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Unable to increase power above 20%

Hi first post I have a problem cutting 5mm plywood on my K40 with mini Gerbil. At 20% I have a fine line and it's cutting but not all the way through, I've dropped speed but when I try to increase power above 20.5% the beam/cutting stops. Is there a power cap or something I'm unaware of?

Hi, there is no cap, so 100% is the max which is about 18mA on the K40. Running at laser at 100% will reduce the lifespan considerable from 500-1000 hours to about 10 hours so always run 80% at max.


  1. Are the S parm aligned in mini gerbil ($30 value) and Lightburn S=1000?
  2. Is the return for the 5V - ground connection solid? e.g. screw terminals tightend
  3. Is the laser ground to the mains earth solid? e.g. k40 case earth terminals have sometimes a plastic washer! SeeĀ K40 laser grounding instructions

Let's us know if that helped.


Cheers, Paul awesome.tech

tried all you suggested and all seems good, but unable to get anything over 20.5% 8mA. even checked the mA metre wiring. below is taken from console and screen shot of 1000 in settings










(ATC M6, pulse/ff)


(ATC Tool Td, milliseconds)


(ATC M6 Td, milliseconds)






(Softstart, milliseconds)










(Spindle freq. 0 to 15)



































(x:mm max)


(y:mm max)


(z:mm max)


(a:mm max)


(b:mm max)


Uploaded files:
  • IMG_20200730_123201405.jpg

Have you tried to lower $30 settings say to 500 and retest? If that does not work that it's likely that the tube has expired (gases do deteriorate over time even when not used).

Cheers, Paul awesome.tech

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