Welding Tips and Tricks

A friend of mine wants me to use my MIG along side his to weld in some floor boards. I'm thinking that this is a bad idea as we are using the same common ground, "the vehicle" and this would most likely damage both welders.
Am I wrong on thinking this ?

Hi there,

Its no worries doing this. i have done it many many times.

mick

Ok, thats good to know. I wasn't sure if one would feed back into the other.

Thanks for the quick reply

Hey,

Pleasure, Just make sure to put the ground cable from each mig as close to the area each machine is welding. also disconnect the battery from the car before welding.

Mick.

Will do, thanks again.

Here is another variation along the same lines.
In our school, the welding shop is actually a metal trailer and everyones work stand is connected to the metal floor. Here is the par I had a hard time getting square in my head! One person is welding DC+, and right beside him, there is another person doing TIG and is DC-.
In my way of thinking, this is a dead short! But the machines are able to sort this out just fine. They are all Lincoln Invertec V350's.

Hey,

When something just "works", say, "a wizard did it". Seriously though, find yourself the electircian teacher at your school. They should be able to give you the exact answer. Well better than most welders can anyway.

Mick.