A former woodworker, industrial engineer and inventor says he has received a patent on a flesh-sensing table saw safety braking system. David Butler, who is principal of Whirlwind Tool, Cotuit, MA, says he has spent years developing the system intended to prevent serious injuries among table saw users.
Table saw safety is under increasing scrutiny as the Consumer Product Safety Commission considers a requirement that table saws be outfitted with some type of electronic safety device that would freeze the saw blade it it comes into contact with flesh. California is also considering a law that would require table saw safety brakes. SawStop is the only producer of saws outfitted with such braking systems.
A search of the United States Patent database reveals Patent No. 8,082,825 was issued to Butler on December 27, 2011. It covers an earlier version of his table saw safety braking system. Originally applied for June 9, 2009, Butler's "Health and safety system for a table saw" describes a system incorporating a plastic blade guard with sensor, an aggressive dust collection system, and a saw motor braking system:
a blade guard that protects the operator from the saw blade, and contains and collects sawdust; a proximity detector and emergency saw motor braking means for use in connection with such blade guard; an anti-kickback device for use in connection with such blade guard, a rip fence adapter for use in connection with such a blade guard, and hoses and fittings to connect the dust containment and collection system of said blade guard to a shop dust collection blower or vacuum system. The system protects the saw operator from potential traumatic injury to a hand, and from ingesting potentially carcinogenic sawdust.
Whirlwind Tool has developed versions of the saw safety device incorporating "Proximity Sensing" for Makita, Delta, Rigid and Powermatic saws. The latest version, called a "Black Box" table saw emergency blade brake, is a bolt-on/removable device that can be incorporated into use with millions of existing saws, including band saws, and to other woodworking machinery already in the field.
Butler says the prototypes showcased on his site differ from previous table saw blade guards and emergency blade brakes, since they use an "electronic fence” blade enclosure. Removable, extended safety shields can be wide or narrow to offer varying safety margin depending on user comfort and experience.
"If the operator approaches or touches the clear blade guard fence, the proximity detector will immediately shut down the saw motor and stop the blade, without damage, in one-eighth of a second — long before the operator can contact the spinning blade," Butler explains on his website. "The saw can be restarted almost immediately." Butler says he hopes to license the technology to a large company that can bring it to market.
