Making a 220v recep fed from (2) 110v outlet adapter
I have a 220v portable welder. The problem I have is that not every place I take it has an appropriate receptacle to plug it in to. I have an idea to make and adapter for this. I would use a junction box with the appropriate 220 receptacle and have 2 short whips feeding it, each with a 110 male plug on the ends. If I were to run a heavy gauge extension cord from each whip to different 110v outlets (each of which was fed by one of the 2 different legs in the circuit panel)Then I would have 220v at the adapter, right? Breakers in the odd number column of the panel are on one leg and even numbered breakers are on the other leg. So if "Living Rm" is breaker "12" and "Laundry" is breaker "9", then running one of the extension cords to each of these rooms should work. Am I looking at this correctly? Is there any reason not to do this?
My next question is amperage. If the above can be done, how is the amperage figured? If each of the (2) 110v circuits are 15a, does that give a 30a rating after the 2 legs are combined through the 220v receptacle, or does it remain 15a? Thanks for any input.