Someone in the past has broken off a 1/2-13 tap in the 'nut' that one of the belly pan bolts threads into. I'd like to remove the tap before I reinstall said pan. Have a stick welder and plasma and would hope not to set myself on fire working upside down under machine. Hydraulic lines directly above so blowing plasma upwards not a great option. Suggestions on how to proceed with either mqchine???
you can try to weld a nut onto the broken tap , let it cool down , as its cooling you can spray some penetrating oil on it and then ratchet it out, this may take a few times but it usually just unscrews out...if you had a mig welder you would have more control, but a stick welder will work fine, try a 7018 rod right down the middle, the flux from the rod will help protect any threads if the tap broke blow the surface...
Plug weld a washer to the tap first, then weld the nut to the washer. Washer makes it harder to weld the tap/bolt to the parent threads on accident.
Sounds like a nut that's welded to the frame that the bolt screws in. If possibly you have access to the nut they're typically just tack welded to the frame, maybe you could grind the welds that tack the nut and simply tack weld in a new one. But again, that's if you can access the nut
They make broken tap removal tools if it's not mangled and grown in there.... being a tap it's gonna be hard and it'll be tough to get a good weld to it. I'm with Willie if you can cut the nut off and replace it that might be the best bet.
If it's not a separate nut but in something more solid, maybe you could move over a couple of inches and drill and tap a new hole with a corresponding hole in the belly pan? 1/2" isn't too outrageous to drill.
You will have to get the tap HOT first and let it cool slowly and get the hardness out of it. Then you can drill up the middle and easy out it.
If all the suggestions above don't work it might be possible to beat the crap out of the tap and bust it up to get it out piece by piece. Just be sure to wear eye protection as chips will be flying. Can you get a piece of sheet metal above this hole the tap is in to allow you to use the plasma? No matter what you do if you use any heat or fire I would suggest having someone stand by with a couple known good extinguishers and if possible do this outside and not in deep weeds or grass.
Last resort-Heat it cherry with the torch, hit the oxy for a second and blow it out. May have to tap it the next metic size bigger.
Beating them works. I shattered one with a good 6 lb. beater with my Dad holding a good punch with a vise grip. A few good raps and it busted up enough to turn out easily with a pick. A full face screen is nice if you don't like bleeders. Eye protection is a must as Ken said.
Been there, done that!! And always Keen-serts available.
Oh! just thought of something not mentioned above. Once you do manage to get it out and have cleaned up or repaired threads Anti-seize/Never-seize or something of that nature is your friend! I always tried to make it easy on the "next guy" to do the job as that SOB might be ME! Also I would make it a standard maintenance item to drop belly pans to clean them out and re-lube the bolts. Sure it may be a bit of a hassle but when that hose up under there fails while working in the mud the time saved will be well worth it!
I buy anti seize by the dozen..lol....amazon has there add on items super cheap, but if you buy enough of them to get over their minimum price, you can just buy that item and not have to add it on to something , so it ends up super cheap..anything that comes apart and has threads gets anti seize back, unless its bolts being torqued down, that are important( inside engine , etc)...
They only made AS ONCE in the 1930's, everyone knows that, same company that made SPAM. One drop of AS will circle the globe five times without interruption! and the last can of SPAM was canned in 1945, never will run out as no expiration date!! I have a t-shirt to prove AS continues to spread FOREVER and resists washing!!
As to internal engine Boltings, we used Detroit Diesel International Compound #2 LIMITEDLY for head studs, DD, Mack some old Allis to set the head studs and get a accurate torque on them, Cummins and Cat head bolts got a drizzle of 90wt just before insertion and torque so they would evenly pull down.