Question about Power Levels

OMTech 2028-80 (Ruida): If I set a “Max Power” level on the cutter’s control panel does Lightburn’s power settings override those? Or are the power levels shown in Lightburn computed as a percentage of the max I’ve set on the machine? Example of what I’m asking: Say I’ve set a Max power of 60% on the machine’s control panel. In Lightburn if a layer is set to 50% does it burn at 50% of the full power of the laser, or at 50% of the Max power setting of 60%, i.e., 30%?

If you load a file, it will run the values from Lightburn. If the file is running when you change max power it will effect the executing job or override the current running parameters…

As far as I know, the min/max are really for modifying the job you’re running.

Generally speaking, the Ruida will produce a pwm of the selected power percentage. There are laser settings within the Ruida that limit or control some of the power when the head changes speed, if you set it up that way…

There is a min/max power setting in the Ruida, it will not go below or above those settings.

What you get out of the tube, is really how you set up the lps.

Make sense?


I just went thru this on a different controller but I assume others are similar.

My tube max is 25ma so you target for about 70% of max. I’m using 18ma
Set Lightburn cut setting to 100%. I don’t think you can go higher
Take test cuts while adjusting the controller percentage to not exceed 18. My controller now says 45%. This is a parameter in the controller
So no matter what I do in Lightburn it won’t exceed 18ma.

Bought a new Cloudray power supply that has a knob to adjust power independent of controller. Obviously setup above is made at max setting on the PS. I’m not sure how useful the power supply adjustment will be. I’ll have to play with it.

Not follow what you’re doing here…

Is this layer power? Again, I’m not following.

There should be two numbers. Working current and maximum current.

I’d be conservative, if not stated, that 25mA is maximum.

An easy setup…

Set the pwm to 50% power, adjust your lps for 50% of the selected maximum mA. This correlates the power selected with the current/power you set in Lightburn. Using 50% ensures you won’t allow too much current flow when doing the setup.

Just keep in mind that you are using percentage applied to current.

It may be that max current ≠ max watts out. Tubes are negative resistance devices, meaning Ohms law doesn’t apply.

Make sense?


I guess I’ll try to be clearer:
Pick a max working current that’s under the rated max current of the tube. Why? So you don’t overdrive the tube and possibly case damage. I chose 18ma
Set the controller to some percentage that no matter what you do in Lightburn you don’t exceed that max working current. The actual working current is just what it takes to penetrate the material. I run most cuts at 8ma because it makes no sense to me to run the machine at max power all the time.

As Jack mentioned this is all established via a PWM (5 volt max) applied to the power supply which you really don’t need to know about because the controller doesn’t mention voltage. Maybe the 45% is actually 45% of 5 volts but I don’t see how that’s important to know as long as I’m always cutting at 18ma and below.

I’m sure there are folks on this forum that are highly technical and are interested in all possible details. My responses are to those who just want to get it to run. OK.

Exactly correct.

Where are you changing this?


So I’m using this old light object branded controller that works for me. No rotary. I never found a way to set controller parameters in Lightburn so I use some old laser program provided by light object.
No one is interested in those details however my point is that all controllers have parameter settings that sets the max PWM out signal and is the safeguard to not overdrive the tube.

Maybe I shouldn’t say all. It possible that some power supplies have similar local parameter that accomplish this same thing.

If you want percentage current or output power. With a 50% pwm or 2.5V on the IN terminal of the lps, you set the lps current limit to 50% current.

That will synchronize the the percent power on the machine to percent power in Lightburn.

You can still set upper/lower limits in the controller. I have mine bottom set to 9.5%… lowest I can go and still lase. My maximum is 99% I like to have the ability to use my full 40W if I want to.

You can pick tube current or watts out to set your percentage.