The bolts that hold the front of the rear belly pan have broke off in the frame. Not 1, not 2, but ALL 4 OF THEM!! Anyways, I got some drill bits, a bolt extractor, and planned to drill them and back them out with the extractor... Wrong!! These bits won't even scratch the surface of the bolts!.. Plan B was to weld a nut on the back side and try to bring them out that way. The bolts are flush with the frame, so there wasn't anything for the nuts to get a good bite on. I tried welding them on, but the weld just kept breaking. Now, as a last resort, I have about decided to just blow them out with a torch. My thinking is that if the torch distorts the threads, I can just weld a nut to the frame on the backside. I welcome your thoughts and ideas in this. Thanks.
What a pain in the ass. Is the frame threaded or are there nuts/nut plates inside the frame? If there is nuts/nut plates then I'd try heating with the torch and getting a air hammer on it to break it loose.
I had good luck blowing several of mine out with a torch, didn't damage any threads, however I did get a good burn in the process. Works good but not the best position to be using a torch.
The frame is threaded.
Here are a couple of things I have done for this problem. See if you can drill a small pilot hole first; even if it is with smaller than an 1/8 in bit. Anything to get a clear passage for the crown of the bit on the next size up. Once you have a hole there is an exit passage for slag. You can cut right up to the threads that will be a little cooler for a second or so and not damage them. Don't worry about slag in the threads since that will clean up with a tap afterward. Another great tool to have is a Drill Doctor. These are very handy and simple to use bit sharpeners. I paid $130 for one about 12 years ago so I am guessing they are under $200. you can make a dull bit sharp as new in a minute or so. Take your time and good luck.
Use a all Cobalt bit. They will drill thru anything. Then heat the frame and bolt cherry red. get your extractor ready, while red hot get a can of freon upside down take the fitting off the front of the hose and try to spray just the bolt and quickly insert the extractor and it should come out easy. I did a fre thousand like that and it never failed yet.
Yes. a cobalt drill and once you get a hole through it get plenty of heat into it and it should come out easy.
have you tried using a welding rod that is made for removing broken bolts? i guy i work with that works on tractors/ dozes etc swears by them. http://www.hobartwelders.com/weldtalk/showthread.php?14860-Messer-MG600-broken-bolt-removal
Another option is a carbide bit. Yes, cobalt and carbide bits can get pricey, but the masonary bits from the hardware store have a carbide tip and if you have a Drill Doctor (or similar), you can resharpen them to have a "normal" end on them. Andrew
I haven't heard the freon trick, I'll try it. Heat and screw extractor alone have had a very low success rate for me. I have had very good luck on larger bolts with drilling a hole through them then blowing them out with a torch. One thing that would be helpful if you drill through both bolts in the same frame-rail before torching them otherwise the pressure inside the frame builds up a little as you cut, and it makes it harder to cleanly cut to the threads, especially upside down.
Good drill bits are well worth the money for this kind of work.
Well, in that case I think I would try heating the area around the bolt then. The heat should expand it and you can hit around the bolt with a air hammer. This should "jar" the broken bolt enough to break it free. I've had good luck with this method. If that didn't work then I'd heat the bolt red hot and push it through with the air hammer. Worst case is you tap to the next size up and drill out the belly pan.
A good welder can weld onto the broken piece down in the hole and build up and out. The heating and cooling from this will usually break them loose and you can just back them out. The hard part can be finding a GOOD welder who'll crawl under there and do it.
All good ideas. My plan of attack is leave the welding till I've tried other things. Once you hit the Grade 8 bolt with the welder you won't get a drill through it without a lot of grief. Once you get a hole through a bolt and its accessible you can blow it out with a cutting torch. With a clean tip its easy to get it all out and leave the threads un damaged. Unfortunately the broken stud jobs that I get someone has usually attacked them first. Usually hard weld metal and broken off ezyouts An Artu drill or the spark eroder will get them out.
Are the bolts broke off flush with the frame?
