Got a patch job project to do , I've seen in the restoration threads where McMark had a similar patch project , just looking for some advice on the gap size between the two pieces of sheet metal ( cut a section out of a scraped car ) . This is my first time to do any body panel welding , got .024 wire on mig , voltage/amperage set on lowest setting , hasn't burned through so far on other pieces I've welded in , just want some ideas about gap size , butted up together , a tiny gap between the two ,or maybe a certain distance apart. Thanks for any replies as I do not want to screw it up rrreeeaall bad that I can't grind it out.

Jack / Jaxdream

The distance of the gap between the two pieces of sheet metal should be about the thickness of the sheet metal you are using, so 18 gauge ...Maybe a little less,( I would error on the side of a smaller gap), good luck!

I agree. The bigger the gap the harder it is to fill without burning an even bigger hole. I have heard someone say that the size of the gap should be about the thickness of the wire.

Is it real MIG or flux coated wire? My limited experience with flux coated wire is that it's more difficult than real MIG.

You need a copper "spoon" to back up the gap where you are welding. The "spoon" is just a thick flat piece of copper with a handle on it that you hold tight against the gap you are welding to prevent blow through.

You don't want to run more than about 1/2 to 1" max of bead to minimize warpage. You have to skip around and let each small weld cool before you go back to stitch up more.

Yep it's real mig ( 75% Argon / 25% CO2 ) and got one of them copper spoons from Harbor Freight a while back , 230 volt Lincoln 130T with a good sized coil of 10-2 grounded ( solid )as an extention cord of sorts to reduce the voltage and doin a great job at that. Just wanted some idea of gap size that is usual practice, some of the little things sometimes goes unmention , and I, the same as most have that half zymers also and don't really expect every little thing to be mention in a thread , that's why I ask , the only stupid question is usually the one not asked. Thanks guys !!!!!

Jack / Jaxdream

The gap will end up being whatever it is, but not huge or it's just a PITA to weld in. You want some gap because as the welds shrink the gap will disappear.

Also, I've recently had MUCH better results from welding slowly around the perimeter of the patch and not jumping around from place to place. What I discovered was that if I used 8 spot welds to hold the whole patch in place, then the heat/shrink from welding would cause slight buckling and warping because the piece couldn't move. By welding along the cut line, the warping isn't 'trapped' and can work itself out as you go.

Kinda hard to explain, but it's really worked well for me.

I believe I do understand what you're getting at , instead of tacking it all around the perimeter , you just start welding the gaps as you go around it , giving it space to move into . I like that idea as the tack the perimetr method was what I was looking at doing. Thanks McMark , the patch job you done on the blue car is very close to what i have in front of me but both sides running across the middle also basically the bottom setion of the panel where the sound pad rusted the panel out , being a newbie I wanted as much advice as possible , got one shot and hoping not to screw up . Thanks again to all.

Jack / Jaxdream