Any good welders on here that can help me out? Ive tried to weld some floor panels Ive patched and my repairs keep coming out bad.
At first I tried flux core .30 stainless wire on my little 120v mig and that seemed to work ok but I couldnt get a nice solid bead. I kept getting lots of spots. Then when I tried to fill in the spots Id get burn-thru.. you get the idea.
When I tried .30 stainless with the gas I got good looking welds except for the same thing, lots of popping no matter what I did, and lots of spots or burn thru, no middle ground. Very rarely could I get that deep sizzling hum that Im assuming means youve got it dialed in.
Any tips?

 

A good properly setup mig welder should have a crackle to it. I don't know what you mean by popping, but its not going to be nice and quiet like a stick welder.

I have to ask, why stainless and what shielding gas are you running?

I have a 135 Miller 110v. Currently running .023" 70,000 psi tensile strength wire, 75% argon/25% CO2 shielding gas. Mine works great once its set for the material correctly.

Burn through usually means your running too hot, too slow, or the material is poor (i.e. rust doesn't weld too well).

 

Splatter, or the wire pushing your hand away as you run usually means your welding something dirty or rusty. Is your area pretty clean?

I've never had much success with flux core. We usually run .030 with the argon mix.

You have to remember, you are welding tin (pretty much). You might try "stitching", meaning running about an inch and a half or two, then skip ahead about 6 or 8 inches and put down another stitch. This method will help with warp and burn thorough (keeping your base cooler). The heat gets worse and worse the longer of a bead you try to lay on realtively thin metals.

 

I am a welder and what you are doing is abit out of sorts. the other two posts pretty much hit it bang on. Flux core needs to run a little hotter and it is not for body work, Stainless is a harder material which inturn needs more heat. and when you mix stainless with mild steel it contaminates the stainless so you have really not gained anything. As well stainless is not very ductile and you will find that it will crack next to the more ductile mild steel parent metal. The argon co2 mix is good , but just straight co2 is fine for a mild steel weld. PJ 's advice on stiching is good advice on all points he mentions. A wire wheal on a grinder helps a lot to clean up the parent metal. Good luck and wear face and eye protection with a wire wheel or you may look like you where biting on a porkypine.

 

Ok, so that explains why I did better with the flux core than the stainless. I used stainless because thats all they had on the shelf at the time. I got a spool of .025 and that was very difficult to dial in. Went back to the .030.
the popping I was getting is an inconsistent weld.. like no matter how much I tried to get started on the molten pool it would skip and lay down spots instead of a bead.
I did the surface prep on the side I was welding, its possible it was screwed up behind the panel.

 

It sounds like something is contaminating the weld and it is possible that it is coming from the other side.

 

Get some pics of the welding area so we can see what might be going on...

You need to make sure you have both pieces to bare metal, and your ground also bare metal and on a good spot...
Remove paint, rust, grease, etc that could contaminate the area youre trying to weld...

 

It depends on what type of stainless wire you are trying to run. A 309 type wire is for dissimilar metals (eg mild steel to mild steel or stainless) where as a 311 type wire is for stainless to stainless only and will not work well at all if you are trying to weld mild steel.

Have you tryed to lay down a decent bead on just a piece of scrap steel first to get you settings close? You do want to clean both sides of the piece you are going to weld.