I do it with tig because you can pinpoint the blob of weld ,specially if the stud has snapped inside the hole you can build it up until you can get hold of it , it works both ways !
I have drilled out a couple of broken head bolts. Had to use a modified masonry drill bit, and it certainly wasnt an easy job at all. Got shown the weld blob idea, and I think its only ever failed to work on one bolt.
That sounds encouraging.....and I do appreciate more heat transfer with just the blob.
We've now got 3 camps.....the drill-it camp......the nut camp and the blob camp (both with MIG/TIG).
Of the three I'm inclined to try the blob method first. That's not to say the other methods are wrong i.e. they may well prove to be the preferable method but I've got to pick one to start with and by definition can't please everyone.
If I can't find someone with a portable MIG/TIG set to do it for a reasonable price...I'll try and drop put some blobs on with my Kel-Arc and wonder what the best rods are for this and whether I need flux and if so what sort is best.
It would also help to know where I can get this stuff from around the South Birmingham area.
Yes...that does worry me. The only reason I haven't started yet, other than knocking the stud about with a hammer and WD40 and being careful not to damage the alloy joint face, is I don't want to *&^!....things up.
What about my propane torch on the bolt tip.....would that do any harm to the head i.e. I can get a grip on the 5mm with grips but it's too badly rusted in to turn, requiring either heat or drilling.
A member popping around seems by far my best bet. Good to hear that the propane torch won't hurt. If it won't help either...I've not lost a lot. Thanks for the advice.
As heat causes differential expansion and therefore relative movement between the bolt and it's associated female thread this is always worth a try, if heat is difficult to apply try a can of freezer spray to try and crack the seal and then rubberydeefawlty or similar,hth,Chris
The other option if you have to drill it is to make up a drill guide. That only needs to be a piece of thick bar with three holes precision drilled to match the head stud spacing with the middle hole a 8.5 and the outer holes 10mm. You could then bolt it on and drill down through the stud.
Arc welder has little chance of working, and if you choose to weld a nut on you have less chance of success as heat will be directed into the nut more than into the body of the bolt, which isnt that great an idea. However if the stud is very badly corroded into alloy, you may well find that drilling it out is the only thing thats going to work in any case. If you are good at drilling, and have a carbide drill bit to drill pilot hole, then its possible to do free hand, but would be a lot easier if you could get someone to turn a drill guide bush, so the pilot hole ends up exactly in the centre of the bolt. Propane torch is a waste of time, just wont put enough heat into the block.
When I've welded nuts on I've threaded the nut on a couple of turns and then I direct the weld pool directly on the top of the bolt/stud, the weld builds and then fuses with the nut. Most of the heat is therefore going into stud.
If an arc machine was all i had for this job, I would drill a 10mm hole into a peace of 5mm flat 30x30mm, Put the 5mm (washer) over the stud and puddle weld the stud to the plate, Then weld a nut say 16mm to the flat.
Then i would use an impact gun just nice and steady and work the stud for and aft until it was free.
BUT.. on a job like this an inexperienced welder could do more harm than good if they got too much penetration through the plate.
IMO forget eezy outs if the bolt sheared trying to undo it any eezy out big enough to take the torque is going to spread the remains of the bolt so it'll never come out then shear off in there makeing spark errosion the only viable method.
if there is enough pokeing out to grab with a decent set of mole grips i'd cgive it a quick brush dose of pentrating fluid and heat the block around where the stud is with a propane torch and grab the std with a decent pair of mole grips ( decent brand with jaws that arn't worn ) it may come out takeing the tension off a stud and a bit of heat can do incredible things. if this dosent work at least nothing is lost.
2nd line of attack would be to place two thin strips ether side of the stud ( or a washer over it ) and then place a sloppy nut over it probaly m12 or m14 then weld the stud to the nut don't be shy with the power the heat will help free it off. once it's cooled a bit try working it free heat the block a bit with a propane torch if it dosent come free to start with.
drilling would be a last resort, it's more than possible do such a drilling operation by hand, problem is bolts/ studs that have corroed in aluminim often have a deep layer of corrosion that has a glassy like appearance and it's hard as hell a new bolt or stud will drill very easly in comparison. if it dose come down to haveing to try and drill it out i actualy find it easyer with a good cordless rather than a mains drill. if it was a closed deck iron block i'd suggest borrowing a mag drill but sadly it isn't. slow and steady with plenty of cutting oil is the way if need must with a drill.