Just picked up a 2016 Case CX490D machine. Bought it right knowing it needs some repairs. Looking for options on how to properly repair this issue on the main boom section. Can a repair shop fix this crack and actually make it last or should I start shopping around for a replacement? If someone were to repair the crack would the boom need to actually be removed from the machine or could it be done while still installed? Also wondering what might cause this issue in the first place? Looking for any ideas or opinions! Thanks
I'm no expert but I wouldn't expect just welding that crack to hold even the first time around. It should be grooved out, welded and then plated in my opinion. I'd do the repair with the boom on for sure. Could could use the machine to tighten up the crack if need be. Move the hoses out of the way and do the repair.
Yeah whoever attempted to repair it the first time definitely didn't do a very good job.
Also anyone know what the main reason a boom would crack like this might be?
I've been around two broken booms. One was a 245 loading big ugly Rock on night shift at a damn job. It cracked right through the boom cylinder bosses, broke off and dropped the stick and the end of the boom into the back of a terex. I would chalk that one up to just gross abuse. The other was a Long reach hoe that I ran after it was repaired. It was broken in the same area more or less actually a little forward of the boom cylinders. Those things are just very flexible and easy to abuse . I would be giving the rest of that machine the stink eye because it very well could have taken a hell of a hit.
Usual SOP for cracked booms is to remove from the machine then the boom can be rolled over to make access & welding easier. Repair often involves cutting holes in the box structure of the boom in order to repair cracks in internal bulkheads that can’t be seen. If the internal cracks aren’t fixed properly then any external repairs are literally “papering over the cracks” and are a waste of time and money IMHO. My 2c, YMMV.
Looks to me like someone was swinging to the right and smoked something or was beating against something on purpose.
Check out IC Weld YouTube channel - he does heavy equipment repair and has a few videos of boom/stick welding repair.
Very common with guys who drop boom n bucket mid swing. Waste machines are notorious for this failure. Speak with the dealer, there is a specific repair procedure to follow. As Nige mentioned, there are internal stiffeners or bulkheads. The manufacturer will have detailed information on how to perform that repair correctly and with the right materials
This can be repaired, I have done it many times. Need to close it up vee it out weld and grind it smooth and plate it top bottom and side. A good welder can do it in place hyd lines and whatever else might be in the way will have to be moved for access.
I think Nige showed how a boom was repaired using the Cat procedure in an older post. Preheat and a competent welder is required but it can be repaired. A really good welder may be able to repair it on the machine but all the hyd. lines and stuff need to be removed. Yes, it needs to be inspected internally. Case/Sumitomo may have a welding procedure too. Even it costs several thousand bucks to repair I think a new boom would be almost astronomical in comparison.
Larry The Cable Guy says: "I believe: Sometimes you gotta wreck the truck to get insurance money to make the truck payment." I admit that has nothing to do with this. The good news is you don't have ductile iron. Bad news is this is a BIG machine with power enough to tear itself apart. Do NOT try to take a shortcut. Last repair effort was wasted. Might as well use duct tape. Remove it. cut it open. repair all layers. On the innermost layer put backer plates. Use preheat, (I'll leave temperature to other people better informed than I). On steel ground clean, and shaped for full penetration use multi pass welds to fill. Experts will disagree on process & filler. Some of them will suggest 7018 stick. Others would favor dual shield flux core with shielding gas. My non expert opinion is you need a good fusion with old steel. The very strong fillers will shrink as they cool & tear away from the cold steel. 7018 is famous for its ability to stretch as it shrinks to maintain fusion integrity. I believe basic dual shield wires work as well. It is the ultra high tensile fillers prone to ripping loose from workpiece. In any case, find a very competent welder to do this. Amateur efforts will fail.
Even better if you beat the **** out of it with a needle gun after every pass to stress-relieve it. Double duty as it removes the slag at the same time. And if you want something even better, Eutectic Xuper Nucleotec 2222 electrodes are the dog’s bollox. Originally designed for welding nuclear pressure vessels they have an elongation factor in excess of 50%. They were our go-to for anything that we thought had the remotest chance of re-cracking. Pricey though.....
