Tooling Router Bits 101: Know Your Bits

Anatomy of A Router Bit

Anatomy of Router Tooling Bit

There are a few facets to a Router Tooling Mill Bit measurements like (a) Total Length, (b) Spiral Flute (c) Shank Diameter, (d) Shank Length, (e) Bit Length, (f) Bit Diameter, to name a few.

Tooling End Geometry

Different end-geometry lends its self to different applications & finishes. 

Spiral Flute Count

A general rule of thumb is that the higher the flute count – the higher the possible the cut rate.

Spiral Angle & Direction: Straight vs Up-Cut vs Down-Cut vs Compression-Cut Toolings Straight Bit
Straight Bit Up-Cut Bit
Up-Cut Bit Down-Cut Bit
Down-Cut Bit Compression Bit
Compression Bit
  • Good Edge Quality On Most Materials
  • Moderate Chip Clearing
  • Best Ejection For Chips, Away From The Kerf.
  • Good Quality On Bottom Faces When Cutting Through.
  • Allows For Faster Speeds Than Downward Cut Tooling Bits.
  • Ejects Chips Down Ward, Good Face Quality On Top Face.
  • Downward Force Helps With Cutting On Thiner Boards
  • Designed To Cut Vaneer Or Laminate Materials At Full Depth In One Pass
  • Cleaner Edge On Top And Bottom Face
Less Efficient Than Spiral Tooling
  • Prone To Chipping Or Fraying Of Top Edge
  • Upward Motion Can Cause Lifting In Materials
  • Prone To Chipping Or Fraying Of Bottom Edge - When Cutting Through.
  • Lower Feed-Rates That Up-Cut Tooling Bits.
  • Due To Nature of Construction, Compression Toolings Are A Lot More expensive.
  • Prone To Heat Issues - Due To Less Effective Material Ejection Rates.
Recommended Materials
Generally Fits Most Materials
Plastics, Aluminium Etc. Generally Materials With Lower Heat Tolerances.
Plywood, Laminates, MDF, Hardwoods, Softer woods.
Plywood, Laminates, MDF, Hardwood, Softer woods.