safety
	machines hurting people
	people hurting machines
the 5-fold way
	work machines
	make useful parts
	make beautiful parts
	make parts quickly
	make beautiful parts quickly
materials
	aluminum
	steels
	copper
	brass
	delrin, telfon, ...
	pure, dislocations, single crystal
cutting
	plastic flow
	fracture, ballistic
tooling
	sawing
	grinding
	waterjet
	drilling
	turning
	milling (plunge, climb)
speeds and feeds
	squeal: instability
	groan: torque (inertial force, sharpness, lubricant)
	tentative, loading force, cutting dynamics
	wasting time