I saw your post about the crappy wire in your build thread, and did not tie the two together. haha
Speaking of wire, that got me thinking, I have some wire in my welder now that results in a weld that is tough to grind. I have another roll on the shelf that I think is softer. (the wire itself is easier to bend).
I probably should have tried this a long time ago. haha . . but, I still have quite-a-bit of welding to do. I can save the hi-tensile wire for structural projects.
Only reason I have hesitated so far, the soft roll is .030, and the existing is .025. . . does anyone weld sheetmetal with .030?
I posted this on my build page, but should be here as well, since I did start this thread about it...
When I started this project I had no welding experience with MIG. I thought all of the issue I was having was me and my technique.
Turns out after burning through a 2 lb roll of wire that my boss got me from "Advanced Auto Parts" my welds looked no better, had little penetration and I had to grind my backside off to make them look decent..
Well, I went to a local welding supply house and I picked up a new roll of the same spec wire size, grade etc... and what a difference it made..
Beautiful welds, nice penetration and easy clean up... Boy did I learn a valuable lesson... Don't buy crappy wire...
Clean the area thoroughly..I even used denatured alcohol to remove grease/oil etc...
Are you purging the gas supply line before starting to weld?
If you are filling holes or if the tack holes go through both pieces of metal you need to "back" the opening with copper( a flattened piece of copper pipe works great) or aluminum. This prevents air/oxygen from reaching the weld from behind.
. . did you figure it out?