Proper way to spot weld with a MIG welder

[jds319]

I just got a MIG welder, and my first project is replacing the inner steps on my '56 Chevy pickup. The guide I find online says to drill out the spot welds and put new spot welds in their place.

Anyone out there know the proper way to spot weld with a MIG welder?? How long, for example, do you hold the gun in that one place for a solid spot weld? I thought I read somewhere that you're supposed to "turn up the heat?" What's that mean?

[dwcsr]

Test on some sheet metal first. I hold the MIG nozzle 90 degrees to the hole. With everthing clean and tight, let out about an inch of wire touch it to the spot you want to weld and pull the trigger. If the hole is small enough thats all you do. If if bigger then a slight swirl to the gun to cover the hole. the hole should be at least 3/16 so you get weld on both pieces and not just the top.

Turning up the heat (amperage) will just make holes in the bottom piece.

I reccomend that you drill the spot welds from the back side so you only have a small hole left in the front side. when you have the junk out then open those up a little and weld thru those to the new panel.

I see your an AGGIE but I still think you can do it. if you need I can type slower.

[jds319]

Beautiful. I'll give it a try. Thanks, and Gig 'Em!

[dwcsr]

Don't practice on Galvanized metal. The fumes will make you sick as a dog.

[bondobob]

I find you can turn up the heat more than recommended for a given material thickness because you are welding on to solid metal on the lower piece and you are only "there" for a few seconds. I like 5/16" to 3/8" holes to weld thru because with small holes the arc tends to jump to the upper piece and not get a good bond to the lower piece. Get the arc started in the center and do a little swirl around the hole and you are done.

[Detroit3100]

what about when using flux-cored wire?? w/o any gas?
any tips would be great.

[Bills_49]

you will see a difference not using gas over using it. same as when ur welding and the gas goes out you will get holes in ur weld, lil pin holes u will get when u grind. the gas acts as a shelid around ur weld keeping it clean and smooth. if that makes sense

[55dude]

Originally Posted by Detroit3100

what about when using flux-cored wire?? w/o any gas?
any tips would be great.

don't use flux core on sheetmetal, use solid core. go to this site metalmeet.com and search around. any local welding supply or shop will tell you the same thing. google spot welding

[72lb4x4]

I think there may be an issue with terminology... You aren't spot welding with a MIG, its plug welding to replace spot welds that were often drilled out.

A plug weld is used to simulate a spot weld when you don't have a spot welder.

[Detroit3100]

metalmeet.com is the junk!
I feel a lot better about tackling my rusty floors.

I made my first part las night, the front cab support. $6 piece of flat stock turns into a $60 repair panel

[55dude]

after checking out metalmeet.com and posting about a rust issue with my 54' sedan delivery rear door had tons of response and what was even better was the pm's saying "get ready to screw up some stuff and have the patience to redo it until its done" attitude. the neat thing was the different things that are being created, i can only watch a new door skin being attached so many times but being created is a different story. post some pic's of your project dude!