oxylance to make a hole in them and with the heat they should comme off with the easy out
Yair . . . This can be a major problem and I sometimes wonder if folks suggesting thermal lances and such have ever had to deal with the problem. It can be seriously difficult to maintain a sense of humour and composure when working with hot slag dripping from above . . . and it is really hard to see what you are doing and stay safe as well despite the gloves and face shield and leather aprons . . . I have been there lots of times. At the risk of repeating myself . . . . . . It is almost impossible to weld a nut directly to a bolt broken flush with the surface. The procedure is to weld a flat washer to the bolt . . . a good beefy flat washer a little smaller than the bolt diameter, even if you have to make them. Set them up perfectly centred and hold in place with magnets a tack of weld onto the frame or whatever . . . there is no bloody point in holding it up there and trying to tack it to the bolt, it has to be right flush against the frame and centred on the bolt. Once in place start your arc in the centre of the bolt using slightly more amps than normal, and weld the washer to the bolt with a series of 'dabs'. Stop every few dabs and chip and wire brush and then continue until the washer is welded all around with no voids or inclusions . . . if you have some grind them out and start again. Once you are happy lay into it with weld don't worry if it drips you want a decent weld but the object of the exercise get that flat washer glowing and the heat transferring up into the bolt. You then grind the weld until you can get it level enough to sit a nut on and get a decent weld on (say) three flats. Very rarely has this ever failed me and once it is cool (provided they are blind holes) you can usually back them out with a shifter. If they are through holes with corrosion on the portion of the bolt beyond the threads it is a whole different ball game and it will be necessary to drill. I usually weld a piece of 5/8" plate to the frame to take a magnetic base which makes it a simpler and safer job than trying freehand . . .a rented drill would be money well spent. On a couple of occasions I have recovered butchered mangled belly plate holes in main frames by (on a D9) counter sinking holes into some 4x1" flat bar and turning the heads of (I think) the 3/4" bolts into countersinks and welding them in place . . . the whole thing was then offered up to the frame and easily welded. It stepped the belly plate down one inch of course but no big deal. the same thing could be done to smaller machines. When I do these sorts of modifications I usually suggest to the customer that they make one side hinged as it makes life easier and encourages cleaning out on service days. Cheers.
The bolts were broke off flush with the frame. I tried welding a nut onto one of them, and after some PB Blaster, things were looking promising when i had to add a cheater bar to my wrench. After some grunting, groaning, and a few vulgaraties, the nut broke off.. (I've never claimed to be a GOOD welder). We broke drill bit after drill bit trying to penetrate them, so we brought out the torch. After a LOT of acetylene, we finally got them all blasted out, although not as clean and pretty as I had hoped. After doing so, I got some nuts and welded them to the inside of the frame, so now I'm ready to slap the pans back on. I'm just wondering which one of y'all will come hold the pans up for me so that I can bolt them back in? Hahaaa!!! :beatsme
Yourve done it again Scrub,that sound like a really good method and one I had not heard of,thanks.
here we work with a smaller thermal lances like this http://www.oxylance.com/sure-cut-kits.php with a fleet of 120 grabage to maintain i been useing it in some akward way including upside down just build your self a slag shield out of v bar it also help you keep it straight but never use it on belly pan yet but i have to agree that not evry shop have one and your way to doing it is probably the best
Yair . . . Garrie Denny . I reckon a good magnetic base drill with a good low speed, and a set of slug cutters or carbides are one of the handiest tools you can have in the truck. An bit of time spent tacking on a level base can save a lot of cursing and broken drills and knuckles. As regards recovering belly pan holes it goes without saying that it would be easier just to weld tapped flatbar to the frame but that particular client wanted the studs. texaschad25 . As with all through bolts make sure a minimum ... preferably no... thread extends beyond the nuts. This applies particularly to roller/rockgaurd/cutting edge bolts. On your own machines bit of extra time spent cutting bolts to exact length can save a lot of heartache later . . . the rust and corrosion on the exposed threads can be an issue down the track. bob_00 . Those oxylance kits look handy as . . . I couldn't imagine not having one if I was still in the game. The only ones we ever had were cobbled up ourselves . . . going back forty or fifty years of course. (big grin) Cheers.
Scrub: If I get this right,the washer islightly smaller than the diameter of the stud Right ? do you only weld the centre of the washer or the outside edge as well ?
be glad some idiot didnt weld the rear belly pan to the frame like my komatsu d75s
Yair . . . Garrie Denny . Yes, the washer should be slightly smaller in ID than the OD of the broken stud. In effect it is just a transition piece that prevents the arc getting at the interface of the threads and facilitates getting a sound weld between the broken stud and the nut that is welded on to turn it out. Once you have that washer tacked on there nice and centred it is a lot easier to lay a good weld in there. You can see what you are doing for starters and if you get some slag or inclusions you can chip or grind the buggers out. If you really wanted to I suppose it would be possible to pretty much rebuild the stud. In my experience though the combination of heating and slow cooling with a good weld onto the broken stud very seldom fails. For bench work on small components. . . broken stainless studs and cap screws on legs and outboard motors for instance (right down to quarter) is very simple with a magnifying lens in the helmet and a steady hand on the TIG. I would imagine a good operator on a MIG could make it work as well. Cheers.
We had two old blacksmith brothers in town when I was a kid that always drilled out broken bolts using left hand cutting drills. They drilled as much of the bolt shaft as they could and it was amazing how many of the bolts turned right out with the drill as he broke thru.
Always worth trying before you hit it with the welder. My L/H drills have saved me time more than once.
Well said! Worked numerous, numerous times for me!! A bigger width wise washer works well too as you can get more weld on it and see a little better in bad spots! Not the ID but the OD.
I personally use a mig welder and build up the end of the broken off bolt then weld a nut to it and while it's still glowing I melt a crayon around it and turn it out. This process hasn't failed me yet.