How to remove a broken tap?

Ol' Flinter

Ol' Flinter

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I was tapping a through - hole with a new 8 - 32 tap, well lubed and somehow I guess some cuttings clogged the tap and it got stuck with about 1/16" of the tip protruding through the metal plate. It broke off just at the surface of the entry side of the plate so there is nothing to grip to try to work it loose. The tap is HSS so it should be able to be shattered but I am at a loss as to what to use to shatter it. If worse comes to worse I can destroy the tap and hole then re-drill and tap for 10 - 32 but would prefer to work this out and save the original threads if possible. Any suggestions that have worked for you? I am sure I am not the first one to have faced this problem...
Thanks
 
HSS might not shatter; high carbon sometimes can be.

What sort of metal plate is it broken off in?
 
couple of things you can do, if there is enough sticking through the plate and you can get at it. a small pair of vicegrips try and get a hold of it and turn it out in very small movements like wiggle it back and forth in the direction that seems to have the easiest movement.or if you can not do that a small pair of needle nose pliers from the broken side if you can get the points of the pliers into the voids between the flutes of the tap. If all else fails a good center punch and chip away at the flutes a little at a time should get it broken up so that it will come out. you are lucky it was not a blind hole thats a different kettle of fish
 
It is in a lock plate bolster and the hole was to receive the cross bolt in a muzzle-loading rifle. I just checked the tap and package: it describes the steel as "heat treated alloy steel" and claims a hardness of C58 - C61 Rockwell so I was incorrect to have called it HSS.

I tried to grip what protrudes but it is short and small diameter and I cannot get a grip on it at all.
 
A Dremel with a diamond burr can be used to cut up the tap.
You could punch it back out. This may tear little channels in the threads, but the hole can be cleaned up and threaded with a new tap.
 
Don't forget to use compressed air to blow any small chunks out while trying any of the methods above. The smallest bits of metal can throw a monkey wrench in your efforts.
 
Get a 8-32 nut. Try to thread it on. Tig, solder or crazy glue the nut to the tap. While it's still warm(if you used heat) slowly remove it. Some times I'll use a tig arc to melt the tap out. Those small taps can cause red and watery eyes.
 
Got a Dremel tool?

How much sticking out the other side? Enough to grind a set of flats on to grip (carefully) to back out the broken stub?

Got some dental burrs? Careful work with a series (because you WILL break several of them) of dental burrs, can grind out enough of the tap to get you free and clear.

Brute force approach is to punch it out with a flat nosed punch. Use a close fitting hole through a suitable softer metal plate as a backer on whatever you use as an anvil, and you can drive the remnants out cleanly. As said earlier, it can still be tapped, though a larger hole would be a better solution.

If the tap is a carbon steel tap, then you may be able to soften it by heating. Either by pressing a red hot rod against the remains of the tap and allowing all to slowly cool, or by playing a torch over the part. If the part can stand some heat, even easier. Once soft, drill it out.

Going to depend on whether the tap was broken by side pressure or too much torque on a dull tap, too. Dull taps are harder to remove. They tend to be bound in pretty tight. Side pressure broken taps can more often be worked loose and unscrewed.

Broken tap extractors work best if the tap is pretty damn close to being able to be removed by hand. Not a good investment, IMO.

Cheers
Trev
 
With Oxy Acetylene heat the tap up very quickly red hot and while keeping it red hot screw the Oxy up higher and the Acetylene down... the high carbon in the tap will feed on the oxygen and burn up or explode out of there... a little tricky to do but I have done it a couple times with good success. Maybe try it on a scrap first and see how that goes.
 
guntech's suggestion seems like the best so far. Don't be afraid to drill the newly empty hole out larger and silver solder a plug in and redrill etc. Actually I would silver solder a tube rather than a solid plug because it makes it easier to center the tap drill. I have had mixed results the few times that I have tried shattering a tap out of a hole.

cheers mooncoon
 
I broke an 8-32 off in a blind hole on a friends rifle... damn near cried because it wasn't my rifle I was screwing up. I used a broken tap remover but chucked it up in my milling machine to keep it lined up and square. Tap came out slick as a whistle, and the hole was saved. Another time I took and old pair of small needle nose pliers and ground the tips down to tiny points to fit a broken 8-40 tap worked just great

Shortly afterwards I stopped tapping any small holes "for friends"

Way worse was shattering a 223 chamber reamer while chambering a $400 custom barrell for yet another friend . Long story that I wont bore you with. Took 6 months till I stopped screaming in my sleep
 
Look in the yellow pages for an EDM shop and pay the $20 or so to burn it out.

Best $20 you'll spend in saved time and frustration if the metal you are tapping has any value to you.
 
The reason gunsmithing taps are made of carbon steel is so they can be HEATED TO ANNEAL THEM when they break then you can drill them out.

Using HSS taps can get you in hot water when they break unless you know someone with an edm machine.
 
I think I will try the EDM route as I have a neighbor in the business and I don't have oxy - acetylene at my disposal. I torqued it off when some cuttings jammed it it place. So far have shattered away enough to get about 2 mm below both plate surfaces but still have about 3 mm jammed in place in the middle. I used/destroyed 3 Dremel diamond cutters last night in vain: the cutters would grind the shank of the broken tap but had no effect on the stuck, broken threaded section so the threaded part must be a bit harder. old, dull drill bits just shattered when I tried using them to break up the stuck cutter or punch it out.
 
Somewhat along the lines of a suggestion already made. Using tiny needle nose pliers in the flutes and you might be able to turn it back out. If it's REALLY in there, you can use a small punch and small hammer, with LIGHT taps, to try to turn it back out.
 
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