Paint/coating? Is the 16G clean & bare metal?

 

You should set your welder for 16 gauge settings not 1/8th inch settings. Otherwise you'll just burn through the 16 gauge stuff. With such a size difference (16 gauge = 0.060 inches, 1/8 = 0.125 inches) you will never get full penetration on the 1/8th inch material and probably shouldn't try to.

 

maybe one or both of the metals are galvanized. also I dont ever remember spot welding 2 different size metals unless the thinner overlayed the thicker one with the plug hole in the thinner one. u then let the puddle of the thicker behind metal flow and just touch the edges of thinner top metal as you go around the inside edges of the plug weld and stop in the center.

 

The 1/8 inch is an overlay over the 16 gauge. The 1/8 inch metal is clean, the 16 gauge is as clean as I can make it on the outer accessible surface. Louie1961, Under the circumstances I will try that. But this seems counter to most orthodox welding advice.

 

Are you sure it is 16g? That combination would not be difficult to weld unless you are butt welding over air? I think you have a finish that need so come off or perhaps it is 18 or 20g. Thinner than 16g is A different experience.

Clean and Clamp things tightly. You have to establish a puddle the wash or onto the thinner metal.

 

Not that I'm an authority on any of this but my best guess is that frame has some unusual alloys.

 

I think if you set your machine for the 16 ga. or maybe just a bit hotter, you will find you can build your puddle on the edge of the 1/8 and with a very short whip motion flow down to the 16 ga. and then return to the 1/8 to rebuild your puddle. You will need to watch your puddle close so as not to cold lap or burn through the 16 ga. With a little practice, this is a very easy type weld. Good luck.

 

[FONT="]I know this question has probably been addressed on this forum many times before but the search engine wasn’t getting me to the answer. So, I was welding frame stiffeners to the underside of my Cherokee today and was experiencing difficulty. The stiffeners are 1/8 inch steel and the frame is about 16 gauge. I adjusted my Miller mig welder settings for 1/8 inch, and I was using gas(75/25). When I pointed the mig gun and started on the thicker stiffener material I got the very satisfactory buzzing sound of good settings and proper wire feeding, but as soon as I tried to shift the weld puddle toward the thinner frame I heard intermittent sputtering and felt the wire kick back intermittently. I was only trying to do spot welds, I know better than to try and weld a bead on this combination of materials. If I kept the wire pointed at the thinner material a little longer, it would start welding and sounding normal, but then a fraction of a second longer, it would burn through. I had a hard time joining the materials. Also, because I know someone is going to ask, the ground clamp is connected to the car frame, the same material that is giving me the problem. I’m not new to welding, but obviously, I’m missing some key skill.[/FONT]

What size wire are you using? I would suggest .023

I would also drill some holes in the piece and plug weld it. (like mentioned already)

I've installed patches on my 98 XJ rear frame... so it can be done Just go slow and make tack welds and skip around to avoid overheating