MIG Power/Speed Setting Question

[MarkoStephano]

Can anyone help out a beginer? If I am welding a thinner .035 steel to a heavier, .125 thick steel, what should I use as a power setting/speed? I wish to plug weld the .035 onto the .025 thick base metal. So I am punching 3/16ths inch diameter hole in the thinner steel and "spot welding" it. Am I to add the two together to figure this, or do I just go with the thinner material's gage to determine the settings? To clarify things I am replacing the floor pans in a Volkswagen. Any advice would be greatly appreciated!

[Hotfoot]

It would help if you told us what welder you were using, and what wire. I assume you are using solid wire with C25 gas, correct? (Flux Core is barely able to do this job, and then not at all easily or well).

On my HH180, I would go with .024 wire, and run my machine on #1 tap at 50 speed (slower never seems to do as well for me). Clean both surfaces (I use aflap disc in my grinder), but do not "over-prep", because you will make the metal way too thin.

Keep your initial welds distributed far apart, and opposing each other to fit the pans in very nicely (you DID pre-fit everything, right?). I even use a few sheet metal screws to hold it all in place, and they are removed last, then their holes plug welded. You do not want to overheat any one area, or the pans will warp and buckle, giving you the dreaded "Oil Can" floors (aka" Boinky-Boink Floors), which will then need strips of angle iron plug welded to the bottom to cure, and you really don't want that. I keep a spray Windex bottle full of water to quench as I go. Be sure to get under that bug and seal all the seams after you are finished, or rust will come in very fast, then undercoat the whole pan and seams with a spray on undercoat.

[MarkoStephano]

Thank you for your help Hotfoot. I am using .030 solid wire with the Argon/Co2 gas,
I have the Handler 140. Sorry I wasn't quick to reply, but i can not figure out how to set up the reply notification on this site!

[Hotfoot]

Hit the "Reply" bottom located to the lower left below this post.

[MarkoStephano]

Hi Hotfoot,
I was refering to the setting(s) that would send me an email notifying that someone (You) had responded to my post. At any rate, it in fact works now!
So I am wondering if to figure out the the proper settings on my Handler 140, if I should add the the two material thicknesses together, and divide by two(as if I am welding two pieces of the same thickness-as opposed to welding a thinner material to a thicker one?). I am using Cleco temporary fasteners to make sure the two are touching and held tight together. I am just a little leary of not getting the proper penetration for mechanical strength. Should I be able to see heat discoloration as well as a slight slump on the underside of the thicker piece- in this case the central "Backbone" of the VW chassis? Or just discoloration at each plug weld?