Torch Broken Bottom Roller Bolts

[charles miles]

I just bought a D5K that I am currently repairing. It has a missing bottom roller and all four 16mm mounting bolts were broken off. I have two out by welding on a nut which has proved to be difficult to do overhead, but nevertheless somewhat successful. I have been using 3/32 super missle rods and stud extractor rods. I have welded on the other two with no luck. I am considering torching the remaining two bolts out. I fairly proficient with torch but not a professional. First question: is there a reasonable chance of torching the two bolts out while saving enough threads to remount another roller? Second question: Torching will have to be done from bottom side blowing up with limited visibility. I have about one foot of clearance between the mounting rail and the ground. Would it be advisable to drill about a 5/16 hole through the broken bolt (about and inch deep in a tapped through hole) before trying to use the torch to wash out the bolts? I am thinking this would minimize the blowback in my face and allow the bolt to heat faster and therefore reduce the chances for damaging the threads in the bottom roller mounting rail which is about 1"x3" material. Thanks in advance for any experience and advice you can share.

 

[Tugger2]

Drilling the hole thru the center of the bolt works well if you can get started thru the hard spot where you have tried welding it. If you can make some kind of centreing jig that will help a lot ,either something that will fit into the existing hole if the broken bolt is deep enough.Or something with a 5/16" hole you can tack to the bottom of the track frame centered over the broken bolt. Get some good grade drill bits. Set up some kind of lever that you can push on the drill with ,i use a piece of 2X4 as a lever blocked against the back of my 1/2" Millwaukee cordless.Sounds ruthless on the drill but mines done a lot of them that way. Some good cutting fluid and slow speed with pressure and you should drill thru it. Once its drilled heat it good and hot with your torch.Have a solvent sprayer/atomizer hooked to an air line sucking out of a bucket of water ,hit it with this as soon as its hot ,cool it right down. Might take a couple of shots of this . An easy out might get it after that or go back to welding a small chunk of pipe onto it.
If the hole is a bit messed up can you twist the bolt in until its clear of the threads or is the hole blind tapped? In summary the hole is a good idea ive done it with bolts and brake anchor pins on my cranes .The heat n shrink with air water is the key. Im not familiar with the D5K,last undercarriages i did were on D8 H s and old D9 s . we allways had the track frames off and upside down. welded tons of roller bolts out then .Filled them up with 3/32 7018 then a flat washer and finally a nut ,they allways came out. Those frames had a pocket for 1/2 the roller shaft if they were too beat up we cut the whole pocket out on both sides and jigged in new roller pockets. Usually the first roller aft of the idler.

 

[Bobcat Crazy]

I just bought a D5K that I am currently repairing. It has a missing bottom roller and all four 16mm mounting bolts were broken off. I have two out by welding on a nut which has proved to be difficult to do overhead, but nevertheless somewhat successful. I have been using 3/32 super missle rods and stud extractor rods. I have welded on the other two with no luck. I am considering torching the remaining two bolts out. I fairly proficient with torch but not a professional. First question: is there a reasonable chance of torching the two bolts out while saving enough threads to remount another roller? Second question: Torching will have to be done from bottom side blowing up with limited visibility. I have about one foot of clearance between the mounting rail and the ground. Would it be advisable to drill about a 5/16 hole through the broken bolt (about and inch deep in a tapped through hole) before trying to use the torch to wash out the bolts? I am thinking this would minimize the blowback in my face and allow the bolt to heat faster and therefore reduce the chances for damaging the threads in the bottom roller mounting rail which is about 1"x3" material. Thanks in advance for any experience and advice you can share.

Hey Charles welcome.
I don't know about your torch skills, but with mine this would be a no-no. With the space that you have I do not see this ending with a good result. If it were me, I would make more attempts at welding the nut.

However there are Guys on this site that have so much experience and so many great techniques that it reminds me I am a rookie when it comes to these big machines.

If some of the Guys pick up on your thread I'm sure they will have some great ideas for you.

Good luck!

B-Crazy

 

[Delmer]

I would not torch it, I would drill and heat it with a cutting torch but don't hit the oxygen, just let it sizzle a minute at that temp, then smack the bolt to upset it. Let it cool completely and it might turn out with a screwdriver. Or weld another washer and nut on.

 

[Welder Dave]

Have to agree on trying to weld a nut on again. Would probably help if you could clean up the old weld a bit with a die grinder so you can get better fusion. I had a couple roller bolts I had to weld more than once to get them out. Putting extra weld to get it hotter might help but let it cool some before trying to remove it.

