Fixing a BIG weld

[Lanse]

Hey guys...

So, I was at the scrap yard today and I picked up a nice little welding job.

They have a skid-steer and someone tried to make them a forklift attachment for it. Theres a big weld about an inch tall by an inch and a half wide, and about 4 feet long that needs to be redone. Its terrible, full of holes, welded too cold, etc, and Im their guy for the job. I pick it up tomorrow on my way home from school, and Im taking it to school to arc-air the old weld out at school the next day, and then bringing it back home to get some quality time with the stickmate. Ive done 21 bead welds with 7018 and 7024 just like this, but first i have to get rid of the old weld. They have a business to run, and they spear cars with this thing and toss them around all day long. They literally need it fixed yesterday.

Unlike the 21 bead welds we did in class, Im going to start this with a 6010 root pass just for a little more penetration. This is welding a 3/8" "lip" to a solid plate thats about an inch thick.

I guess the welding isn't what im asking about, its the prep work. Ive arc-aired many times before for practice, but that was on clean, new plate, to get the hang of using it. Its a simple question, when do I know when the old weld is "out"?

Thanks guys. Many a picture to come

 

[Dick K]

Lanse
BE CAREFULL
You will be welding on alloy forks,which in the case of a problem can be a big liability.Can't ad vise on the alloy,but I don't think 60 or 70 rod will match up.

 

[charlie n]

I usually don't get in on topics like this but I have to agree with DickK on the liability factor.I've looked at your work and it is pretty but if that weld would fail and damage property or a person you'll be responsible.Thats why very few if any around here will weld metal furniture.Good Luck.

 

[NCWayne]

Hey Lanse, to answer your question about knowing when the old weld is out, the best thing to do is to cut until you can see a crack between the pieces. It might not be the easiest thing to see if the pieces were tightly fitted to start with but given the application/situation it ought to jump out at you when you get to that point. If doing this will cause the pieces to fall apart then make sure that you either clamp the together before cutting that far, or cut only part of the weld completely out at a time, and as you cut a section go behind yourself and put a good tack back in place of the weld you removed to hold things together til you get done cutting and start the new weld.

Cutting to where you see the joint like this, with an air arc, will typically leave you with a small undercut area between the two pieces that you'll have to fill in when you reweld it. Question for you. Does the school have a plasma cutter? With the proper tip a plasma cutter will gouge out an old weld at least two to three times faster than carbon arc and leave alot less overall mess, and clean up to the area, before you can begin the new weld. That said make sure you clean up all of the old mess because welding over even a little bit of slag left from the carbon arc will make the weld look like sh!t and more importantly be weak in that area.

Beyond that I wouldn't worry about using anything but straight 7018 rods for your welds. I've been doing repair welding on heavy equipment for alot of years and have never had anything I've welded crack, break loose, or have any other problems for that matter. I know there are alot of WELDERS on here that might tell you this or that and under ideal conditions the things they say are 100% correct and have plenty of merrit but when your welding on material that has been in the dirt, oil, grease, and grime for years like most junk yard forks usually have, the 'perfect situation' examples really don't mean much. Like I said don't worry about a 6010 root pass because with the undercut you'll most likely have from cutting and grinding the old mess out, the surface area contacted by the root welds will be greater than the one you'd have if the pieces met at a true 90 degree, so the 'extra' penetration isn't going to matter any anyway because the weld root will actually be larger than the single bead you'd origionally have had. The main thing is to use the largest rod you've got and burn it as hot as you can to get a good burn in. For something heavy like your talking about a 3/16 or even a 1/4 rod would be ideal but I imagine your just going to be running alot of 1/8 passes. Wish you lived closer and I'd be glad to give you enough 1/4 7014's to do it all with if you could get it positioned right to use them. Anyway with the 1/8 rods you should have the opportunity to get everything dialed in on your welder and after a pass or two, with everything right, the flux should start pealing itself off the weld about 2 inches or so behind you. This makes clean up between passes alot easier. On that note, with multiple passes I know you know that you have to get all the flux off of the previous weld before going over it with the next pass. Otherwise you'll wind up with a mess that looks as bad as what you are taking off.

Beyond that from what I've seen on here of your work it all looks pretty good so don't let anyone say anything to make you doubt yourself. Remove the old weld, grind everything clean, use the largest rod you have burning as hot as you can burn it, and make it happen. If possible post a few pics when your done so we can admire/critique/criticize ((((you know how this board can be sometimes...LOL))) your work. Wayne

 

[Puddles]

I always liked a carbon-arc for taking welds out. When you're digging down to find the fusion line, the carbon arc will open it right up so you can see it. Sometimes when grinding a weld out, the dust will cover up / fill the fusion line, and make it harder to see. Once you get down to the fusion line, you'll want to bevel / V out the sides. Then make sure you grind every little bit of carbon tracks out of the weld zone! I like my plasma cutter for scarfing small welds out, it has a lot smaller kerf than say a 1/4 inch carbon rod. It is only an 80-AMP unit so if the weld was really big it would take quite a bit of time. Where as a 3/8 inch carbon with 400 to 500-AMPS and 150 + PSI behind it will flat remove some iron! :lol:

Lanse you're not going to be welding on the forks them selves are you? Most likely they'll be T-1. That will be a whole new ball game for you! If they are T-1 you might want to pass on this project and this point in time! T-1 can make a very experienced weldor look like a fool in short order!

