CNC Router Feeds & Speeds for Wood – Beginners Guide

Introduction

This tutorial provides a beginner-friendly guide on setting CNC router feeds and speeds for wood projects. Understanding feeds, speeds, and chip load is crucial for achieving clean cuts and extending the life of your router bits. Whether you're using a Makita spindle, Altmill, LongMill, or any other CNC router, this guide will help you navigate the essential factors for efficient CNC routing.

Step 1: Understand Feeds, Speeds, and Chip Load

• Feeds: This refers to the speed at which the CNC router moves through the material, usually measured in inches per minute (IPM).

• Speeds: This indicates the rotational speed of the router bit, measured in revolutions per minute (RPM).

• Chip Load: This is the amount of material removed by each cutting edge of the bit per revolution. It's calculated using the formula:

  Chip Load = Feed Rate / (RPM x Number of Flutes)
  

Practical Tips

• Aim for a chip load that’s appropriate for your bit size and material. A general rule is to maintain a chip load between 0.001" and 0.005" for wood.

Step 2: Calculate Your Feed Rate and RPM

1. Select Your Router Bit: Choose an appropriate bit based on your project needs.

2. Determine the Chip Load: Use the recommended chip load for your bit type and material.

3. Calculate Feed Rate:

   • Use the formula:

     Feed Rate = Chip Load x RPM x Number of Flutes
     

4. Set Your RPM: Depending on your router and bit, adjust the RPM accordingly. Refer to the manufacturer's recommendations for guidance.

Common Pitfalls

• Avoid setting the RPM too high, as it may cause overheating and burning of the bit.
• Ensure the feed rate is balanced with the RPM to prevent bit breakage and achieve a clean cut.

Step 3: Adjust Stepover for Finish Quality

• Stepover: This is the distance the router moves over between passes. A smaller stepover results in a smoother finish.
• Recommended stepover ranges from 20% to 50% of the bit diameter.

Practical Application

• For roughing passes, use a larger stepover (around 50%).
• For finishing passes, use a smaller stepover (around 20%) for better surface quality.

Step 4: Avoid Common Mistakes

• Bit Burn: To prevent burning, ensure your feed rate is high enough and that RPM is set appropriately.
• Overheating: Monitor the temperature of the bit; if it feels too hot to touch, slow down the feed rate or reduce RPM.

Step 5: Utilize Resources for Setup

• Download the free IDC Woodcraft bit database and mobile app for quick references on bit specifications and settings.
• Access the Chip Load Calculator online for quick calculations.

Conclusion

By understanding and applying the concepts of feeds, speeds, and chip load, you can optimize your CNC routing for wood. Always start with recommended settings and adjust based on your machine's performance and the characteristics of the wood. Utilize the resources available to ensure your setup is accurate and efficient. Happy routing!