UNC coarse bolt chart (ASME B1.1)

14 rows · EngiRef · sample of the first 8 rows

UNC coarse bolt chart (ASME B1.1). The Unified coarse series from the numbered sizes upward: threads per inch, major and internal minor diameters, tensile stress area and wrench size, all in millimetres.
Size	Threads per in	Major dia D mm	Minor dia D₁ mm	Tensile area mm²	Wrench mm
#4-40	40	2.84	2.01	3.89	5.56
#6-32	32	3.51	2.49	5.86	6.35
#8-32	32	4.17	3.15	9.04	8.73
#10-24	24	4.83	3.51	11.3	9.53
1/4-20	20	6.35	4.98	20.5	11.11
5/16-18	18	7.94	6.4	33.8	12.7
3/8-16	16	9.53	7.8	50	14.29
7/16-14	14	11.11	9.14	68.6	16.67

Tensile stress areas follow ASME B1.1, At = 0.7854(D − 0.9743/n)² in², converted at 645.16 mm²/in². Minor diameter is the INTERNAL thread minor D₁ = D − 1.0825p. Verify against the current standard and the fastener manufacturer's data before safety-critical design.

Reference values are provided for study and quick reference. Verify against current standards and manufacturer data before safety-critical design.

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