troubleshooting (bad welds)

[parth096]

I'm welding thinner gauge metal tubing (20-16). Sometimes, i notice that when i let go of the trigger, my pool "grows" and gets a point on it. What is happening here and what can I do to fix this? I'm running autofeed at about 3.8 volts. If i go higher I risk burning through.

[MMW]

1 - Contamination, likely coming from the back side but can also come from the front side. Back gassing/purging it should get rid of it. edit (For some reason I thought it was stainless but I guess not.)

2 - Try releasing the trigger for a split second at the end of the weld & then squeeze/release the trigger like putting a tack at the end. This adds a little more wire & also puts more shielding gas on it while it cools.

[ryanjones2150]

Yup, contamination. Looks like a little volcano doesn't it? Clean the inside of pipe too. All the mill scale, rust, oil...all of it. If you're using old junk, like I do, sometimes it's hard to get away from all of the contamination. If you can tig weld it, dab in there with some 309 stainless and all that trouble goes away.

[aametalmaster]

Galvanized? Pics? Too many volts or too much wire feed....Bob

[tackit]

Maybe it's because when you let go of the trigger, you're at the end of the weld and the tube has gotten much hotter than what you set the machine to at the beginning of the weld, that's pretty thin metal it heats up fast. Perhaps skip welding around the tube will allow the tubing to cool a bit or readjust the machine down when you are nearing the end of the weld.