The Stovebolt Site Forums The Shop Area The Tool Chest Plasma cutter questions

Recently, I bit the bullet and bought a pretty nice 110/220 volt MIG welder, a Hobart Handler, and I'm pretty pleased with its performance. It welds mild steel and stainless from sheet metal thickness to 3/8" or so with no problems. I haven't set it up with a spool gun for aluminum, but a friend who has a similar machine reports that he's using his machine on aluminum plate with no issues as long as the metal is clean and joints are properly fitted.

Now I'm considering buying a plasma cutter. Some of the Ebay ads I'm looking at feature multi-purpose machines that can stick or TIG weld, plus plasma cut fairly thick metal. Prices vary from $200-ish to $1k or so. I'm considering a machine in the $600.00 range that welds up to around 200 amps, and plasma cuts at 50 amps. I know that a VERY dry air supply is needed, as even a tiny drop of water in a plasma torch has explosive consequences. That shouldn't be a problem, as I've had plenty of experience dealing with air line moisture in a body shop environment.

Anybody with some plasma cutting experience got any comments or suggestions? Thanks!
Jerry

I've been using a Miller unit for the past bunch of years. I forget the model number. Maybe the Spectrum 375? Anyway, clean tips cut better. A plasma will never leave a super smooth edge. A worn/dirty tip will make an even rougher edge. The model may say that it cuts up to 1/2", but, if you drag or push your torch too fast, the flame will push off to the side and that's where your cut will be. Sometimes my guys will grab a painted/rusty whatever to cut. I'll usually tell them to sand off the paint as a plasma needs good conductivity. Bad conductivity will give you a bad or impartial cut. Making shapes is easy. I've made plenty of 3/4" plywood patterns that will make the shapes I need. See the image below that started as 1/4" plate and became motor mounts. Straight lines are as easy as using a piece of angle iron. Dry air line? I haven't given it much thought and have never had an issue.

Actually, that might be 3/16" plate.

I have the Eastwood Versa cut 60. Works fine for my garage/hobbyist applications. Not so good if you try to cut thicker than the recommended thickness.
don

I've got a couple of mobile home frames that are just begging me to find the gooseneck trailers that they're hiding inside them, so there might be some pretty ambitious fabrication projects on the horizon. A medium-capacity plasma machine would help those projects immensely!
Jerry

I went through several plasma cutters back when we hauled bulk fertilizer in stainless steel trailers. The only one that was really was worth buying was a Miller that cost around $4000. I still have it, but use it very seldom. I have a refrigerated air dryer in my system and then a desiccant dryer on top of the machine. Dry air is the secret of success with a plasma cutter. The only time we use a plasma cutter is on aluminum. The consumables are expensive and I don't see the point for steel. I use a Victor Journeyman for cutting steel. I have an old Harris propane torch that is about 3 feet long that we used to use cutting up wrecks. It still comes in handy at times. I bought a self contained plasma cutter that has a compressor in it. It only works on days of low humidity.

Plasma cutters do well for cutting straight lines, but clamping a jig on my Victor and running the jig along a straight edge does just about as well and it cuts rusty metal.

I agree with crenwelge. The cut is not much better than one made with a correctly adjusted oxy-acetylene flame cutting torch and the consumables are expensive. With the advent of water jet cutting plasma cutting doesn't seem to be cost effective.

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.

I have had a Hypertherm 625 for about 14 years. It will do a fine job but you must keep the consumables in good condition. It is rated to sever 3/4 inch but I use it mostly on 3/8 or less and ocasionally on 1/2 inch mild steel. It does a very nice job on stainless. I find it very useful for some jobs and the trick is to keep the torch steady.

Ive been wanting 1 also. But have never used 1 either. Ive actually seen 1 on Jeggs website for pretty cheap. Actually surprisingly cheaper than expected. I dont know what to look for though. So i dont know if its a good deal. But might be worth a look.

Years ago I was the lead person in the steel fabrication shop at a company were we made lawn equipment for the golf course and we had a portable plasma cutter. We also had a oxy-acetylene torch with templates but once the plasma cutter came in the oxy-acetylene was never used again. Ours would work really good up to 3/8" thick steel. Trick was to keep your tip 90 degrees to the surface, keep it clean, and watch the speed you drag it across the steel as the thicker the steel the slower the speed. Once your part is cut it only took a couple of taps with a hammer on your work to knock the slag off. I would change tips at least 2 to 3 times a day if I had a lot of work to do. I always wore a mask as the black crap the plasma cutter puts out is nasty to breath.