I'm sure if the censors knew what you said they'd black out most of it. Still, it is good advice.......I think.
Yes to peening and since it's a big machine may consider having it stress relieved using flexible ceramic heating pads. Some booms come stress relieved from the factory where they are likely placed in a large furnace in 1 piece. A vessel shop near where I live has the largest stress relieving oven in N. America. This is the same company that built an 820 tonne vessel that was transported to site on over 900 wheels. Do it right and it will good or better than new. Do it wrong and it's a big waste of time and money. I personally don't think you need to use the real expensive specialty rods for the repair but need to use something similar to what was used at the factory. Case may be able to tell you what type of steel it is. Something like 8018C3 (1% Nickle) may be suitable. It is used to repair crane booms and the 1% Nickle gives extra toughness. Dual-Shield Flux-Core comes in comparable types to most stick electrodes. I think if you get it repaired properly for under 10K you're doing good. I could be way off on the repair cost though.
Def repairable, by someone that knows what they are doing. Airarc, plasma, and my needle gun are def my friends doing a repair like that, and it is always easier to have have the piece off the machine so I can put it up on heavy stands and move it around.
It looks like the people who built that boom are the same ones who built the Cat booms that have been failing for years. Nige is correct in that the boom has inherent defects inside that will have to be corrected in order to stop the cracking. Just welding the outside will allow you to use the machine for awhile but the crack will just show up again. You might be able to fish plate the top and sides and have it hold together. That might be an easier than cutting the boom open and fixing what is wrong on the inside.
I'm curious, what would one use to fish plate? Certainly not basic mild steel? A 15000LB rental machine I've seen several times with broken dipper has been patched several times by the worst welder in the world. It looks to be MIG welded without any effort to cut for full penetration. Then random pieces of irregular shaped rusty steel picked from a junk pile are scabbed over partially covering the break. I'd guess it takes only hours to break it again.
This .............. Good quality structural steel plate Willie. From memory I think the spec is an ASTM A572 of 42k pounds minimum tensile but without digging for the exact info I would stand to be corrected on that. The procedures for weld-repairing a cracked boom usually involves cutting it open for access, attending to the internal cracks, reinstall or replace the plate over the access hole, AND finally installing a fishplate over the outside when everything is finished. A kind of "belt & braces" fix if you will. i could go into detail for a repair procedure but it would be without the benefit of knowing exactly where the bulkheads are inside the structure. In this case a section of the top plate a minimum of 12-15" long would be cut out in order to gain access to the inside (it would be replaced by a section of new plate afterwards which gets rid of one of the cracks straight away). The exact length of the piece and the location of the two transverse cuts would depend entirely on the internal design of the structure, and that's where some info from the OEM would be essential before getting the plasma torch out.
There are a few ways to look at the repair. 1 involves cutting access holes and repairing everything internally and then repairing the outside, then welding the cut out plate(s) back in place. Doing this way and possibly stress relieving would give you a boom close to what the original was without requiring fish plates. The 2nd option is to repair the cracks you can see and add fish plates over the cracked sections. More of a redneck fix and not nearly as good as the 1st option. Also likely to crack again. 3rd option is to repair like the 1st option and also add fish plates. This may be the best option or just overkill??? The good thing is the fish plates wouldn't have to be very thick material to add strength to the area. I think even 1/4" thick higher strength material would add a lot of piece of mind. Fish plates need to have rounded corners where welded on the boom. Oval shape would work. Still need to look at what a whole new boom would cost. I would bet tens of thousands. Fix it right the 1st time or don't even bother trying.
