April 13, 2025 On April 13, 2025

CNC V3 Shield with 4 A4988 Drivers

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CNC V3 Shield with 4 A4988 Drivers

Complete Arduino-compatible CNC controller for 3D printers and milling machines

Introduction

The CNC V3 Shield is an all-in-one motion control solution that combines an Arduino-compatible microcontroller with four A4988 stepper motor drivers. This robust shield provides everything needed to control CNC machines, 3D printers, or robotic applications with precision and reliability.

Key Features

⚡ 4-Axis Control

X, Y, Z axes + 1 additional axis

🔌 Integrated Drivers

4 × A4988 stepper drivers

🔄 Microstepping

Up to 1/16 step resolution

🔊 Fan Control

Dedicated PWM fan output

🔥 Heat Management

Large heatsinks + cooling fan

💡 Endstop Inputs

3-axis limit switch connectors

Technical Specifications

Compatible Boards	Arduino Uno, Mega, Duemilanove
Stepper Drivers	4 × A4988 (replaceable)
Motor Outputs	4 axes (X,Y,Z,A)
Max Current per Axis	2A (with cooling)
Microstepping	Full, 1/2, 1/4, 1/8, 1/16
Power Input	12-36V DC (recommended 24V)
Logic Voltage	5V (from Arduino)
Spindle Control	PWM + direction
Fan Output	12V PWM (max 1A)
Endstop Inputs	3 × mechanical endstops
Dimensions	68.6mm × 53.3mm

Pin Configuration

Connector	Function	Arduino Pin
X.STEP	X-axis step pulse	D2
X.DIR	X-axis direction	D5
Y.STEP	Y-axis step pulse	D3
Y.DIR	Y-axis direction	D6
Z.STEP	Z-axis step pulse	D4
Z.DIR	Z-axis direction	D7
A.STEP	A-axis step pulse	D12
A.DIR	A-axis direction	D13
FAN	Cooling fan PWM	D9
SPINDLE	Spindle control	D11

Installation Guide

Power Down: Disconnect all power sources
Mount Shield: Align and press onto Arduino headers
Insert Drivers: Place A4988 drivers in sockets (observe orientation)
Connect Motors: Wire steppers to appropriate axis terminals
Power Input: Connect 12-36V DC to power terminal
Endstops: Connect limit switches if used
Cooling: Connect fan to FAN output

Important: Set current limits on each A4988 driver before first use

Current Adjustment

Procedure

Power off and disconnect motors
Set multimeter to 200mV DC range
Place probes on driver potentiometer and GND
Power on system
Adjust until VREF = I_Trip × 0.8
Repeat for each driver

Example Settings

NEMA 17 (1.2A): 0.96V
NEMA 17 (1.5A): 1.2V
NEMA 23 (1.7A): 1.36V
NEMA 23 (2.0A): 1.6V

GRBL Configuration

// Sample GRBL settings for CNC V3 Shield
$0=10          // Step pulse, microseconds
$1=25          // Step idle delay, milliseconds
$2=0           // Step port invert, mask
$3=0           // Direction port invert, mask
$4=0           // Step enable invert, boolean
$5=0           // Limit pins invert, boolean
$6=0           // Probe pin invert, boolean
$10=3          // Status report, mask
$11=0.010      // Junction deviation, mm
$12=0.002      // Arc tolerance, mm
$13=0          // Report inches, boolean
$20=0          // Soft limits, boolean
$21=0          // Hard limits, boolean
$22=0          // Homing cycle, boolean
$23=0          // Homing dir invert, mask
$24=25.000     // Homing feed, mm/min
$25=500.000    // Homing seek, mm/min
$26=250        // Homing debounce, milliseconds
$27=1.000      // Homing pull-off, mm

Tip: Use Universal Gcode Sender to configure GRBL parameters