Hi all, there really are a number of ways to approach this type of situation, however, the one that I prefer utilizes the GTAW process and stainless steel filler rod. Something that is fairly common with todays engines is having the exhaust studs in aluminum heads shear off when you go to dissassemble them. Whenever possible I have the head removed when I attempt this particular method. Find a way to position the head so that the broken stud hole is in the vertical position so that when you start welding on it you can maintain a weld puddle on top of the stud (this needs to be done at a very low heat with a constant addition of filler material, you may also need to stop every so often so as not to lose control of the puddle and have the built up area collapse or go too far sideways on you). The stainless filler is my choice for rod since it is less likely to be affected by dirt, grease, rust, and othercontaminants. If you use ER70 series fillers you will likely fight the swiss cheese effect to a great degree. The heat generated by the GTAW process will tend to help to break the threads free from the effects of electrolosis, sealants, and other types of retention chemicals that may be in use. As the stud cools after the welding has been done the shrinkage that occurs will also aid in breaking the stud free. Once cooling has taken place, grip the weld build-up with your vise-grips and by working the stud back and forth and unscrewing it a little at a time you will generally be able to remove it. This also works with broken taps and screws and bolts and plugs and many other types of fasteners that might require removal. This works particularly well when you are talking about the removal of hardened and quenched bolts and studs or broken taps since they generally are not readily drilled out with most available methods. With some practice, you can actually remove items as small as a broken 4-40 tap or fastener and you can also reach into holes to depths of 1/2" or more depending on the diameter and your ability to see and stay steady while forming the weld pool and adding the filler material. Regards, aevald
Hello Aevald;
Along the same lines of discussion, I'm on a job right now that involves the Millwrights removing an large number of 3/4, 7/8, and 1 inch broken bolts from a large block of steel (about 30 tons). They clean the broken end of the bolt and weld a heavy washer over the broken bolt with fresh E7018. The use of the heavy washer ensures good access for the root passes and it is easy to chip the slag before welding the nut on. They weld the nut to the washer going around the perimeter of the nut and then fill the hole in the nut (to bolt) with weld. I have yet to see where their technique does not work. They use an air impact wrench on the nuts to back the bolts out and the welds hold beautifully.
However, the smaller bolts and studs are without a doubt easier to weld with GTAW as you say. A good example of "tricks of the trade" for this section!
Best regards - Al
Hello Al, I have seen the nut welded to the broken end of various fasteners before and the scenario that you are describing makes really good sense as it insures good access for the welding to the broken portion and also allows a good base to weld the nut to. Thanks for bringing this method to everyone's attention and mine as well. Regards, Allan
I only wish I could say it was my idea!
You have to keep an eye on those welders, they're always thinking!
Al
That makes sense. One of the stuck bolt removal tricks is to heat the end of the bolt to red and let it cool down. One theory is that the heat expands the bolt, which is restrained by the surrounding metal so the metal upsets axially; so upon cooling the bolt diameter is slightly smaller than before (at least on one end, the other end probably doesn't get hot enough). Welding the washer and nut might do the same thing. Either way welding the washer on first sounds like a good idea. Thanks for passing it on.
why not cut them out with a torch
DD Equip,
I think I can hear the barman calling you,
Regards,
Shane
maybe you think i am full of it but in my line of work
i do it all the time
DD,
I would think that it would depend on the line of work you're in, so it could very well be common place in your work. ;-)
i DO PORTABLE ALIGN BORING AND WELDING
REPAIRS ON HEAVY EQUIP
DDEquip,
I apologise for having a shot at you. The earlier postings were about removing small bolts that is why using GTAW was suggested.
I would say it is nigh on impossible to cut a 1/2, 3/4 or 1" etc bolt down the centre with a cutting torch without damaging the hole thread.
Gotta go, can hear the barman calling,
Regards,
Shane
Set em up, Shane, I'll join you at the bar!
Shane,
Steel in steel may be another issue, but not by a whole lot due to conduction of heat. I burn out steel exhaust studs- actually a kind of bolt- from the end of the cast iron exhaust manifolds all the time, and usually only need to run a brush or very light chaser through the hole to restore the original threads. They're, something less than 3/8 or so diameter, whatever Chevy used in their small blocks.
Regards
d
If the bolt is of course a bolt, and has axcess/clearance both sides to blow the metal through okay. If a stud on a bottom hole there is no place for the cut to go to. Plus it is pretty touchy not nicking the threads.
To remove pressed cast iron sleeves from engine cylinders, just weld long ways on the sleeve usually about 90 degrees from each bead. The shrinkage forces many times will cause the sleeve to drop out.
I like that washer deal. Also to remove bearing races that have no way of getting behind them, run a bead around the race and it will fall or pull out.
I'm telling you, I learn something new everyday on this site
When dealing with small dia bolts that are broken of below the threads you can insert a pieice of copper tube stick your rod down the centre weld for a sec or 2 quickly remove rod from stinger allowing the rod to stay attached to the top of the bolt. Let cool and it usaully will be loose enough to turn out by hand. Same theory different twist. Sure like that whasher and nut procedure can't wait to try it.
Al,
Had the chance to try this trick the other day and it worked great , Thanks for posting it.
Another little help in these situations is at the point the you've completed your welding ,and the material is still very hot; melt some wax buy rubbing a candle up against the hot surface and let it drip into the bolt and the edges of the adjacent hole. Capilary action will draw the wax down into the threads and act a lubricant excellence while you are attempting to rotate the bolt remains out of the hole. I've been doing this for years on marine engine blocks and castings to remove broken bolts and pipe plugs as it much faster than using an EDM.
Hope this helps!
Xpertfab
Hello XPERTFAB, I'll have to give that one a try the next time I need to do some stud removal, haven't heard of that one. Is it mainly something you do on aluminum, or do you use it for all materials? Regards, aevald
It has worked for me equally as well on cast iron, cast steel, alumuinum, magnesium, titanium and garden variety steels. I am told that some upper grade tool steels are not real tolerant of wax on machines surfaces and the wax usually requires some good solvents such as wax and grease remover or heat to remove following the extraction process. I did use this method on some tool steel plastic injection mold sections that had become stuck together on the alignment dowels. The engineer was a little dismayed that wax was used on his areospace molds. However, the owner of the plastics company was thrilled that he did not have to spend upwards of $150,000.00 for new tooling when all else had failed to seperate them. Wrong alloy of material used in the alignment pins. Good luck in your use!
XPERTFAB
The wax isn't going to do any harm to the tool steel, but it would be a contaminant in the mold cavity when production resumes, as would any "not approved" compound.
Allen
thats a thoughtfull post with ingenious solutions to everyday problems,,,,I have used the washer technique as well as the weld build up technique for many years now....i did not think of these on my own,,,"old hands" showed me these solutions and just drive home the point....someone has to be around to pass on this experience,,,,it may seem trivial but jeez its a life saver when you are against the ropes on trying to get a "critical" job done and in the hopper.
again Great post man
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