I had (until a lizard crawled in the box and fried the board) a CNC equipped with a plasma torch. Cut decorative ranch signs. garage signs, and custom parts for about 13 years as a sideline business. Even mass produced retail product for Academy Sports & Outdoors for a couple years, so I have some experience. My last two projects were large reproduction garage signs for my shop. I cutout a large Mobil Pegasus that ended up about 12' long. I also have a large "garage" sign that one of these days I will finish up. Art deco style. multiple layers similar to a marquee sign that would have hung outside a garage in the 50s and 60s. Enjoyed cutting all of those, as they were unique pieces. I was actually transitioning my business focus to large custom garage signs when my board got fried. Still don't know how that lizard squeezed into that box.
Plasma cuts clean when the metal is clean, air is dry, and nozzle and electrode are new. Dry air is a requirement. I had a water trap next to my compressor, a dedicated dry air line for the plasma, and a motorcraft toilet paper dryer at the plasma. Basically a filter that took a roll of brown paper that looked like toilet paper i got from my welding supply house.
I ran a hypertherm powermax 600. I actually went through 3 of those machines over the course. I bought the first one brand new, the other two used. Apparently, the pilot arc controller goes out under heavy use. And I could buy a used machine cheaper than I could fix the others. I have two on a shelf that someday I'll fix. Just have to source the parts. Watch craigslist or ebay for deals. Just like welding, consistent speed and distance are requirements for clean cuts. The more consistent speed you can keep, the smoother the cut. When I could punch in the Inch Per Minute and design, I could cut parts smooth as silk. Mine would cut up to 1/4". Cut 3/8" once. Had to stop every 6" or so and let the machine cool or it would overheat. I still have the last one and I don't like handcutting. Just cant cut as smooth as I'm accustomed. Can't justify the money to retrofit the controls to make my CNC run again. Thin metal is tougher than thick. Damp air kills tips. Hypertherm made a drag tip with wheels that made freehand easier, but there is still a trick.
Good tool to have in the box, but there is a little learning curve.
