Stryker saw

I still find it counterintuitive* that there is a power saw that will not cut human skin. The Stryker saw is used to cut the cast off a broken limbs and to remove the cranium during an autopsy. Rather than circulating, the toothed blade oscillates, so it just wiggles a surface that is not rigid. And the idea is not new - it was patented by American doctor and inventor Homer Stryker (1894-1980) in 1947. Dr. Stryker writes in the patent:

"My improved implement is highly efficient in the cutting of casts and other hard surfaces but yielding surfaces or materials are not cut or injured thereby in the event the cutter should accidentally contact the skin of a person and it does not cut fabrics or other objects unless they are supported by a fairly rigid backing."

When sawing off a cast, the site www.fixbones.com recommends that the orthopedist demonstrate - especially to children - the operation of the cast cutter on his or her hand to show the patient that it will not harm soft tissue. Earplugs or headphones can also be employed to reduce the noise of the saw and attached dust vacuum, which may otherwise provoke anxiety.

What is a new invention is the SawStop table saw (be sure to watch the "hot dog demo" video). First offered in 2005, this circular saw works in a different way. The blade carries a small electrical signal. Since the human body conducts electricity, the signal changes if it contacts skin and activates the safety system within 5 milliseconds. A brake is applied to the blade, which is lowered beneath the table, and the power to the motor is cut off. Inventor Steve Gass, interviewed on NPR, is lobbying the Consumer Product Safety Commission to pressure the power tool industry to adopt this kind of safety device. Table saws alone cause more than 60,000 accidents each year, 3,000 of which involve amputation (caution).

*One of my favorite words.