need to repaid this cracked backhoe boom

admin

I have to repair this 410g john deer boom for work there is one new replacement in the country at $8500.00. not an option. the crack in the boom is close to 4' and right at the weld .I will sand blast all the welds in the area to closely inspect for other fatigue,then grind this out and do a proper repair. the ? is in the boss area that holds the bushing which was also cracked and came right out .we cant get a new piece and don't have much for good machining tools. it is also cracked a little on the bottom side. can I grind the boss area out as much as possible and weld it pre heat and spray mig then grind to fit a new bushing? any help on this one will help.  I will get more pics when I get back to work on Mon. Attached ImagesLife is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:ASE, looks like it has been repaired at least once previously.  I would be very carefull and see if you can find the WPS for that part prior to taking it on.  You could weaken it if you dont follow the correct temps and procedures.  Could get you or somebody a ride in the hurt wagon or worse.  As far as a bushing goes you could get a local machinist to make one for a reasonable price, but any way you go this doesnt look like a done before lunch on monday kind of project.  Good luck and post up some pics when you get it done.BobI'm spending my Kids inheritance, I dont like him that much anyway!!!!!!Enuff tools to do the job, enough sense to use em.Anybody got a spare set of kidneys?  Trade?
Reply:It sounds like you have a good plan.If it was me I would remove all the paint and look to see if there are any more cracks and determine if it is repairable.I am sure it is.Then I would call the manufacturer and ask them what the metal is that makes up that weldment.While I have them on the phone I would ask if it is a known issue and if they have developed a repair routine.Please let us know how this goes and send more pics for us. Thanks.BTW....I noticed it is cracked On THE WELD. MAybe it had poor fit up or some other issue and the manufacturer knows all about it.Last edited by Donald Branscom; 03-26-2011 at 06:16 PM.AWS certified welding inspectorAWS certified welder
Reply:I'd like to see some pics of the part from a greater distance. It looks like that long crack might be on the corner of a reinforcement plate, either factory or installed as one of the previously repairs. If it is, I would completely remove the plate, get to the bottom of the cracks, and weld out.You have many hours ahead of you.Keep us posted.Just my  opinion, not from a book, just from the road.Howes Welding Inc.www.howesweldinginc.com
Reply:ASE - Need to see more pics, but from what is seen its no big issue. I have done it on trackhoe booms on many occasions , the KEY to the job is going to be PREP. , dont take any short cuts. After seeing more details of the cracks then you will be able to determine how to handle it. Good luck     keep us informed.
Reply:One more thing. You see the crack goes in three directons.Each weld should be started on the outside, and welded toward the center where they all meet together.AWS certified welding inspectorAWS certified welder
Reply:this has not been repaired before. we have called JD and the dealer (does not like to help on these problems only they can fix it) only said they would repair for$4500. the Parts book that came with the rig said no longer available use updated part # .that tells me it was a poor design to begin with. the bushing boss is very hard. I have informed them it will be a week or more.city DPW union ya know!Life is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:Most of these booms are not made out of high tensile material, so a repair should not be a problem. If the damage is only on the one side, you should check to see if has been twisted. This may not have been checked at the time of the previous repair, so that uneven stresses are being applied to the boss, causing it to tear out. When you weld up that boss, you will have to check the bore for roundness. If it is already out of round, then you should get a local machinist to bore one out for you. This is a common repair, but a critical one none the less. FWIW, even though I have a selection of welding equipment available, I always use SMAW with low hydrogen rods for these repairs, as well as a preheat. Good luck!
Reply:I repaired the other part of the boom that attaches to that on a JCB hoe. I was surprised at how thin it was.Leo
Reply:Just saw your new post. The welds around the ends of the boss don't really look factory, and the picture is a little too close up to see how the boom is constructed. As for the boss being hard, I have my doubts. It could be machined from 4130 which is tougher than mild steel, but there is no reason to use hard steel for that application.
Reply:Arcair the the crap out of itLast edited by ed mac; 03-26-2011 at 07:57 PM.
