Welding Tips and Tricks

Hello, I just joined today and was hoping for some advice. I am a self tought by trial and error welder starting out with a harbor freight 220 stick welder and harbor fright 90 amp flux welder (hey ya gotta start some where right) I currently own a lincon 180 T, wire mig wlder, I am running .35 flux core wire and using the settings on the inside pannel as a starting place. I have made some really nice welds but every now and then i get a bead with tiny air holes in it. it dosent look like a bad weld and the slag comes off nicely in big chunks but upon further inspection thee arew these tiny pin holes in the weld. the strange part is that it will lay down a perfict bead one time and then do this the next with no change in the settings. I would like any opnions or ideas on how to solve this problem. I will also not that this happes even though the puddle looks good and full while welding.
P.S. I really wish I had found this websight a year ago there might have been more trial and less error!

Most likely, the problem you're having is from the metal you're welding not being clean enough.

The problem you describe is called "porosity", and is the result of impurties "cooking" out of the weld. It's quite common. It even happens when you've ground every surface. (On a fillet, don't just grind the faces to be welded, grind the edge, too.) Sometimes the grinding wheel wil leave impurities that must be removed with solvents (think x-ray quality welds), and sometimes the oils from your hands are enough to make bubbles in your weld.

A little bit of a breeze mixing with your shielding gas can cause this, too.

Poor grade filler wire is another potential problem, and low-grade steel can have impurities in it as well, but this isn't that common.

Steve

Great thanks, that would make sence, i was in a hurry and just grinding enough paint to do the welds and should have done a better prep job. I tired cleaning a wider path this weekend and had no pin holes or problems, thanks again.

I have same thought as Otto Nobedder.

Another possibility for porosity is a leak in the shielding gas line. This can pull air into the shield. This problem is also prevalent in "tig" welding.