For help on cabling your GRBL board, please visit https://github.com/gnea/grbl/wiki/Connecting-Grbl.

Adjust stepper current

If you didn’t adjust the current of your stepper drivers yet, do it now.
It doesn’t make sense to configure acceleration and max feed when the stepper current is not correct! Set the current to a value where you have good torque but don’t overheat the driver and motor.
See the documentation of your machine or stepper drivers on how to adjust the current. Details can be found on http://reprap.org/wiki/Pololu_stepper_driver_board.

Calculate steps/mm

You need to know how many stepps each axis has to go for 1mm distance. This is depending on pully sizes or spindle pitch and microstepping.
There is a nice calculator on http://www.prusaprinters.org/calculator/#steppermotors.
 
 

To find the right acceleration settings, do the following:

1. Load our acceleration_test.jpg (right click for download) into LaserWeb.
2. Then create a raster operation and change pass to 1 and cut rate to 6000 mm/min
3. Generate the gcode.
4. Click on COM tab, select the machine port and connect.
5. Click on JOG tab. On the lower right of the screen you see the console line.
6. Type $120=1500 into the console line and press shift-enter. This sets your X acceleration to 1500mm/s2.
7. Run the job.
8. If the acceleration is too height, you will hear/see lost stepps on the sides (when changing direction). Then lower the acceleration value by 10% and test again.
9. If there was no lost stepps, increase to value by 10% and test again.
10. If you found the limit where loosing stepps begins, reduce the value by 15-20% and set it to $120 and $121 (X and Y axis).

To find the maximum feed settings, do the following:

1. Load our feed_test.jpg (right click for download) into LaserWeb.
2. Create a raster operation and change pass to 1 and cut rate to 6000 mm/min (= 100mm/s).
3. Generate the gcode.
4. Click on COM tab, select the machine port and connect.
5. Click on JOG tab. On the lower right of the screen you see the console line.
6. Type $110=30000 into the console line and press shift-enter. This sets the max X feed of GRBL to 30000mm/min.
7. Type $111=30000 into the console line and press shift-enter. This sets the max Y feed of GRBL to 30000mm/min.
8. Run the job.
9. If the feed is too height, you will hear/see lost stepps during X moves. Then lower the feed vale (in step 2.) by 10% and test again.
10. If there was no lost stepps, increase to value by 10% and test again.
11. If you found the limit where loosing stepps begins, reduce the value by 15-20% and set it to $110 and $111 (X and Y axis).

To configure your GRBL based board, you need to be connected with LaserWeb or a terminal program.
In LaserWeb, you can send commands manually with the command line on the bottom right of the screen. After typing in the command, you have to press SHIFT-ENTER to send it to GRBL.
Send $$ to get a list of the actual configuration. To set a param you have to send $num=val (ex. $10=0).
Make sure the following values are set:

$10=0      ;send work coordinates in statusReport
$30=1000   ;max. S-value for Laser-PWM
$31=0      ;min. S-value
$32=1      ;Laser Mode on
$100=160   ;steps/mm in X, depending on your pulleys and microsteps
$101=160   ;steps/mm in Y, depending on your pulleys and microsteps
$102=160   ;steps/mm in Z, depending on your pulleys and microsteps
$110=10000 ;max. rate mm/min in X, depending on your system
$111=10000 ;max. rate mm/min in Y, depending on your system
$112=10000 ;max. rate mm/min in Z, depending on your system
$120=1000  ;acceleration mm/s^2 in X, depending on your system
$121=1000  ;acceleration mm/s^2 in Y, depending on your system
$122=300   ;acceleration mm/s^2 in Z, depending on your system
$130=400   ;max. travel mm in X, depending on your system
$131=300   ;max. travel mm in Y, depending on your system
$132=100   ;max. travel mm in Z, depending on your system
$$         ;to check the actual settings

(see https://github.com/gnea/grbl/blob/master/doc/markdown/settings.md for more details).
We use this software in house on our Laser Diode Engraver and it works really well. We use GRBL 1.1 on an Arduino UNO and CNC shield.

IMG 20170621 200045 DRO

3dpBurnerBasicWiring

IMG 20170712 181630

laser engraver