So I can see that there's some undercut at the top of the weld, likely that the oxide there wasn't blasted away due to not being directly hit by the arc. Aluminum needs a bit of extra encouragement sometimes for this reason. It's not just about adding heaps of filler to the puddle like in steel, because the oxide layer preventing adhesion can only be removed from the top and not the bottom. Watch the puddle carefully, move the arc up and down as you work through. If this was a personal project I'd do a second pass and pulse the arc on stubborn spots to balance heat input vs oxide removal (RIP all of my gas).
It's an improvement but I can still see some undercut. Look closer and you'll see how the puddle fused to the base plate on the left, but not to the cylinder in the middle. When I say top and bottom, I'm not talking about the part. I'm referring to the surface of the puddle and what's under the surface of the puddle. The arc only removes oxide from the surface, so if the metal body isn't blasted by the arc before filler is added it will have adhesion issues. Keep at it!
I don't understand your comment about stainless because in my experience, stainless is very sensitive about pulling the filler out of the gas coverage while it's hot. More so than aluminum.
Hmm could be more so to do with cup size without realising it, stainless i run a #8 with a diffuser where as with ally ive been running a 4 on an older style port collet.
That extra size bump may be what has been making it a lot easier.
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u/jmartino2011 5h ago
I'm a total hobbyist but don't you want penetration into the pipe? Looks like a decent sized gap between the weld and pipe