Reply:i would burr out the cracks with a smaller ball burr then mt it to make sure that i got all the cracks out.and would probably weld it up with 7018 then mt it again.After the arc has died the weld remains
Reply:This rig was bought new and has not been repaired. I will know more on the failure as I clean it up and test the metal for fatigue and poor fitup . we may try to get a new boss made at a local machine shop, also we are going to JD R&D for more details in the proper repair if we can get to them.THANKSLife is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:Not the first time I've seen welds like that on a back hoe, theres one over at my tech school that looks the same and still has the factory paint on it so I wonder if its a case of third world manufacturing outsourcing.  Not an expert but I'd carbon arc it then fill with low hydro 7018 and preheat to 125 with interpass temps of 300 and as others have said please provide work in progress pics and end results and I'll bring the pretzels and beer.
Reply:(repaid) you should get you spelling right . i dont care and new what you mentbut some people hear will come down on you for thatmaybe they have nothing else to do or maybe there just mean
Reply:Originally Posted by asemasterThis rig was bought new and has not been repaired. I will know more on the failure as I clean it up and test the metal for fatigue and poor fitup . we may try to get a new boss made at a local machine shop, also we are going to JD R&D for more details in the proper repair if we can get to them.THANKS
Reply:I had done a similar repair on a cat boom.   I had l local machinist make me a brand new round end for it for $500.  BTW it was 12 in in diameter and he had bored an 8 inch hole in if for me.  I welded it up with lincoln fleetweld 5P+ 6010 avg of 150 amps with my vantage after I had welded the ends up complety. I took a quarter inch plate n cut it where it fit on the boom towards the round thang bout 4 ft top and bottom and bend the plates in and weld it all the way around.  Never had a problem with it again and it been 4 years now.  I was the only one who can keep their equipment together and I dont know whyOf course I don't look busy.....I did it right the first time!
Reply:Looks pretty straight forward to me.  Gouge it out ALL the way and then 2-3 inches past the crack, clean ALL of the carbon out from gouging, depending on thickness, you may not need to preheat as most of these booms are made of pretty ligh material.  Weld it up with 7018 or hardwire.  If you do not plan to bore the hole, it would be most advisable to install your new bushing BEFORE you go to welding on that boss or you may not get it in when your done, best way would be to complete the repairs and then bore it.6 Miller Big Blue 600 Air Paks2 Miller 400D6 Lincoln LN-25's4 Miller Xtreme 12VS2 Miller Dimension 812 4 Climax BW-3000Z bore welders Hypertherm 65 and 85Bug-O Track BugPair of Welpers
Reply:From: Rutland City Dpw, Equipment Maintenance [mailto:[email protected]]Sent: Thursday, March 24, 2011 12:21 PMTo: Day CraigSubject: City of Rutland Back hoe boom Attached ImagesLife is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:this is the under side Attached ImagesLife is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:Looks like a simple matter of the boom being too light for the use and length of use.  It's coming unglued. "The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Originally Posted by asemasterThis rig was bought new and has not been repaired. I will know more on the failure as I clean it up and test the metal for fatigue and poor fitup . we may try to get a new boss made at a local machine shop, also we are going to JD R&D for more details in the proper repair if we can get to them.THANKS
Reply:Originally Posted by asemasterFrom: Rutland City Dpw, Equipment Maintenance [mailto:[email protected]]Sent: Thursday, March 24, 2011 12:21 PMTo: Day CraigSubject: City of Rutland Back hoe boom
Reply:Originally Posted by Donald BranscomThat long  crack looks like it is in the heat affected zone next to the weld.
Reply:I will be posting pics as I clean it up. this tractor is used to dig up blacktop and cement roads ,it has a heavy lift extend a boom with a 24" bucket.the heal or heat effected area of the weld is definitely in the problem area. what gets me is they knew it would fail when they built it and are not responsible for poor engineering.Life is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snaponYou have quite a job in front of you...In all reality to do this correctly you have to take this all apart and have it repaired in a shop rather than on site..Lots more to that than you see even in these pics..I am pretty sure you will find even more cracks and stress tears.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by asemaster this tractor is used to dig up blacktop and cement roads.
Reply:Originally Posted by MrLeadManThere's the problem. I would bet that the operators use the bucket and boom like a giant sledge hammer. Hoe booms are made to dig, not take the shock of being used as a wrecking ball.