Sure wouldn't hurt to find the part number for the boom, go on machinerytrader and see if there are any cab fire machines with a salvageable boom. Obviously it was designed by humans, welded together by humans, and can be fixed by humans. But I don't know where you'd find a shop that I'd trust, and I wouldn't guess what it would cost you these days, or how long it would take them. If this was an old farm backhoe, then you could probably get away with grinding it out, welding it up and keeping an eye on it. Can't do much to this without removing all the hydraulics, then you might as well remove the boom. Have to at least try the manufacturer to see if they have a procedure. If you have it sitting on the ground, then you want it done right. No reason in my mind not to do it yourself if your welding is up to snuff, the design of the repair is critical, the welding in position with the proper prep isn't especially difficult.
I think it needs a very competent weldor(s) for the repair. They are out there. Can't take any short cuts and preheat needs to be maintained. If could find a good used boom, great.
totally agree with Nige
When I started making a living at this we used a lot of 1/4” mild or HY80. In the last twenty years or so we used 3/16” T1 for the fish plates. The stick welding was done with 5/32 7018 when flat and 1/8” when out of position. When the squirt guns became popular, I recall using E70T dual shield in .045 size. The cracks were air arced out, ground smooth and welded. The weld was ground smooth and the surfaces cleaned of paint. The fish plates were cut so they had no points and there were holes cut for plug welding. Keep in mind that in those days the makers never admitted that there were any faults in their designs. The failure in the photo has a workmanship or design failure inside that will need to be addressed.
Regarding steel the usual was something of a similar or identical specification to the original plate, thus removing any issues of fusing dissimilar metals with the welding repair. A fishplate for the top/bottom of a boom would look something like the example below. The quantity and size of the holes for the plug-welds would be dependent on the overall dimensions of the reinforcement plate.
Fish plates could be concave like Nige shows or convex. As long as they are rounded. Air ArcIng is great for speeding things up BUT you have to make absolutely sure everything is ground to clean steel. A tiny spec. of carbon would produce a weld flaw. What a waste of time if this happened.
That's why my preference is to use a plasma cutter in this type of repair.
Used to use T1 for everything, my current favorite is Weldox, now called StrenX from SSAB. In thinner material, Domex is great, also a SSAB product.
There was no such thing as a plasma cutter when I was putting booms back together. Fish plates for booms looked sort of like what Nige shows but were never straight like that and always had a radius where is drawing shoes the end points. I'll have to look for some old photos. I don't know anything about the names of the newer materials. I would be curios about the costs and if those materials are a bit exotic for repairing booms with. 7018 was used because it would work with any different material. The tensile would allow for expansion and contraction between the T1 on the fish plate and the mild steel in the boom. What we were doing back then was standard for the industry.
That drawing above was a bit on the small side John. I know where the document was and lifted it straight from there. In the flesh the plate had a 5/8" (15mm) flat on the corner and the ends were welded as shown in the photo. At least one bead of the fillet weld down the side was run out 3" past the end of the plate, and the fillet weld in the radius terminated about 1-1/2" short of the end of the plate. Another snippet is that Cat booms are manufactured from A572M steel and have been for around the last 20 years to my knowledge.
After John Canfield's recommendation on the previous page I took a look at the guy's channel and saw that one too. I like the comment he made at the end - "Not the best, but not the worst either" Note that he entirely reconstructed about a foot and a half of the bottom end of the stick in a number of steps to keep everything in alignment. One thing I didn't hear mentioned was how long it took to make the complete repair. I bet it was a while.
We always try and find out and match the existing material as best as possible. Same goes for truck and trailer frames.
Didn’t matter what the name was attached to the steel. They kept breaking and were still welded back together with 70K tensile wire or stick.
For that Volvo repair video above, I thought you weren't suppose to weld across the top of bottom of the boom?
Would you plug weld a larger fish plate?
Welding past the fish plates and always putting end of weld craters somewhere in the middle of the welds is something I forgot to mention. T1 is great for strength but requires a 11018 rod that may not be suitable for the boom material. I would think that current booms like the OP's would use a better a steel than a boom from say an 80's machine. Try to find out the type of material and then match a filler metal and possible reinforcing plates to that. I'm guessing it might be something a little stronger than 7018.
