TRX250R.ORG
General => Lounge => Topic started by: 2ndmoto on May 09, 2020, 09:06:11 PM
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Any welding pros out there? I need to cut out a hardened steel pin. It's 1.5" x7". If I cut it radially I have about an 8mm gap. cutting on axis I have a clear shot, but it's 7" of material to cut through and there is danger of cutting through parts I need to keep.
Looking at using oxy acetylene but I am not sure of the different torches and types of regulators. Any concerns with buying used? Suggestions are appreciated.
Best regards
-Jason
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A 7" deep cut is not a problem if you have large enough bottles. Your average homeowner size bottles are going to struggle. At work we would use a big bottle of liquid oxygen and the biggest bottle of acetylene to cut stuff 3-4 inches thick. If you can cut it radially I would use a 00 size cutting tip with 10psi acetylene and 60psi oxygen. I wouldn't attempt to pierce the 7". Have you seen those diablo carbide sawzall blades? You should try that.
Loren
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Perhaps rent a plasma cutter. I used one to cut 2" of steel, and used to have one that cut 1"1/8" very nicely, and weighed less then 80lbs.
desertR
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Thanks Norm. This pin is making things personal now. I tried an 8lb sledge, I tried heat, I built a 20 ton press, lots of on blaster, and I have tried the diablos. My latest attempt is using cobalt drill bits. They do drill but not very fast.
This is a stabilizer arm on a back hoe. I am trying to rebuild the cylinder, but I need to get the pin out. There is about an 8mm gap between the clevis and rod end. Do you think the gap is enough to cut it? Damaging the clevis or rod end would not be ideal. It's an older back hoe and parts are not easy to come by.
Regarding torches, should it be looking at a particular size?
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Thanks DesertR. I am a little limited on resources. There back hoe is located on some property I bought which has not utilities. I bought a 30A gas gen, but I don't think it does 240V....should have spend the extra $ for a bigger one
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Carbide drill bits will cut the pin, but very slowly. The pin is probably case hardened 4140 or something. If you do get a hole in it you should be able to wash it out of the bore. Like I said it's going to be hard to pierce 7" with a torch. If you are looking for a torch, I personally like Victor. They have a "journeyman " size. Really any regulator set that doesn't leak will be adequate. A 250 oxygen cylinder and a 150 acetylene cylinder are a good size for most things. A #4 cutting tip will cut a big swath once you get a hole in the pin. It would take forever to heat 7" enough to blow a hole. Can you get a mag drill mounted on the backhoe so you could drill it? Might be time for a 20lb sledgehammer? Or maybe heat everything in that area with a propane weed burner so everything grows then spray the shit out of it with Kroil? Then let it cool. It should grow and shrink to maybe break loose?
Loren
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Thank you Norm. I appreciate the information and suggestions.
For drilling I was attempting to remove material in order to get it to yield at the clevis. The drill bits are not long enough to drill half way through. Was thinking about a carbide burr and try grinding it, just to hollow out the pin which would make it easier to press/hammer out.
Regarding heat, the stabilizer arm is a pretty large piece of cast, so it is difficult to get heat into it and not the pin. I have been using some propane torches, I am sure a weed burner would get move great in quicker.
I might actually have access to a mag drill, but the surface of the clevis does have much surface that is perpendicular to the pin. And the pin is horizontal.
I have heated it and used pb, have not tried kroil. I'll have to give it a try. During my research many peeps swear by it.
If I cut the pin radially, then I have a much shorter piece to deal with. Would be closer to 2.5" long vs the 7". I'll check into the journeymen's torch
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I am dying for an update. Did you get the pin out?
Loren
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I appreciate you checking in. I have not had a chance to get back to working on it...I have been working out of town the last few weeks. Hopefully there are some torches and regulators at the house when I get back this weekend. Just have to get some bottles. Maybe Saturday I can give it a go. If you see any stories on the news about a backhoe catching fire in Texas...well that will probably be me.
