Welding Tips and Tricks

i have a millermatic 120. its an older guy and 230v. i stated having problems with alot of porosity in the welds. i changed bottles, hoses, everything i could think of. i havnt used it in a while because of this. but it would weld great, then out of no where would weld like shit. i made sure the gas was coming out, not getting blown away. didnt think about it until i seen a couple things on here about the ground clamp. could this be the culprut???? any ideas would be greatly apreciated. i'm at my wits end with this thing. thanks, Hammer

The main cause of porosity in mig welding is lack of shielding gas. If you are not getting shielding gas then this may be your problem. Another possible cause of porosity is the surface condition of the metal. If the surface of the metal is rusted that could also cause porosity. As for as the ground clamp that should have nothing to do with porosity in your welds. Good luck.

i've checked everything i can think of. the gas is fine, the metal is always cleaned prior to welding. soemone told me once it would be an electrical problem, but it didnt sound right to me either, but i just cant figure it out. i've been using my 110 lincoln fluxcore for all my welding because i cant figure it out.

I can guarantee one thing. It is not an electrical problem that is causing porosity. You only have three things in the equation to check. That is if you are not having the shielding gas blown away. 1. Gas cylinder/Regulator 2. Base metal 3. Filler metal. You say the base metal is clean. What kind of wire are you using? Is it copper coated or bare? Is the wire clean? Is your Gas cylinder full? If it is near the empty level, that can cause porosity because of garbage in the bottom of the cylinder. What kind of base metal and filler metal are you using?

Jim

i changed the bottle, the wire, the tips, blew out the hose to make sure it wasnt that. the reg is good. i thought it might be a crack or hole in a hose, but i checked them all and they were good. i run copper coated wire, er70s6, .030. i also changed out the liner, diffuser, and cup. i'm guessing there might be some way that the hose got contaminated inside, but not sure how it could have happend and how it wouldnt have cleaned itself out. i guess i will get some new hose and try that next. was kinda hoping it was the ground. i thought first it was a bad bottle and i bought a new one. they didnt want to hear it was contaminated, go figure. of course it wasnt either, unless i got another one that was. dont know. thanks for the help

ok the first time i had to certify on a weld test i couldnt figure out why i was getting porosity either.
first things first pull the wire out of the liner turn the machine on and check your gas. check and check it lay on the trigger and make sure there isnt some short in the gas solenoid circuit and giving you an intermitent problem. do it for 1 min to 10 minutes just make sure your getting gas all the time.
secondly if make sure the regulator is set to 35cfm to high or low could cause porosity. i dont know why too high would but it happened to me it could happen to you.
it should feel like a gentle breeze coming out of the gun.
then for some reason the angle you point the wire at the base metal. look at the miller website. says 15 degrees forward (as pulling the bead) all the way to 15 degrees back( as pushing the bead) and watch your stick out. thats what happened to me. i spent ten hours trying to make weld 5 inches on a 1/4 inch plate, but everytime i ground into it to clean it up for a bend test it looked like swiss cheese.
and finally make sure all fans are off and theres no moving air that could blow the shielding gas away
hope it helps if doesnt then im a jackass

the ruber o rings on the whip itself where it connects to the wirefeeder are real bad for dry rotting and letting air into your sheilding gasses wich will cause the same problems as not getting gas