OOPS! I see this was a double post! My 'Puter crashed when I tried to post it the first time and I can't delete the first one . Sorry!I've welded alluminum vee groove's with backing strips.That is not too bad! I have to test on D17.1 on .062 thick 6061 alluminum plate and would like some input on the joint prep and if a purge is necessary or if a copper backing strip can be used? Should I run a little bit of a land and bevel with a small gap or just square edges and closed gap? Gas is straight argon with 4043 wire in 1/16" diam. I'm thinking when I get a chance to see the WPS it will give me my parameters, But I am waiting on it to make it down to my level. Any tips will give me a heads up and make life easier when I go to test! ThanksLast edited by seaplane; 12-05-2011 at 09:01 PM.