 

[charles miles]

You are correct in that the bolt is now hard where I attempted welding in it. I was thinking about getting a carbide drill bit to get through that. The hole is a tapped through so there is a possibility the bolt could be turn out on either end of the hole. I think I going to try welding a few more times and then go to your suggestion if that does not work.

Drilling the hole thru the center of the bolt works well if you can get started thru the hard spot where you have tried welding it. If you can make some kind of centreing jig that will help a lot ,either something that will fit into the existing hole if the broken bolt is deep enough.Or something with a 5/16" hole you can tack to the bottom of the track frame centered over the broken bolt. Get some good grade drill bits. Set up some kind of lever that you can push on the drill with ,i use a piece of 2X4 as a lever blocked against the back of my 1/2" Millwaukee cordless.Sounds ruthless on the drill but mines done a lot of them that way. Some good cutting fluid and slow speed with pressure and you should drill thru it. Once its drilled heat it good and hot with your torch.Have a solvent sprayer/atomizer hooked to an air line sucking out of a bucket of water ,hit it with this as soon as its hot ,cool it right down. Might take a couple of shots of this . An easy out might get it after that or go back to welding a small chunk of pipe onto it.
If the hole is a bit messed up can you twist the bolt in until its clear of the threads or is the hole blind tapped? In summary the hole is a good idea ive done it with bolts and brake anchor pins on my cranes .The heat n shrink with air water is the key. Im not familiar with the D5K,last undercarriages i did were on D8 H s and old D9 s . we allways had the track frames off and upside down. welded tons of roller bolts out then .Filled them up with 3/32 7018 then a flat washer and finally a nut ,they allways came out. Those frames had a pocket for 1/2 the roller shaft if they were too beat up we cut the whole pocket out on both sides and jigged in new roller pockets. Usually the first roller aft of the idler.

 

[charles miles]

I just bought a D5K that I am currently repairing. It has a missing bottom roller and all four 16mm mounting bolts were broken off. I have two out by welding on a nut which has proved to be difficult to do overhead, but nevertheless somewhat successful. I have been using 3/32 super missle rods and stud extractor rods. I have welded on the other two with no luck. I am considering torching the remaining two bolts out. I fairly proficient with torch but not a professional. First question: is there a reasonable chance of torching the two bolts out while saving enough threads to remount another roller? Second question: Torching will have to be done from bottom side blowing up with limited visibility. I have about one foot of clearance between the mounting rail and the ground. Would it be advisable to drill about a 5/16 hole through the broken bolt (about and inch deep in a tapped through hole) before trying to use the torch to wash out the bolts? I am thinking this would minimize the blowback in my face and allow the bolt to heat faster and therefore reduce the chances for damaging the threads in the bottom roller mounting rail which is about 1"x3" material. Thanks in advance for any experience and advice you can share.

I am a little surprised that nobody that has posted has been a fan of torching the bolts out. I know it is done on heavy equipment but I don't know the success rate or the look outs to make sure it's successful.

 

[Tugger2]

Ive torched lots of bolts out when theres better access. and usually bigger bolts. You can wash the threads clean with some practice. Id avoid it in your situation. Are the broken bolts flush or broke inside the hole?
If they are flush take a slightly smaller flat washer and weld that on first it protects the edge of the hole. Then weld a nut on .This work 99.9 % of the time.The Pictures are from a Vulcan air hammer that broke on us ,but same idea.

 

[Bobcat Crazy]

I am a little surprised that nobody that has posted has been a fan of torching the bolts out. I know it is done on heavy equipment but I don't know the success rate or the look outs to make sure it's successful.

Again I am much less experienced with these bigger machines than most of the Guys on here. I think the torch (cutting) would be very useful when dealing with larger bolts. When I have used a torch for anything but heat on smaller of this size it has not been the fix I was looking for but only caused more work for me.

 

[charles miles]

I have one broke flush and another about 1/4" down. I have taken bolts out like you are suggesting. I think the difference is the overhead welding and limited accessibility required in this case. I am going give the welding a few more try's. I agree the torch should be the last option, but I feel I am getting close to that point.

 

[Jonas302]

Is there room to put a nut on top and a longer bolt even if you have to weld a rod the nut and fish it in That would be a backup plan if you blow them out and no threads left as chances of success in saving the threads are low working upside down with no room chances of pain are high (;


Sometimes carbide tipped masonary bits can get you though a hard bolt a solid carbide bit snaps very easy in a hand drill

 

[Bobcat Crazy]

Ive torched lots of bolts out when theres better access. and usually bigger bolts. You can wash the threads clean with some practice. Id avoid it in your situation. Are the broken bolts flush or broke inside the hole?
If they are flush take a slightly smaller flat washer and weld that on first it protects the edge of the hole. Then weld a nut on .This work 99.9 % of the time.The Pictures are from a Vulcan air hammer that broke on us ,but same idea.View attachment 278658 View attachment 278659

Whoever said a picture paints a thousand words (or more) was right. Thanks for the posting those.

