Curious if anyone has run into this. Recently my plasma cutter has started not firing every other time the trigger is pulled. So for example I turn the machine on, make a cut, post flow air turns off, I try to make another cut, and I just get air and no arc. Click the trigger again and it fires and works until I stop the cut, then I just get air.
The manual suggested that it is a consumables issue. I replaced everything on the torch and it still does it. I took the torch apart and inspected everything, and nothing stands out as being a problem… it was pretty clean and this is a low mileage unit to begin with.
I don’t think it’s an issue with the torch itself, sometimes I use this on my OG Crossfire plasma table so there is a trigger cable wired into the board in the machine. I have the same issue when the CNC controller software tries to turn the torch on… it fails every other attempt in that scenario as well. This problem just sort of started one day when I was cutting up a trailer for scrap and hasn’t gone away.
I seem to remember another forum guy who had a similar issue. I will see if I can dig it up.
For now, I have to ask that the air pressure supply to the machine needs to be 120 psi and 70 psi at the torch while it’ss cutting. Air pressure is used to fire the pilot arc inside the torch head. Not enough pressure and it won’t fire. Just a thought.
Being only 27 amp doesn’t give you a lot of metal cutting choices. Plus the duty cycle at 27 amps is only several minutes I would think. According to Hobard 27 amps at 240 v input is 35%. At 120 v input it 20%. It designed to be a hand type small shop cutter. Having it on a plasma table is a stretch.
Thanks, I will check the air line. It is totally possible something got dropped on it since I was outdoors using it for cutting up scrap when it started happening. Maybe it got kinked.
I don’t think it’s an air pressure issue, I have a 60 gallon compressor that is rated at 16cfm @ 100psi with a max pressure of 135PSI. I’ve ran this setup for years with no problems until it started acting up. You are totally right about it being a small machine for a plasma table but mostly I am just cutting out tabs and small suspension parts out of 1/4” mild steel at most. I’ve been meaning to buy a better plasma cutter with a machine torch but this one has worked well enough so far that it wasn’t really necessary, and I have a TON of consumables for it.
I finally had a chance to mess with this last night and in summary, I had no luck fixing it.
The hose is a huge PITA to check out. I fully disassembled the torch body, separated the hose in there and also inside the machine and tested it with 135psi compressed air. It does not leak anywhere that I can tell. I didn’t pull it out of the liner to check for kinked spots. Maybe I should have but I was getting a bit frustrated with the spaghetti mess of wires and stuff in the torch body and didn’t want to make it worse.
I put a little bit of air tool oil on the valve inside the torch body. That did not seem to help or hurt. I also messed with the internal regulator - two full turns to increase air pressure made no difference. I also tried one turn less from the factory position and that also changed nothing.
One thing I did notice is that if I make a cut, let the post flow air run through its cycle, and attempt to cut again, it’ll work perfectly, every single cut. I just have to wait for the post air cycle to finish. It’s only when I interrupt the post flow air that I get no arc and that kind of leads me back to an air pressure issue. Maybe I just need to pull the hose all the way out and inspect it.
@mechanic416 I am using OEM Hobart consumables. I have also tried some aftermarket ones from Plasmadyn, same problem.
Side note, I did buy a backup Titanium 45 unit for $300 last week. I wired in a cable to use with the Crossfire table and so far it’s working pretty good. I may just use this one with the table indefinitely and buy a machine torch for it, and keep the Hobart around for other stuff that I cut by hand since it sort of works.
If it will not re-fire with post flow on, this normally means it has the wrong retaining cup or plugged holes in the cup not letting the air purge fast enough. Also you need to check for a air restriction, you should have 120 psi to the plasma cutter.
The retaining cup, swirl ring and o-ring are brand new but I’ll double check and make sure it’s clean.
I don’t think air is a problem, I have 3/8 air line and 3/8 fittings on everything in the shop and my compressor kicks on at 100psi and shuts off at 135. One thing I have not tried is bypassing the dessicant dryer, water separator and regulator that I have in line before the plasma cutter. Easy enough to try that, I can hook it right up to the compressor. I don’t know why that would matter though, I’ve had that setup for a long time and it was never a problem before and isn’t a problem for the new machine.
Further troubleshooting: I removed the entire air hose from the torch to check for kinks or damaged sections. There were none. For those interested, I do not recommend doing this. It is impossible to pull the hose out from the torch end. I imagine this is because it’s woven between and against the other wires in the rubber jacket… so I cut slits every 2’ and pull it out bit by bit. Now I have a bunged up rubber jacket and the stupid thing still doesn’t work.
I disassembled the air valve in the torch, cleaned it, and that made no difference.
I removed the air dryer/regulator and ran a hose straight the compressor. No change.
I increased the internal air regulator by 4 turns. No change.
I tried cleaning the cup, swirl ring, etc. They are clean, no restrictions.
I took the air solenoid apart and tested it with a 12v battery. It clicks off as soon as voltage is removed and does not appear to be leaking. I also cleaned the inside of it (looked fine to begin with) and stretched the spring out a bit as suggested in other threads. No change. I may just replace it…
The only thing I noticed that I probably forgot to mention before is that if you try to initiate a cut during post flow, the CUP light starts blinking until you click the trigger again. From what extensive Google and Grok searches have suggested, it could be a cup that’s too loose or too tight (tried both, ruled that out.) Could be air supply, ruled that out. Could be a bad air solenoid. Could be a shorted out cup (unlikely, it’s new, and I tried several others.) Could be consumables (already beat that horse to death.)
Not sure what to think. A new air solenoid is $10 so I may try that. Pretty frustrated at this point. Buy a good plasma cutter they say… jeez this thing has really low miles on it and has been nothing but problems.
Side note, the Titanium unit is working great once I turned up the internal regulator and got a good set of consumables. The Amazon special ones were total shit and didn’t fit right. I bit the bullet and bought some from HF just to rule things out and I got it cutting much better with no error codes, but the cut was really jagged. I gave it some more air and there is a night & day difference.
I have a pressure gauge on the compressor and at the moment just a hose run straight off of it to the plasma cutter. The compressor shuts off at 135psi and that’s what it reads when I have been attempting to troubleshoot so I have no reason to suspect that there is any less than that up to the plasma cutter’s internal regulator. Past that, I am just guessing. I could plumb a pressure gauge right after the air solenoid if that would be helpful for troubleshooting, that’s easy enough.
I wasn’t really getting a flickering pilot arc - I wasn’t getting one at all if I try to interrupt the post flow air to make a cut - but that’s where I was getting the blinking CUP light on the front of the machine.
One other thing I did do was lightly sand the tips of the contact pins just in case they were corroded and I made sure they move freely. I can watch the pins get depressed as I screw the cap on so I guess I assume they are making contact.