Product Review

CNC Shield Board:
Latest CNC Shield Version 3.0
GRBL 0.9
4-Axis support (X, Y, Z , A-Can duplicate X,Y,Z or do a full 4th axis with custom firmware using pins D12 and D13)
2 x End stops for each axis (6 in total)
Coolant enable
Compatible with A4988 or DRV8825 stepper driver
Runs on 12-36V DC

R3 Board:
MCU: ATmega328
USB interface: ATmega16U2
Operating voltage: 5V
Digital I/O pins: 14 (including 6 with PWM capability)
Analog input pins: 6
I-I/O pin output current: 40mA max
3.3V output current: 150mA max
Flash memory: 32 kB (0.5kB used by bootloader - included)
Static RAM (SRAM): 2 kB
EEPROM: 1 kB
Clock speed: 16MHz

A4988 Stepper Motor Driver:
A4988 Stepper Motor Driver Board is a breakout board for Allegro's A4988 DMOS Micro stepping Driver with Translator and Overcurrent Protection;

Low RDS (On) Output :
Automatic current decay mode detection / selection
Mix with slow current decay modes
Synchronous rectification for low power dissipation
Internal UVLO
Crossover-current protection
3.3 and 5 V compatible logic supply
Thermal shutdown circuitry
Ground fault protection
Load short-circuit protection
Five selectable step modes: full, 1/2, 1/4, 1/8 and 1/16
Warning: Connecting or disconnecting a stepper motor while the driver is powered can destroy the driver. (More generally, rewiring anything while it is powered is asking for trouble).

Package Contents:
1 x CNC Shield Board
1 x R3 Board
4 x A4988 Stepper Motor Driver
4 x Heat Sink