Lotos plasma cutter supreme cut60d Ideas to get it to work with CrossFire better?

So I ordered a lotos plasma cutter supreme cut60d awhile ago when it was one of the CrossFire compatible Plasma cutters. Now that my table should be almost here they have taken it off the list because some folks have had interference issues with them. Anyone got any Ideas what I can do to the unit to cut down or eliminate the interference? buying another plasma cutter anytime soon is not in the budget. I had to sell my old one off at a loss because it wouldn’t play nice with the Crossfire…So I sorta gotta make this one work for awhile. I’m not afraid of cracking open the case or adding a ground between the case and the outlet. Just need to know what worked for others if anything.


I hope / suspect that Langmuir will chime in here with advice, but from what I recall I think these are some of the things you can do to help improve your chances with the Lotos cut60d:
Install a ground rod for the table. (There are a couple ways to achieve this. One is drilling a hole through your concrete pad and driving a ground stake right there by the machine. You can go “one better” by running two ground rods outside that are more than 6’ feet apart. (I would do 2 each 8’ ground rods that are about 8 ’ apart from eachother and run the large copper wire (6 gauge or 4 gauge for strength) to the two ground rods in series. (run to the first rod, clamp it down, continue the run to the second ground rod, clamp that down). Two ground rods give you a very low resistance path to ground for any stray electrical noise right from the table. The other end of this ground cable is clamped onto the plasma table itself.

EDIT: Thanks to @Lil_Abners_Kustoms below I’d like to point out that the table should be grounded to the service ground and the 2 ground rods in series. Instead of calling the ground rods dedicated, I should call them supplemental ground rods. You can see HyperTherm’s link below, and just like HyperTherm says, you should follow all codes and consult an electrician before taking any ol’ yahoo’s advice on the internet. :wink:

Second, you can buy cheap clamp on magnetic ferrites for all your computer cabling (especially USB cables). Ferrites act like inductive “chokes” and keep stray surges from traveling through cables. When I setup a CNC Mill, I put ferrites near both ends of the USB cable. This might be a little overkill, but they were cheap and easy to install, so I figured why not. If one falls off or gets knocked loose, I still have the other one in place.

Third, move the plasma cutter as far away from the control module and your computer as your plasma cutting lead will allow.

Fourth, (This might be considered part of #1, but it is worth spelling this out) Make sure that your plasma cutter power has its own dedicated ground going all the way back to the main panel. Bad Example: If your computer / Langmuire controller are plugged into a 120V outlet that is right next to your 240V outlet and let’s say the wiring wasn’t done properly and they end up sharing a ground connection, that is bad. The 240V outlet should have its own dedicated ground wire going all the way back to the main panel. The 120V outlets should have their own ground wire going back to the main panel. If you aren’t familiar with outlet wiring, I suggest you get an electrician to help you verify this.

Fifth, (I would probably try the other stuff first, and only try this if it was absolutely necessary), you can try wrapping your plasma cutting lead and ground cable in metal foil and grounding the metal foil at one end. (Not both ends, because that can create a noisy ground loop)

I believe they got the Lotos Cut60D working, but they did have to go through a number of things to isolate the noise it was generating. Sounds like you may have already read about it, but if you haven’t seen what ended up working, I suggest you dig back through the forum and find it. I think the solution that worked for that one was in the thread that had people with several different plasma cutters all in one tracking thread.


I have had no problem with mine .

All good points except the grounding. It is not advised to create separate earth grounds where there is one source of power. If simply looking to improve or assure there is a good bond, then the running of two ground rods and connecting them in series to the shops main ground bond is best. A separate path to ground could cause a potential difference between the plasma table and something that is grounded somewhere else. That difference in potential voltage could be lethal if it were to ever occur.

Best, Steve.


Grounding and Shielding Best Practices

This shows a ground rod for the table, less than 20 feet away from the table.

On second inspection, it looks like they also have a service ground wire running to the plasma power supply ground. So both grounds are bonded together. You still want the ground rod for the plasma table and a second rod 8 feet away reduces the resistance to ground providing an even better connection to the earth.

Maybe I shouldn’t have used the term dedicated. What is a better term to describe the ground at the table that hopefully would be readily understood by others? I didn’t want to call it the EMI ground, but that is exactly what it is, but that might not make sense to others at first.

I like what HyperTherm calls it at one point: Supplemental Ground. That’s exactly what it is even if it doesn’t quite say what it does. The key is that it comes off of the table, to earth less than 20 feet away. Adding a second ground rod 8 feet away from that and daisy chaining it means that it will be a lower resistance ground path, keeping much of the stray EMI far away from your computer circuitry where it could cause a computer fault.


