Extracting sheared bolts

The tool you are thinking of is probably an "Ezi-out" (I think that is spelled right). The genuine ones are better than the cheap imitations (but they are not cheap), but be warned - if the bolt is so tight you broke the head off, it is unlikely that you will succeed with one of these - and a hardened screw extractor broken off in the bolt is even more of a problem! You need to think as well about what can be done to unstick it - heat, penetrating oil etc. as well as getting a screw extractor. JD

In news: snipped-for-privacy@posting.google.com, dht blithered:

You'll probably need the taps. The tool you refer to is often called an easyout, it has a reverse thread taper on it so that when you screw it into your previously drilled hole it easily unscrews the offending broken stud/bolt. Be warned though, they are made of exceedingly hard material and the cheaper ones are very very brittle, they have a tendency to shear off flush with the offending bolt/stud leaving a nigh impossibly hard core to it, that will resist/destroy any drill bit applied in its vicinity. So you could easily change a sheared bolt into a hardened plug! Make sure you get the right size easyout for the seized stud!

The toll which is SOLD to do this job is an "easyout" or spiral flute screw extractor.

However, they are by no means fool proof. I reckon a sucess rate of about 6 of of 10 using them.

Note, from the first link, a tap wrench is a far better tool to use on the end of the extractor. With an adjustable, you are likely to put a bending moment onto the easyout, which are very hard, thus brittle, and will snap.

If the easyout fails, my next recourse is to a LEFT handed drill bit, just below the minor diameter of the thread, which (with luck) will bite into the bolt and end up screwing the broken bit back out as you drill.

Or drill it to the tapping size and re-tap.

Or drill it to the helicoil tapping size and helicoil.

Failing that, weld a bit of bar onto the broken bolt.

Good luck.

In message , dht writes

It is a stud extractor. There are two types

1, looks similar to a plug socket, which is OK for protruding studs. 2, is a course left hand threaded tap, which when you have drilled the correct size pilot hole in the centre of the flush stud, you can fit this to you tap handle and screw it left handed to remove it.

What you have to remember is that if the stud/bolt does not want to come out then these are a waste of time. Then it is a matter of drilling out the old and re-tapping or heli-coiling.

Machine mart sell a set of various seized stud extractors for about £10 I bought one, and it's worked perfectly on a couple of broken bolts in various blocks..

I thought that id have no chace of getting one of my broken water pump bolts out, but it came out really easily with the extractor!

It is much easier if you get your pilot hole as central as possible. I spent a fair while doing this. start off with a tiny drill bit, and work up using bigger bits until you get the right size for the tool.

One way that I have found to work is drill down the centre of the bolt and hammer a Torx bit into the hole not guaranteed dependent on how seized it is Snap on do a set of fluted stud extractors that work on the same principal The problem I have when using eaziouts is they tend to spread the bolt if it doesn't come out straight away

Andy

"Andy.Smalley" wrote in news: snipped-for-privacy@uni-berlin.de:

Do a Google on Groups. There are some interesting threads on this. The best, in my opinion, is to place a nut over the stud and then weld the two together. Then simply unscrew. Special rods are available for this which ensure nut and stud are welded and not the block. The heat also helps lossen things up. I've forgotten the details but it is in Google somewhere.

Derry

On or around 14 Jun 2004 22:55:39 GMT, Derry Argue enlightened us thusly:

provided you have access, this is a good technique. done it with gas welding torch and also with mig.

I've heard of spark erosion machines used on very old and rare equipment which cannot be replaced or will cost squillions to have re cast if damaged beyond repair. Interesting process - like a spark plug I suppose. There was a UK based model magasine - Model Engineer's Workshop that had plans.

I've had to resort to this once, when an eezyout broke! Not sure about old and rare though - it was a VW Type 2 van cylinder head.

Pete

I've got a set of these and they really are the dogs-dangly-bits when it comes to extracting broken studs. The harder you turn them the tighter they grib.

Cheers Gary

We bought a proper spark erosion machine here at work from an ad in machine mart, and by the time we'd fixed it, rather wished we'd made our own in the first place. Spark eroders are THE tool for breaking out studs or taps, The ME article you refer to is quite good, but there is a book available from Camden Books by Dave Gingery I thnk that tells you how to make a rather more efficient unit - and one that can be clamped over the offending stud and put to work in situ.

Our machine will break out a 1/2 UNF tap (HSS) in under 30 minutes.

Of course if any fellow 101'ers ever need anything sparking out, please drop me an email !

Steve

Can you explain how they work? Do they just blast little bits out of the offending stuck item? How do you erode the bit you want, and not all the bits around it? Sounds interesting.

David

Not quite like a sparkplug more of a copper tube which has current passed through it whilst pumping a cooling fluid through the centre, the whole thing the vibrates to break the "weld" that occurs. This method is widely used across the engineering industry and will even remove solid tungsten carbide (broken easyouts are no problem) The drawback is the part needs to be removed from the vehicle first and that if too much current is applied the parent metal gets eroded as well If the part has to be removed from the vehicle then its easier to set up on a machining centre and drill the stud/bolt out. Al

Neat article.

Steve

Not quite how it works, the electrode doesn't touch the work.

Some tap disintegrators will actually work in the vehicle - like the Gingery machine I mentioned.

Steve

The neat bit is the "electrode" which constitutes the tool whose shape will be imposed in the work piece. Burning out taps is a simple case of using a cylindrical tube, with a dielectric (Paraffin works) passed through it.

The REALLY neat thing is that the tool can be made of cheap, but electrically and thermally conductive material, graphite or copper are often used, and is of course a "male" part, much, much easier to shape. mould cavities for exotic shapes in horrible tough alloy steels used for injection moulds, or for punchtools can be made very easily. With the right tuning, the tool wear is much lower than the removal of stock from the job. Our machine needs periodic kicking in JUST the right place to achieve this....years of training etc etc. And a mallet.

We used our EDM to make 4 pockets in the inside of a 1" bore, about 1/2" square and 10 thou deep - 1 inch DOWN the inside of the bore. Absolute, probably impossible, bastards to make anyother way.

"Wire cutting" EDM is also nice, where a contiuously reeled wire, like a bandsaw, but not an endless belt is reeled past a workpiece while under spark action. A cut of less than 0.5mm is easily achieved in X,Y and two angles.

Steve

Hi Steve, small world!

No 101 but a 30 year old Rangie might produce some custom when the engine strip/rebuild starts.

Nick