broken bolt

You can try to weld a nut onto the top of the bolt. While it is still hot from the welder shoot some PB Blaster at the threads the try to remove it using the nut as a new bolt head.

 

Heat works great if you can use a torch without messing other things up. Other than that soaking with Liquid wrench, shocking it with a hammer or drilling it out would be the standards. If you know a welder that's real good with a TIG welder they can weld another bolt right onto whats left of the old bolt. The TIG puts real concentrated heat to the bolt without heating up the areas surrounding it. Usually after doing this the bolt unscrews by hand becuase the fast intense heat expands the broken bolt and breaks whatever bond is holding it in place. The bolt shrinks back when it has cooled and usually comes out easy.

I have Tig welded onto broken bolts/studs even when they are slightly recessed below the surface without damaging the threads.

You might even find that just heating up the broken bolt with the TIG and letting it cool will allow you to remove it with a pair of plyers.

 

that's a good idea

 

what diam is the bolt ,can you use an easy-out?,,also try left-handed drill bits,also try getting it hot [red] then try putting a candle on it ,letting the candle melt into the treads,,be very careful using wd-40 and other penetrent oils on real hot metal the smoke they give off is clorene gas [also used in ww1 to kill people]

 

It's unlikely the bolt is something really hard like a 12.9 grade. It's probably more like 8.8. A good drill will drill that out just fine but you've got to start with a decent new drill. A lot of the chinese drills are pretty junky to start with so avoid those.

Make sure to center punch the broken stub first so you get well centered then just drill it out with increasingly large drills. Stop as soon as you see a thread coming through and then you should be able to just fish the remains out pretty easily with a small spike.

 

I would recommend drilling out.. but you need an air drill with a good bit.. Start small then increase in size until you get the job done..

R

 

If you are going to drill you need a Cobalt left handed bit Titanium-Nitride coated preferably. A good quality cutting oil and a high quality drill with a very low speed.

Air Drills are useless as they don't have much torque at low RPM's. Drilling at high speed will only result in a burn drill bit. When using a Cobalt bit just make sure you don't put much pressure on the drill as you can snap the bit quite easy. The slow rpm and a sharp bit will do the work for you.

 

That's very good advise. Used this method successfully a few times myself. Do make sure to center punch the screw to prevent the bit from wandering as you start the drilling.

 

Although some cleaning solvents contain chlorinated compounds, WD-40 does not.