Ahelical compression spring made from unpeened oil tempered wire with plain and ground ends is needed to support a load that varies between 1 lbf and 17 lbf with a stroke of 1 inch. the solid height of the spring cannot exceed 2 inches and the free length must not exceed 4 inches. the spring must operate over a 0.75-inch diameter rod. a 0.06 inch diametral clearance allowance should be adequate to avoid interference between the rod and the spring due to out-of-round coils. design the spring with a minimum static safety factor of ns