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  • MMW
    started a topic Komatsu boom crack repair

    Komatsu boom crack repair

    Started this on Thursday afternoon & finished up on Friday. Cracked twice & welded by the companies mechanic (he's good but always rushed). This time he wanted me to do it. Right where the side plate meets the casting. Gouged it out completely so I had a 3/8" open gap to the inside. Snaked a piece of 1/4" bar inside with a rod tacked to it to hold onto. Pulled it tight up against the inside & tacked it good. Preheated, then welded it up.

    Not really much to see. Basically like a weld test.

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    Last edited by MMW; 05-04-2013, 05:32 AM.

  • weldonwelding
    replied
    And also... i dont just work delaware, i do the whole penninsula and also sometimes new jersey, north carolina, west virgina and Pennsylvania. Where i live is kinda nice, i can walk to maryland in 10-15 minutes. Pa and Nj is 1.5 hrs away

    Leave a comment:


  • weldonwelding
    replied
    [QUOTE=JSFAB:307369]
    Originally posted by admweld View Post
    Not just once either Joe.Five times.
    I'm amazed. There are 5 excavators in Delaware???????? And all of them cracked in exactly the same place????? No wonder they keep breaking there (a relatively low-stress point), they must be banging into each other every time they swing around. I suggest moving three excavators out of the state, thus leaving just enough room for the other two to work.

    I would also suggest the resident "expert" concerning welding/repairs in that state, keep his mouth shut, otherwise some of the guys in neighboring states will realize how easy the competition is in Delaware. Heck, even I'm wondering. I came from Mass. originally, I'd have no problem going back. And "wire" isn't necessarily .035 hardwire, it's also the various dualshield wires and innershield wires, I can easily double or triple stick deposition rates, both flat or out of position.

    My apologies to MMW, you posted a valid problem, and a correct solution to the problem. I admit, like you, I probably wouldn't have slugged the back of the weld, without specific advice to do so. With hindsight, I realize now this is probably the best way to approach this repair. Thanks for posting up, that's what this message board is for.

    Really.. u cant just let that go can ya?.... well as i said before, i also use a feeder. WHERE NEEDED! But just out of curiosity.. lets say you had a cat bucket, 8' wide, you cut the old edge off and replacing it with a new cat edge. Whatcha gonna weld it with? Wire size? Machine? Wire type?... i agree he fixed this problem pretty close to what we have done. I wasnt saying anything but i have seen quite a few of these, their pretty common. I dont see the problem with what i said, exept you just have to start ****. I have been fixing heavy equipment since about 15yrs ago and with that strictly welding was the specialty in the shop i learned in. This is what i do. So why is it surprising that i have done this?... or very close to this

    Leave a comment:


  • weldonwelding
    replied
    Hmmmn..... obviously there is a manufacturers problem here.. i really didnt think much about it, nor did i think i would get a bunch of **** about it. Komatsu is having problems with their robotic welds cracking on the main boom is several places.. Not on their newer models but older. Every one i have repaired has been far out of warranty. Theres lots of quite large excavators in good ole delaware.. mostly due to all the sand and gravel pits. I also do a little for komatsu dealer in baltimore. Since i have done them before they usually call me, and volvo, and cat, and kubota.. they do too. Soon i will have the case dealer too... hopefully. I used to do all their work when i worked for welding by jackson. Now when i worked for jacksons.. **** i couldnt even tell ya how many boom repairs i made for komatsu. Its kinda become a specialty.

    Leave a comment:


  • JSFAB
    replied
    Originally posted by admweld View Post
    Not just once either Joe.Five times.
    I'm amazed. There are 5 excavators in Delaware???????? And all of them cracked in exactly the same place????? No wonder they keep breaking there (a relatively low-stress point), they must be banging into each other every time they swing around. I suggest moving three excavators out of the state, thus leaving just enough room for the other two to work.

    I would also suggest the resident "expert" concerning welding/repairs in that state, keep his mouth shut, otherwise some of the guys in neighboring states will realize how easy the competition is in Delaware. Heck, even I'm wondering. I came from Mass. originally, I'd have no problem going back. And "wire" isn't necessarily .035 hardwire, it's also the various dualshield wires and innershield wires, I can easily double or triple stick deposition rates, both flat or out of position.

    My apologies to MMW, you posted a valid problem, and a correct solution to the problem. I admit, like you, I probably wouldn't have slugged the back of the weld, without specific advice to do so. With hindsight, I realize now this is probably the best way to approach this repair. Thanks for posting up, that's what this message board is for.

    Leave a comment:


  • admweld
    replied
    Originally posted by weldonwelding View Post
    I see.. from your reply I kinda assumed this was your first time ever seeing anything like this.
    Ya i have not seen to much.

    Leave a comment:


  • HayFarmer
    replied
    Originally posted by MMW View Post
    Hayfarmer, The reason I used the backer was the day before I got there the rep had stopped by for something else & happened to discuss this with the mechanic. He described the way they fix it in their shop which uses the backer so that's what I did. I most likely wouldn't have backed it if it wasn't mentioned. The side plate was about 5/8" thick & the "ear" on the casting was about 1"? thick. The outsides were flush but the insides weren't. The 1/4" backer I used layed on the inside of the side plate & butted up against the casting "ear". The backer was hot rolled steel. I don't know for sure but I think the side plates are hot rolled steel also.

