I'm just getting into TIG, I bought my current machine from a friend this weekend. He loaned me the Argon cylinder he was using with it. I need to go get it filled and I'm trying to decide if I should just fill it (80 CF) and use it, or if I should rent/buy a second one for myself. I like the idea of a backup cylinder since my LWS shops (Airgas/praxair) are both only open on weekdays during the hours I work my 8-5 job. I really don't know how much argon I'll be using, I have been using my fluxcore about 3-4 nights a week and have gone through about 8lbs. of wire in about 2 months.