IIRC, someone mentioned in this forum that they were considering purchasing a CO2 laser that runs on gcode.
Is there anyone that is familiar with this brand?
Are you talking about the Monport K40?
Search the Forum for it and you will learn all you need to know.
If I move to a CO2 laser, that would be my first choice due to the simplicity of the electronics. And because it is GRBL.
Basically, this is only dependent on the mainboard used. You can change any CO2-laser’s mainboard for one that is running grbl firmware. Though this has some drawbacks, like losing the display and buttons, for example. But technically, there is no difference in driving the motors and the laser source.
That’s the one, Thanks Mike
True, but a big difference on how you can manage the controller parameters. I know almost nothing about the Ruida controllers, except they are a lot more expensive.
Usually a K series devices is wired a bit different to the laser power supply, which is a bit different than most I’m used to.
The K40 basic controller won’t work with Lightburn, but is usually amended plus to indicate indicate an upgrade to grbl control. @misken refers to it as the main board, but I call it a controller. It’s a “Tomato, tomahto” thing.
Might check out maker forum, they have a pretty extensive bunch of K40 and K40+ issues.
It’s always nice to include a photo of the machine… Is it really a Monport or some other clone?
Wondering, does it really matter? 
I think the initial question was about that specific machine. The Omtech K40+ (the “+” is important) is a “new” version of all the K40s out there. It is well designed electrically and includes a mainboard/controller that uses a grbl firmware. As such, it runs fine with LB Core.
It’s the only K40 I can recommend. You can unpack and start lasering. With all the cheaper K40s (and there are hundreds of versions), you better rework the machines before using it 
You can find some pictures of the K40+ here (in German, but doesn’t matter for the pictures): Omtech K40+ im Test: Der verbesserte CO2-Laser für Einsteiger
It translated pretty well to English.
Most K40 types do not have a laser enable output, like the DSP types do, so they use the pwm, not to set the power, but to enable and disable the laser.
The results are if you set it via a manual pulse to maximum current and use the power percentage for control, anytime it lases, it will be at 100% power, turned off and on with the pwm.
Monport attempted to fix this by using the pwm on the IN (for current control) and enabling the laser at all times via the front laser enable. The first one that came here couldn’t get full power, when we had them take photos and show them, Monport drove the IN terminal with a 3.3V signal. Meaning it could never reach full power. When I figured out what they did, clearly no testing, I decided I wouldn’t own one of their machines.
I’ve read how people set these up and many use the pwm on the H input to enable the laser. Setting whatever your maximum value is only useful by a continuous pulse long enough to actually measure the tubes current.
I believe one of the people at the makers place site has one of these, along with many. He sets the current to maximum allowed, then claims he never runs over 80% power. The truth is that it’s running 100% power any time it lases.
Few lasers have this in the documentation, although OMTech has always seemed to have it.
| Laser tube life: | 2000 h ( <40% power) / 1200 hours ( 40%–70% power) / 600 hours ( >70% performance) |
|---|
Even the manufacturer claims only 2000 hours at <40% power. One of the guys I respect has stated he thinks it’s average and isn’t destructive, I disagree. The data seems to indicate whose correct.
Since these have no laser enable, they run the glass tube like a diode, digitally. Using an digital device to digitally drive an analog device is questionable, but is quick and cheap.
| PWM Frequency (hz) ($33) | 6000 |
|---|
The other question I have is they specify the period (pwm frequency) at 6kHz, with a period of about 0.00016s compared to the 1kHz period of 0.001s or 1ms. The standard lps we see has a response time of <=1ms. I think 6kHz is a bit quick.
Do you know how they are internally wired as far as pwm and laser enable?
Nice article, too bad the translation did work in the photos. lol.
Thanks for your input everyone.
I’ve been doing a lot of shows lately (not lasered work) and the person next to my booth had his original lasered artwork. On and off between customers we had a chance to talk.
I was hesitant on getting a CO2 laser because I didn’t feel like dealing with it’s maintenance. He assured me how simple it was and convinced me to get one.
At this point I don’t plan on selling anything lasered. Most of the shows I do don’t allow selling two different types of media without going through a very strict judging process. If it wasn’t accepted I’d lose my spot that I’ve had for many years.
https://monportlaser.com/products/monport-40w-lightburn-laser-engraver?variant=43667530350791
Don’t know what you do, but couldn’t you just ask them and not change whatever they are targeting?
Seems like a good business would allow you to expand on what you’re selling.. At least IMHO.
@jkwilborn, thanks for the writeup! I find this very interesting. D/A converter circuits and modules have been around for ages. I am surprised the D/A has not been mentioned in any of the descriptions. Or maybe I just did not recognize it when I read about it.
I’d definitely not recommend the Monport one. I was not able to find any picture of the electronics inside apart from a video that is more than 3 years old, but this video showed bad electronics. The only well-designed K40 is the K40+ from Omtech, as far as I know.
This is from the Monport video:
There’s only a single power supply, no safety circuits, etc.
This is the Omtech K40+:
You can see a second power supply for the driving electronics, safety circuitry, and an industry-standard cable management (mostly
)
The blue things, are they relays?
Yes. Actually all of them. The rightmost are high-voltage security relays (I think they called them like this), the middle ones are just control relays to activate IO lines (I think), the leftmost are also relays; they might disconnect all periphery lines. I have to check closer, I didn’t do that yet.
National Art Shows don’t work that way.
I can see what you are talking about. Sadly, we are only seeing the edge of the Monport circuit board so who knows what’s there.
Thanks for the heads Melvin, very much appreciated. I’m definitely leaning towards the Omtech now.
https://omtech.com/products/40w-co2-laser-engraver-cutter-usb-032b-us?variant=40595697762369
Do you think there any significant changes to the EU model over the US model?
I don’t know, though I guess it’s cheaper to produce just one model. In EU, only true class 1 devices are allowed to be sold, and regulations are quite strict. The K40+ seems to be the first sub-$3000 laser that complies to the standards, as far as I have seen. But of course, I might have missed many
Good evening everyone, I owned a k40 that I modified by installing a mks dlc32 and enlarged the working area to 600x270
From my experience converting inkjet and laser printers from the EU for use in the US the only difference is the plug and the way it’s wired in.
While I never looked at a laser from the EU, I’d be surprised if it’s any different, especially with the under $3,000US lasers