A typical workshop welder is a 400 amp arc welder, it w […]
A typical workshop welder is a 400 amp arc welder, it will run all day. However you don’t want to be moving it around, it’s too big and heavy.
The most common stick welder is a 140 amp machine but there’s no guts in it. It's very simple and easily runs off a mains electric plug. It will only run for a few minutes before it cuts out and has to cool down, even with thin electrodes (sticks).
I have a 270 amp stick welder, and this runs continuous weld runs (in other words 20 minutes until you have to stop to move the work around) on everything up to 3.2mm rods (1.6mm, 2.5mm, and 3.2mm). It will run 4mm and 6mm rods if you need to weld thick plate. Sorry I don't know the US rod sizes.
But it is heavy, maybe 150 pounds, and needs at least a 16 amp mains supply at 230 volts. It's on wheels and has a pull handle.
One of the most important features of a welder is its duty cycle: how long it will run for before it overheats and shuts off automatically, giving you a long wait while it cools off. This is one reason a bigger welder is better, even for small jobs; the other reason is that a bigger welder is easier to strike the arc with (start the arc off at the beginning of a weld run).
My portable welder is a 160 amp inverter welder that weighs almost nothing, and does DC arc and TIG. It has a hot start facility - a boost to start the arc - and is extremely easy to use. It runs 2.5mm rods all day and 3.2’s if you let it rest a bit. Today these machines use IGBT power transistors not the old MOSFETs, which were sticky on arc-up an burned out in the end; and a 180 amp IGBT inverter is all most people are ever going to need.
If you’re doing thin plate, a MIG is the usual choice, a 180 is enough. TIG does nice work on thin stainless and ali. If you get a TIG welder for fine stainless work, make sure it has a foot pedal for the argon gas. The cheap ones don’t and you blow through bottles of gas too quick.