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If it does catch fire just sit back and watch the show lol. The bright side is that you won't have to worry about getting that pin out lol.
On a serious note... Have you tried to hit the pin with a pneumatic chisel? Or maybe a pneumatic rivet buster? Those rivet busters are like a mini Jack hammer. They do take quite a bit of air, but pack a pretty good punch. You could heat the shit out of the knuckle and then start hammering the hell out of the pin. The vibration/impact might knock the pin loose. Or maybe you could build a porta power bracket and use a porta power ram to push the pin out.
I recently replaced the steering clutches/brakes on a komatsu dozer. I completely exhausted my tool hoard and then went through my neighbor had. I also had to build several tools just to save $5000. So I know what you are going through.
Good luck man
Loren
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(https://thumbs2.imagebam.com/9a/52/fb/cffcfc1345172406.jpg) (http://www.imagebam.com/image/cffcfc1345172406)
Maybe put something like that together using some 3/4" all thread and a 50 ton porta power ram? You could probably rent one.
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That's a great idea. Now that I am working out of town I have to weigh out the options. Time vs cost. I have been trying different things without much success. I have been trying to be aware of repurposing any thing I buy, so its not a one use tool.
Side note, don't buy a backhoe sight unseen. Lesson learned
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:-\
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Most bottle type jacks won't work on their side
desertR
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This one had no issue. It yielded the uprights on the press and was deflecting the clevis. Not a good scenerio if I break that stabilizer arm.
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Hey just a thought.... is there a grease fitting on the clevis? We had a frozen 8" pin on our krupp stacker/reclaimer. We loaded up a grease gun with Kroil and pumped it into the grease fitting after heating the crap out of it. It loosened the joint and allowed it to accept grease. We couldn't take the pin out as it was supporting about 100 tons of structure so this was a last ditch effort.
Loren
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Thanks Norm. You are a wealth of good information. I have no doubts that you would already have this pin out, cylinders rebuilt and the hoe moving some dirt.
The clevis doesn't have any zerk fittings at the pin. I was thinking about drilling, tapping and installing some. That would be a wise move for added serviceability in the future.
Speaking of the future, the stabilizer rods are pretty worn. Pitted, peeling and grooved. New ones around $400/ea before shipping. I have heard of people buying chrome shafts cut to length. Then having the old eyelet cut off and welded to the new shaft, then having threads machined in for the piston bolt. People are claiming $150/for for this. I am not sure where people are buying the chrome shafts or who they send them to for the machine work.
I have heard of others of grinding out all the peeling chrome, burned out contaminates and using jb weld, super glue or similar to fill the imperfections. Afterwords sanding it smooth and running them. These are suggestions, but I have not heard of people claiming fails or successes after trying this fix. I am tempted to try. Seals kits are cheap.
Bugets are made to be blown, and this hoe is has been a money pit. The farther I dig the more issues I will find, which will require more time and money. I am one for doing the job once by doing it right, but saving coin sounds really nice. The hoe is just going to be used for farting around at my property.
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Well I slept in today, so I didn't have a chance to get bottles. I did rebuild a different cylinder. One down, 11 more to go. Kicked my bum. I am getting too old for this and it is getting way too hot.
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I have used an epoxy called devcon to fix the seal area on a centrificical pump. It works pretty good, but you have to machine it after applying it on the shaft. If not it will wipe out the seal in a few minutes.
Loren
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Was able to cut it . Did this a few weeks back. It took quite a bit of heat. Now I need to get the pin end out of the clevis. Unfortunately the backhoe did not catch on fire, so have to continue to work on it
After all that, it would cost too much to fix the shafts. Ordered 2 new shafts and 2 new caps. New front main seal, rebuilt the injectors pump and hydraulic pump. New water pump and alternator.
Going to try and drill the rest of the pins out this weekend
Thanks Norm for the assist!