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WNCWA Western North Carolina Woodworkers Association


Serving Woodworkers in
Western North Carolina


HomeSawStop® Table Saw – What Causes the Brake to Fire?

A Five-Minute Safety Brief for the Western North Carolina Woodworkers Association

Presented on February 14, 2026 by John Fenwick

 

What Makes a SawStop Trigger?


SawStop technology works by placing a small electrical signal on the spinning blade. Dry wood and air are poor conductors, while the human body conducts electricity very well. When a conductive object contacts the blade, the system detects a rapid change in the signal and instantly fires an aluminum brake into the blade, stopping it in about five milliseconds.


Materials That Can Accidentally Trigger the Brake


Not all brake activations involve fingers. Any sufficiently conductive material can cause the system to fire, including:


  • Wet or green wood with high moisture content
  • Pressure-treated lumber
  • Hidden metal such as nails, screws, or staples
  • Metal tools contacting the blade, such as miter gauges or tape measures
  • Foil-backed insulation or laminated materials with metal layers
  • Carbon-fiber composites
  • Very wet hands or gloves
  • Metal-filled epoxies or conductive finishes
  • Miter gauge too close to blade.


How to Avoid Accidental Activation (and Stay Safe)


SawStop saws include a bypass mode that allows you to test questionable materials without firing the brake. Recommended best practices include:

  • Use bypass mode to test wet, green, or unknown materials before making a cut
  • Inspect reclaimed or construction lumber carefully for hidden metal
  • Allow wet lumber to dry whenever possible
  • Plan cuts carefully when working with potentially conductive materials
  • Never remove blade guards, riving knives, or other standard safety equipment
  • Remember: bypass mode disables the brake; it does not make the cut safer


A Short True Story



A woodworker cutting pressure-treated deck boards on a SawStop experienced a sudden brake activation with no contact to the blade. The cause was moisture and chemical treatment in the lumber, which made it conductive enough to trigger the system. The blade and brake cartridge were destroyed, but no one was hurt. A quick test in bypass mode would have revealed the risk before making the cut.

 

Bottom Line: SawStop is a last-line defense, not a substitute for good technique. Understand what can trigger it, test materials when unsure, and treat every cut with respect.