I agree with Ryan, you can a arc but not a mig that I am aware of. The arc conversion also relies on scratch starting as well as a flow valve for the argon, and even then you still dont have the ability to weld aluminum with AC, because they wouldnt have a balance or a frequency setting, even if you had the ac. There is a new machine that does arc/mig & tig but after the purchase price I felt like I might as well have a mig and a tig (tig generally has arc capabilities also) since if that one for all broke you are SOL and if one of my others goes down I have the other machine still available. Besides if you have ever used a poor quality welder you will defintly consider spending the bucks up front for a really good unit, I simply needed to take the chance of a "poor quality machine" out of my book of excuses, I need all the help I can! Best of Luck Matt