Hello, I work with Arduino and GRBL 1.1h. This works well with LaserGRBL. I want to switch to LightBurn, but I’m having problems.
I installed Lightburn and set the basic data.
My work area is X440 x Y400mm, the limit switches are on the front left. That should also be the starting position.
If I now switch on LB, the homing is done correctly and the laser is moved 5mm (as set in GRBL) from the limit switches. When retrieving the coordinates, X-435 and Y-395 will be displayed. The entire navigation plays in the minus area.
What am I doing wrong?
And how can I correct this?
Greetings Manfred
You most likely have a work offset configured.
Can you run these commands in Console and return output?
$H
$I
$$
$#
?
Note that the first command will home your machine so be prepared for it.
Where did you get the firmware for the Arduino? Normally I’d expect it to zero-out after homing but that’s not the case here. And not only that it’s put you in negative workspace. I don’t believe the default build from GRBL does this so I’m curious.
You can resolve this by introducing a work offset. Run these commands in Console:
G10 L2 P1 X-435 Y-395
$10=0
Rehome and then retest please.
OK THANKS it works now.
I load the GRBL with LaserGRBL
Could it be the wrong GRBL?
Are you using your machine only for laser operation or do you also use it for CNC operation? Does your machine have Z axis controls?
If you don’t use CNC and do not have Z-axis then I’d suggest you use the firmware marked “v1.1h, custom, XY Homing 20190830” in LaserGRBL.
Yes, I also have a Z axis. I mill and cut foil with the machine.
I will test it with the other firmware. It should also work for the other jobs.
Many thanks for the help.
That firmware will not allow for Z-homing. If that’s okay then you should be fine.
If you still have a work offset defined then that might cause problems. In that case revert the previous changes:
G10 L2 P1 X0 Y0
$10=3
thanks i test 
Hello, I tested again extensively.
- I downloaded and tested several GRBL from the net.
- All work correctly at the beginning.
- But as soon as I do a homing, I have a negative workspace.
- only exception is the XY Homing 20190830” in LaserGRBL. But my laser, which I switch on with the spindle relay, doesn’t work with this one.
Can you explain this? How is this wired and what’s the complication with this firmware?
complication 1. after homing, my working range is in the negative, i.e. X -420 Y -400. For example, if I enter X30 as usual, the X-axis wants to move to +30 (i.e. crash).
complication 2. When I turn on the laser, PWM is active. However, the 12V for the laser are missing because they are switched with the spindle relay.
After a long read I found the solution in the config.h (will test tomorrow)
to 1.
// After homing, Grbl will set by default the entire machine space into negative space, as is typical
// for professional CNC machines, regardless of where the limit switches are located. Uncomment this
// define to force Grbl to always set the machine origin at the homed location despite switch orientation.
// #define HOMING_FORCE_SET_ORIGIN // Uncomment to enable.
to2.
// #define USE_SPINDLE_DIR_AS_ENABLE_PIN // Default disabled.
How do you have your controller wired to the laser module and relay?
Arduino Pin11 = PWM, Pin13 = Spindel on/off
after enabling "#define USE_SPINDLE_DIR_AS_ENABLE_PIN, pin 13 switches analogously to pin 11 (required for LaserGRBL)
Confirm that $32=1 in the LaserGRBL firmware. Are you using M3 or M4 to test? Test with M4 please. You should be getting 5V at Pin13.
OK, tested it in LaserGRBL.
M4 turns on pin13, but M3 (for PWM) turns it off again.
It works in LightBurn. How to see what commands LightBurn gives?
LightBurn will by default use M4 if you are using the “GRBL” device profile. If you use “GRBL-M3” device profile or use “Constant Power Mode” setting in the Cut setting then LightBurn will issue M3 for those.
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