CNC Router Drill Bits: A Quick Guide

CNC Router Drill Bits: A Quick Guide

To get the best results from your CNC router, it’s important to understand the basics of router bits and how they work.

Key CNC Routing Terms
Chipload: Size of the chips (material pieces) removed during cutting.
Feed Rate: How fast the bit moves through material, measured in Inches Per Minute (IPM).
Speed Rate (RPM): Spindle speed in Revolutions Per Minute.
Flute: Cutting edge(s) on the bit.
Toolpath: The programmed path the router follows to cut.

Types of Cuts
Different bits are suited for different materials and cutting directions:

Up Cut: Most common; removes chips upward and away from the cut.
Down Cut: Good for laminated or thin materials; pushes chips down.
Compression Cut: Mix of up and down cuts; clean finish on both top and bottom.
For plastics and aluminum, use single flute bits. For wood, double flutes are ideal.

Use bit sizes that match your material—e.g., a ¼” bit for a ¼” plastic sheet. Thicker bits allow deeper cuts but be careful not to waste material.

Before You Cut
Know the material, thickness, and type of cut (e.g., engraving, pocketing).
Decide if you’ll use single or multiple passes.
Follow the manufacturer’s recommended chipload, usually found in manuals or online.
Use this formula:
Chipload = Feedrate / (RPM × Number of Flutes)

Tips
Chips too big? Lower the feed rate to avoid breaking the bit.
Big chips cool better; small chips are gentler on the machine but can overheat.
Typical RPM is ~18,000. For aluminum, try ~16,000 RPM.

By understanding these basics, you’ll maximize your CNC router’s performance and prolong your bit life.