What is stick-slip?
Stick-slip is the false impression you get when a screw has been tightened to an appropriate stress level when it has not. Instead of the screw rotating uniformly as the torquing effort continues, there can be a point before final torque readings have been achieved where this uniform rotation converts to a stop and start pattern. The torsioning effort on the screw is being absorbed as excess friction between the threads or the underside of the head and the mating parts of the clamp body instead of contributing to stress in the joint element. If the stresses are low, that collar will not hold well. This stick-slip condition can be elusive. A silky-smooth operation of the clamping screw during torquing is your best assurance that stick-slip is not present. Use of torque wrenches will not help overcome stick-slip because, in fact, the springiness of most torque wrenches invites this condition.