Yes. Some prefer to use a "plug hole" shaped like an athletics track, basically a rectangle with a half circle at each end. The long sides of the rectangle would run lengthwise down the structure. Depending on the size of the hole it might be practical to only weld the long sides of the hole and not the ends, then all welds would be parallel to the structure.
All the large plates had round plug holes. Stacker booms, large excavator boom and such. We used the race tracks on things like loader bucket floors and dozer push plates. I also used the race tracks on reinforcement plates on excavator sticks when we were installing thumbs back in the days. We were always told the plug welds were to go all the way around and there should be no points. We picked that up from factory drawings on repairs. It might be a preference of the engineer, or not.
This technique of doing a small weld fill on the run out ends worked well for me on reinforcing plates and thumb mount bases. We would gring and polish the ends of the weld without digging into the base metal. I always used plug welds ,oval or round in the centre of the boom with assumtion you were welding in the neutral axis of the box. The idea came to me from the method Hitachi used on Cyl lugs and reinforcing cover plates. We cut up brand new machines and made them into high walker log loaders,back in the days of UH16 s and 181s. John deere guys came to our shop and said it wouldnt work so well. Look at them now. All that said i would not be afraid of repairing that Case boom.Ive repaired much worse when loggers i worked for started road building with 245 Cats
That was the first broken boom I saw a 245 cat. When it broke off and flopped into the terex, it broke all hydraulic lines and sprayed oil all over too.
Nige, there should be a grade number after the A572 to define the strength of the steel. Any idea of the grade?
I agree, but I would need to go looking to find it.
OK, so I went digging into the specs. It's a low-carbon steel, 0.22% or less for rolled plate. (Slightly different carbon % for bars & other structural sections). Steels meeting ASTM A572 or A572M specification of either Grade 42 or Grade 50 are an acceptable replacement for the OEM material. The minimum yield strength requirement is 290mPa (42k psi) which I would imagine would be the equivalent of the Grade 42.
Cheap stuff. Mild back in the day was 60K yield. So basically use any steel you want on a Cat boom. I know for a fact that you can use any mild steel you want on Sumitomo booms and sticks.
Thanks Nige. Here in the States Grade 42 would be the next step up from A36 (36K psi yield strength). No special welding fillers or post weld heat treating should be necessary.
Always figured on 50000 yield. Those 245 s introduced me to broken boom ends, broken boom foot ears and a torn off rotec . As a yougster i managed to bushwack them all back into operating condition
With the heating and cooling and stress from such an extensive repair stress relieving would never be bad idea. Not all pressure vessels are stress relieved but critical ones are and it's the 516-70 boiler plate.
Should say same boiler plate and depends on thickness. Some booms are stress relieved from the factory. I would think current booms use thinner but stronger steel than older machines to save on weight and weld size, etc.
Take advice at face value from Welder Dave. He knows his stuff. He helped me along with repairing my broken yoke on my old beast. Still going strong without any issues.
When machinery manufacturers use high strength steel & sophisticated welding & normalizing procedures it makes it more difficult to repair. It also makes the probability of a re break greater.
This stuff isn't rocket science and there are no exotic materials being used for mass produced machines that have to be competitively priced. 36 or 42 thousand PSI tensile is not high strength steel. There is nothing fancy in any manufactures' booms and sticks on excavators. Their strength is in their design and workmanship and not in the materials they build them from. I have yet to hear of any manufacturer state any kind of welding rod other than 7018 or similar for repairing booms or sticks. The only preheat used is to drive out moisture before welding and I've never seen a specification for post heat.
The Case backhoe booms that are made from ductile iron are the only ones out there ive seen that are a problem to weld. Im not sure why they would go with throw away stuff like that.
Cheap, and built to stay that way!