 

[charles miles]

I think the nut on top might work if the threads are destroyed in the torching process. Thanks for the suggestion

 

[Delmer]

See that bolt next to the tap, it didn't get hot enough at the end and came out harder than it could have. drilling the center and washing just a bit out through the center, or welding the center back up even, will heat the whole length and get it to shrink loose.

That bolt on the upper right broke loose on the first try, then came out with another nut welded on to it, right? I would have drilled that one before trying to weld that deep, but if it's cast iron, the weld doesn't stick much, and doesn't do much damage as long as the rod is in the middle of the bolt.

 

[BillG]

Might be a little late here but last winter I had to do quite a few broken ones. If the bolts protrude a little, take a piece of heavy angle iron (however much clearance that you have) drill a hole near the end that the bolt will go through. Weld the angle to the bolt and get it hot. At that point you can either use an adjustable wrench or a big hammer to loosen it. Your success will depend on the heat of the bolt and your welding skill, you can get better penetration and coverage around the circumference of the bolt than in a nut when welding in a difficult place.

 

[Welder Dave]

I am a little surprised that nobody that has posted has been a fan of torching the bolts out. I know it is done on heavy equipment but I don't know the success rate or the look outs to make sure it's successful.

Bolts are too small in an awkward location to get at and see what you are doing. It would be way too easy to destroy the threads on the track frames. I suggested cleaning up the old weld so there would better fusion and more surface area on the bolt for a new weld to stick to.

 

[charles miles]

Might be a little late here but last winter I had to do quite a few broken ones. If the bolts protrude a little, take a piece of heavy angle iron (however much clearance that you have) drill a hole near the end that the bolt will go through. Weld the angle to the bolt and get it hot. At that point you can either use an adjustable wrench or a big hammer to loosen it. Your success will depend on the heat of the bolt and your welding skill, you can get better penetration and coverage around the circumference of the bolt than in a nut when welding in a difficult place.

I think overhead welding skill is my limiting factor at the present time. I have to start and stop a bunch of times to keep weld from dropping off the stud. I am using 3/32 rods and I am having to stop and chip a lot also. Maybe I should go to larger rods so that I could build up one larger puddle over the stud and washer.

 

[Delmer]

That's definitely hurting your success. I've never done one overhead, and I can see it not working well, you want as much heat as quickly as possible into the bolt, the rapid heating is what does the work. Not a huge deal to torch it out, but I'd drill a hole first, and if you have the hole, then heating the bolt to burning temp (liquid on the surface sparking, and let it flow up the hole several seconds), that heat will shrink the bolt and it will turn out easier than washing it all out down to the threads and cleaning up the remains. IMHO.

 

[OzDozer]

It will be nearly impossible to extract the broken bolts cleanly using a gas axe and working upside down. The only really successful way to get them out cleanly is to invert the track frame.
Yes, drilling a hole through the centre helps, but working upside down means you lose accuracy, and the slag can't get away fully.

I once spent 3 weeks rebuilding my D6C undercarriage. I'd estimate fully half of the roller retaining bolts broke off flush with the track frame. I tore the frames off and inverted them and it still took me days of gas-axing and chiselling to get out all the remnant bolts.
The biggest problem was Cat had installed roller retaining bolts that were too long, and the exposed threads on the inside of the frame had rusted, making unscrewing them cleanly almost impossible.

The technique I used was drilling a central hole, torching as close to the threads as possible, then using a sharp small chisel and a solid seal pick (made from discarded stainless dentists picks), along with a pair of needle nose pliers, to pick out the remnant threads. I seem to recall I had to helicoil a couple, the threads ended up too badly damaged.

By far the worst stud/bolt removal job I've ever had was taking the studs out of a 1920 Brockway truck engine block (actually, two blocks, because the block was split). These blocks had been in some terrible mineralised water that effectively bonded the threads. I had to weld nuts on 5 or 6 times sometimes to get out the remnants.
And these were only Grade 5 studs - Cat Grade fasteners have the peculiar feature of hardening if heated to dull red, and simply left to cool. This is a feature of all low-alloy steels.

 

[Welder Dave]

The bolt extractor rods are supposed to burn through the slag but using them overhead puts a wrench in the formula. Maybe getting a nut welded as best you can and then heating it red hot with a torch afterwards to super heat the bolt would work.