledge ? Jack
JR Jack

Some times you can place a nut over the broken end and then weld the nut to the tap. Then if you are lucky you can back it out.
Talking to it with a BFH is asking for serious trouble.
Sandy
Sandy Saunders

Sheared off bolts can be removed with an Easyout. Dunno about drilling into the hardened steel of a tap though. Keen to see how you get on. Cheers
Peter TD 5801
P Hehir

If its not a spiral tap, there are broken tap extractors available.

http://www.mcmaster.com/#tap-removers/=1486uh4

I have never used one and I would expect that if the tap is stuck, they will not work.

If any of the tap is sticking out, you can usually work it loose by grabbing with locking pliers and working it back and forth with penetrating oil.
If the tap is entirely in the hole you must break it up with a hard point, like a center punch and remove it piece by piece.

There are machine shops that can remove it with a Plasma tool.
Expensive but it will save the piece.

Jim B.
JA Benjamin

Can you snap a pic of it so we can see maybe to help you?
M Grogan

I agree, a pic would help. Also, agree with Jim, a tap remover can possibly help. I've also successfully used a carbide grinding tip to carefully grind out the center of the tap and then you can pick out the bits on the sides.
Kevin McLemore

If you have access to an oxy set, use the finest tip and direct the flame down onto the broken tap until it reaches cherry red heat. By doing this you can soften the tool steel so you can drill it out.

The pulverizing method may work as well however it usually results in the female thread being damaged.
G Evans

Jack,

Similar to what G Evans said, you could likely blow it out with an oxy-acetylene torch. This works, I think, partly because the metals have different melt points, and partly because it is very difficult to cut two pieces of metal at the same time even if they are identical.

For example, If you want to cut matching pieces of metal from flat sheet, you might think you could stack one on top of the other and cut them at the same time. But, you will find it very difficult to get the bottom one to cut.

If you try this, one caution: Make sure you blow it all out at one time. Once you recess the face of what you are trying to melt, it is very difficult to get it started again.

I have only done this to blow broken studs/bolts out of cast iron, but I suspect it would work on a tap as well.

When you finish, you should be able to clean the slag out of the threads with a new tap.

Charley
C R Huff

I would be concerned about trying an oxy torch, only because I would suspect the hardened steel of the tap might have a higher melting point than the exhaust manifold, causing melt damage to the manifold threads before you "blow" the tap out.
The manifold can be repaired by a good cast iron welder, but I would try locking pliers, needlenose pliers, anything to get in and wiggle it out first if possible.
I was able to purchase a replacement manifold for about $75, probably cheaper to go that route than expensive shop time...
Geoffrey M Baker

One remedy you can do at home is to grind it out, then drill the manifold hole larger and install a heli-coil (or other thread repair) to return it to original thread. Since it's a through hole, this would be a simple operation. I'd prefer to get it out without damaging threads but without an EDM machine it may or may not be possible. Good luck!
Steve Simmons

The best and safest way is using an Electric Discharge Machine, sinker type, wire EDM won't get it.
If you want to drive up to the Ann Arbor area, we can do it at my shop, while you wait.
JRN JIM

I've successfully blown them out with an oxy torch. It's not for the faint of heart but it works quite well. As CR said, do it all at once. Cast iron does not burn like steel so it works.

Better is to mig a grade 8 nut on it like Sandy said. That works aces. Here's one I cleaned up and snapped a photo:

JE Carroll

Many thanks all, very interesting suggestions. JRN/Jim thank you for that kind offer, if I weren't 8 hrs away or on the way to Twisty's I'd take you up on it or at least visit. I'm going to try some manual efforts first, the tap has broken off below head level so welding a nut won't work! I'm going to tackle this over the weekend so I'll report back with my efforts. Jack
JR Jack

Even if the tap (or stud) is below the surface you can sometimes remove it by pulsing a MIG weld down the hole. When you have built up enough weld, slip a nut over this and continue with the pulsing. You do need to be proficient with a MIG welder and the hole needs to be a fair size (not 2BA!)

Jan T
J Targosz

The trick to welding onto a broken bolt is first weld a washer onto the exposed end... so much easier to join those two together. Afterwards, weld the nut to the washer/weld.

One of the benefits of using the weld trick is the thermal shock.

One issue with attempting to "lance" a broken bolt or tap with an oxyacetylene torch is the tap may be a high alloy that does not oxidize away like a carbn steel. Stainless bolts melt out, not "burn" out. They form a oxide under the O2 stream and do not disintergrate.

JIM
Welding Engineer
JRN JIM

The picture I attached was one of the prettier tap extractions I had lying around. As Jan said, you can build up one that's below the surface and weld to the build up. I've been successful at that but never photographed it. It doesn't look pretty but who cares if it's out? I never tried welding a washer, just welded through the nut.

I've never had a tap or carbon steel bolt fail to burn. SS doesn't burn so I never tried it. I might try to TIG a nut on one if I ever am faced with it. TIG is very controllable so unless it was really deep it should work.

I've burned a lot of broken exhaust studs out of cast iron manifolds, generally by drilling through if possible then burning as it gives the slag somewhere to go. Blind holes are problematic as it comes back at you and tends to start to melt the iron a bit.
JE Carroll

Try taking a small punch and tap the side the flute of the tap counter-clockwise with a smaller hammer and try to walk the tap out. Please ware safety glasses as the tap is extremely hard and can chip off. You may have to rock the tap both forwards and backwards to rock it loose. I'm an old toolmaker with a EDM machine but would try this first. Best of luck.

Bill
TD24570
Bill Brown

Many thanks to all who took the time to reply with suggestions and opinions. I tried most of the mechanical hints and nothing really worked. I even tried a pair of needle nose pliers slid down along side of the tap and then a big screwdriver between the blades to twist it out. That worked a little bit until the plier blades started to sieze and bend, &$@)*^%@*. I'm giving up the trial & error and taking it to a machine shop like Bill Brown suggested and have then wire EDM the bugger! Thanks again everyone...............Jack
JR Jack

JR, find out how much they charge for shop time... You could pay more for an hour's shop time that it costs to replace... here's one on ebay for $100 or best offer...

201669652237

Geoffrey M Baker

I thought it was broken off in the cylinder head. I had one of the studs at the bottom of the exhaust manifold for an MGB go once. I left it for the shop so I wouldn't screw it up.

Stuart
S Grimm

This thread was discussed between 18/09/2016 and 28/09/2016

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