Cracked my 36" backhoe bucket removing small stumps

[robstaples]

I would like some welding advice on the carelessness with my new thumb. I was pulling out 5" buckthorn stumps ( live-fresh cut) . Grabbed them at the top and pinched with my foot peddle and wiggle and pulled toward me (Must have been the fatal mistake for crack 1).. and Voila broken bucket. Pinched one on the right end of bucket too (crack 2). It was fun shaking the dirt out of them, etc, until I notice the arc in the bucket edge.

I have MIG and TIG available and thought to v-grove the cracks and multi pass the fill. I have 308 and tri-gas for stainless, also ( wondering about a harder fill material). What I know little about is the pre heat, slow cool, and the best wire to use with xxx ( is it cast steel??)( I'm absolutely terrible with stick)
My damage is below. the cracked is in 1/2" material. Crack 1 and crack 2
Your Suggestions would be appreciated:

 

[Shield Arc]

Do you have a carbon arc? I would drill holes at the ends of the cracks first! A grinder will work, but sometimes a grinder will cover up a crack. Where as a carbon arc will open up a crack. I like Lincoln's L-56 Mig wire. I'd preheat to 200 to 300-degrees, after welding cover with a welding blanket, or house insulation until cold.

 

[LD1]

How old is the machine? I see you still have paint on the bucket. Warranty?????

I find it hard to believe that IF there wasnt something wrong with that bucket, that you would be able to crack it like that (in the 1/2" material) with a L39. But I have a hard time visualizing what exactly you described that you did.

But if it were mine, It would be drill the ends, grind out, fill in. And no need to grind it down smooth after it is welded again. Leave the weld bead.

Weather I used stick or mig would depend on whether I broke it at my house (mig) or at my parents (stick)

 

[mguitas]

Ya , i bet you had a 12 inch bucket that wouldn't crack. The smaller the better for stumps.

 

[robstaples]

Yes, I have a 12" and will be putting it on. No quick connects for me, unfortunitly or this wouldn't have happened
LD1 the bucket is about 5 years old. I used it as a quick load wheel barrow for landscaping where I couldn't get the front load bucket in. and digging holes for tree plantings-- not much wear. In this case, I pulled on the wood stump which probably concentrated the force in the middle where it cracked. I'm surprised by the end crack.
Questions: do you fill the drilled holes in the last pass ? I understand it's to arrest crack creep(?) Secondly: I have plasma- up to 80 amps, and I see there are gouging tips. Will that work? I would practice, first. I think I risk blowing a lot of metal away and making the situation worse. I would/am consider/ing a pro if I knew they knew what to do. Local recommendations (SW Michigan) will be pursued.

 

[Shield Arc]

robstaples this is no big deal really! Pre-heat and slow cool down are needed for that AR-cutting edge. Your plasma will work great for scarfing out the cracks, in some ways I'd rather use a plasma than a carbon arc. Here is a weld I scarfed out with my plasma. You can bevel with it too. You'll have to really clean the area good before welding. I don't know if it really matters, I've done it both ways. I'd fill the hole first, and weld to the other end.

 

[Mark @ Everlast]

You could get another cutting edge, and cut it out and weld it back in. I'd also weld a reinforcement on that bucket. Kubota tries to get away with the lightest metal they can and still be strong, on their loaders and back hoes. They've often "underdone" it. I've fixed a bucket or too and that metal is much thinner than you think.

 

[Arc weld]

With the amount of new paint still on the bucket and the teeth like new, I'd certainly be talking to Kubota. With the size of the teeth, there's no way that bucket should have cracked like that. Now if you were banging rock or really abusing it, maybe it could crack like that. Trying to get a stump out, the hyd's. should have failed before the bucket cracked.

Maybe we should examine the cracks and try to understand why they happened. I think there's a good possibility that the mass produced bucket was just that. The cutting edge is obviously higher carbon or AR plate and that's why it cracked. Mild steel doesn't usually crack like that. My theory is when they built the bucket they didn't preheat the hard cutting edge and the heat from welding the bucket/teeth on made the edge even harder and that's why it cracked. If you notice the cracks are in the HAZ(heat affected zone) right along the edge of the welds. One of the main reasons for the preheat. It was also welded with a wire feed process, most likely dual shield flux-core. This is a faster process that also results in more rapid heating and cooling which would contribute to the HAZ zone cracks. :2cents:

Kubota should at least be giving you a credit of a couple hundred bucks or so for your trouble. A new bucket would be the best but you should get something. I'm sure the hoe cost a few thousand $$$. If you grind it and weld it, weld from each end of the crack inward so there's no craters at the ends of the crack. You can get a Tempil stick temperature crayon at a welding supply in many different temperatures. I think maybe even 400 deg's. is recommended for AR plate. Should be able to look on the net. I think T1 is 400 so AR should be close to that.

Oh and there is one more thing... Don't even think of trying to weld it with a 120 volt welder.:hissyfit::anyone:

 

[Shield Arc]

Oh and there is one more thing... Don't even think of trying to weld it with a 120 volt welder.:hissyfit::anyone:

 

[Ken45101]

You are lucky! At least yours is still in place. When I cracked my 30" mini-ex bucket (Kubota KX-121-3), the cracked part bent several inches:





(for some reason, the system is turing the pictures upside down!)

Attempts to bend it back were totally futile. I ended up cutting out the bent section (gulp!) with the plasma cutter and then welding it back with 6011 and 7018 rod. So far, it's been holding up just fine (knock on hard head!)

BTW, I broke mine on a stump too, a big stump and I unwisely tried rocking the stump with the bucket in a crotch.