hi guys, i've found this on a repainted machine, is it a paint crack or the boom is definetly cracked ? :beatsme the " crack " is not deep, i've got different point of view, some told me it's not a crack and other it's a crack ointhead if anyone can help on this !!! if need more photos no problem :drinkup
Only way to be shure about your question is to get a quality controller to bring his weld controlling equipment and check. Ultrasound equipment will get U the answer imediately. But it looks like the area has been welded/worked on under the paint. That stripe might be a smal crack just in the surface of the weld. If so, it shurely is not a quality weld made there... I would quess lack of preheating or to quick cooling, so the tension/stress in the weld was so high it cracked after som use. In your 1.pic it looks to be a area where the thicknes of the plate is increased/decreased towards the big weld. Then it can shurely be a area where a crack would appear. I don't think u got so much movement in that area to get a paint crack there. But if the paint is real thick in that area, it can be a crack in the paint. We are then talking about several millimeters thick paint Next question is if it matters? I would say yes, only a smal crack may be the startingplace for a big problem later. Sourface should bee smooth to avoid the stress beeing buildt up under/in the crack. How long it takes before it gets real bad is impossible to say. Carefull use and it might last long, heavy use and it can break real quick. If u tell us which machine and age, i bet somebody here can give us some experience in that area. Looks to be in right by the main bolt for the boom. There is some pics in the thread "Norway pics" from a komatsu PC750 with a broken boom in that area.
Boom /stick cracks tend to grow a lot better than my garden did this summer! Can not be sure from that picture. You may have some Bondo ,Trying to cover up an unsuccessful repair - not all that uncommon with stuff run through an auction A grinder would answer all
Hello Alfapillar. It looks like a cat machine. Am I right? In that case, I would be a litle sceptical. I'll showe you som pics of our cat 345c Dont know if you get some answer of this, but it's my experience that if you see somthing looks like a crack in the boom off a cat, you should replace it asap... :usa
crack on a few 320 and 315 machines ive seen they tend to crack behind the boom piston mounts. ive seen sticks crack just below the pin that hold them to the boom. our 320l has a paint crack at the end of the boom that i marked with a marker when we bought it...its been 4 years and a lot of hours later and it hasnt spread. the line in the pic is allmost the entire thickness of the boom. id have it looked at before id buy it.
Take a small grinder and clean away some of the paint. You will clearly see a crack if it is there. No reason to bring out ultrasound equipment, this should be very easy to diagnose. Now the repair on the other hand well that will be a little tougher.
It's too straight to be just a crack in the boom. Also being that wide it would have run into the top plate. I'm thinking it's Bondo. Grind it out a little to be sure. I'll bet its power and not sparks that will fly of the wheel. Good Luck!
seems like i've heard this before.
Get some iron filings from a workshop with a magnet make tem all stickey apply them to the boom and watch ,if there is a crack when you stick the magnet on to the jib close to the crack the filings will allign themselves to a crack radiating from one end to the other on both sides ie like pencil arc shaped lines
Thanks guy's for replying :drinkup It's a 2000 Cat 330BL, with around 10000 Hours, the machine was parked in a sea port for more than 5 months, could it be a result of this long time parking ? :beatsme When we buy this unit, the " crack " wasn't there, and the machine didn't work since we got it, habitually we go away from repainted unit, but on this one, the seller state that the machine don't have any crack :Banghead maybe a stupid question what's a Bondo ?
bondo is presumably some sort of filler. paint doesn't just crack in my experience, fillers can and do crack but not usually in such a straight line or over such a distance unless there is an underlying problem. what is very clear is it is a crack over either a repair or a weld and therefore should be investigated. i'd hit it with an angle grinder tho the iron filings trick might be worth trying (its a new one on me) my guess is they've done a bodgy repair on it and thrown some filler over a crack without bothering to weld it, painted the thing then offloaded it to some poor sucker (you in this case....) good luck!
Bondo is autobody filler
What seems odd is that the "crack" seems perfectly straight. Metal does not break that neatly. Either grind or scrape the paint off and you will soon find out what lies underneath. Let us know what you find.
If it look like a "quack," and "quacks" like a duck, then it's a crack. I've seen many of these on Cat excavators and I'd bet the farm that you have more serious cracks in that boom. Biggest problem is that cracks of this nature can not be repaired from the outside. The real problem is inside and for that you have to remove a big enough piece of the boom side to actually be able to get inside the boom to repair the metal there that is damaged. Some folks would just repair the crack on the outside as looks like what was previously done in your picture. Others than might weld a fishplate over that in an ill-fated attempt to strengthen the boom. That doesn't work long term either. I believe your boom has been seriously damaged and that whomever had it previously just welded up the outside and tried to make it look as though nothing ever happened. The marks under the paint point that out. Good pics by the way. Check with your local Cat house and ask for an engineering drawing of that boom section. Those folks can also point out to you how to properly repair that section. Good Luck!
Just last month had the boom on our Cat 308C fall off - cracked completely thru at pin-boss. Will post pics when I'm allowed.
Its not to straight to be a crack, if there is a baffle there then a crack can be almost perfect. Seen it before, just not sure if there is a baffle there on a Cat.
