Millermatic 200

[PocketAces]

Were all those passes on the same wire speed and heat setting?

The first welds were the ones on the right. I turned the voltage up one setting somewhere in the middle. Probably before the burn through pass. I was playing with the wire speed. It seemed to work well between 40-60%.

Run 75/25 gas.
.030 is not a bad wire to weld sheet metal with.
Looks like you need to move faster, your beads are way too thick to prevent sheet metal warpage.
You have to spot weld sheet metal, and even then it will bow in and out with out support on the other side.
Brass is your friend, weld will not stick to it.

These practice welds were done on 1/8" material with .035 wire. I was also experimenting with different ways of moving the torch. I was getting nice beads and good penetration with a series of lower case cursive letter e's. Probably not appropriate for sheet metal, eh? I did switch to 75/25; the pure Argon was useless; not sure why the previous owner had that on the machine. Hopefully my .023 rollers will come in tomorrow and I can start practicing on 20 guage. I'm going to pick up a welding spoon and some butt weld clamps at harbor freight.

I think I would still drop down to the .023 wire. That'll let you run less heat and clean the beads up a bit.

Agreed. I think I will need all the help I can get to avoid warping and burn through. I hope I don't have feed issues with the thinner wire.

 

[PocketAces]

I got the .023" drive rolls on Friday. This weekend I experimented on sheet metal for the first time. I was welding 22 gauge and I can weld it but it's pretty easy to burn through if not carefull. I have the voltage set one notch above the lowest setting. I really can't get it to weld on the lowest setting. On number 2, it welds nice but I have to keep moving or it will burn through. I think it will be quite a bit easier on 20 gauge which is what these cars are.

 

[toplscuda]

I got the .023" drive rolls on Friday. This weekend I experimented on sheet metal for the first time. I was welding 22 gauge and I can weld it but it's pretty easy to burn through if not carefull. I have the voltage set one notch above the lowest setting. I really can't get it to weld on the lowest setting. On number 2, it welds nice but I have to keep moving or it will burn through. I think it will be quite a bit easier on 20 gauge which is what these cars are.

Just remember with sheet metal you will not run a bead on it, just make spot welds. This will help keep you from warping the metal.

 

[72bluNblu]

Just remember with sheet metal you will not run a bead on it, just make spot welds. This will help keep you from warping the metal.

Totally agree. For sheet metal you should be spot welding for the most part. With heavier gauges you can do some skip welding, ie, running a few inches of weld and then skipping a section and repeating. But no continuous welds, that's just a recipe for lots of heat soak and warped metal.