Gas flow

What is the rule of thumb for gas flow in non gas lense nozzles?

With non gas lens you can’t really get much out of them as the design creates turbulence if you run too much gas flow and this tends to pull in ambient air. About 10LPM is the most you can run from a normal tip before you start running into problems so it isn’t a case of more is better. Depending on amperage I would run between 7-10 LPM. It's a case of testing in that range and seeing what gives the best results.

There are many variables as well. What size cup and also what size torch you are running. With a smaller the cup size I’d be down on the lower side of that flow range, again to avoid the turbulence.