Torch hesitating after beginning a cut

OG Crossfire, Hobart Airforce 500i, part drawn with NanoCAD, CAM in SheetCAM, cut with Mach3.

Material is 16ga mild hot rolled, 90ipm cut rate, 0.5 sec pierce delay

Problem: torch will fire and begin cutting and then will randomly pause somewhere in the first inch or so of the cut. Arc stays on during the pause and it will resume cutting normally after a second or two. The weird thing is that it doesn’t do this on every cut and doesn’t necessarily do it on the same spot if I cut the overall design more than once.

To further complicate things, if I do a dry run with the plasma cutter turned off, all is well.

Any ideas?

Sounds like electrical interference from your plasma cutter to me.

Is your computer plugged into the wall?

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If you aren’t already using ferrite chokes on your usb cable you may want to try it.

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I can definitely try putting a choke on the USB cable. As far as the computer goes - it and the control box for the table are both plugged into the same power strip which is plugged into the wall from there.

how close is the cutter to the control box? Also are your cables looped or on top of each other?

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If your computer plug has a ground pin you may want to break it off or use a grounding adapter. For some reason if the control box and your computer both share a ground it causes interference issues.

Try this before the choke or do both. Also check your wires as @nicaDd suggested.



The cutter is usually a couple feet away from the control box. Yes, cables and stuff are always looped over each other. It is a mess but they are so short that it is what it is and I don’t have a dedicated spot in the shop where this is set up all the time, it just gets rolled out when I need it. I can see where that could cause issues and I will be more cognizant of that in the future!

ok at least have the work clamp “ground” cable away from the others, especially the usb cable. that can cause major interference.


I wonder why that would matter…? I can sure try that, I have some of those adapters. I could also try plugging the control box into a different outlet that is in a different circuit but it would be on a 15’+ extension cord.

Seems kinda weird that sharing a ground would matter, technically everything in the building shares the same ground and so do the neutral wires. Perhaps it’s just the proximity to other devices on that ground?

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Yes you are right. That’s why it works to break off the ground pin or use a ground adapter. Unless you have a separate ground rod for your table… which some guys do… any outlet you plug into will be sharing a ground if you have a grounded plug.

I cant tell you why it matters. I’m sure there are a few guys on here that could explain it in further detail. I think I first read it either in the assembly manual or on an old post somewhere. If you searched it you could probably find the initial post from langmuir that addresses it.

I only know that for some reason having your table and your computer attached to the same ground can cause interference. Allot of guys(including myself) get around this by using a laptop on battery power. But if I need to plug in I use a ground adapter.

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Unfortunately this system has a shortage of ‘artists’ so bandaids like running on battery or cutting off grounding posts seemed to be acceptable ‘solutions’ to some.

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I guess as long as the bandaids work… honestly I am kind of frustrated with the whole table, it is a pretty useful tool and the price was right for a hobbyist level thing but it seems like I’m always “just another little tweak” and “just a couple hundred more bucks” away from it working the way it should have right out of the box. Stuff like this happening at random is making me think twice about dropping any more cash on a water tray or XL kit and just live with/fight what I have. I guess it’s good that I don’t mind a project.

Were you able to resolve your issue?

Haven’t had a chance to try it thus far this week but I do have a sign that I need to cut soon. I will report back!

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