screw extractors

[ace llani]

Please, don't. ever.

If you have a male thread stuck in female thread, because the bolt head or nut wasn't sufficient to turn it..

How can drilling a small in the male thread, and trying to turn it with a screw extractor work? I used to sell them, i tried them, I never will again.

They are tapered, and bite into the male thread, like a woodscrew in a rawlplug. and expand it.

They are also much smaller diameter, and more brittle than the thing that already failed.

and when they snap, they are hardened, and so much harder to drill out etc.

[DefTrap]

I have to say I found the same - tried once, never again. This was over 20 years ago, so I assumed I was doing it wrong, they're still selling them after all.
I find it easier to take my time such that I don't get into a situation where a stud extractor is even needed ..

[Skub]

I used to get them and broken taps out using spark erosion.

[iansoady]

I still have mine somewhere. I must throw them out just in case I'm ever tempted.

[Le_Fromage_Grande]

I had one snap in a 250LC crankcase in 1987, it had to go off for spark erosion to get it out, crappy things.

[MrLongbeard]

Only used 'em once, as a last last resort, worked out OK, but I'm wary.

[Skub]

They can work ok if the bolt isn't 'too' tight.

[Taff]

They're not supposed to be used on a fastener that's corroded in place.
I've used them loads on screws that have been done up so many times that the cross head is just worn without ever breaking the extractor.

[Demannu]

The tapered ones are shit.
The blue point extractors on the other hand, fluted shafts, are pretty good.
However, it all depends on what you're trying to remove. If it's a steel thread into an alloy block (exhaust stud perhaps) then weld a nut on the end of whatever thread you have left and hope the heat overcomes the chemical bond.

[Mussels]

I've used them successfully after drilling out the middle of the bolt, not sure if it's the heat of the drill or the reduced pressure but extractors work then even if the bolt was seized.

[Asian Boss]

Just drift it round and out with an old dot punch.

[kendo57]

I have used them loads of times, they only snap if you force too much pressure on them, same as the bolt.
If the bolt doesn't move, then you take the extractor out and try something else.
On the model engineering websites where they snap small taps off for fun, they use Aluminium Sulphate which when dissolved in hot water you
can put the alloy part in and overnight it will dissolve the steel tap.

[ZRX61]

Years ago I successfully removed all the exhaust bolts on the 390FE in my '64 Galaxie without breaking a single one. I'd been spraying then with AeroKroil for a week or so before trying.
Afterwards I was told by many FE owners that it was "impossible to remove all of them without breaking a few". I told them no one told me that before I removed then so I just went ahead & did it without breaking any...

As for buggered ones, I've always had success by welding a nut to the bolt.... or this method: