I am using an Omtech K40 with stock Nano M2 Controller.
Constructing with Lightburn, exporting to SVG file and lasering
with K40 Whisperer. Works like a charm, but i wanted to control
the laser directly via Lightburn, so i bought an Monport V2 Controller.
Installation was plug&play like the manual, Laser was recognized in LB and i was able to start.
Controlling the power and movement work both, but then i ran into a problem:
I cannot reduce the power enough to make some light carvings.
Even with 1% power i have a current of about 4mA. Way too much!
I set S-Value to 1000, what matches $30 = 1000 in the controller.
I can power up the current easily, but it will not go further down
than 4mA.
Tried to adjust PWM frequency with $33, but it is immediately
overwritten to default “1”
The controller is useless if i cannot reduce power and
i think about returning it.
Generally these new boards use the PWM to adjust power, which is correct. Do you have a voltmeter?
If you check from ground to pwm, it should read 5V * percentage chosen with Lightburn. If you have it set for 50%, it will be 50% of 5V or 2.5V
It sounds like you have it configured properly. PWM period (frequncy) won’t matter and may not be adjustable on your controller. Anything from 1kHz and up, reasonably, works with the laser power supplies (lps).
The only thing I can think of is $31, which is minimum spindle speed and this should be zero for a laser. I’ve rarely seen this as an issue. The controller uses not only $30, but it’s reference is based on minimum spindle speed.
This sets the spindle speed for the maximum 5V PWM pin output. Higher programmed spindle RPMs are accepted by Grbl but the PWM output will not exceed the max 5V. By default, Grbl linearly relates the max-min RPMs to 5V-0.02V PWM pin output in 255 increments. When the PWM pin reads 0V, this indicates spindle disabled. Note that there are additional configuration options are available in config.h to tweak how this operates.
$31 - Min spindle speed, RPM
This sets the spindle speed for the minimum 0.02V PWM pin output (0V is disabled). Lower RPM values are accepted by Grbl but the PWM output will not go below 0.02V, except when RPM is zero. If zero, the spindle is disabled and PWM output is 0V.
Thanks for your answer.
Yes I have a voltmeter, but I decided
to return the monport. There are a lot of
people here who have issues with power
not getting low enough.
I had exact the same issues with the controller
from awesome.tech (MiniGerbil).
Perhaps my LPS is not compatible with
PWM from controllers.
I don’t know what signal comes out of
the digital panel of the K40 but that
signal works, although 11% there means
already 7mA at the Amperemeter and
15% are 12mA!
I never went over 19% and 16mA.
Monport gave me a full refund without
sending the controller back to them.
They told me, that there is a minimum voltage output at the PWM connector, which can not be reduced by the settings in Lightburn.
They apologize for inconvenience and will
consider it with the next version.
Thread can be closed for further comments.
Thanks indeed!
