800W rotozip, 60% efficient (guess but typical) = 480W cutting. Ity probably doesnt maintain 20krpm cutting, say 15krpm

then Power = torque * revs, torque = Power/revs where power in Watts, revs in radians/sec (= rpm*2pi/60)

so torque = 480/ (15000 * 6.28/60) = 0.3Nm... for a 10mm cutter (radius = .005m) max force therefore = 0.3/.005 = 60N although you'd never actually get to that in practice...


500N as a test force (how did you measure it BTW) is probably overkill!