Broken tap solutions

[cr17]

Ok I need help here. I broke off a 4 flute 1/4 tap in the %%##^%# hole - well below the surface in a piece of aluminum. Any recommendations on getting it out? Walton tap extractor? EDM if I can find it, anything else? Anyone tried the old alum method. Did I mention %#^#^##^#

Thanks

[mike in co]

there is a kit sold for this. try a couple of the online machinest stores. emco, grizzley.

or buy a dremel type tool and a couple small carbide bits. cut the tap in pieces.
go slow....

mike

[scb]

Yea, being a 1/4" tap you may be able to cut it out with a carbide burr in a dremel tool. I've done it. But like mike said go sloooow. If you break that carbide burr off in the hole then you are screwed. Done that too. I haven't used it but MSC is selling a carbide drill set specifically to drill out broken taps. If it one of those "must save" parts I think I'd give them a try. steve

[10-x]

How tight is the broken tap in the hole? Were you cutting threads or backing it out? Is it a blind hole or through hole? Blind holes are hard to deal with.If backing it out try the tap extractor using acetone as lube. If cutting try tapping on the broken end of the tap with a small pin punch and a small hammer to loosen it up and then the extractor and acetone.
Another reason to use 3 flute taps.
Good Luck

[johniv]

GO SLOW, I havent used the new tap removal stuff for sale now, but years ago I brok a 1/4 " tap off flush in a hole (blind) and a MASTER welder in the shop TIG welded a small pillar on top of the broken tap and forked the top, it was then removed with a plier. key word here is MASTER welder.
also it was broken in a steel workpiece so this may not be possible for you. Just my 2 cents worth.
I feel yer pain.
John

[Sam]

Get with your dentist and get your hands on some old dental burs.
They are diamond an dcut much better and are easier to control than carbides.
They will easily remove the worst broken taps.
Instead of cutting off the "webs" of the tap cut straight down the center and then cut outward. They break like glass.

Unless you are really really really good at it never use HSS taps.
Broken carbon steel taps are much easier to remove

Sam

[JIMinPHX]

You’re in luck because it’s in aluminum. Put a 5/16 nut over the hole & stick a mig welder down in the center of it & weld the tap to the nut. Don't be shy with the heat. About 5 seconds after the orange glow goes away, turn it out with a wrench. Steel mig wire doesn’t stick to Aluminum & the heat from the weld will expand the aluminum & loosen the tap. Aluminum expands much more than steel does when you heat it. I’ve done this for broken exhaust bolts on Harley shovelheads several times. It works great.

[Lloyd Smale]

you just taught an old dog welder a new trick. thanks!

You’re in luck because it’s in aluminum. Put a 5/16 nut over the hole & stick a mig welder down in the center of it & weld the tap to the nut. Don't be shy with the heat. About 5 seconds after the orange glow goes away, turn it out with a wrench. Steel mig wire doesn’t stick to Aluminum & the heat from the weld will expand the aluminum & loosen the tap. Aluminum expands much more than steel does when you heat it. I’ve done this for broken exhaust bolts on Harley shovelheads several times. It works great.

[Bret4207]

Don't bother with the tap extractors. Do as Jim recommended or go EDM.

[dnepr]

I thought there was a chemical the would attack the steel tap but was safe on aluminum . For the life of me I can't remember what it is called . The idea is that you fill the hole with this stuff and it disolve enough of the tap to make it loose but this stuff doesn't touch the aluminum. It is supposed to be a slow process it takes somthing like a week to get the tap loose enough to come out.I remember hearing about the stuff but I have never tried it myself. The old memory isn't what it used to be.

[fishhawk]

what i have used in the past before i was "wealthy" enough to get the brownells tap extractors was nitric acid takes time but it does eat the steel and iron. it can be found in small quanities know as "aqua fortis stain" many muzzleoaders are stained with it after aplying it then heat. just not sure what it will do with alum.

