Quick start CNC shield v3 for Arduino (Part Two)

Posted by Marius Cloete on

This continues from the previous tutorial

quick start CNC shield v3 for Arduino

for this tutorial, we will be using the following hex file:

 Grbl v0.9j Atmega328p 16mhz 115200baud with generic defaults (2016-03-17)
        Baudrate is now 115200 (Up from 9600).
        Homing cycle updated. Located based on switch trigger, rather than release point.
        Variable spindle is now enabled by default. Z-limit(D12) and spindle enable(D11) have switched to access the hardware PWM on D11. Homing will not work if you do not re-wire your Z-limit switch to D12.


The main thing to note is the updated location of the z-limit. Unfortunately, there will now only be a +z limit for the CNC shield v3.

 you will need to move your +z limit to the spindle enable (SpnEn) pins:



The next thing we will be doing is adding the jumpers for micro stepping.

Jumper are not provided with the CNC shield but you can by them here:

Pitch 2.54mm Jumper


Jumper configuration is as follows:

Pololu A4988 Stepper Driver configuration:

MS0 MS1 MS2 Microstep Resolution
Low Low Low Full step
High Low Low Half step
Low High Low Quarter step
High High Low Eighth step
High High High Sixteenth step


I have selected the Sixteenth step so all pins will have a jumper on them.

If you need more torque you will need to set the micro steps to a lower value.


For my GRBL I used the following settings.

$0=10 (step pulse, usec)
$1=25 (step idle delay, msec)
$2=0 (step port invert mask:00000000)
$3=1 (dir port invert mask:00000001)
$4=0 (step enable invert, bool)
$5=0 (limit pins invert, bool)
$6=0 (probe pin invert, bool)
$10=3 (status report mask:00000011)
$11=0.010 (junction deviation, mm)
$12=0.002 (arc tolerance, mm)
$13=0 (report inches, bool)
$20=0 (soft limits, bool)
$21=1 (hard limits, bool)
$22=1 (homing cycle, bool)
$23=7 (homing dir invert mask:00000111)
$24=25.000 (homing feed, mm/min)
$25=500.000 (homing seek, mm/min)
$26=250 (homing debounce, msec)
$27=1.000 (homing pull-off, mm)
$100=3200.000 (x, step/mm)
$101=3200.000 (y, step/mm)
$102=3200.000 (z, step/mm)
$110=500.000 (x max rate, mm/min)
$111=500.000 (y max rate, mm/min)
$112=500.000 (z max rate, mm/min)
$120=10.000 (x accel, mm/sec^2)
$121=10.000 (y accel, mm/sec^2)
$122=10.000 (z accel, mm/sec^2)
$130=3200.000 (x max travel, mm)
$131=2700.000 (y max travel, mm)
$132=750.000 (z max travel, mm)

You can view your settings by typing $$ in the command line of the universal gcode sender.


More on GRBL configuration can be found here



I have also found a better gcode  sender 

Have a look here :




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