Yeah that’s not it. It’s usually the very first cut that doesn’t work and it’s usually that it’s gouging the plate and not getting through it.
I have tried manual cuts and straight line fire control cuts and they work fine.
Waiting on two new plasma cutters to get here and I brought home the o-scope and signal analyzer/recorder from work to see what’s up with the mosfet.
I’ll report back when I get more data.
I mean plate. I’m going to braze the work lead to the plate.
Try a longer pierce delay for the first cut. There are some plasma units that require a longer delay for the first cut than subsequent cuts. It’s been discussed here in the past so it wouldn’t be the first time it popped up.
Yeah, I’ve tried all the way to 2+ sec in .1 second increments. I think when I got to a certain point the computer finally just said “nope.”
I contacted the power source manufacturer and asked to get a schematic of the rectifier/MOSFET to put it on my O-Scope to see what the waveform looks like. I’m starting to suspect it’s not getting both legs of the 240 or there’s a problem going from AC to DC. There is a limit to what I’m willing to do in terms of electronics because it’s still under warranty. The basic principle of an inverter is just upping the frequency to take it from 240v and 15amps to 40amps and 114volts (open circuit) and then running it through a bridge rectifier to get it from AC to DC. I suspect one of the diodes might be kaput on the rectifier.
OK everybody, it was the power source (on the plasma cutter). I sent the old WeldPro back for warranty and bought a new one on Amazon, a cheapo Hynade Cut60. Works great. First attempt produced a perfect part. I don’t know how things will work tomorrow when I try again, but I like that cheap ass hynade CNC ready Cut60. Has ports on the back to wire in THC. Has more power than my last one. The Weldpro was not a bad cutter when it worked, and I’ve generally had good luck with that brand. I also own a Tig ACDC and a nice multiprocess, so I like Weldpro, but it may not be right for CNC. Maybe I just got a bad unit, who knows. I don’t want to throw shade on the company. They are good people.
Anyway, thanks to everyone who stuck with me. @TinWhisperer you are always the first to offer your time and expertise and I want to thank you in particular. And, @TomWS too. And everyone else. I’ll post some finish shots when I get time to take photos.
@langmuir-reilly you may want to note that the WeldPro Cut40NH doesn’t work well with your system. I tried for literally 7 months to get it to work, and while I’m not a CNC machinist, I am an engineer and it befuddled me for a long time.
I am very tired, so I’ll report back with pics tomorrow. Thank you to everyone.
Anyone want to buy a new in the box WeldPro Cut40NH? They are sending me a new one that’ll I’ll be willing to part with for a song.
Maybe keep your new one for a back up 
I am marking this solved!
Here’s the first finished “thing.” It sucks because I used it to troubleshoot, but the cuts it did on the cruciform plate were/are excellent, in my opinion. I did a little finishing because my clearances were off for 1/8th inch plate. And of course, ignore those gouges from where it was misfiring when I had all this trouble. But, I’m excited to have it working.
Oh and before you ask, it’s an “earring tree” for the wife to hang her jewelry on and organizer. About 6 inches tall and the base plate is 4 inches across the flats. I don’t claim any originality in the idea, but the design was knocked out in an hour so maybe V2 will be better.
Pretty cool when it all comes together!
Might regift it for x-mas to a kid who needs a trade, to be honest. If I can keep just one young person from wasting their time going to engineering school, it’ll be worth it.
I agree the Trades are a great thing. Mike Rowe is the man when it come to the Trades!