I'll bet you even know what a whale tail is. Kinda obvious you are one of the few people on this thread who has actually welded on a boom. I'll bet a couple of these sexual intellects has never even struck a arc on one. Bob
That'd be me. I never said I did. That doesn't mean I don't want to know. I'm not in a place where I'll ever have that opportunity. I see so many machines rendered useless by some hammer head with a stick welder, no grinder, no gouge. They step up with 6011 and gobber over the crack. In what world will that work? I don't pretend to know how, but observation has shown me how not to do it.
Pre heat has never been easier with the price of infrared thermometers at $50. Pre Heating the surrounding steel to slow the cooling of the weld immediately after laying the bead is the cheapest insurance you can buy against cracking. Throw some insulation over it when your done to further slow the cooling. These are cheap and easy precautions. It makes no sense NOT to do them. I would repair that boom. But then again, I do a lot of stuff others wouldnt!
Maybe someone can explain why booms on mining excavators are stress relieved? Taking extra steps to ensure a good repair is never a bad idea. All the welding has to put stress in the boom. Stress relieving makes the grain structure as close to if it was 1 piece as possible. Repairing it similar to if were a critical pressure vessel is the best way. Price out a new boom for giggles.
Lucky guess according to some I suppose but what do I know. First picked up a stinger in 1980.
The reason strict procedures need to be followed.
Maybe you should start by showing an excavator manufacturer’s written procedure for a boom repair.
Occasionally we'll get a custom deal made from something like 514 (aka T1) but most mass produced stuff if similar to that Cat booms, something like a low grade 572. Typically 7018 or a comparable dual shield or gasless flux is our jam on those repairs. There's 2 parts to the preheat department, one is of course if the metal requires it, the other is thickness/size of weldment and you should also be thinking ambient temp too if you're doing a field repair. Trying to put good heat into a big ol chunk of cold metal just doesn't work out, get the weed burner first.
My experience in the mining world is fairly limited . I welded the lip on that shovel bucket that shows my pickup parked in it 45 years ago. You run into thick materials 3"and4" and more ,that bucket lip was about 14"thick manganese alloy .Different alloyed materials welded together. Lots of stress relieving that we would never consider on excavator repairs but is critical on big mining stuff. Two different worlds in the repair business.
That's a different animal entirely. Procedures and specifications will come with the parts you purchased. When I was welding all the time I loved that kind of work. Ripper noses, bucket lips, shanks, blade lips and push plates. I suppose I got lucky in that my employers decided I was worth more to them working on hydraulic systems, engines and transmissions. Ship yards here let hundreds of welders go so they became less expensive and I apparently avoided the bad lungs and heavy metal poisoning that shows up in life time welders when they get past their late fifties. Today my hands shake a little too much and my eyes have a lot of trouble in the smoke.
+1 for the weed burner. I start there when I have serious rosebud work to do. I have a 500 gallon propane tank there and a 20 minute drive to town for oxy acetylene bottles. The big caveat is preheating for welding purposes, propane produces a ton of water vapor in the combustion process. Just saw your post, @John C. I miss the cracks about half the time now, really annoying!
If OEM' were so good with boom fabrication why are booms cracking in the first place? Why do mining booms get stress relieved? A 450 is a good size machine. Why not repair it like you would a mining size machine? All the work to repair and it cracks again because a step was missed.
I'm laying in the hospital and somehow the thread has turned I to a pizzing contest. Good job!
Sometimes it's a manufacturing defect, like an automated weld with almost zero penetration, but looks good on the surface, seen it. More likely though, it's operator abuse, long hours of hammer operation, twisting moments from thumb use, or being too lazy to swap that wide cleanup bucket for a digging bucket when that's what you should have on there. And/Or a long stick when you should have a short one on. All of these are actual cases from personal experience, humans are gonna do human things.
In my book there is nothing wrong with leveraging procedures & practices (pre-heat, needle peening, run out tabs, post heat, etc, etc) that are obligatory to use in the repair of a much larger machine to do a similar type of repair on a smaller one. I think that it likely increases the possibility that the repair will live long-term. Many posters have commented that you can’t just weld over the existing repair, so the question then becomes how best to do it in such a way that maximizes the chance of success. Like Dave I can’t see why that thought process should descend into a pi$$ing match.
