Burning broken studs, easy-outs, etc. out of cast housings

This is prompted by the question below by Navajo350 on removing broken manifold bolts, particularly the response by RBoots. Please tell me what I am doing wrong. I have a John Deere 630 with what appears to be a broken tap about 1 inch deep in a stud hole in the axle housing. I've tried burning it out with a cutting torch (propane), but have been unable to get the object sufficiently hot to melt. It appears that the spent combustion gasses back-flushing out of the blind hole are keeping the necessary heat from reaching the object. Would I do better with an acetylene torch? Is there a special technique that has escaped me? Thanks for your thoughts on this.
John

Propane won't get hot enough for what you are trying to do.

Propane will absolutely not be hot enough. You need the heat of oxyacetylene, with a medium sized tip. That way you can get the metal hot quick and start blowing it out immediately. Taps are a little harder to blow out due to their composition, but you can still do it no problem. If you have something broke off flush near the top of the hole (not in your case) its best to hold the tip of the torch at an angle to what you are blowing out so the slag goes away from you and the tip, obviously as you go deeper you have the torch more straight up and down so you don't gouge the sides (more of a problem with steel). If you're torch doesn't start melting the object within a few seconds, or have been burning it out for a bit and the tip starts popping, pull it back for a bit and let the tip cool, that popping is the gas trying to burn inside the tip, and if you go too long it will ruin your tip. If you had a bunch of holes you will usually ruin a tip by the time you're done anyway. Sometimes with a tap, if you use a pin punch you can chip away at the edges of the tap until it is broken up, sometimes easier after you have heated it. When blowing out holes, the threads are usually clearly defined by the temp difference between the two. Most of the ones I had to do were laying on my back under the machine, blind holes, in steel, which you have to be more careful not to gouge the threads. Bigger fasteners, say 3/4 and bigger, you can usually split the broken piece right across the middle and take the middle 1/3 out and knock the two halves in.

Ross

works good with acetylene but if you screw around enough youll burn the cast to you need to get it hot and get it done

I never had much problems getting a broke bolt out of cast iron.I never resorted to the torch anymore cause nine out of ten times the treads get burned.
when the bolt is broke at or above the surface then welding a nut to it is often enough to twist them out, sometimes a second or third try is needed if the nut comes off but out they come.
When the bolt is broken a little deeper in and the tread is damaged i drill the hole up a bit to get the treads out of the way then i build them up with welding til i can weld a nut to it.
If that don't work then i drill them out with a bushing the size of the finaldrill centered over the hole and bolted to the casting guide to start a center and for the final pass.
I only use an easy out if the stub appears to be loose enough to avoid breaking the stupid useless things.

If you thought you could do it with propane, it may be possible that your skills may be insufficient to to it with an acetylene torch without damaging it.
Practice this on junk before you do it for keeps.

My neighbour does dozer repairs. His technique for broken studs is electric welder using stainless rods. And he will go deep into a casting if that is where it broke.

Technique is to get the arc started in the centre of the broken bit. Then the flux protects the thread. Get it white hot while you build the metal up and when you're above the surface weld a nut on. Then plenty of WD 40 or what you prefer and start rocking - forward first. And as he says eventually you'll feel it crack. Then more lube, more rocking and it will come out.

Definitely needs practice on something that doesn't matter. I'm now game enough to start some way down the hole.

I have cut an awful lot of steel with an lp cutting torch, is it true that it won't build enough heat for a broken tap?

i think mcmaster carr has tap extractor tools

Propane works great for cutting steel, but has a longer preheat time. When blowing stuff out of holes, as was previously mentioned, get it done and get out. That way the threads don't get screwed up by too much hear too long.

Ross

Thanks!

Machine shoe next door to me gave me some sort of carbide drill bit . I had an exhaust bolt broken off in head which turned into a tap broken off in head. This drill bit ate right through that tap .

You would be surprised how much can be done in the time it takes to try a faster or easier way. I would take a dermal tool with small grind stones and just stay at it until it was ground out. I used to load up a mold insert and take it to a tool shop with an EDM and have it burned out. I then figured out that I could have it ground out with a dermal in the time spent driving and then pay a shop minimum to have it burned out on top of gas burned. I have a drawer of bent tap extractors that not a single tap was removed with one. It is just above a drawer with easyouts that have been converted into center punches. You know, all those wishful short cuts.

Interesting discussion. Thanks to all of you who contributed.
John

Basically use a big torch and it should take about 5 seconds. Do practice on junk before risking the real parts