Ive started using Lightburn with the laser I built, I ended up installing a Ruida RDC6445GT to control the system. My laser (Coherent Diamond E-150) supports up to 100khz pwm freq and the controller does as well but the PWM override will only allow me to go up to 100khz, is there a possibility of getting the software updated to allow me to enter frequencies past 50khz?
It actually does matter with this laser, frequency and duty cycle on this laser have a large effect on peak power output which affects material processing quite a bit.
I’d expect the 6445GT to be similar but could absolutely be wrong.
I’m not quite following this. You’re able to go up to 100KHz but with PWM override but are looking for something to allow frequencies past 50KHz? Can you clarify?
Also, are you doing this at the controller or in LightBurn?
When I was checking the PWM override in cut settings in LightBurn for my 6442G I could enter values up to 60KHz. I didn’t validate whether or not I could actually cut with that value.
Have you tried changing the frequency on the control panel itself?
I just tested RDWorks and it doesn’t seem to have any check for the frequency override at least in the cut setting screen. Not sure what will happen if the job is sent to the laser.
I can understand duty cycle certainly. How does frequency affect the work that you’re doing?
These hobby lps cannot respond to a 50uS (20kHz) pwm signal, let alone to 1uS (100kHz).
With an lps specified response of <=1mS, it limits it to about 1kHz change rate. Most of us have looked at what we can find with these lps and have concluded that the input filtering pretty much excludes high end pwm frequencies.
Also keep in mind these work fine with a dc control voltage.
Might help with an RF excited machine (pwm is generally set to 5kHz). I’ve varied mine many times, as low as 1kHz, where I can see it turn off and on in the output, and up to above 50mHz, can’t really say I could see a difference.
There is no specifications that I can find that state what the input frequencies range can be in these lps manuals.
This isn’t a Chinese laser. It’s a good ‘ol made in America Coherent RF laser. It’s not like the cheaper rf lasers where it just puts out a rf signal proportional to the pwm duty cycle. This actually has a pulsed output with peaks around the 375-400w range with a 150w average power. When you start getting to the 100khz range you start seeing the rise time of the laser being about the same as the rep rate of the rf pulse and you start getting into a semi-QCW operation. The Coherent lasers we use at work are operated into the 200-300khz range.
It may have been 60khz, I’m not sure. I just know it was not 100khz. Right now I have the laser set to 100khz on the controller itself and use the override if I want to set it lower.
Nice. It’s making me question the other article I listed for the 6442G but it is an older model so there’s that.
If that’s the case, I think Jack may be onto the limiting factor of this being the LPS. Typical LPSs used in these machines are not passing the PWM frequency to the laser. If that’s the case, I don’t see how you’d be able to access these characteristics from the laser. Or are you saying you can actually see differences in cutting behavior with your current LPS at these frequencies?
@ednisley has done a lot of research into LPS behavior for these typical Chinese lasers and may be able to provide additional insight.
Oh. I completely misunderstood the original post. I thought this was an upgraded laser for an existing Chinese base. Missed that this was entirely custom.
This is merely a software limitation for lightburn, the box that you enter the parameter into is just set to not allow anything past whatever frequency it is currently set at. Just like the lead in/out box does not allow you to set anything beyond +/-90 degrees,
Thanks for the manual… Guess I just like reading them…
Most lasers here are not like yours… I looked at your profile and I think you need to add RF in there so we have a better idea of what you are dealing with…
In the video, how much power is that commonly for an 18G cut operation?
It’s hard to say what would be normal for 18Ga steel, on a commercial system they would be cutting with big CO2 or Fiber laser or even the new direct lasers. Talking 1kw or more. I have cut up to 16awg so far in steel and stainless, if I use air as an assist gas im looking at about 2mm/s max cutting speed. If I use oxygen as an assist gas I can cut 16-18 awg at about 25mm/s. I can probably cut thicker because the oxygen is doing the real work of cutting. Ive heard of cutting 1/4" steel with oxygen and 200w. The only issue with oxygen is fine detail, small details can get overheated to a point where they catch fire in the oxygen. But if I use air and go slow it works out. One possibility is mixing air or nitrogen and oxygen to adjust the oxygen content and control it. There is a lot of experimentation to be done to find optimal settings.