Exactly, it's no different than how to change a flat tire, the procedure and time it takes, effort required will vary tremendously based on the make, model, year, tire size, front or rear, etc. Excavator booms, and the exact failure vary so tremendously that each and every failure has to be evaluated and a plane put together, which likely will change some as you open things ups.
Also what do you do if there is no repair procedure established by the OEM?
Use common sense, experience, best advice?
Can sometimes be hard to know which is the best advice. Would really suck to do a 10k repair only to have it fail because a step was missed or not followed.
I think the heat is so high the .moisture isn't a problem. Weed burners are the method of choice for most preheat requirements. Inter pass temp. is important too.
It all comes down to how much it costs, who is paying the bill and who has to stand behind the fix. On booms and sticks there is no need to get all crazy on exotic procedures, materials and processes. It isn't necessary and even the factories only give you so much money to complete the repairs. Actually weed burners are not the choice for any weld shop I've worked in or run. Preheat was always done with rose budds and oxyacetylene. As skying1 says, they are a good start when working on big components, but the rose budds come out to get the temps up high and I've never seen a weed burner used to control interpass temps.
You haven't been around much welding then. Weed burners heat a much bigger area and preheat isn't red hot. Straightening is but acetylene is lot more expensive than propane. Using it for preheating thick steel instead of a weed burner certainly isn't going to appeal to the person paying the bills.
Maybe, but then again, I've actually been paid to put booms and sticks back together again. How about you?
With all respect to your experience John, but acetylene has gotten stupid expensive within the last several years. I remember $20 for 125 ft3, now its over $90 for the same tank.
I can actually burn bigger than 5/32" electrodes. And you why wonder people like Tctractor left the forum. If you worked in a vessel shop and used a rosebud to preheat a 3" thick x 10' long shell prior to welding you'd likely be given the boot. Yeah, I worked on stuff a heck of a lot more critical than an excavator boom. Weld procedure qualifications have been around a long time. An excavator boom would be way down the list but the same procedures that have been established for decades could be followed if you want a repair to last. You seem to like to stir pot. You're not likely to when it comes to welding. Most members are wishing me well and you're trying to start a pizzing contest. Now everyone can see your true colors. Hope you're proud of yourself.
I grew up in a pipe and tank fab background, that was the original focus of the family biz. Weedburners and a BBQ tank have always been a thing on pipeline rigs, not so much a shop thing at least around here. For me if we're just heating it doesn't make since to waste getting the oxy/acet out, bending/straightening different story.
I've never welded together a excavator boom. The cranes I'm around, range from the dumbest of dumb old iron, to what they tell me is pretty exotic steels in the new ovaloid booms coming out of germany. Most manufactures of the crane booms, don't want to give out much in repair procedures. They just want it condemned. And don't really want to sell new sections to repair any thing either. Or the manufacturer is simply gone. So you do the best you can with what you have to work with- experience and a guess at what might work. I've held 1 1/2" - 2" wall 16-24" pipe at a natural gas pumping plant, while they welded all day to make a joint. They would weed burner preheat after breaks and lunch. Everything was stress relieved and xray inspected. But we're talking about a bomb that takes out a couple square miles if things go wrong. So everything is pretty spelled out. Same deal with all the steam pipe at a powerhouse project I worked on. I think Dave comes from a manufacturing background, where there's blueprints and procedures for everything. Nobody freelances in a environment like that. John C. has been out in the woods with little in the way of backup, with a welder and a can of 7018 and not much else. But has to get a boom patched back together. Whether there's any procedures or not. I find it interesting to read both perspectives. As far as the original issue- I think Case is going to mess with you for months on end trying to get any kind of a repair procedure, and you may get nothing from them at the end. Its not like your buying 10million in equipment a year from them- you aren't even the original purchaser. I think they're going to tell you to pound sand. I'd cut it open and patch it up inside and out and hope for the best, but I'm just a dumb old farm kid. I know you've got some health issues right now dave, but just because someone disagrees with you, doesn't mean they are wishing ill for you. They just don't agree with you, because they are coming at the job from a different experience background. It doesn't have to be personal.