[leftiye]

Lloyd, .... What do you weld on them dogs? (I know, .... couldn't resist)

[John Taylor]

Have removed many broken taps with a milling machine and a carbide end mill. I use old broken end mills and sharpen them like a cold chisel. Run the RPMs higher than normal and you can drill right through the center of the broken tap and then dump out the pieces.

[cr17]

Well I should give an update. I went for Jim's solution but I can tell you that convincing the local welder was a challenge. (Mind you this was all in French, and my technical welding vocabulary is nil.) Neither he nor his father, an old machinist from the logging/mining camps up north, believed it would work. In fact, he bet a gallon of maple syrup that it would ruin the whole piece. So no I have a gallon of maple syrup coming when the sugaring starts, a piece that I can use ( I buggered the hole in my ham handed attempts to get it out) and a new technique.

Thanks all

[scrapcan]

Sounds like all worked out well. You will ahve a lot of use for the gallon of maple syrup. and best of all I got to learn a new technique also.

[JIMinPHX]

I’ve also got another little broken screw removal trick that involves a cam shaft & a left handed drill bit that a lot of people tell me can’t work, until they see it done. That’s a story for another day. I’m glad that this worked out for you.

In the future, if you’re tapping 1/4" threads in aluminum, you may want to consider a roll tap (Also known as a thread flower, a forming tap or a Ballax tap). Roll taps make threads by displacing material rather than by cutting it. They actually swage the threads into shape. In aluminum, they make stronger threads because of the surface compression. These taps are also much harder to break because they have no flutes cut into them. They just look like a screw. If you use one of these, you need to drill a different size (larger) pilot hole. You also need to use plenty of thread cutting oil. These work great in aluminum, but they are not so good in less ductile & less malleable materials.

My second choice would be a two-flute spiral-point gun tap, if you want to stay with a “cut tap”. The gun taps are much stronger than a standard hand tap & take abuse much better. You also don’t need to stop to clear chips because they push the chips ahead in front of them. You just run them straight through in one shot. With a 1/4" gun tap, I usually just put it in the chuck of a cordless drill, dip it in oil & run it right through. The only down side to a gun tap is that they are not the best in a shallow blind hole because the chips that they push in front of them have no where to go. Gun taps can be had for pretty much the same money as a standard hand tap & they use the same pilot hole drills.

Since you have a half buggered hole already, you may want to go with a heli-coil or thread insert collar to fix up your current piece. These are not hack & slash repairs. Some of the aluminum aircraft parts, that I used to make, specified heli-coils in the original design because they provide a more robust thread than a straight tapped hole. The other tapped holes in aluminum aircraft parts were usually specified as roll tap only. You can get roll taps, gun taps & a good selection of thread inserts from places like MSC.

[MtGun44]

I have never needed it, and with modern fears about mercury, maybe
nobody would do it, but ---

Brownell's gunsmithing kinks book years ago said you could heat the
broken tap up to red head with a small tip acetylene torch and drop
a drop of mercury on it from an eyedropper to cool it ultrafast. Of course,
this would vaporize some mercury, so do it outdoors, etc., etc. or don't
do it at all.

They claimed it made the tap so glass brittle that you could break it up
into tiny chunks with a pin punch and pick out the pieces.

Never tried it, but it was so interesting that it stuck in my rat trap of
a brain,using a liquid metal to get a cooling rate faster than with water.

Bill

[EMC45]

I have always heard to use a selfloading punch and just pop it and it "should" break!

[Morgan Astorbilt]

This will work with carbon steel taps. HSS will just peen over. That's why I always use carbon steel in the small sizes, if available. These are sold by Brownells for this reason.
If in a bind, you can have it shattered, I think ultrasonically(some scope mount companies used to offer this service), or cut out with an EDM(this may be what they used).
Morgan

[JIMinPHX]

I usually just try to use taps that don’t break easily & treat them properly. When I was doing production work that involved tapping a 1/4-20 thread an inch deep in 6061-T6, I would get about 1200-1500 good tapped holes before I’d break a tap. The taps that I was using were not much more expensive than the ones you find at the hardware store. They were just better matched to the job at hand.