¬Required force for vertical grasp = Weight x
gravitational force or Fr =
W x G = 20 lb. x 2.5 = 50 lb.
¬Friction force = coefficient of friction x normal force
or F = mN.
¬The equivalent weight of
50 lb is opposed by 2 friction forces,
one on each side of the part, so each friction force is 25 lb.
¬So N =F/m and 25/0.85 = 29.4
lb on each face of the part.