Mini Gerbil: Laser on/off vs. PWM outputs
Hello,
Can someone explain how the Mini Gerbil controls the laser on/off signal (the 4th connection in the power supply socket) vs. the PWM output? I noticed that when cutting with LightBurn, the on/off signal stays on for the duration of the cut job, and the the PWM output is used to turn the laser on and off between individual cuts. Are there specific Gcode commands to control both of these outputs independently?
I sort of liked the behavior of the M2 Nano board, where it uses the on/off signal to turn off the laser between cuts. This caused the "Laser Active" LED to flicker for each cut of the job. With the Gerbil, the LED stays on for the duration of the job, even when the PWM output is set to zero and the laser is effectively off.
This would be interesting to me as well.
It seems that I can not generate fast enough pulses to engrave small details with the MG.
Crazy but this wasn't an issue with my Chinese Newlydraw board.
I am having to run things much slower to give the laser time to hit the smaller details in my vector engravings I am sure this is affecting raster engraving as well.
The LO screw terminal is controlled via the M3/4 and M5 commands while the IN screw terminal is controlled by the S parm in Gcode.
e.g.
S100, set laser output
M4, turn laser on
G0 Xaaa Yaaa, do some movements
M5 turn laser off.
If the laser is lacking behind then you can set the $31=min power to a higher value eg. 40 and/or add a G4 P100 dwell command before laser-ing
S100
M4
G4 P100 (dwell 100 millisec to start the laser)
G0 x100 Y100
M5
@dbtoutfit ... did you ever find a fix for this? I can't raster any vertical line less than 1.5 mm at a reasonable speed compared to my stock k40 board. Sounds like a similar problem to what you had. Thanks!
Quote from Justin Reece on February 14, 2021, 1:01 am@dbtoutfit ... did you ever find a fix for this? I can't raster any vertical line less than 1.5 mm at a reasonable speed compared to my stock k40 board. Sounds like a similar problem to what you had. Thanks!
I found turning off bi directional engraving gave me incredible results but it also doubles my cycle/run time. So that showed me quickly where the problem was. Backlash and Laser Firing Time.
So I begin with tightening all my belts and carriage wheels as much as I could without any loss in speed to get rid of all my mechanical backlash.
I dialed my mirrors in so the beam is hitting the center of my focus lense no matter how close or far the head is.
After removing all mechanical backlash and slop I moved on to using Lightburn to dial in the last bit which is the fire timing.
Going into Scanning Offset Adjustment and creating a profile for every 100mms (100-200 etc) and really dialing them in, my laser is now engraving absolutely perfectly clear and very small details I could never do before.
Hope this helps...
Excellent information, we came across the LB blog on scan settings https://github.com/LightBurnSoftware/Documentation/blob/master/ScanningOffsetAdjustment.md
It gives a good description on fixing the backlash.
Cheers!