chasis welding tips / MIG

[kikiturbo]

Hi, first of all let me say what a great forum...

I am restoring my car and have to do a lot of seamwelding on it, and also some light fabrication using mild steel or 4130 tubing.

I am to use a 200 amp MIG, with Ar/CO2 gas, but the only mix I can buy is something called Krysal which is 82% Ar and 18% CO2. Is this OK?

Also, I will be strengtherning existing panels by addition of sheet steel. What should I use on the panels as a rust protection before I weld (meanig the surfaces that will be inaccesable after welding...)



cheers guys

vlado

[HAWK]

kikiturbo,

The krystal gas, 82%argon/18%carbon dioxide will run fine. It may run better giving you a bit less penetration than 75%ar/25%carbon dioxide. This will be helpful in the seam welds. I run a 92% argon/8%carbon dioxide which is a hotter gas for spray arc mig, but provides less short arc mig penetration for 99% of all MIG applications. Maybe someone with more primer/paint experience will chime in on the primer protection.

[Paul Seaman]

kikiturbo:
Welcome aboard Hawk is dead on with the gas and penetration won't be any trouble with a 200 amp machine. As for the paint try www.eastwoodco.com
This is the great restorers spot with hard to find items.

Good luck,

[kikiturbo]

thanks guys, great help....
one final question, what wire size do you reccomend, for general bodywork.... ?

cheers

vlado

[HAWK]

kikiturbo,

You can run a .023" ER70S-6 for the thin sheet body panel, but .030" should also do well and be more general purpose especially with the lower (18%) carbon dioxide in the gas mix. I vote for the.030".

[klsm54]

Almost all of the Auto-Body shops that I have for customers use .030 ER70S-6 mig wire. 1 or 2 use .023, but like HAWK said, the .030 is more versitile and will weld as thin of material as you should encounter.

[Paul Seaman]

The only addition to what HAWK and klsm54 had to say, I keep some of the others available in small quantities for extreme cases when .030 is too light or too heavy I keep 2# of .035 and .023 just in case.

Good luck,

[dhdh71]

Hello! By far the best product for that use is 3m Weld-Thru coating. It is made exactly for the purpose you describe, and does an excellent job of protecting areas that cannot be reached once welding is done. I have used it many times behind filler panels when shaving door handles etc or in general panel repair. To use just degrease areas to be sprayed, and spray area with 2 coats with a few minutes flash time between coats. It takes only 15 minutes to dry and be ready to weld. Place panels as desired and you are ready to go. It will not interfere with the weld characteristics in any way, and I spray the patch panel as well as the existing oem metal beneath the weld area. Once I tack the panel in place I take a die grinder with a wire wheel to clean coating from the exposed weld area, then go to work! The coating has minimal burn off from the welding heat, as leaves a zinc-rich coating for rust prevention. It is available at better auto body supply houses. Sorry for the long post, I hope this helps!

[kikiturbo]

thanks to all. I found that 3M spray and will be using it. The idea about having different wires... of course it ain't that expensive to have a small roll of thinner wire around... thanks again...