MIG Welding a Patch Panel

[Figbash]

I am in the process of making patch panels for the lower part of both front fenders on my '72 Chevelle. I have the left side made and tack welded in place, but how do I go about finish welding it without warping the hell out of things. Do I just keep tacking until I have a solid weld, or at some point can I run longer beads? How about grinding? do I grind the tacks down as I go, or wait until it's completely welded. I'm also going to hang quarters on the car, but I want to get the weld technique down before attempting them.

Thanks,

Tom

[Wray Schelin]

Hi Tom,

Start in the center at the top of the panel. Knock down with a grinder ( be very careful not to grind the fender metal or the patch metal) two of the tacks to surface level and then weld up between them. After the weld cools ( let it cool down by itself) grind the weld to the surface or just a slight bit proud and stretch out the shrink with a slapper and dolly ( you will need to grind the adjoining tacks first befor slapping to make room for the slapper). Watch closely for any distortion. Only work in the 1" wide heat affected zone. After you get that weld ground and smooth weld up another 1". Essentially that is it. You might get some cracked welds, some mig wire will be prone to crack more than others. I tig weld but if I do mig weld I prefer .035 dia. wire for sheet metal.

A shrinking disc will fix any distortion problems you might encounter after you weld and hammer the whole perimeter.

[Ernie Ferrucci]

Hi Tom

Welcome to Metalmeet . Use the search tool and type in "patch panel". There are pages and pages of discussion on your subject. Pay close attention to posts by Randy Ferguson, he has posted some excellent tutorials on using a mig to weld in patch panels.

Ernie Ferrucci

[Figbash]

Thanks Ernie, I'll give it a try tomorrow.

Tom

[josh]

Originally Posted by Wray Schelin

Start in the center at the top of the panel. Knock down with a grinder ( be very careful not to grind the fender metal or the patch metal) two of the tacks to surface level and then weld up between them.

So this is actually an inch long continuous bead (between two tacks), rather than a series of overlapping tacks?

--Josh

[Wray Schelin]

Originally Posted by josh

So this is actually an inch long continuous bead (between two tacks), rather than a series of overlapping tacks?

--Josh

Yep, a one inch bead between tacks will work very nicely. I do the same with tig and gas. If you go more you risk more heat and more shrinkage. If it gets a way from you you will have the dreaded waves. Never let it get away.

If it does get away you can fix it but it will be a struggle and it will take a long time.

[Figbash]

Thanks for the tips Wray.

What shade filter do you use when MIG welding sheet metal? I'm using the #9 that I use for TIG and I can't see the seam when I'm welding with the MIG.

Tom

[Wray Schelin]

Originally Posted by Figbash

Thanks for the tips Wray.

What shade filter do you use when MIG welding sheet metal? I'm using the #9 that I use for TIG and I can't see the seam when I'm welding with the MIG.

Tom

Hi Tom,

If I'm mig welding sheetmetal ( something I don't usually do because I tig weld all my sheetmetal) I will cover the cup with my glove, I don't even look at the seam. I'll turn my head wait till it cools down and then look.

I use a helmet when mig welding heavier stuff.

Those little one inch welds happen in only seconds. You only need to hold the nozzle correctly and move it along in a straight line and the same height under your glove.

All welding is about become a robot, the more robotlike your hand movements are the better your welds will be.

[Don Thorne]

[QUOTE=Wray Schelin] I tig weld but if I do mig weld I prefer .035 dia. wire for sheet metal.

Wray,

Why do you use .035 rather than .024 wire for sheet metal? Is it because the arc will be a bit hotter and allow you to get in and out quicker making a smaller heat effected zone?

Thanks
Don

[Wray Schelin]

[QUOTE=Don Thorne]

Originally Posted by Wray Schelin

I tig weld but if I do mig weld I prefer .035 dia. wire for sheet metal.

Wray,

Why do you use .035 rather than .024 wire for sheet metal? Is it because the arc will be a bit hotter and allow you to get in and out quicker making a smaller heat effected zone?

Thanks
Don

Hi Don,

I like everyone else read stuff, then I try it out. Everything I read said to use .023" wire. Once I try something and it works I'm still not satisfied, so I try doing things differently. Sometimes this experimentation yields better results than what I was getting so I adopt the new method ( .035" wire) until I find something even better. <grin>

The .035" wire worked better for me than the .023" wire. You just move a little faster when welding.