Doright wrote:Jim
Most of us started with Mig Most are still using a Mig for their own reasons.
I only use the Mig process when it fits the repair I am doing I use Mig, Tig and Gas just depends on the repair, Where its at how easy it is to get access too how strong repair needs to be and what I want after welding.

I learned how to weld with Gas Originally then played with Stick and then bought a Mig and loved it! A Mig is great for welding so many things BUT Thin sheet metal is not one of them in my opinion.
You would be better off Gas welding Body panels in my opinion yes your gonna have a Bigger heat effected zone BUT gas welding weld Bead is softer and easier to Hammer and Dolly than Tig weld bead yes this means whole panels being affected by heat requiring More Dolly work to straiten.
It really is possible to Gas weld with the precision of a Tig IF your really good I have seen it done. Gas really is the best for Auto sheet metal and its cheap to get into!
https://www.youtube.com/watch?v=Rv5bKXJ3kEM

That said Yes Mig weld bead SUCKS! Yes its rock hard, Yes it cracks when Hammer and dolly-ed, Yes its very Porous and Yes you got pin holes! these are the things the promoters of Mig welding thin sheet metal never talk about!!! Or Show in their pics!

After your happy with cleaning up your bead this means grinding front and back doing ALL your hammer and Dolly work, Paint BOTH sides with EPOXY Let it fully cure this can take DAYS depending on Temps! SCUFF it THEN Yes cover both sides with Fiberglass filler Sand as required before paint.

There are many opinions and thoughts on what to do with Weld bead:

Some say to metal treat both sides of weld with a Phosphoric acid treatments before Epoxy, As a rule Epoxy does not like acid of any type! so cleaning surgically clean after treatment is a Must and easier said than done! Advanced stuff not for the lazy Stay away from Acids Till your really willing and able to completely neutralize and surgically clean the metal after treatment this point can not be overstated!
Super clean Lots of soap and water, YES water! and SCRUB! red Scotchbrite and YA! YOUR GONNA GET WET! I like this process for rust protection with a Cold Galvanizing system I use I do whole cars this way But I get help I get a few people involved with the process.
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I have played with just cleaning with Alcohol first As Alcohol is water based, then cleaning with Acetone or MEK then painting with Zinc rich Epoxy followed by Fiberglass and have had good results so far.

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Another Idea is to Tin it and then use Lead which would be the ultimate in my opinion as The Tinning coat will not stick to metal unless its super clean and rust free. Chevman is the guy to talk to about lead hes got it down really good I encourage you to check out his Nomad Build.

viewtopic.php?f=12&t=17047

https://www.youtube.com/watch?v=87fuTnBS2bE

Another idea which would be really cool is Brush Plating which is really out their and over kill BUT would be really Cool. BOTH require surgical Cleaning before and after repair!
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Some just Grind there bead and cover with filler and Paint the car and swear by it!!!!
Point being its your car their is no rite or wrong, really! its up to you decide which is best.

chopolds wrote:A quick hint: sometimes porosity is not a shortage of shielding gas. On the older stuff we work on, it could be contamination on the backside of the metal being welded. As the metal melts, it also brings forward rust, undercoat, and such, from the inside surface. Try cleaning the backside of the seam before welding, if possible.

Doright wrote:Jimmy

Yes their are other filler wires to use. If you have been doing your research on this web sight you would have read about my choice for Auto metal..... READ.

IF you can get to the back side clean it to bare metal Treat with EPOXY only! front and back Then cover with a Fiberglass filler front and back and leave it alone Then move on. Brush or spray it doesn't matter. DO not try wonder gimmicks or treatments stick to what works clean bare metal epoxy and fiberglass filler. your patch will work fine as long as you use that.

Practice your welding try different wires Try different techniques try Gas welding its cheap to get into, read a lot and Practice! A LOT! go to junk yard get some old hoods or fenders cut them up weld em back together.
You will get their NO it will not happen in one project or over nite!
I been doing this for a very long time It takes time, it takes practice, it takes money!

jimmystoys wrote:I was on the Eastwood site, checking out new tools and what not, and came across this Magnetic Welding Copper Backer. Any thoughts?