 

[Greenday]

Like Dick K said be careful because of a liability issue. Remember CYA!

 

[Stan in Oly, WA]

Hi Wayne,

In welding in the flat position with 7018 where multiple passes are required, I'm often uncertain whether to run the welds as hot as I can for maximum deposit or at the temperature where the slag peels itself off. There's usually a huge difference in the amperage.

When you tell Lanse to "burn it as hot as you can to get a good burn in", and later that "after a pass or two, with everything right, the flux should start pealing itself off the weld about 2 inches or so behind you" do you mean that these two are the same setting? Does that mean that any setting for 7018 higher than where the slag peels off as you weld is actually too hot?

Thanks, Stan

 

[NCWayne]

Short answer to your question, yes, if the slag is pealing off your running at pretty much the optimal setting for the rod. If your running any hotter you might pick up a little bit of extra penetration but you'll pay for it in the quality of the weld. Like I said in my post to Lanse there are probably some WELDERS on here that can give all the technical details on everything off the top of their heads. With me I've read the books and know where to look if I get in a critical situation and need to refference something in particular in regard to that particular set of circumstances (like when I did a frame repair on a lifting crane some years back). Beyond that I've also learned through the years that in the real world of repair welding in the field, under less than ideal conditions, you just have to go with what works, not what some engineer says should work as the two, unfortunately, aren't always the same.

 

[Lanse]

Ive always liked carbon air period... Its loud and
fun

I just with we had some bigger machines, but all
we have are dialarcs and idealarcs. Thats the
answer that I was looking for, thanks a lot!! I
figured it would be something like that. This
thing is actually worse than I thought it was,
there is a lip that is welded to the plate that is
the main part of this contraption, and the bottom
of that lip is actually like an inch and a half
from the plate, its bent that badly. So, I imagine
that il arcair out most of it, and then just end
up breaking it off with a big hammer. The weld is completely cracked about half way through. its a
mess. Thanks for the advice, thats what im
planning on doing. Im working on this at school,
so I doubt that I can take pictures of it.

ONLY an 80 amp unit?? Ours are like 40 amps. Our
teacher doesn't like them, hes too old school. I
use the things every chance I get, and someday, I
hope to buy one. Getting oxygen and/or acetylene
around here is a really big chore.

And no, Im not touching the forks. Yet.

The welds on them seem to be holding, but theyre
not pretty, and I think they might be my next job.
I told the boss at the scrapyard that it should
take me 3-4 hours for everything on this, and he
said not to worry about it. He cant afford the
downtime and wants it done right, because, "I'm
tired of screwing with it". Alright.

He also mentioned that he might want to build a
new one in the future, sometime soon.

And so Im just wondering, how would I weld
something like that, to a regular mild steel plate
for a base? Id just use 7018 since that seems to
fix everything, but according to you its a different type of steel, and Im sure youre right
about that. It looks different. Ive heard of dis-
similar metals welding rod, maybe something like
that? Could be fun

 

[Lanse]

Thanks Wayne!!

Yeah, Im planning on running lots of 1/8" 7018 on this one. We have some massive 7024s (Korean made rods that are literally 4 feet long), but I think ill pass those up, to get the qualities of a 7018 weld.

A trip to the nearest welding place is about a two hour ordeal, and they dont have much of anything in stock anyway. I wish we had a place near us, where I could just run down the street and pick up some 1/4" 7018s and be on my way, but we don't.

I'm going to clean and grind and start welding at school tomorrow. I stopped by the scrap yard tonight and picked up this contraption, and now its sitting in my truck.

Im really excited, because this is my first real welding job. Its a good feeling.

This thing is dirty and covered with broken glass in every imaginable place (they go through windows to pick cars up) and that should make it fun to work with. I cant promise any pictures since this will be mostly done at school, but I'll do what I can.

What kinds of stuff have you worked on?? I really like working with thicker materials, and big old junkyard stuff looks really cool

 

[Lanse]

Thanks guys, but I dont have to go near the forks on
this one. Maybe later, those welds dont look so good

 

[Puddles]

For T-1 you'll want to use 110-18, with 300-degrees preheat, and a very, very, very, slow post heat!
But I'd try and figure out a way to mount the forks on the new unit without welding on them. Start searching for forks on large loaders for ideas. The last fork I welded together came off a 966 Cat loader. It was broke right in the heel. Something like 4-inches thick, and 8-inches wide.

Here is a set of forks I built for my tractor, I copied the design off a Ingersoll Rand forklift.

 

[Fullthrottle]

I run into that alot also Wayne, that situation is called "it looks good on paper". LOL Good luck Lanse sounds like you've got a good project ahead of you. Just use what you've already learned as far as process goes and I imagine it will go pretty smoothly.