I am Matthias from Germany - an enthusiast in medieval arts and crafts … I am neither a native speaker nor good in electronics or programming. So please excuse any stupid expressions or questions :o)
I am absolutely new in laser cutting. I just anhanced my CNC mill by a laser module.
It worked fine for a short time. I managed to engrave text and to cut an “O” from a 8mm beech plywood board.
When restarting the machine I recognized, that the laser fired for a second in the moment when starting lightburn.
Some days later - meantime I didn’t touch and I didn’t change anything - the laser fires permanently on full power when switching on the controller - lightburn not running yet. Even when starting lightburn, M5 won’t shut it off.
I tried many different things:
flashing firmware again
changed grbl settings: e.g. laser mode off etc.
altered connection (I thought of wrong wiring)
- I disconnected the laser driver from the seperate power adapter (see image) and tried to put
24V to the 4 pin input plug - laser doesn’t fire at all.
- When I unplug the connection to the xpro and start the power adapter, the fan of the laser
module starts, the laser does not fire. Therefore it seems like the XPro permanently sends a
PWM signal in full power.
- Also unplugging the “second” ground wire between the laser controller and the XPro didn’t
change anything.
Nothing helped. That’s really dangerous and frustrating, as now I can’t use the machine at all.
One power adapter for Controller and laser: Kingwen 24V 20A Adapter Transformator 480W
Controller GRBL settings that once worked well:
$0=4
$1=255
$2=0
$3=7
$4=0
$5=1
$6=1
$10=1
$11=0.010
$12=0.002
$13=0
$20=1
$21=1
$22=1
$23=3
$24=100.000
$25=800.000
$26=250.000
$27=10.000
$30=1000.000
$31=1.000
$32=1
$100=320.000
$101=160.000
$102=320.000
$103=200.000
$104=100.000
$105=100.000
$110=2500.000
$111=2500.000
$112=2500.000
$113=1000.000
$114=1000.000
$115=1000.000
$120=50.000
$121=50.000
$122=54.000
$123=200.000
$124=200.000
$125=200.000
$130=600.000
$131=1190.000
$132=150.000
$133=300.000
$134=300.000
$135=300.000
Maybe I do not need the laser module controller board? But if so, how to connect the module directly to the XPro controller? And most interesting: Why did it work once???
I am almost sure it’s something simple…
Check the pwm with a voltmeter. You can remove power to the laser and just read it from the controller. If it has voltage on it the laser is probably firing… if it’s stuck at 5V that’s the problem.
PWM is a ttl signal in the range of 0 to 5V. If you read the voltage at the pwm pin, relative to ground it should be the percentage of voltage…
If it’s 50% pwm you should read 50% of 5V or about 2.5V, 20% about 1V…
Thanks again. I am a bit farther - just to run into the next problem.
I managed to control the laser on/off by leading the pwm through the relay (see image below)
Now I can use lightburn for engraving.
The next problems:
1 As soon as I start a GCode, the laser starts firing as soon as it moves (in G0) instead of first moving to te engraving starting point and then starting the laser. Using the “Fire” button on 0.25% starts the laser on high power, burning everything underneath. I guess the root caus is the same as before: The PWM sends permanently 1,33V instead of 0 when not activated.
2. New motion problem: Really surprising is, that engraving a circle actually ends up in a narrow elipse. The y axis seems to go way too far. When I order any axis to move, let’s say 50 mm, it does so perfectly - but not when a GCode file is running.
I really don’t understand what could have happened since it worked in my first test. Neither the PWM problem nor the offset problem.
