Music Wire Spring Calculator

Inputs

Wire diameter (d)

ASTM A228 music wire diameter.

Mean coil diameter (D)

Center-to-center coil diameter. Outside diameter is D + d.

Active coils (Na)

Coils that deflect under load.

Free length (L0)

Unloaded spring length used for travel-to-solid.

Working deflection (x)

Compression at the working load point.

End type

Sets inactive end coils and solid height.

Default result

Spring rate(k)

1.239N/mm

Also computed

Spring index(C)10

Corrected shear stress(tau)361.2MPa

Below music-wire static allowable stress.

Allowable shear stress995MPa

Estimated tensile strength(Sut)2,211MPa

Force at deflection(F)12.39N

2.786 lbf

Solid height(Ls)10mm

This load line uses ASTM A228 music-wire material assumptions and stops at the calculated travel-to-solid.

Method notes 3 notes

Material is fixed to ASTM A228 music wire with G = 79.3 GPa and static allowable shear stress taken as 45% of estimated tensile strength.
Music wire is high-strength cold-drawn carbon steel and is commonly limited to about 250 F / 121 C service temperature.
Static check only: fatigue, set, shot peening, corrosion, relaxation and supplier tolerances are not modeled.