This is the same document that i have for my cutter, and a good one for reference. Note in there that the Power, Plasma cutter and table chassis are all on the ground same plane. That is the key element to remember when doing this work, not allowing for a potential difference to be created when connecting equipment together. All AC power returns back to the ground bond at the service entrance, keeping that path intact is vital.

And to what you’re referring to with the EMI / RFI the grounding of the all the parts on the table back to the same buss which is in turn then grounded by the service entrance and the ground rod (all same plane) , does exactly what you’re saying to combat those issues.

Since I have to run new Power wires for the Plasma cutter to the location that the table will live. It looks like I’ll be in good shape. If I start seeing issues I can add a set of Grounding rods with out much issue. I have a father that has done industrial electrical work for 40years…maybe I will have to cook dinner and have him take a look at it.

Thanks guys make’s me feel better that It looks like I didn’t waste money on this one!


Just wanted to update everyone on my progress with this.

Out of the boxes assembled like directions I got the following results.
Table would move with plasma off
arc on table would not move Mach3 stopped responding.

New 8’ ground rod driven into ground tied to outlet ground with #6AWG solid bare wire and #4 stranded coated wire to ground block on table leg. From Ground block The X and y rail had a #10awg stranded coated wire screwed into them.
Table would move with plasma off.
Table would not move with Arc on. Mach3 stopped responding.

Next test the above grounding was left in place. Stock USB cable was removed and replaced with a Tripplite with Ferret cokes on each end.
Table moved without plasma on.
Table moved with arc on.

Through all of these tested the plasma power source, laptop, and table were not moved.

wondering if the USB cable wasn’t the issue the whole time.

Now time to go burn some more metal.


You bring up a good point: All cables going into the laptop should have ferrite chokes added to them if they don’t already have them built into the cable itself. (They make cheap easy to attach clamp on varieties). Thanks for sharing your recent experiences on this.

Is there a machine torch out there for this cutter.

Yes there are. gamblegarage here can hook you up with one. But be warned it costs about 65% of the purchase price of the cut60d.

So I had the same issue with my lotos … I simply took the laptop off the metal stand I bought with the table and all works great now… I put a 1/2 ply wood between the computer and stand and no prob… no grounds or anything .that was the problem…

I didn’t/don’t have the laptop stand on my Crossfire. First thing I tried was get the laptop as far away from the table, and the plasma cutter power supply as far away from the table in the opposite direction. But found the USB cable my issue.

I think that the multiple possible issues and solutions might be why Langmuir put the Lotos units on the 'Not Officially supported"…but probability will work list. They don’t want to have to support the multitude of problems they can create. With Electrically noise equipment each unit will create it’s own challenges. I’m also sure that for the price we paid for the lotos units many of the parts in them are parts they can get at a set price. So the tolerances vary which means out of 10 units 2 might not create any more noise than other companies units. 6 might make a little bit more noise and 2 might make your neighbors radio rattle. You will never know which one is in your box till you fire it up.
But Sharing the problems we see and how to resolve them helps the next guy with different steps to take to fix theirs. Keep adding to this thread as we go.
I will add anything I find out when the Pro gets here. I got a unit with all the bells and whistles (a laptop tray too :joy: ).

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Another couple of suggestions to mitigate electrical noise interference . 1. The work lead should go directly from the plasma cutter to the ground rod, shorten the work lead so there is no excess (no loops, no crossed wires) and use a piece of the same wire (multi stranded welding wire) to make a short connector from the driven earth ground to the frame of the table. Use lugs and bolts, not the welding clamp that your plasma was supplied with. In most cases 2 earth grounds are not better than one, and the driven ground should be as close to the Langmuir table as possible. 2. Buy a good quality Office type (get at office supply store) UPS (uninterruptible Power source). Plug the Langmuir electronics and the laptop power cord into the protected outlets. (Be sure the UPS is sized to handle about 1.5 times the wattage of the electronics and computer). The UPS offers some isolation from noise that can enter from the AC power system. Keep in mind that the earth ground is not there as a safety ground (many electricians get confused by this…so don’t even call it a ground, call it an earth!). It is there to route any stray RF noise to earth…instead of allowing this RF noise to travel through low voltage logic signal lines in the electronics and laptop. Jim Colt

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I used the documentation that is out there from Hyperthem on Bonding and earthing the plasma table when I was trying to solve my issue. It is one of the only practical documents about this online. Everything you note is good stuff! but in my case non of it worked (ok I didn’t try the UPS. did’t think of it at the time).
I would still recommend that anyone going to use the Lotos cutters follow these steps as well. Just add a new shielded USB cable to the list as well.