I’m using lightburn with a 10W diode laser (Ortur laser master III). My hardware is completely vanilla and at the latest firmware.
I use Ortur’s own phone app (Laser Explorer to create a calibration card for a sheet of 1.25mm cardstock.
The calibration card tells me that I can cut all the way through the cardstock at 200mm/min and 25% power. I run the calibration sheet again on a different sheet cardstock from the same batch and replicate the output.
I then use these exact settings in Lightburn, and it only gets about 1/2 way through.
After some experimentation I end up having to use 100mm/min and 75% power in order to cut through the cardstock.
Every other variable is the same.
I’m not sure if this means that Lightburn is under powering my laser, or driving it too fast, or if Laser Explorer is running it at a higher power than it’s reporting\a slower speed.
That’s the trouble with consumer-grade lasers: when things go wrong, you’re at the bottom of a very steep learning curve.
GRBL (or one of its many descendants) is the firmware running in the laser controller. It accepts commands called “G-Code” and turns those into motor and machine control signals.
One of those commands originally set the speed of the spindle motor driving the cutting bit: S1000 would set 1000 RPM. The output of that command is (effectively) the voltage controlling the spindle speed.
GRBL also needs to know the maximum possible spindle speed, because that corresponds to the maximum possible voltage. That’s what the $30 configuration value does; the dollar sign is how GRBL designates that particular setting.
Lasers don’t have spindles, but use the same command (because it made sense at the time and why not?) to set the laser power level: S1000 now sets the laser to deliver 1000 units of power, with the maximum number of units set by the $30 value.
LightBurn’s layers have a power setting given by a percentage from 0% to 100% (maybe 99%). In order to create the S command for GRBL, LightBurn must also know the maximum number of power units, which is determined by the S-Value Maximum in the Edit → Device Settings dialog. LightBurn could read the GRBL $30 value, but there are good reasons for having separate settings.
So the whole chain goes like this:
You set a LightBurn layer to 50% power
LightBurn multiplies that by the S-Value Maximum to get the units of power and sends an S command to GRBL
GRBL divides the S command value by its $30 setting to scale the voltage
If the $30 setting happens to be 1000 and the S-Value Maximum is 100, then having a layer set to 50% power actually produces only 5% at the laser:
0.05 = 0.50 × 100 / 1000
So:
Go to Edit → Device Settings and look at the S-Value Maximum number
Turn the laser on & connect it
Go to the Console window, type $30, and whack Enter
Compare the number you get back with the S-Value Maximum number
If they agree, then the answer to my original question is “Yes” and something else is causing the low power output.
If they disagree, then set them both to 1000:
You can change the S-Value Maximum directly
In the Console window, type $30=1000 and whack Enter
Then see if that improves the results.
Again, all of that rickety sequence made perfect sense at the time, but … now you’re a little higher on the learning curve.
Something that might be happening is you installed your OLM3 on Lightburn in “find my laser mode”
This would for the most part give your machine a GRBL M3 controller.
As @ednisley explained this is relevant because legacy M3 controllers default Smax value to 255.
Go to Edit _> Device settings
Take a full screen shot and paste here, it will be evident if this is the case
if so, basicly you are using 25% of the full power of the laser
Looks fine.
Therefore assuming you are using mm/min and not mm/sec by mistake (which you can confirm on Edit - Settings page)
Lasergrbl and lightburn should have equal outputs
I use two PC, one that I use for setting up cuts and the other which is actually connected to the laser which actually controls it during cutting.
The device settings were completely different for them. The S-Value max was only 255. So, that would track as to why I’m getting such poor cutting. I’m only using the first 2.5w of my 10w laser.
