I recently set up the mini grbl controller in a k40 I just purchased. Using lightburn with it, I can’t seem to get the laser power to adjust at all. When engraving an image, it seems to not skip the white parts either. I’ve tried adjusting my min/max power and also my power on the lcd of the k40 but still seems like its always constant consistent power.
I attached an image of what I was running some start up tests with, the image and then the results. Once I saw that it was just straight filling the whole thing in I stopped and tried again at different settings. I also attached an image of my mini grbl plugs just in case it’s something with that. Hoping someone might have some better insight 
Images: https://imgur.com/a/ujWekch
A few other things I’ve attempted to make it work:
- Checked my lense to substrate distance
- adjusting various speeds and power on LB and Power panel
- switching from image to line and fill
- drinking a beer
- trying different woods
- various $ settings from
Thanks for taking a look!
Here are my $ settings:
$0=10
$1=255
$2=0
$3=1
$4=0
$5=1
$6=0
$7=0 (ATC M6, pulse/ff)
$8=100 (ATC Tool Td, milliseconds)
$9=100 (ATC M6 Td, milliseconds)
$10=1
$11=0.010
$12=0.002
$13=0
$19=0 (Softstart, milliseconds)
$20=0
$21=0
$22=1
$23=3
$24=2000.000
$25=2000.000
$26=250
$27=2.500
$28=5 (Spindle freq. 0 to 15)
$30=1000
$31=1
$32=1
$100=157.000 (x:stp/mm)
$101=157.000 (y:stp/mm)
$102=160.000 (z:stp/mm)
$103=160.000 (a:stp/mm)
$104=160.000 (b:stp/mm)
$110=12000.000 (x:mm/min)
$111=5000.000 (y:mm/min)
$112=5000.000 (z:mm/min)
$113=5000.000 (a:mm/min)
$114=5000.000 (b:mm/min)
$120=8000.000 (x:mm/s^2)
$121=3000.000 (y:mm/s^2)
$122=3000.000 (z:mm/s^2)
$123=3000.000 (a:mm/s^2)
$124=3000.000 (b:mm/s^2)
$130=320.000 (x:mm max)
$131=230.000 (y:mm max)
$132=200.000 (z:mm max)
$133=200.000 (a:mm max)
$134=200.000 (b:mm max)
but rather hardware. When I get home from work though I will try it out and post results though in case anyone else comes across this. Fingers crossed lol