The Centrifugal Physics of Router Bits
A woodworking router is one of the highest-RPM power tools in existence, spinning between 10,000 and 24,000 RPM. Centrifugal force increases with the square of the rotational speed and linearly with radius ((F_c = m imes omega^2 imes r)).
Why Large Bits Must Spin SLOW
A tiny 1/4" bit spinning at 24,000 RPM has a gentle outer rim speed of ~1,570 SFM. However, if you spin a large 3-1/2" raised panel bit at 24,000 RPM, the outer carbide tips are traveling at over 22,000 SFM (nearly 250 miles per hour!).
At that speed, dynamic air resistance causes extreme flutter vibration, and any microscopic brazing flaw will send 1/2-ounce carbide teeth flying through the workshop like high-velocity shrapnel! Large bits must be throttled down to 10,000 - 12,000 RPM!
Handheld vs Router Table Safety Rule
Never use a router bit larger than 1.5 inches in diameter in a handheld router. Large-diameter bits generate massive rotational torque that can violently kick the tool out of your hands. Any bit over 1-1/2" must strictly be operated in a rigid, table-mounted router with a sturdy fence and featherboards.