A helical compression spring is to be cycled between 150 lbf and 300 lbf with a 1-in stroke. The number of cycles is low, so fatigue is not an issue. The coil must fit in a 2.1-in diameter hole with a 0.1-in clearance all the way around the spring. Use unpeened music wire with squared and ground ends.
(a) Determine a suitable wire diameter, using a spring index of C = 7.
(b) Determine a suitable mean coil diameter.
(c) Determine the necessary spring constant.
(d) Determine a suitable total number of coils.
(e) Determine the necessary free length so that if the spring were compressed to its solid length, there would be no yielding.