Mig Welding Thick Steel

[mitchash]

I have a project at work to weld 3/8 thick plates together. They are 18x48 inches. I have to weld them together on the 48 side. The plate will be used to cover a hole in the driveway/storm drain. I will be using a Miller 211 Mig welder with .030 solid wire with gas (because that is all we have). Any suggestions? I figure I will be running the welder pretty much maxed and will weld both sides. Should I stitch weld or run solid bead? I have never Mig welded something this big/long of bead before. At home or other jobs I have had in the past we would just use a stick welder. Thanks

 

[bikerdc17]

I'd go bigger wire for sure. .035 or 045. Welder is 220 I'm assuming which should be plenty for the material

 

[Kernopelli]

I have welded quite a bit of 3/8" with a little 120V Lincoln weld pack. You'll have no problem. I agree with going to thicker wire.

 

[Anakist]

Stitch it so you don't end up with a banana. 48" of weld in a row will curl it up like a mad thing.

Are you being paid to do it? .030 wire isn't great. V the two sides so the edges look like this >< then start.

Mark every 2" and weld 2" on one side then the other to try and stop it from curling. Also back weld, go from the inside mark outwards then go to the next inward mark and weld to the place you started the previous weld. Weld.com on youtube has a few videos talking about long welds and edge prep and things like that. Well worth a watch. 1983 Kubota Bucket Rebuild - YouTube

Best of luck!

James

 

[LD1]

The welder is more than capable with proper joint prep, as is the .030 wire....though less than ideal.

IF you have a HEAVY and SOLID weld table top that isnt gonna flex, I wouldnt be opposed to vee-ing and welding from ONE side with it solidly clamped down to save constantly flipping the heavy pieces to prevent warp.

But if that isnt an option then you need to flip it alot to keep the warp evened out. And as others said.....not one continuous weld along the 48". Id do a few inches on each end and a few inches in the middle....then flip and do the same thing. Then flip and continue each of the end welds a few inches and each side of the middle weld a few inches....then flip and do the same. Keep repeating until done

 

[RickB]

The welder is more than capable with proper joint prep, as is the .030 wire....though less than ideal.

IF you have a HEAVY and SOLID weld table top that isnt gonna flex, I wouldnt be opposed to vee-ing and welding from ONE side with it solidly clamped down to save constantly flipping the heavy pieces to prevent warp.

But if that isnt an option then you need to flip it alot to keep the warp evened out. And as others said.....not one continuous weld along the 48". Id do a few inches on each end and a few inches in the middle....then flip and do the same thing. Then flip and continue each of the end welds a few inches and each side of the middle weld a few inches....then flip and do the same. Keep repeating until done

I'd agree with all of this except I'd start in the middle and work to the ends. I was taught to weld cutting edges this way.

 

[Sberry]

Bigger wire wont help that little welder. Only thing it will do is overheat it faster. If this is for work have them buy a plate, use the scrap for something else. The idea that a 211 is suitable for this leads one to believe this is less than well designed to start with? Driveway, storm drain, what is the potential for this to be driven over with heavy truck?

 

[LD1]

I'd agree with all of this except I'd start in the middle and work to the ends. I was taught to weld cutting edges this way.

That is how I do cutting edges too. OR any dissimilar types or thicknesses of metal. Because you dont want to work down to where two welds meet in the middle because there is a chance of the thinner metal wanting to buckle/pucker and result in a bigger gap and fight clamping it back down.

However with two thick plates and a butt weld, that isnt a concern. Starting middle AND edges is gonna be fewer flips. And especially that initial flip of two 48" long pieces, I'd want a little more than just a few inches in the middle holding them together and true.

But either way will work and result in a flat plate. The key is try to weld both sides equally each time to balance out the tendency to warp.

 

[TractorGuy]

Your welder and wire are adequate.

Are you welding one plate on top of the other to make it 3/4" thick or butt welding the edges?

If welding one on top of the other cut two sides back to make the top plate about a 1/4" smaller on all sides. Clamp them together and fillet weld stitches alternating sides then complete enough stitches to make it secure. Don't try to fill the whole gap on the first pass. You can come back and weld over all the first pass welds.

If butt welding the edges bevel both. Clamp both plates down and alter stitching to prevent bowing.

 

[workinonit]

So my question is when you do the stitch welds on one side and flip it do you want the welds on the other side in the same location or should they be staggered?