    As far as stress risers, I'm no engineer so I couldn't begin to figure out if this will be one or not.

    As far as ag vs. excavating equipment, I don't find them much different. At least with the newer ag stuff anyway.
    So you had some input going in to it. I would have liked that myself. Im not an engineer (at least that type) either and I wonder how some field decsisions are made. Im not sure I would want to make those choices w/o considerably more knowledge.

    I have really no experience in heavy equipment so its a black box to me. I would have thought the arms on machines like that would be made from some high strength alloy.

    Leave a comment:


  • weldonwelding
    replied
    Originally posted by admweld:307287
    Originally posted by weldonwelding View Post
    If ya look in my pics... pretty sure theres pics of a very simular repair on a pc 400.. ****. Since there is a komatsu dealer very close to me i do lots of work on them. They keep me pretty busy
    There,s a dealer about 2 miles from shop.And ive worked on few also for them.
    I see.. from your reply I kinda assumed this was your first time ever seeing anything like this.

    Leave a comment:


  • MMW
    replied
    Hayfarmer, The reason I used the backer was the day before I got there the rep had stopped by for something else & happened to discuss this with the mechanic. He described the way they fix it in their shop which uses the backer so that's what I did. I most likely wouldn't have backed it if it wasn't mentioned. The side plate was about 5/8" thick & the "ear" on the casting was about 1"? thick. The outsides were flush but the insides weren't. The 1/4" backer I used layed on the inside of the side plate & butted up against the casting "ear". The backer was hot rolled steel. I don't know for sure but I think the side plates are hot rolled steel also.

    As far as stress risers, I'm no engineer so I couldn't begin to figure out if this will be one or not.

    As far as ag vs. excavating equipment, I don't find them much different. At least with the newer ag stuff anyway.
    Last edited by MMW; 05-06-2013, 05:21 AM.

    Leave a comment:


  • MMW
    replied
    Originally posted by kerr74 View Post
    MMW...I'm still learning....what do you mean by stringing?...like the pics an explanation on how you did the repair
    Kerr74, Stringers are basically normal size welds overlapping each other to create a large weld. Here is a link explaining it.

    http://www.weldmyworld.com/quick_wel...ger-beads.html

    Leave a comment:


  • admweld
    replied
    Originally posted by weldonwelding View Post
    If ya look in my pics... pretty sure theres pics of a very simular repair on a pc 400.. ****. Since there is a komatsu dealer very close to me i do lots of work on them. They keep me pretty busy
    There,s a dealer about 2 miles from shop.And ive worked on few also for them.

    Leave a comment:


  • weldonwelding
    replied
    Originally posted by aametalmaster:307268
    Originally posted by weldonwelding View Post
    i have fixed about 5 of these so far on pc400's.. and also where the main boom cylinder goes into the bushing. The last one i fixed was from a bad weld, it was full of porosity on the whole bottom half of the weld. Not real good QC to let something like that come off of the line
    Prob robotic welded and the 18 yo QC guy didn't care or didn't know. I saw it alot...Bob
    Yep.. definetly robotic.

    Leave a comment:


  • weldonwelding
    replied
    Originally posted by admweld:307270
    Originally posted by weldonwelding View Post
    i have fixed about 5 of these so far on pc400's.. and also where the main boom cylinder goes into the bushing. The last one i fixed was from a bad weld, it was full of porosity on the whole bottom half of the weld. Not real good QC to let something like that come off of the line
    Of course you have.You,ve seen it all.
    If ya look in my pics... pretty sure theres pics of a very simular repair on a pc 400.. ****. Since there is a komatsu dealer very close to me i do lots of work on them. They keep me pretty busy
    Last edited by weldonwelding; 05-05-2013, 06:49 PM.

    Leave a comment:


  • HayFarmer
    replied
    Originally posted by MMW View Post
    Yes it is cast steel. Not sure if it's common but the rep said he has seen this before on this model (PC400). The machine also has 11,000 hours on it.

    The first passes I used 7018. One from the backer strip to the side plate & one from the backer to the casting. I did this because stick usually burns out any contaminants better than wire & I wanted to make sure I had a good root in there. I then finished with innershield wire doing stringers. I had about a 3/8" gap at the root & maybe a little more than 1" gap at the outside.

    I didn't have my temp gun with me but tried to get it to about 300* at the start. There is so much steel there that I didn't worry to much about interpass temps. I just didn't rush it & cleaned each pass real good.
    I was thinking about the backer and theres no danger of it becoming a problem later on? My familiarity w/ backers is they must come off. I think they can become stress risers. Also did you try to match the backer to the original material or just use mild steel/whatever you had on the truck?

    To me it seems very difficult to repair heavy equipment. There are so many variables you may or may not know or be allowed to know. Ag equipment seems a lot more doable. Guess its all about what you know....

    I find these threads very interesting! Thanks a million for explaining what you did and why.
    Last edited by HayFarmer; 05-05-2013, 06:17 PM.

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  • admweld
    replied
    Originally posted by JSFAB View Post
    lol ......

    Thanks, Billy, you just made my day.
    Not just once either Joe.Five times.

    Leave a comment:

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