I like your post Crane Operator but John C has a problem with me. He thinks because I'm not a mechanic or welded a boom I have no business responding. He made it personal not me. Don't need to get into the thread where he started the name calling. I am a 40 year welder though so know a little bit about fabrication and steel work. I guess all I was trying to say is that excavator boom repair procedures aren't some special type of procedure that took month's or years to develop. I suspect Cat or whoever else relied on tried and true repair procedures that have been used on structural steel, trailer and bridge type fabrication work for years. I think when you're looking at a potential 10K+ repair because you have to hire it out, you would want the best chance of a successful long lasting repair. Paying a little more for piece of mind is what I'd do. You want to take out some of the steps or cut corners, that's up to you. If you needed a crane boom weld repair you'd have to follow all the steps because it would have to be certified. I agree some OEM's don't want to tell how a repair could be done because they want to sell you a new part. Why not do the same with an excavator boom? You could have had your crane engine rebuilt but chose to get one from Liebherr. I think you made the right choice even though it may have cost you more. I'll bet you had much more piece of mind getting an engine from Liebherr? I think most members on here are intelligent enough to know if someone is giving sound advice or not. What's frustrating is when you give good advice and they don't follow it. There was a thread in the TLB forum where this was the case. Every thing laid out in detail and the OP ignores it because he's in a hurry or something. It was a fairly simple repair and it just makes you shake your head. Why bother asking if you're just going to do a redneck fix? I'm just glad I'm not the one paying the bill for the repair. This didn't have to become a big heated debate. I'm really sorry it did and apologize to the members reading it. Most of what I posted was because I had nothing better to do laying in a hospital bed. It took my mind off my pain and made me turn my brain on. As far as the pain I wouldn't wish it on anyone. I was taking Dilauded like candy for quite a while. Dilauded is a high strength Morphine and about 8 times stronger. I was taking long acting 12 hour with 2mg booster injections every 2 hours. Dr. said some people abuse it but I really needed it. Compression fractures in 10 of your vertebrae tend to hurt a little. Laughing doesn't work, it makes it hurt more but so did a hiccup. Much better now. Hope everyone takes care of themselves! Dave
Here is a cracked boom repair that an aforementioned YouTube welder just posted. Looks to be worse than yours.
I like his comment at the end " this is not a how to do it video, this is how I did it"
The guy is a good welder and good with a gouging torch but I would have used a grinder or even die grinder to clean the gouged edges. There would be a thin hardened edge that may have carbon in it from the gouging. Don't know if there was internal damage as well. Probably would have been good to take a look. I like how he said it is how he fixed it. Customer should have had the top plate replaced like the welder wanted. Could have seen inside that way too. Very nice 7018 vertical up welds. Root. Pass looked to be 5P+ 6010 which would burn little bits of slang out.
Since there is already a thread I figured i'd post here. I noticed some cracks on my mini hoe where the thumb plate is welded on, nothing bad but figure fix it before it gets worse although I know some of the cracks have been there for at least a year or two . What do you guys suggest is the best for a fix? Just grind out the cracks and weld them back up? Should the thumb plate be welded past the corner?
Pics. Are a little too close up but I'm on a phone. Maybe you can highlight the cracks?
That is a pretty common failure. There should have been a plate welded to the stick first and then the cylinder bracket welded on top of that additional plate. It might have been OK if the original weld had been whale tailed but no use worrying about it now. You didn't say the model of the machine but on most minis, people will air arc out the cracks and just weld them up. I used to do a three pass stringer when I filled up the crack and grind off the top to about the level of the original plate. I would put the whale tails in after you fill up the cracks to make it last longer before they may show up again. You could spend a bunch of time making it pretty but most owner's just want the machine back working again.
