Pocket milling (rectangular) in CNC Programming - Mini Project: Build & Apply

Pocket Milling (Rectangular)

📖 Scenario: You are programming a CNC machine to mill a rectangular pocket in a metal plate. The pocket is a hollowed-out rectangular area that the tool will cut out by moving along calculated paths inside the rectangle.This project will guide you through creating a simple CNC program that defines the pocket size, sets the cutting depth, and generates the toolpath commands to mill the pocket in a rectangular shape.

🎯 Goal: Build a CNC program that mills a rectangular pocket by generating the correct G-code commands for the tool to follow a rectangular path at a specified depth.You will create variables for the pocket dimensions, set the cutting depth, generate the toolpath commands using loops, and output the final CNC program commands.

📋 What You'll Learn

Create variables for pocket width and height with exact values

Create a variable for cutting depth with exact value

Use a loop to generate G-code commands for the rectangular pocket path

Print the final G-code commands as output

💡 Why This Matters

🌍 Real World

CNC programmers use similar scripts to automate the creation of milling programs for machining parts efficiently and accurately.

💼 Career

Understanding how to generate G-code programmatically helps CNC operators and manufacturing engineers reduce manual programming errors and speed up production setup.

1

Define Pocket Dimensions

Create two variables called pocket_width and pocket_height with the exact values 50 and 30 respectively.

CNC Programming

# Define pocket dimensions
# Your code here

Hint

Use simple assignment statements like pocket_width = 50.

2

Set Cutting Depth

Create a variable called cutting_depth and set it to the exact value -5 to represent the depth below the surface.

CNC Programming

pocket_width = 50
pocket_height = 30
# Set cutting depth
# Your code here

Hint

Remember the depth is negative to indicate below the surface.

3

Generate Rectangular Pocket Toolpath

Use a for loop with the variable corner to generate G-code commands for the four corners of the rectangle. Use the variables pocket_width and pocket_height to calculate the X and Y positions for each corner. Store each command as a string in a list called gcode_commands. The commands should move the tool to each corner at the cutting_depth.

CNC Programming

pocket_width = 50
pocket_height = 30
cutting_depth = -5
# Generate G-code commands for rectangular pocket
# Your code here

Hint

Define the four corners as tuples and loop through them to create the G-code commands.

4

Print the Final G-code Commands

Print each line in the gcode_commands list to display the full CNC program for the rectangular pocket milling.

CNC Programming

pocket_width = 50
pocket_height = 30
cutting_depth = -5

gcode_commands = []
corners = [(0, 0), (pocket_width, 0), (pocket_width, pocket_height), (0, pocket_height)]
for corner in corners:
    x, y = corner
    gcode_commands.append(f"G1 X{x} Y{y} Z{cutting_depth}")

# Print all G-code commands
# Your code here

Hint

Use a for loop to print each command in the list.