Mig porosity out of nowhere?

[MinnesotaDaveChalmers]

If I get into a project that the Mig can not weld to my liking,I use the old standby, the stick welder.

Yep, just one example: I was welding some used heavy iron that had heavy galvanized coating - mig wouldn't weld without porosity even after grinding almost all coating off. Stick had no problem.

Happens pretty often really for a variety of reasons.

 

[MinnesotaDaveChalmers]

I'm a MIG only guy, I've never owned or tried a stick. I saw them as being ugly and barbaric machines that made weeks that you have to beat the flux from, while the MIG lays these pretty and clean welds that you last down and then walk away.

Maybe I need to buy and teach myself stick if your saying that it handles bad conditions better. And maybe it allows for welding upwards where a MIG trips all over it's pecker.

Not sure why you think that about stick, makes really nice welds
Vertical up mig works well, but proper machine set up and weld technique are required.

 

[Al 2]

When I got my last bottle of gas I had a similar problem. After doing all the checks as others suggested I finally determined they sent the wrong gas.
Al

 

[Rock Crawler]

LOL, I've never gotten it to work well welding up. I can weld like a champ pointing down, pretty decent sideways, up.... The end only way I can weld up is if I can flip the object upside down!

 

[Cord]

Had a simular problem the other day and I believe it was a slight breeze blowing the gas away. The strange thing is that the repeated passes produced the same result. My thoughts are that the base metal was somehow contaminated and it continued to contaminate the replacement bead.

 

[shaeff]

Winter around my area is always windy, much more so than summer. I swap over to .035 Fabshield 21b for winter projects, no more worrying about gas blowing away, sitting and waiting for the exact right time to pull the trigger and shield the weld with my free hand.

Clean it up, tack it, run it through.

I'd do as others suggest, check flow out the nozzle, check your regulator, the liner, check the hose from your bottle to the welder, the O-ring near the drive rollers, etc...

 

[MinnesotaDaveChalmers]

LOL, I've never gotten it to work well welding up. I can weld like a champ pointing down, pretty decent sideways, up.... The end only way I can weld up is if I can flip the object upside down!

I can relate, at one time I thought the same for stick welding vertical and overhead

If using a mig that has a door chart, drop down one or two metal thicknesses and use those settings for mig vertical up.

Resist the urge to point the gun up, straight in or a slight drag (gun tip pointed down) work much better.
Pointing the gun up (in the direction of travel) can really screw up metal in a hurry sometimes - lol.

Vertical up mig is best used for material 3/16" and up.
1/8" and thinner are great for vertical down, but some people can still weld 1/8" vertical up.

 

[dragoneggs]

I can relate, at one time I thought the same for stick welding vertical and overhead

If using a mig that has a door chart, drop down one or two metal thicknesses and use those settings for mig vertical up.

Resist the urge to point the gun up, straight in or a slight drag (gun tip pointed down) work much better.
Pointing the gun up (in the direction of travel) can really screw up metal in a hurry sometimes - lol.

Vertical up mig is best used for material 3/16" and up.
1/8" and thinner are great for vertical down, but some people can still weld 1/8" vertical up.

Thanks for this advice Dave! I need to start a notebook with these tips.

 

[yomax4]

I usually can get anything clean enough to mig weld with a grinder, wire wheel, long carbide burr or needle scaler. But. There are times when they can't get in there well enough. Break out the stick. I just started stick welding again a little bit. kinda fun actually and stick welders are almost free. ( Still would go inverter though )

 

[JimRB]

Yes, even after grinding back to base material and re-welding that area it came back in that segment. I agree with what your saying, it has to be the paint smoke/fumes from the inside where I could not get the flapper wheel or grinder in good to clean. I tried to get it cleaned as well as I could, and I thought I had enough space between paint and the weld placement area, but it really screwed me up. Sometimes I hate welding. I had a buddy drop an old log splitter that the foot tore off of the beam. So I went and bought a section of 10" mid weight C channel and welded it onto the main beam. The thing had a hydraulic leak for years, and I swear to you... I battles that thing for hours! The hydraulic fluid seemed to have impregnated the pores and no matter what it kept boiling and blowing holes. I used brake cleaner (and waited a good half hour so as to not die) and still got holes. It took 4 or 5 times grinding it out before I got a weld that had minimal porosity, but still was far from perfect. I added a couple gussets to help compensate for **** welds, and it's been a year and it has not broke. Lets hope I do not need to re-visit that repair!

I seldom have nice new clean stuff to fix, all my buddies have nasty, rusty, greasy, oil soaked stuff that they break. Such is life. But at the price of... free... I guess they can not complain!

Brake cleaner can kill you some say.

DANGER using BrakeCleaner to clean your Parts