Broke screw extractor off. What now?

Trying to extract a broken off 1/2 inch bolt. And, of course, I did the one thing I didn't want to do--I broke off the extractor flush with the top of the bad bolt.

Now what? The extractor is hardened. How do I extract the extractor?

Many thanks.


Grouse

When I do that I usually take the cutting torch and blow the extractor out of the bolt. IF your careful you can do it with out ruining the hole. Then take a die grinder with a carbide cutter and grind out all of the bolt you can. Then take a pin punch and grind it at an angle. So you now have a rounded backed chisel. Use that to knock out the threads you can not grind out. You can usually save enough of the threads to where cleaning them out with a tap will still leave enough useable threads.

Lots of ways, depending on what you have for equipment and where the part is located. If it's part of an assembly that can be taken off and moved, a machine shop will use a EDM to remove it. If you're stuck doing it by hand, you can sometimes break them up with a chisel--the hardened metal will chip and shatter, and you can remove the pieces with a pick. If you're brave and good with a torch, you can burn it out. A carbide burr in a die grinder can also help.

A carbide burr in a die grinder should work.

Nitric acid , as shown here ;

https://www.youtube.com/watch?v=7pN-fnUeA3o

I've used punches to remove broken taps more times than I care to admit, but.....WEAR EYE PROTECTION!!!!

A 1/2 nut and weld it to the bolt,the heat will help it come out. Stick or Mig will be fine.

Thanks for the advice, guys.

More on the situation:

The bolt is one of the ones that holds the sway blocks near the 3 point hitch on my Deere tractor. So it's not something that can be detached and brought to a machine shop, unfortunately.

The tractor is at my hunting property, so I have to work on it up there. I don't own a torch.

The welded-on nut is a great idea, but the broken bolt is counter-sunk in the hole.

I think the die grinder and punch approach is what I'll try. I'll have to use an electric grinder.

Question: Can I use a die grinder to drill a hole in the broken extractor and then use another extractor to extract it?

Otherwise, JDSeller, I think I'll try your technique next.

Many thanks.

Grouse

Given the situation, you may still be able to use the old "weld on a nut" trick. Remember, "success" in this instance is getting the BOLT out, not the EXTRACTOR out, and the heat of the weld will often break the bolt free, allowing you to remove it, with the extractor coming along for the ride. Hardened steel is difficult to weld, but you're not trying to get a full-strength bond here, you're just trying to get enough of a hold to get the bolt out. In similar circumstances I've even used a "washer" made out of copper (failing anything better a chunk of copper tubing pounded flat with an appropriate size hole drilled in it will work) or a U-shaped copper shim under the nut, both to protect the surrounding surface from splatter and to give you a bit of room to TIGHTEN the nut once the shim is removed. A light touch on an impact going both tight and loose in succession will often bring the whole works out, and if the nut comes loose just repeat the procedure. I would MUCH sooner do this before I tried drilling another hole in the extractor, which will more than likely just put you right back where you started, but with TWO broken extractors to remove, as the second one will, of necessity, be smaller than the first and thus even more likely to break.

I'm having trouble envisioning how the weld on nut trick can be done given that the bolt is broken off slightly recessed in the hole.

I've seen this done where a couple of threads were proud of the hole.

There will be a gap between the bottom of the nut and the bolt. How can I avoid welding the nut to the surrounding piece as well as the bolt, thus fixing it in place even more?

Thanks.

Grouse

What I've done is bought a carbide drill bit and drilled the extractor pretty close to it's physical size. Then since they are brittle break out what is left with a punch.

Again, a bit of copper scrap can protect things. I've stuffed a piece of appropriately-sized tubing down the hole and welded inside that before. Of course this is all easier with a large enough bolt to give you room to work, but can be done with a smaller one if necessary. Using a fast-freeze, high-penetration rod like 6011 can also help. You're trying to get a heat differential between the bolt and the surrounding metal, which in turn will cause an expansion/contraction rate differential, which will help break the rust bond. Sometimes you have to build up the weld--drop a small hump on the bolt, let that freeze, drop another and another until you're up to the top of the nut--it usually only takes a few, and each one helps by giving you another hot/cold cycle to break the bolt free. As mentioned originally, this is not a welding technique suitable to a nuke plant--it's only intended to give enough of a hold to allow you to get the bolt out. It takes longer to write than to do, and can be repeated if the first one doesn't hold.

A neighbour taught me this method.

He uses stainless stick rods. If you start the arc in the centre of the bolt the flux protects the threads. Get the pool as close to white hot as you can as you build up the bolt. Then weld on a nut. The heat helps with persuasion. Then rock the nut back and forth till you feel it crack - with plenty of your favourite lube. Then you can work it out.

I'm not that game as yet but he will work pretty deep to get them out.

TimV

Off this thread but you can also use the copper pipe trick the other way around.

I had some dozer grousers that had been held on with about Grade 0 hardware store bolts and worn the holes. I built them up by putting pieces of copper pipe in the bolt holes of the track chains and aligning the grousers around them. Then building up the holes around the copper pipe. The grousers are still in place and tight a couple of thousand hours later.

Yes the copper pipe trick really does work Ian Not as a severe application as your dozer grousers but it worked very effectively when repairing this wallowed out hole in a FE 35 stabiliser bracket

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