Welding Sheet Metal

There has been some great advice about welding on the board, but I would like to ask something specific to my situation. I have a pretty basic wire-feed welder, the Lincoln SP-135. (It has a Nascar Logo on the side, which means that it must be better than other models.)

I have done some welding with it, and I suck, but I can get a good result with patience. I am welding sheet metal on the MR2 for some repairs, and I tend to go slow, move the heat around, and stitch weld to keep warpage to a minimum. My question is about the wire, and gas.

I use whatever wire was available and on sale at Lowes. I have never considered size or properties at all. All I do is keep it clean and dry (Thank GRM articles!). Can using a specific wire help me out at all or make the job easier?

I can also invest in a kit to add gas to the unit. How much of an improvement will it make and how much harder is it to use? I am not looking to lay a perfect row of nickels on unfinished aluminum (people who do that live on Mt. Olympus) and I have lots of grinding tools available.

Have you considered going to a local welding supply store like AirGas?

I have the same welder you do (minus the NASCRAP logo and with gas). For sheetmetal work I use .024 wire. I have .030 also, but it doesn't work well on the thin stuff, at least for me.
As far as gas goes, I use CO2 for general work, and CO2-Argon mix with stainless steel wire. I sure do know it when I run out of gas, as the welds get much worse. But if you are using flux core wire, which you should be without gas, the difference may not be as great. I'm not an expert, and I'm sure others will correct me if I'm wrong, but I have been doing it for many years, so TIFWIW.

http://www.millerwelds.com/resources/articles/MIG-GMAW-welding-street-rods-Ron-Covell

I've done a good bit of sheet metal with mine using .035 flux core. I haven't tried gas with mine, I have a buddy with a Miller that uses CO2 and I can lay a better bead with mine. 90% of that is probably because I am used to my machine. I learned the hard way that the flux core wire from Harbor Fright etc blows goats. Spend the extra for the Lincoln wire.

Anyway, instead of stitch weld I stack tacks. The metal needs to be very close but not touching, I got some of those 'intergrips' from Eastwood and they do help a lot.

Unfortunately, they can't be used everywhere (won't work with curved surfaces or where there is no access to the back).

The trick for me is to take my time; let the tack cool till it shows no red before doing the next one, space them about an inch apart. If the metal starts to shift, a body hammer and a wood block help put it back in place.

Using gas and .024" wire will make the job eleventy times easier.

bravenrace wrote: I have the same welder you do (minus the NASCRAP logo and with gas). For sheetmetal work I use .024 wire. I have .030 also, but it doesn't work well on the thin stuff, at least for me. As far as gas goes, I use CO2 for general work, and CO2-Argon mix with stainless steel wire. I sure do know it when I run out of gas, as the welds get much worse. But if you are using flux core wire, which you should be without gas, the difference may not be as great. I'm not an expert, and I'm sure others will correct me if I'm wrong, but I have been doing it for many years, so TIFWIW.

This is my experience as well, I started off flux cored .030 doing sheet metal, the only trick I found that allows you to continue this without stepping down wire sizes and going gas (which is the best thing to do) is to use thicker sheet in the patch areas, as it helps to act as a heat sink and prevent burn through, but I'm a total amateur at welding...

I used .030" wire in my welder since the day I purchased it. Then one day I tried .025. It made a fantastic difference. Can't guarantee you''ll see the same results. When I weld anything really thin, I always have a bucket of water and a rag. I use the rag to cool the sheet metal back down as soon as I'm done welding. So far, I've had good luck.

I'm also a total amateur, but I find it MUCH easier to weld sheet metal with a MIG than flux core. I have a flux core welder running the smallest wire they have at Home Depot, and my friend has a Hobart Handler 140 running .027 (I think) and I've used them back to back. The true mig is MUCH easier to get good results with.

You can weld sheet metal down to 18 gauge or so with .030 flux core wire, it just takes a lot of skill. Using .023 solid and gas will make it much easier. You are using a #10 shade, right?

I use these:

I'M KIDDING! Yes, I use a #10. I will have to check my wire size and look into the gas kit. It also sounds like I am using the term stitch weld incorrectly, I am not doing small stitches, only small tacks and letting cool between.

Just make sure you use a mask and not goggles. Ask me how I know.