I agree with surfer-joe on this one also. Inside the boom is another whole structural set of gussets, and there's more than likely another set of problems that lie beneath the surface. Definitely put a grinder to it and investigate before it get's worse. Nothing uglier than a boom hanging limp off to the side...been there, done that, got that tee shirt with the hood. Had a 245 boom break off in -20 degree weather once, that was a son of a bee to get straightened out. That's where I got my education on the interior gusset system though.
One company I worked at had a 320cl break a boom. Looks a lot like it was in the same general area as your picture. As surfer joe stated, it was a repair that was very involved. It required cutting out a 3 foot long section of the boom on the battery box side. Every weld inside on the other corners was redone. There was extra plate added inside. Then the outside was fitted with a new plate and welded into place. It took 1 welder about 40 hours of work.
or it breaks off and kills somebody
You have lots of good advice already. Do Not Operate This Machine! It is DEFINATLEY a crack, and a bad one at that. I believe it is right where the interior gusset that spans the factory weld joint ends. As stated, the repair will be extensive, and I would get a copy of the Cat welding proceedures and make sure they are followed. There are probabley other hidden cracks, as I do not think the side plate can move that far without the top flange moving somewhere.
My 2.2 cents inc gst is that it is where 2 sheets of steel have been joined to make the boom web . The sheets have not had the Arris removed (vee'd out) before the weld was laid over the top . The weld has then been overground as the surrounding metal shows and the paper thin weld left after grinding has split .
I reckon you might have something there, Iron Horse, we had the same problem with a Furukawa loader frame quite a few years ago. The crossbar was two halves welded together and then welded to the arms, all done by robot in the factory. The material was 3/4" thick but only butt welded with very little penetration and with the twisting of the loader arms it just broke away. We ground the edges right back and penetrated the weld as far as we could and never had any more problems with it. I think if Alfapillar investigates that crack with a grinder, he might find the same thing. Rn'R.
If you look at the area around it ,it looks smoother than the rest of the boom.I would say it has been welded there before and grinded smooth and is cracken again.
Not that my opinion means much , but i think if that join had been welded after the assembly of the top and bottom straps were welded to the web plates there would be evidence of a vertical weld or a grind mark on the horizontal strap plate welds . But to my eye the strap plate weld is uniform , neat and with no signs of a grinding wheel ever been near it . If on the other hand the vertical welds were done latter , you would see were they started and stopped and also you would see were the welds were ground at the intersection .
guys for your point of view and advise, the machine is not operating at the moment, and she'll be sold probably in the next few days, the seller is almost advised about this, and send him a couple of photos, i've thinks about grinding the area and see what heppens under the paint, if the customer agree i'll do it and send you some pics the strange thing, is that the machine didn't work at all since we got it, i didn't inspect it before, just trust the ex-owner, and that was a bad idea to act like this !!! :Banghead :bash Regarding to this boom and the repair , it could be easyier and less expenssive if we fit / or supply another used boom with the 330 ? if i've undrestand all your point of view, this boom is probably in bad condition, that's why i've think about changing / supplying another boom :beatsme
Another boom will cost you a ton and if its used you could end up in the same place you are now. We had a customer do exactly what you are thinking about and the used boom ended up worse than the cracked one. You are going to have to have it repaired by a certified welder. Should take one to two days max if done right, Cat has all the welding procedures for this kind of repair. I would make sure that the welder follows them very closely.
These are the pics of our cracked boom incident.
i might be missing something in those pics...but looks to me as though that machine never got greased?
Your looking at the outer tube that houses the bush it's not the pin that looks rusty . Alfapillar , Just have it ground out to create a 'V' and weld it with a mig . If you do find a baffle at that point , simply grind it out a little wider so that the weld can penetrate all three pieces . It would be a better , prettier weld if the boom was laying on it's side but a good "vertical up" stitch weld in situ will be ample .
Hopefully we can see some new pics of the boom....
Hi Guys, Thanks for your advises and help, i've speak to the buyer of the machine, and he prefere to get it as it is, so i'll not grind it but i'll ask him to send me some pics once he'll weld it and put a plate on the boom. I've got another advise concerning this crack, wich consist on drilling a hole on the two extremity of the crack, in order to stop it, and then proceed to the welding, and finaly weld a plate on the boom, what's your point of view ?:notworthy
ah an easy question. such procedure usually stops a crack spreading but doesn't get to the cause of the crack. i'd not go down that path personally, but then i'd hate to see the boom let go completely
i'll not do it for sure, the futur owned come and see it, and prefer to buy it as it is, and proceed to the maintenance localy, as it'll cost 1/3 of the cost here in france will ask him for some pics once it's done
I would call your local Cat dealer and have them send you the repair specs from the factory. This the BEST method to follow, I have done it several times
Looks to me to be more in the quality of the weld then the grease at this point.The weld from factory was chessy to say the least. Note hardly any weld or penetration in the weld to the base plate.Just my thought.Not good for sure.Good luck:usa
The repair specs (at least with Deere/Hitachi) are usually better than the original welds from the factory. Not really clear why the factories just don't make them that strong to begin with. Okay actually I do.
Alfapillar , equiring minds are still in a holding pattern .
DOH ! enquiring . ointhead
me too the machine is actually at the destination sea port, i'll ask the customer if he can take some shots of the welding / repair once it's done
You da man , looking forward to the pics .
It was finally a crack ! but i don't have pics of the repair actually !
Darn it :Banghead :Banghead I was convinced it was a crack, just goes to show you can never be sure till your sure :beatsme