I have a Longevity combination machine with a plasma cutter in it. I’m relatively inexperienced with it, even though I’ve had it half a dozen years, because I rarely have the opportunity to use that function. It was difficult to start and maintain an arc from the beginning but got to the point that it would start in only one in ten tries then blow out. I know all about proper grounding of the work piece but when it doesn’t work it won’t even cut the ground clamp. The ground clamp circuit is good because it is the same for the stick welding circuit and it works fine up to its 200 amp limit. I got pi$$ed off at it today and spent some time trouble shooting. Tried up and down on air pressure and amp setting. Everything else looked good but I just had a feeling it was in the torch head. I had looked at it a few days before and noticed the electrode (which was hardly used) was unscrewed slightly. It seemed like after I seated it the troubles got far worse. Again changed to new electrode and nozzle (original equipment with the machine) and no difference. I had the feeling that maybe the spring in the torch body wasn’t seating the electrode against the nozzle “firmly” enough to start or maintain an arc. I unscrewed the electrode about 1/10th of an inch (to press harder on the nozzle) and it would start and cut reliably every time on clean stock. Went back to trying to cut up a rusty barrel (yes I ground off a large clean spot for the ground clamp) and while it would start every time it would almost instantly blow out. Question; Will plasma cutters NOT cut rusty metal? Do you think something is wrong with the nozzle ground circuit or is that just for starting?
Jim
Jim
