Westfield Fasteners Product Specification:

BS 3410 - Flat Washers Table 3 Light Gauge

This product guide contains the specification for British Standard 3410 flat washers, specifically those to light gauge table 3 specification. These washers are available in imperial sizes only, and are a stock item from Westfield Fasteners.

Product Description

Thin or light gauge flat washers designed for use with imperial sized bolts and screws. These washers are therefore suitable for use with our UNC and UNF threads, and also with BSW and BSF thread standards, amongst others. The standard refers to these table 3 washers as small bright washers.

Scope of the BS Standard

BS 3410 is a general British Standard for metal washers used for engineering purposes, and covers sizes from 1/4 inch up to 2 inches in diameter. The standard allows for chamfered edges, but these are not seen in off-the-shelf parts. See figure 1 and table below for dimensions and tolerances.

BS 3410 specifies washers made in steel and brass specifically, but makes provision for manufacture in any other material.

technical drawing of a table 3 flat light washer

Nominal size of bolt or screw	Hole Diameter, d1		Outer diameter d2		Thickness, h
Nominal size of bolt or screw	max.	min.	max.	min.	Light Gauge
inches	inches	inches	inches	inches	SWG	inches
1/4	0.270	0.265	0.562	0.557	20	0.036
5/16	0.333	0.328	0.625	0.620	19	0.040
3/8	0.395	0.390	0.750	0.745	18	0.048
7/16	0.458	0.453	0.875	0.870	18	0.056
1/2	0.520	0.515	1.000	0.995	17	0.056
9/16	0.593	0.588	1.125	1.115	17	0.056
5/8	0.656	0.651	1.250	1.240	15	0.072
3/4	0.781	0.776	1.500	1.490	15	0.072
7/8	0.906	0.901	1.625	1.615	15	0.072
1	1.031	1.026	1.875	1.868	15	0.072
1 1/8	1.156	1.151	2.125	2.115	13	0.092
1 1/4	1.281	1.276	2.375	2.355	11	0.116
1 3/8	1.406	1.401	2.625	2.605	-	-
1 1/2	1.531	1.526	2.875	2.855	-	-
1 3/4	1.781	1.776	3.375	3.345	-	-
2	2.031	2.026	3.625	3.595	-	-

BS 3410 - Flat Washers Table 3 Light Gauge

Figure 1: Flat Washer to BS 3410 Table 3 Light Spec.

Table 1: Dimensions & Tolerances