That's so small I'd probably just chase the cracks back to good plate with like a 1/8" edge wheel or a pipe wheel on my 6" then weld em up, run at least part way into those half moons, clean up the edge of the bottom plate and off to the next disaster lol.
That guy used 7018 all the way no 5P. At some point down the road the owner is going to wonder why the main boom pin galled and took out the bushings. Bob
Did he disconnect the electronics before welding, why not cover up the exposed hoist ram rods before gouging and welding, it only takes one spark to damage the chrome with associated seal damage This looks a decent field repair to allow the machine to finish the job after which the boom should be removed and opened up to inspect the internal damage and then repair welded from the inside first,then externally, in my humble opinion.
6010 is common for root pass and burns out slag. Coating looked fairly thin on the rods and the 3 dots on the rod tell me it's Lincoln 6010. Arc sound is rougher to. I'd guess the guy has done some pipe welding. Also he talked about a root pass and hot pass. That's common with 6010 too before fill and cap with 7018. All that said, who really cares? It's pretty obvious the guy knew what he was doing. Anyone attempting a similar repair would choose what rods they want to use anyway. 6010 followed by 7018 is perfectly acceptable as is all 7018 as long as there's full penetration. If you had access to Mig for the root would be even better because it's easiest to tell when you have full penetration and leaves a very smooth pass on the inside that looks like it was done from that side. Tig would be good but very slow and would require a lot more cleaning. One thing not mentioned is preheat would have been a good idea. You really need to stop trying to instigate things that aren't there.
Asking because I don't know and respect others opinions here. Could the arc gouging have been enough to preheat?
All the 6010 I've used is red with 3 stripes and 7018 is grey with 3 dots . If he pipe welded he would put a 6010 root pass in down hand. This guy used the same rod all the way. If he really knew what he is doing I don't think he would ground thru the boom pin. Bob
Pipeline is downhill but is a separate specialty type of welding. There is little to no gap and run very hot essentially melting the beveled edges into the root pass. Standard pipe welding usually has a 3/32" to 1/8" gap and a key hole is formed. The root is primarily weld metal. Pressure tests are done uphill usually with a slight whipping motion but some drag the rod up. Pipeline has it's own test. 3 dots actually just mean it's a Lincoln rod. Starting a debate on which rod was used is pointless as either would work for a root and hot pass. 6010 would burn slag out better. 5P+ is a whiteish colour and far nicer to run than the old 5P that is red. The guy knows how to weld. He could have put the ground in a better location but I suspect the pin grounded on the bosses. I doubt it was his first attempt at this type of repair. As far as members on here are concerned it is a good video on repairing a cracked boom. Could it have been better, yes but overall pretty informative.
Maybe but using a Tempil stick crayon (or temp. gun)) you could ensure it's 200 deg's. or so. Preheating helps slow the cooling rate so there is less stress in the welded area.
No. Preheat serves a few purposes: When weld cools it shrinks. This can create extreme tension where weld meets steel. Expand all the surrounding metal before, there is less tension where it shrinks. Heating slows cooling. Cooling slower encourages a different crystalline structure making steel tough rather than hard & brittle. Heating drives away hydrogen. It's involved, but hydrogen can be compared to PAM in a frying pan, preventing bonding. Preheat will involve the entire surroundings of the weld. Temperature will vary. Higher than that needed to drive away hydrogen, lower than that will draw the intended heat treat already in the steel.
Then there's post heat in some applications.
Here's a picture of what you might call a poor boom repair: (attachment)
That looks like somebody with limited experience trying to save money instead of getting a professional to do it. Similar to the guy who did work for me welding his C frame on a JD 850J WLT. He welded it up and it cracked and he just welded it up again saying when he gets home he'll fix it right. Asked about preheat he says the grinding will preheat it. The steel can't be welded several times and not get fatigued just from that. Fix it right the 1st. time.