UNC fastener in tension
Thread geometry, SAE proof strength and initial preload for a UNC fastener under tension.
Initial preload, F_i2434 lb
Initial preload, F_i10.828 kN
Proof strength, S_p85 kpsi
Proof strength, S_p586.05 MPa
Major diameter, d0.25 in
Major diameter, d6.35 mm
Threads per inch, N20
Pitch, P = 1/N0.05 in
Pitch diameter, d_p0.218 in
Minor diameter, d_r0.185 in
Tensile stress area, A_t31.82 1e-3 in²
Method & references
- UNC fastener in tension — SAE proof-strength system.
The computation is a literal port of the original client-side JavaScript from /calculators/unc_1.htm. Results are verified equal to the original by an automated golden-master test. No formula has been re-derived or “improved”.