Chris

Get the gas set up, small wire, slow and easy,then brag about your beautiful welds.

cdowd wrote: Just make sure you use a mask and not goggles. Ask me how I know. Chris

My guess is you have a beard.

.... Had a beard.

DILYSI Dave wrote: Using gas and .024" wire will make the job eleventy times easier.

this times twelvty.

Buy the Lincoln wire. Cheap wire is made from crap they sweep off the floor and it sucks.

Buy the small spools and if you don't use it quickly, buy a new role or at least remove and store in a bag with desiccant pouch.

To adjust your rig: Point it at the tin and pull the trigger, Count to two.

If it made a hole, either lower the juice or count to one. If it did not blow a hole, raise the juice and count to three.

Your perfect setting is somewhere between the two numbers and settings. The small weld dot that you are aiming for should look the same from both sides of the panel.

Now, all you do is move the tip over 1/2 of the dot diameter and repeat. The ideal timing is to do a dot, move over half a dot and just as the red-glow is going away, hit it again.

You will soon figure out that you can do more of an elongated dot if you move the tip a small amount, but regardless it involves a lot of trigger pulling to weld tin with a Mig.

I fit panels with zero gap if at all possible. I never understood the gap thing since all it will do is introduce warping as the bead shrinks when it cools.

N Sperlo wrote:

cdowd wrote: Just make sure you use a mask and not goggles. Ask me how I know. Chris

My guess is you have a beard. .... Had a beard.

Or a bad sun burn.

cdowd wrote: Just make sure you use a mask and not goggles. Ask me how I know. Chris

Tell us a story, Uncle Sunburn

There are, theoretically, softer wires out there which are designed for easier metal working. I have seen them on websites, but I have never found them anywhere.

Good advice about stuff, but I will add in this- Do your series of tacks, stop, take off your helmet and pick up the hammer and dolly and move your sheet metal back to where it needs to be again. Stuff moves, and its easier to move it back before you weld it solid.

In reply to pilotbraden: I was hopeing no one would really want to know. Pilotbraden saw the results. I had just bought the welder and went to buy a mask and they were out so i bought a pair of goggles. That evening i started playing with the welder. the next morning my face was all burnt an blistered. To make matters worse i was to stand up in a friends wedding latter in the week. I was really proud of myself.

Chris

Streetwiseguy wrote: There are, theoretically, softer wires out there which are designed for easier metal working. I have seen them on websites, but I have never found them anywhere. Good advice about stuff, but I will add in this- Do your series of tacks, stop, take off your helmet and pick up the hammer and dolly and move your sheet metal back to where it needs to be again. Stuff moves, and its easier to move it back before you weld it solid.

This opens a whole NEW can of worms!

Best head off to the Metalmeet forums to fill in the background.

Silicon Bronze welding wire

http://www.usaweld.com/023-Silicon-Bronze-Welding-Wire-p/58223.htm

Lower melt point, easier to grind, doesn't pull back like steel fillers so it minimizes warping yet unlike brazing, paint and fillers actually stick to it. Perfect for sheet metal repairs. Not cheap though.

Rather than butt welding sheet metal, spend $43 on:

An air flanger/punch

...Which is used to make a recessed lip to sit your patch panel on. Welding to this is SO much easier than butt welding panels edge-edge, and you'll introduce less distortion.

Also - in addition to flanging you can punch 3/16" holes and plug weld the panel in with those.

And, as everyone else has offered, .023 -.025 wire helps and I'd consider Co2 to be mandatory. I use C25 (25% Co2/75% argon) in my machine, but I did a whole car - years of bead - w/ C02 only.

I prefer the flange solution myself. Its other benefit is a less porous weld. When you butt weld especially when you use the clamps that hold the panel apart you really should be backpurging the area with shielding gas as you weld. The flange keeps the contaminating atmosphere off of the backside.

I have flange welded sheep metal and butt welded it as well. I have also used the butt weld clamps. To make a tighter butt weld I use a file to make a notch in one or both edges of the sheet metal where I place the clamp I can then position the two edges of the metal so they touch. Using this method I replace part of a rear fender on my race Scriocco and no one can tell where i made the joints. and I did not use bondo on about 50% of the joints length.

I like the flange weld method for floor pans and other areas that require stiffness or if the sheet metal is flat. If its curved I like butt welding better.