A static service music wire helical compression spring is needed to support a 90 N load after being compressed 50mm. The solid height of the spring cannot exceed 38mm. The free length must not exceed 100mm. The static factor of safety must equal or exceed 1.2. For robust linearity use a fractional overrun to closure of 0.15. The spring must operate over a 20mm rod with a 1.2mm diametral clearance to avoid interference between the rod and the spring. Assuming a starting spring index of 10 and a wire diameter of 1.9mm, design the spring.