Removing broken bolts and studs

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Removing broken bolts and studs

Postby seattle smitty » Tue Apr 26, 2016 3:38 pm

"Marty Mopar" just favored us with a useful link that I liked so much that it occurred to me that I might have something to contribute here. I recently posted this to another car-guys' site where somebody asked about how he should get at broken studs that were not easy to drill for removing with an easy-out, or were stuck too badly for the easy-out to work. He was wondering about using a propane or oxy-acetylene torch, which is chancy to use around an engine with lots of easily-melted wires and hoses, and fueled by gasoline. Here was my alternative, which is commonly used in auto machine shops these days:

(Quoting myself) "MIG welders generally work so well for removing broken studs and bolts that you might think they were invented for the purpose. As stated, one method is to place a nut over the broken stud and weld it to the stud through the hole in the nut, after which you may be able to wind it out with a box wrench. But if the welded nut isn't working, as Beast says just try piling metal atop the stud so you can get a Vise-Grip on it and rack it back and forth while it's hot. But with either the welded nut or the piled-up weld metal, you'll probably break it off and have to re-weld it several times before you succeed. I think this is a much better way of applying heat than a torch because it is focused (as well as not melting hoses and wires, and setting fires!). Each weld attempt is annealing the stud a little more, so it isn't so brittle. As you do this, give the stud a smack with a hammer every so often to jar it and to slightly reshape the now-softer threads.

Properly speaking, a MIG welder uses a solid wire electrode in conjunction with an inert gas. But you can do this job with one of the little 120V no-gas wire-feed welders.

Set your welder (by running some beads on scrap) fairly hot and with a good crackle. When piling metal atop the end of the stud, trigger your gun for very quick bursts, and let the piled metal cool down from red before you trigger the next burst. Make a tall enough glob of steel, maybe 3/8" high, that you can grab it with the Vise-Grip and very gently start working it back and forth until it starts to move. Be patient. Again, you'll likely break off your built-up pile of weld bead a time or two or three, but just keep at it. Sometimes you might miss the stud enough to weld to the base metal around it; no sweat, just grind it flush and start again. If you are using a no-gas welder, you probably should knock the worst of the slag away between each addition of new weld-metal.

If you don't have enough room to swing a Vice-Grip, but can use a box wrench or socket, then you have to try to weld a nut to the broken fastener. Same deal, patience is required, and expect to have to make multiple attempts.

If you think this is bad, as a kid I worked on outboards in a little marina next to Puget Sound . . . salt water. And we didn't have a MIG welder (mid-1960s), so "Mercury Special Tool #1 was our oxy/acetylene torch!!

{I go straight to the MIG welder in these situations just because I always have one handy. But if you do not, and must start with drilling and an easy-out, you might want to invest in a few left-hand drillbits in sizes that go with your various easy-outs. These bits are spiraled and sharpened for reverse rotation. I think their advantage is that in use they will occasionally grab in the hole and spin the broken part out of the hole, cancelling the need for the easy-out. But where the broken fastener is very tightly seized or rusted in the hole, they are no better than ordinary HSS bits.)" (end Quote)

A little farther on, I added this:

(Quoting me) "If using a long flame anywhere near a gasoline engine is unappealing, and if you can borrow or otherwise get your hands on a simple old "buzz box" AC transformer stick welder, here's another idea.fai

With the buzz box in your shop, pay a visit to a local welding shop, mobile welder, or welding school and ask for one arc-gouging electrode, in a fairly large diameter if possible, say 3/8". "Arc-air" uses carbon electrodes in a copper jacket, for a different purpose than yours. If you are interested in the USUAL uses of Arc-Air (it's a trade name), here is one of many videos (sorry, I didn't have time to find a professionally-done video, and at a quick glance several of the guys showing this technique seem rather unskilled, but this will give you the idea):

https://www.youtube.com/watch?v=NLUlsfottyg
(Again, this is for informational purposes only. You will NOT be doing anything like this around your engine!!).

Back home, put the arc-air electrode in the electrode holder of your arc welder. Disconnect the ground lead to your vehicle's battery. Attach the ground clamp of the welder to the engine somewhere, and set the welder to, as a guess, somewhere in the 90-140A range; try different settings until it seems to be heating the fastener sufficiently. Holding the end of the electrode firmly against the end of the broken stud (you do NOT want an arc, you are NOT doing anything like what was in the arc-air video above), have someone switch on the welder and stand by to switch it off. The stud should quickly get very hot (if not, dial up the amperage). If you let the stud cool, and then get it red hot another time or two, it should anneal enough to make it easier to drill, if you need to do that. Carbon-arc is an obsolete method of welding, but has been used with good results for over a hundred years for spot-heating chores similar to yours. Generally though, the MIG welder technique described above is the most effective.

If you want to know about the old technology of single- and twin-carbon-arc welding, here's a little introductory essay I posted on a site that used to be called Wiki Answers: http://www.answers.com/Q/What_is_Carbon_arc_welding. Here are some images of the equipment; (And again, this is just for your curiousity's sake). https://www.google.com/search?q=twin+ca ... EQ_AUICCgD (end Quote)
seattle smitty
 
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Re: Removing broken bolts and studs

Postby aussiewoody » Sat Apr 30, 2016 6:27 am

Thanks for your contributions
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aussiewoody
 
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