As per the title, struggling with welding 1.2mm thick mild steel sheet to 2.5mm tube. Keep burning the edge away from the sheet before getting a decent pool. Guessing it's too many amps?
hang on the thick bit till the puddle is going and step onto the thin bit for a lot less time ,, point the heat at the thicker bit more of the time ,, its just practice.
Focus the angle of the arc & puddle on the thicker metal, the heat will transfer easily enough to the thinner stuff, amps is about right for the thicker stuff but way to high for the thin stuff so you need to protect it with the arc position & angle, do you have anything you could use as a heatsink on the thinner stuff?