Reply:Originally Posted by SandyLooks like a simple matter of the boom being too light for the use and length of use.  It's coming unglued.
Reply:Used for black top and cement road work. Sounds like hard duty to me.No wonder it is cracked all over the place. Wonder that it did not just all come undone with all those cracks.Last edited by Donald Branscom; 03-28-2011 at 10:05 AM.AWS certified welding inspectorAWS certified welder
Reply:It's cracked all over the place.By the time you dismantle it ALL, and clean it ALL, and find ALL the cracks, you could probably be halfway done to making a complete new boom out of thicker material.  IMHO.  And that's before you even get into an attempted repair of the (broken all to He##) boom.Your call, but it is NOT just a 'simple' weld up job.Heck, just that bush/boss end for the pin has to be pretty much completely removed because there is almost no WAY you could get to the 'interior' in order to fix those multiple cracks.Hourly rate of welders + machinists + material > close to just go and buy a complete replacement boom.  YMMV.Post some follow-ups either way.  The best laid schemes ... Gang oft agley ...
Reply:sand blasted first thing Attached ImagesLife is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:then inside I cut out a small part of the weld, then pushed it back together and tacked in place. Attached ImagesLife is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:I then plasma gouged out the old weld. Attached ImagesLife is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:after it cooled I removed the tacks and it stayed in place, I then started to grind out to prep for the weld. Attached ImagesLife is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:the rest of the pics are of small cracks under the boss. at this time do to the fact that this is for our own use I will not remove the boss as there is another support plate in the center and I would have to dismantle the complete boom. I will clean up more cracks and weld tomorrow using the wire feed and e70s wire.then fit the new bushing when it arrives. the operator has been warned to use it in a little lighter manner.hahahahahaha. more pics to follow. Attached ImagesLife is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:man, you really need an air arcI agree with ExpatWelder, that is classic side load abuse...seen it many times....just for your own education, did you notice where the cracks and failure points in the weld started?....most of the time it is on the end of a pass, tie-ins, or undercut...when you weld, dont make it look like what you just fixed...
Reply:You are going to have high and low spots in that bore----definately needs to be built up then line-bored to size if you want realistic life out of the bushing.6 Miller Big Blue 600 Air Paks2 Miller 400D6 Lincoln LN-25's4 Miller Xtreme 12VS2 Miller Dimension 812 4 Climax BW-3000Z bore welders Hypertherm 65 and 85Bug-O Track BugPair of Welpers
Reply:Originally Posted by asemasterI then plasma gouged out the old weld.
Reply:Originally Posted by galencwiwas it easier to plasma gouge?  ive never had the opportunity to try it
Reply:Originally Posted by Matt_MaguireIf you're not real deep (like a crack in large shafting) it's the way to go. Very fast, very cheap and very easy to keep the area clean.With a small section work at 25amps and whittle away, large sections bust the knobs off and blow it away.Matt
Reply:I brought in my hi intensity light and looked through the small hole and of course found more cracks so I removed the top. the pics will show the weldment and cracks. cleanup to the point of when I went home today. not having fun anymore. Attached ImagesLife is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:gouging and cleanup so far. Attached ImagesLife is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:I will post more tomorrow of the weld up. Attached ImagesLife is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:Pretty poor factory welds. Production...Tim Beeker.
Reply:you have a good camera, i can never get that type of detail.........
Reply:Originally Posted by ExpatWelderI somewhat agree, but I have ran into this same issue on many different machines, all makes and models and all sizes and most of the tim what it comes down to is operator error.
Reply:wow  when i see gross opperator error and misuse like this i get HOT as hell. thank god that sob "operator" and i use that term VERY LIGHTLY is in a union and very far away from me. i'd yanked him out the seat by his ear whopped him up and down the street.  i get calls for repairs like this  and laugh i tell them you had better be ready for a big bill one from my machinist and one from me. if they say OK then i fix it and if they start telling me "oh no it is just a small crack just weld it quick, just make it stick." i tell them to find some illegal with a 110V wirefeed and quit waisting my time.
Reply:Originally Posted by bravofabwow  when i see gross opperator error and misuse like this i get HOT as hell.
Reply:How many hours are on the machine?