Looking at gas..........

It appears you can use either an Argon mix or straight C02 for plain steel MIG welding.

Ain't called the local welding gas suppliers yet to inquire about gas and if bottle rental is required(I'm sure it is).

I'm wondering about the price diff tween Argon mix and C02 gas, and if there are alternate and cheaper sources for C02.

My bar owner buddy gets his C02 in standard large high pressure bottles from Coke. He says they only ask for bottle deposit and no rental fees, just swap bottles and charge for gas when empty.

How do you guys get/pay for gas?