I recently bought a Firepower FP-18 plasma cutter for sheet metal and tubing walls up to 1/8" thick. It runs on 110-120v and has a built in air compressor.

My question is about cutting rusty parts. Do I need to remove ALL rust before using the cutter (e.g,, with a grinder), just the LOOSE rust (e.g., a few licks with a wire brush), or none of the rust?

My concern is that rust will plug the little orifice of the cutter. On the other hand, I don't want to do work that's unnecessary.

First of all, i don't think rust will plug the orifice, the plasma comes out under pressure and at 20,000 degC+.

I've cut rusty metal, but not tried heavy scaled rust and it worked OK. I know paint isn't a problem either.

On the basis of my first paragraph, try it out on a piece of rusty scrap, I bet it will work OK.

John

Yes, John's right.

The more rust you remove the better life you'll get out of consumables (possibly) but it's more of a compromise really...remove the bad loose stuff then cut away...