Bodywork, Paint, Interior, Trim, & Wiring

Just wanted a couple of opinions on the proper size of wire for MIG welding. I am a beginner at welding but think I am catching on. Also I realize that the size of the wire used is based on the thickness of the material being welded and the settings on the welder. I Have a Lincoln 180C Mig welder and am currently using .025 wire for body patch panels (20 gauge sheet metal) and other light tacking. However .025 is a little light for just about anything else. I have seen somewhere that the person on that site used .035 for everything he welds on cars. So I was thinking of bumping the size up to .030 or .035 and seeing how well that would work on body parts and on some of the thicker metal that may be welded to the car in the future. What size wire do you MIG weld with? Thanks.

Have used .030 for years with good success - from light body metal (w/115v) to 3/8" (230v).

I found .023 or .025 to be easier for body panels, but used .030 sometimes too. The only time I've used .035 was when my son & I built the rotisserie.. If your welder lets you use the small spools it's easy to swap out the wire to what you're welding. Plus depending on where you live, the big spools can rust before you can use more than about a 1/4 of the spool!

Howard, what gas ? CO2 is better suited for thicker steel,(burns hotter). Argon is better for thinner sheet metals(not so hot). Having the best diameter wire for each job, should equal less grinding. Good Luck, roverman.

I use argon/CO2 mix for steel.

I've heard that just like with TIG welding using an electrode (wire0 diameter as close to the thickness of the materail being welded is a good idea, especially with the entry level MIG machines. For most sheet metal work that would be around .023 to .025 wire. I have a roll of .035 in my machine now and I find it hard to work with on sheet metal because it deposits too much material too fast, I'd be better off with thinner wire and more adustment of the feed speed.

I tried straight argon on steel sheet metal and that was a disaster. I was almost convinced the machine was faulty, even took it and had it tested. Didn't start to get good results until I went with the mig mix and .023 wire. That made a HUGE difference but I can't say how much a part the wire size played, since I've not gone back to the larger size.

Jim

Thanks to everyone that has commented. The gas mix I'm using is 75% argon/ 25% CO2. I guess I will stay with the .025 for body work and change to .030 when I am working with anything heavier.

Here is a picture of the current state of my car. Overall, I am very happy with what I have done so far but I am having trouble with the seams shrinking due to heat. I guess having a little more patience when welding would help.

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The gas mix I'm using is 75% argon/ 25% CO2. I guess I will stay with the .025 for body work and change to .030 when I am working with anything heavier.

Excellent idea. Don't think you will need the .030 'til ya start building the trailer. ;)

When I say working with anything heavier, I am thinking about extra structural support and brackets for a four link rear suspension, engine mounts, and things like that. I think the .025 would be okay to tack it in place but I should use .030 or .035 for the actual weld.

Howard,
It looks like you welded new doorsills under your mgb. It looks like you didn't use the original replacements panels. Did you remove all the rusted out door sills. I am just there to start the same job. Any input on that.

Re: I am having trouble with the seams shrinking due to heat.

You probably already know this, but on thin metal you should do spot welds every few inches. Then go back an do spot welds about 1/2 way between those. And keep repeating that process until the seam is fully welded. It's time consuming, but really minimizes any shrinking or warping. Another method is to do the same basic process, but to do it with short welds of about 1" in place of spot welds. That's a bit faster but I still got more shrinking & warping trying it that way so I stuck to the spots.

WernerVC - I did have alot of rust at the door sills and rocker panel. I removed the complete sill and rocker panel then installed a piece of rectangular tubing (5" X 2-1/2" X .120),which fit perfectly though heavier than the original, and then formed my own rocker panels. I am thinking I don't like the square look of the rockers as much as I thought I would and might cut out the front section of the rocker and put a curved piece back in its place. I did buy new outer wheel wells, because of rust, and put a 2-1/2" wide piece of metal between the inner and outer wheel well to allow for larger/wider tires. In this picture you can see the rectangular tube and that the rear fender is flared out.


Rob - That is the process I have been using of spot welding every 3 or 4 inches and then filling it in half way between each time but I guess I'm not allowing enough time between welds. I also think the heat from grinding the welds causes some shrinkage too, did you notice that at all?

WernerVC - A few more pics of what I did, not saying it was the best solution, but definitely alot cheaper than buying replacement parts

First one is of the rust, the more rust I removed the more I found.


Second one is with everything cut out


Third one is with rectangular tubing tack welded, viewed from inside the car.


Last one you can see the rectangular tube and the rocker panel

I didn't get warping from grinding down the welds. I mostly used flap disks like these...
[www.google.com]

For tight spots I used little 2" discs on a air die grinder.