The new Harbor Freight flux 125 welder isn't a great machine, but it's a significant improvement over the previous model because it has rectified output. No wire feed process is meant to run on AC output.
Harbor Freight's flux core wire is junk. Flux core wire, while not as susceptible to moisture contamination as welding rods (flux being inside and all), can still be harmed from long term exposure to moisture. Months spent in shipping containers, warehouses, and store shelves, combined with the crappy packaging and poor quality to start with is everything you DON"T want in a welding wire.
Get a roll of Lincoln .030 flux core wire and start there.
Boiled down to the basics, it works like this:
Wire feed welding is unique in that it uses two separate controls that each affect the arc in their own way. Unlike stick or TIG welding, the output amperage is a factor of BOTH settings. Wire feed is a CONSTANT VOLTAGE process. When you set the "power" on the machine, you are setting an output voltage. This output voltage will result in a particular arc length between the tip of the wire and the metal. As you dial up the wire speed, you're forcing the AMPERAGE higher as the machine has to burn off more wire to maintain that arc length. If your wire speed is too slow, it will burn the wire back faster than it's coming out. If your wire speed is too high, the machine cannot supply enough amperage to continue burning the wire off, and you end up with the spattery piles of burned wire. It's about finding the balance. There will be a wire feed speed range in which it runs quite well at a particular setting. You'll be able to go a little faster or slower, but that range is fairly definite and will depend upon your power setting.
It takes some getting used to. Odds are, you will NOT be using the full output speed of the machine, even with the power set on max. Harbor freight uses the same feed mechanism in many of their cheaper machines, so if you were using say the 180a machine at full-tilt with .023 wire, you'd need the full speed, but not with thicker wire on a smaller machine.
