PSA - Primeweld Cut 60 plasma cutters

I wanted to provide everyone with safety information about Primeweld Cut 60 plamsa cutters, and why they are still listed as incompatible on our website here: Plasma Cutter | Langmuir Systems

There are two generations of the Primeweld Cut 60 plasma cutter, and it is easy to identify which generation you have. The first generation does not have a CNC port, whereas the second generation has a CNC port. Both versions are still not supported by Langmuir Systems, and using it is still at your own risk. That said, these risks are drastically different between the two generations.

The first generation has an EMI issue that interrupts the USB communication between the computer and the CNC electronics enclosure. If you have this version, we do not recommend using it at all. If you would still like to try to use it, you will need to take additional steps to ground the plasma cutter’s power supply, or to shield the CNC electronics enclosure and strengthen the USB connection.

The second generation seems to have fixed the EMI issue. However, we have reason to suspect that the CNC port of the second generation has a defective voltage divider. A high percentage of customers who have wired THC through the divided voltage pins have reported issues to us. There have been some reports of receiving a static shock when touching the CNC electronics enclosure, the laptop stand, or the frame of the machine. There have also been reports of damage to VIM boxes and motion control boards after a period of everything working correctly. We have observed voltage from the divided voltage pins of the Primeweld Cut 60 to be within the typical 50:1 ratio range some of the time (if not most of the time), but randomly and suddenly spiking way too high intermittently. This is when we suspect damage to the VIM and motion control board occurs. If you have a second generation Primeweld Cut 60, you can still use it, but we only recommend internally wiring the THC feature for RAW voltage. The torch firing feature can still be wired via the CNC port.

EDIT - JUNE 2022

There is a third generation of the Primeweld Cut 60 that we have determined is completely safe to use with the CrossFire. Primeweld Cut 60 plasma cutters manufactured 2021 to present should be free from the issues that affected the first two generations of this model. Because of this, our plasma cutter compatibility page now has the Primeweld Cut 60 listed in both the incompatible section and the compatible section: pre-2021 is listed as not compatible, 2021 and newer is listed as compatible.


In summary:

First generation Primeweld Cut 60 plasma cutters do not have a CNC port. We do not recommend using this version at all due to a known EMI interference issue that interrupts the USB connection between the CNC machine and the computer.


Second generation Primeweld Cut 60 plasma cutters have a CNC port on the back side in the bottom-right corner, directly above the power cable. We only recommend using this version with the THC feature wired via RAW voltage, not divided voltage.

Third generation Primeweld Cut 60 plasma cutters have a CNC port on the back side in the top-right corner, to the right of a red hexagonal sticker. As far as we are aware as of this point, this version is free from the known issues that affected the previous two versions, and should be able to be used for CNC cutting without an issue.



Interesting indeed! …Guess I’m one of the LUCKY ones! :beers:

You don’t have a FireControl system so you’re not susceptible to the issues the current systems have.

Hahahaha! …I was TRYING to work around saying it that way! :beers: :rofl: :rofl: :rofl: :rofl:

That’s not entirely true… I started with an OG 2x2 with mach3 and the cut60 and every once in a while it would freeze up mach3 with torch on just like it does with firecontrol. EMI was affecting the USB port and disconnecting the control board to the computer… since adding extension cables to move the cutter farther away from the control box and laptop, haven’t had 1 instance of it freezing. Not even with the Pro Now.

The EMI issues happens with all brands of cutters. Very few users of whatever brand were never affected by it.

In my opinion, Langmuir should have included longer torch on/off and THC cables so the cutters wouldn’t be placed so close to the control box.


I agree with your points WRT EMI. However, I think the main thrust of the OP was voltage and THC issues and that justified dropping the Cut60 from the list. And this, specifically, is what I was pointing out to @Cletus, he doesn’t have those problems because he has a totally different THC setup.

I would debate that comment!!!

There is a reason that the USB cable, torch firing cable, and THC cables are the specific lengths that we provide.

The longer a USB cable is, the more susceptible it is to EMI interference. Our USB cable is just long enough to reach from the CNC electronics enclosure to the laptop stand mounting area, with enough slack that a set of additional ferrite chokes can be added if necessary.

Adding length to the torch firing cable is possible, but doing so may cause a very slight delay between the time that the MCB commands the torch to fire versus when the plasma cutter actually receives the command and fires the torch. In most cases, pierce delay is set to only a fraction of a second, so even a slight command delay could result in misfire. Someone who is aware of this and wants to extend their torch firing cable could negate the command delay by increasing their pierce delay.

