For MIG and SMAW you want DCEP, most of the heat input goes into melting the electrode. Either you can switch leads manually or sometimes there is a lever or switch to internally flip from DCEP to DCEN.

 

If your going to mig tubing I would buy the stuff to drop wire size down around .024 or even .030. .035 is pretty heavy duty for 16ga tubing IMO.

 

Some times when welding light wall tubing and if the air inside the tubing is cold when you start welding the air inside the tubing heats up and expands pushing air into your weld.
When it's cold here (very rare here) we have to purge the tubing or tanks with 75/25.

But if you are having problems with just welding on angle or plate then throw what I just said out the window.

 

soler flux works great on that situation too

 

For MIG you want reverse polarity (electrode positive) To switch polarity, open the cover where the reel goes and look where the whip goes out of the housing, there will be two cables secured with nuts, just switch them.

 

As far as porosity goes to much gas and to much angle can pull air in to the shield. Try 90 degrees to the work about 20 cfm of flow and no more than a 1/2 inch stick out of wire. Check all connections from source to end of gun for leaks. A loose connection can make things ugly.
Mig can be fussy.

 

What's the word? Any success? Here is a pic of the setup we built and are working on right now, testing new contact tip design, so running until burn-back. Can you say a lot of welding? Each bead is 10 minutes long, did 6 today on that pipe. almost 500ipm=lots of wire, hopefully see failure soon. The beads on the far left(with lots of porosity) were made at 30CFH, the other nice bead was exact same voltage and feed speed, but 45CFH. It seemed to be the solution for us, hopefully you get get yours working right BTW were not using CO2 (98% Ar, 2% O)

 

that thing is SWEET!!!!!!!

 

Thanks, the hardest part to make was the rotating ground that conducted well. the first pipe was a little thin

The new pipe is a little thicker

 

thats cheating

 

Cheating what?

 

Wound up welding the tip today, so had to go on a hunt for new ones. Lucky for me, there is none where I live, so I had to go to the city. Wound up getting some tips, new nozzle (much better size than the one that came with the welder), and a new diffuser.

Got that all installed, started welding, still had some porosity and cratering. Turned up the gas a bit, turned down the voltage, and held it more perpindicular, and got some good results. Now just to get more practice and we should be good to go.

 

Good, have fun practicing. Get some pics up.

 

you knows what i mean

 

Using a pipe welder and a trolley? I don't want to weld for almost 350minutes straight, 6 times! Somehow got burned on my face actually, had a mask the whole time, I think some how it reflected off of something, I was careful.