Standard Threads Reference

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Thanks to Dave DuBois for writing this article.
Last modified 2007-02-10.

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TABLE I. STANDARD THREADS - from "Machinery's Handbook", 21st Ed. American or Unified National Coarse and Fine (UNC, UNF), US Pipe (USP). British Standard Whitworth, Fine, Pipe or Association (BSW, BSF, BSP, BA). Metric: French Standard, Fine Thread and International Standard (ISO)

BSW, BSF, BSP BA and French Standard Metric is found in T Series cars (late TDs & TFs use UNF on the rear axle and for wheel studs). Whitworth (W) or BSF marked wrenches fit all fasteners except UNF on T Series cars.

SIZE	Dia.	UNC	BSW	UNF	BSF	BA		French Std.		Fine metric		ISO Metric
	(In.)	TPI	TPI	TPI	TPI	TPI	mm	TPI	mm	TPI	mm	TPI	mm
#2	0.0860	56		64
8BA	0.0866					59.1	0.43
6BA	0.1102					47.8	0.53
#4	0.1120	40		48
3mm	0.1181							50.8	0.50	72.5	0.35	50.8	0.50
#5	0.1250	40		44
1/8	0.1250	40	40	*	*
5BA	0.1260					43.0	0.59
3.5mm	0.1378							*	*	72.5	0.35	42.3	0.60
#6	0.1380	32		40
4BA	0.1417					38.5	0.66
5/32	0.1563	*	32	*	*
4mm	0.1575							33.9	0.75	50.8	0.50	36.3	0.70
3BA	0.1614					34.8	0.73
#8	0.1640	32		36
2BA	0.1850					31.4	0.81
3/16	0.1875	24	24	32	32
#10	0.1900	24		32
5mm	0.1968							33.9	0.75	50.8	0.50	31.8	0.80
1BA	0.2090					28.2	0.93
#12	0.2160	24		28
7/32	0.2188	*	*	*	28
6mm	0.2362							25.4	1.0	33.9	0.75	25.4	1.0
0BA	0.2362					25.4	1.00
#14	0.2420	24		*
1/4	0.2500	20	20	28	26
5/16	0.3125	18	18	24	22
8mm	0.3150							25.4	1.0	25.4	1.0	20.4	1.25
3/8	0.3750	16	16	24	20
1/8 BSP	0.3830				28 Straight thread
1/8 USP	0.3970				27 Straight thread
10mm	0.3937							16.9	1.5	25.4	1.0	16.9	1.5
7/16	0.4375	14	14	20	18
12mm	0.4725							16.9	1.5	16.9	1.5	14.5	1.75
1/2	0.5000	13	12	20	16
1/4 BSP	0.5180				19 Straight thread
1/4 USP	0.5260				18 Straight thread
14mm	0.5515							12.7	2.0	16.9	1.5	12.7	2.0
9/16	0.5625	12	12	18	16
5/8	0.6250	11	11	18	14
3/8 BSP	0.6560				19 Straight thread
3/8 USP	0.6620				18 Straight thread
1/2 BSP	0.8250				14 Straight thread
1/2 USP	0.8230				14 Straight thread

Article by Dave DuBois
Posted on: 2007-02-10

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