Adding any length to the THC cables is not recommended at all. THC reports a very small voltage signal to the motion control board in real-time so that the Z-axis can make quick standoff distance adjustments based on how the arc voltage is changing. This voltage signal needs to be as accurate as possible in order for live voltage to reflect the true arc voltage, and reported as quickly as possible in order for the Z-axis to make real-time standoff distance adjustments that are correct. If any of the THC cables are too long, two different issues may occur:

  1. The signal might be reported to the motion control board too late, causing the Z-axis to delay its movements.

  2. The added length may cause the THC cable to act as an antenna for EMI, which will increase the amount of voltage that is being signaled to the motion control board. The motion control board will think that the arc voltage is higher than it actually is, affecting the way it calculates which standoff distance adjustments to make.


I’ve extended my torch firing cable and my raw voltage 15ft using this cable stainless steel shielded cable Pierce delay for 14g is 0.3, with no adverse effects. I added a 5pin connector above the original cpc port. Wired it for torch on and raw voltage. The extra fifth yellow back grounds the shielding to cutter case. ( end of cable farthest from plasma cutter, the fifth wire is solder to the outer shielding and grounded inside cutter case. From the vim box to table controller is the length of wire provided by Langmuir. Right or wrong it works for me.

I have a prime cut 60 and after the issue with the divided voltage I used the raw voltage taps in the CNC plug. These are protected by 100K resistors and provide a test voltage of 77 volts, with a resting voltage of .3 or .4. The control cable from the Plasma cutter to the Vim box is 20 feet.
With the second wiring plan to date I have zero issues and the THC operates correctly. I have included the Owners manual page with the Pin-out I used.
I will keep you posted if I have any issues.


So are they now on their 3rd generation. My understanding they recently released a new machine where the port was relocated and insulation was added to reduce EMI?

Probably to add isolation…

yes the newest ones have the cnc port towards the top on the back of the cutter. Primeweld sent me one to test out back in July 2021 and i’ve been running it exclusively since then using divided voltage thru cnc port. i put my original “2nd generation” one back in the box and it’s setting on the shelf.

Never had issues with my original one either but Primeweld wanted me to Test the updated one. There are only a handful of users with problems with the “2nd generation” using the divided voltage via cnc port. I’ve always suggested to use RAW voltage from inside the cutter if you have that particular generation.

I believe the newest one has a revised CNC port board on the inside. other than that and relocated cnc port, everything else looked the same to me when i compared them side by side.

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Okay I just wanted to confirm the one you are using is the 3rd generation?

Yes if you wanna call it that… the newest updated one.

I was just referencing the OP (PSA from Langmuir). They mentioned there were two versions. I was just trying to confirm there are actually 3. Curious if they have done any testing with the 3rd generation? I had read your previous posts about your machines. Sounds promising.

I have what I surmise (reading Langmuirs PSA) is the second generation. I had cut a few small things with it. The other night I tried to cut something bigger but still fairly simple and it froze on me locking the torch in the on position it happened in differ t locations on the cut cut the second time happening much sooner than the first. Both times I had to unplug it to get the torch off. I was able to use the run from line feature in fire control to complete the cut but it made me nervous to try anything bigger…

I had also changed where the cutter was in relation to the control box from my previous successful cuts. Still as far away as I could get it just in the opposite direction. I ordered some chokes. I’m hoping putting the cutter back where I had it and using the loop with the choke will do the trick otherwise I will be looking into a new cutter)thinking Everlast 62i) and begging my wife to spend even more money in my new hobby. :stuck_out_tongue_winking_eye::crossed_fingers:t2:

The one they sent me to test is the new updated one and should be out now. I never knew there was one without cnc port.

And like I said, I’ve been testing the new one since July of last year with no issues. Using everything original from Langmuir, I couldn’t make that thing freeze up on me. Even having the cutter right next to the control box, for testing purposes of course.

Now, normally, I have my cutter on the outside of the table, opposite the control box using extension cables for torch on/off and THC. And I’ve ran it like that almost 3 years now.

That freezing your getting could be either a crappy usb cable or your other wires/cables are coiled up or on top of each other. Have them separated especially the work clamp cable.


Thanks I appreciate the input. I wasn’t aware there was a model without a CPC port either that’s why I was trying to confirm what Langmuir said in the OP …that if mine had a cpc port it was in fact a 2nd gen.

I will make sure and follow your instruction and make sure none of the cables are coiled. I’m using the USB cable that came with the machine. The cable already has a choke on each end.

I’m not an expert on USB cables so I have no idea the quality but researching the interference issues it seems like Langmuir has made an effort to provide a quality USB cable to negate the effects of interference.

Are you using raw voltage or divide voltage coming out of cutter to VIM box?

@MechanicJon, who was that question directed to?