1. Here's something I did that made me feel stupid. I had to back chip about 10 feet of Al weld on a edge flange. I did that with a 4-1/2" segregated diamond concrete blade and it worked great. I then came back over the groove with a round edge 60 grit flap disc. Finally I went over the top of it with a 120g flap disc. I brushed it with a stainless steel brush, blew it off with clean air and then wiped it down with Acetone.
Sound O.K. It's not.. The flap disk left crap in the aluminum and the sanding groves caused horrible arc wander. On the next one I didn't use the flap disk. Instead I used a red and then green scotch bright disc on my die grinder. This time there were only two areas of contamination where the blade didn't go deep enough and no arc wander to speak of.
2. Do not use polyethelyne air compressor hose for your tank lines. I make up my own hoses and tried the translucent blue 1/4" air hose that they sell at HD. It's rated at 300 PSI and that was fine. What I found almost immediately was a lot of contamination in the weld puddle. It took me a while to figure out it was the hose and when I changed it for a inert gas rated hose the problem dissappeared.
Just thought I'd share in case you've experienced similar problems.
Follow-up on the air hose... I have a friend that works for the air quality board and I asked him to test the VOC levels of the hose. He did the test and found that with just air flowing the hose is was gassing off VOC's well above alowable limits with high levels of hydrocarbons. He didn't have time to test for specifics but said he would definitly not use it for anything other than air tools and general shop air use. Hummm go figure, that's what the card label on the hose said.. 
Interesting huh.. Now you know why that hose you get at your LWC is so much more expensive.
Interesting huh.. Now you know why that hose you get at your LWC is so much more expensive.
Highly skilled at turning expensive pieces of metal into useless but recyclable crap..
You know, I just blew a 60CF tank of argon trying to figure our what was causing my weld porosity. I had just replaced my tank lines with some bargain $9.99 hose I got a Tractor Supply (not knocking TS)sschefer wrote:
2. Do not use polyethelyne air compressor hose for your tank lines. I make up my own hoses and tried the translucent blue 1/4" air hose that they sell at HD. It's rated at 300 PSI and that was fine. What I found almost immediately was a lot of contamination in the weld puddle. It took me a while to figure out it was the hose and when I changed it for a inert gas rated hose the problem dissappeared.
Just thought I'd share in case you've experienced similar problems.
Looks like a trip to HD tomorrow to get some new air lines - THANKS!