Originally Posted by KLboxeR
Did you have a hole somewhere to vent gasses? (I'm assuming it was a tubular part you were welding) Is there water trapped in the part causing steam to contaminate? Did you clean the inside of the tubing (If it is tubing)
Other suggestions would be to raise or lower the AR flow. Too high may be causing turbulence and allowing contamination or too low cfh will cause obvious problems. Did you try re-grinding the electrode in case it's been contaminated?
That's what jumps to mind anyhow.
Thanks for the quick feedback. There shouldn't be water in the tubing. They were never wet and I saw no sign of rust. I did sand the area near the weld on the inside of the tubing, but not real thoroughly. I also wiped it down with laquer thinner to remove any traces of cutting oil (though there could have been some deep down in the tube that I couldn't get to. I did try regrinding the electrode a couple of times because the splatter was definitely contaminating it. I didn't have a vent hole, but the problem showed up before the weld was even close to being complete.
When I did practice welds on some steel tubing I bought to practive on, they were much better than the ones on the center stand, so it seems more likely contamination, than gas flow issues, but I'll tinker with that next time I am having trouble.
It is typical to drill a hole in tubing assemblies and weld it shut at the end of the welding process? I didn't see any sign of this on the centerstand as it was orginally built with the tubes all sealed.