Whitworth Machine Screws (Imperial BSW)

Whitworth (BSW) UNF UNC BSF BA
Slotted Cheese Head Screws

Slotted Cheese Head Screws

Whitworth - Mild Steel Zinc Plated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
1/2" ✔

Whitworth - Mild Steel Unplated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
1 3/4" ✔
2" ✔
3" ✔
Slotted Countersunk Screws

Slotted Countersunk Screws

Whitworth - Mild Steel Zinc Plated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
5/8" ✔
3/4" ✔
1" ✔ ✔
1 1/4" ✔ ✔
1 1/2" ✔ ✔
1 3/4" ✔ ✔
2 1/4" ✔
2 1/2" ✔ ✔
2 3/4" ✔
3" ✔ ✔
3 1/4" ✔

Whitworth - Mild Steel Unplated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
5/8" ✔
3/4" ✔
1" ✔ ✔
1 1/4" ✔
1 1/2" ✔ ✔
1 3/4" ✔ ✔
2" ✔ ✔
2 1/4" ✔ ✔
2 1/2" ✔ ✔ ✔
2 3/4" ✔
3" ✔ ✔
3 1/4" ✔
3 1/2" ✔ ✔
4" ✔ ✔ ✔
6" ✔
Pozi Countersunk Screws

Pozi Countersunk Screws

Whitworth - Mild Steel Zinc Plated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
1 1/4" ✔

Whitworth - Mild Steel Unplated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
1" ✔
1 1/4" ✔
3" ✔
Slotted Raised Countersunk Screws

Slotted Raised Countersunk Screws

Whitworth - Mild Steel Unplated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
1/2" ✔
5/8" ✔
1 1/4" ✔
Slotted Mushroom Head Screws

Slotted Mushroom Head Screws

Whitworth - Mild Steel Zinc Plated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
3/8" ✔
1 1/2" ✔
1 5/8" ✔
2 1/4" ✔
2 1/2" ✔ ✔
3" ✔
3 1/2" ✔

Whitworth - Mild Steel Unplated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
1/2" ✔ ✔
1" ✔
1 1/4" ✔
2" ✔
3 1/2" ✔
Pozi Pan Head Screws

Pozi Pan Head Screws

Whitworth - Mild Steel Zinc Plated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
1 3/4" ✔

Whitworth - Mild Steel Unplated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
2 1/2" ✔
3 3/4" ✔
Slotted Round Head Screws

Slotted Round Head Screws

Whitworth - Mild Steel Zinc Plated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
1/2" ✔
3/4" ✔
2" ✔
2 1/2" ✔ ✔
3 1/2" ✔

Whitworth - Mild Steel Unplated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
1/2" ✔ ✔
5/8" ✔
3/4" ✔
1" ✔
1 1/2" ✔ ✔
2 1/2" ✔ ✔
3 1/2" ✔

Whitworth - Brass

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
1 1/2" ✔
Hex Head Setscrews

Hex Head Setscrews

Whitworth - Mild Steel Unplated

Length5/32"3/16"7/32"1/4"5/16"3/8"1/2"
5/8" ✔

Related Technical Resources

More information

Whitworth (BSW) machine screws are widely used in restoration, maintenance and heritage engineering where original imperial fasteners must be matched. Their coarse 55° thread form provides strong engagement and reliable performance in timber, steelwork and older machinery.

Typical uses include machinery repair, equipment refurbishment, classic automotive work, agricultural maintenance and any application where compatibility with traditional British Standard Whitworth threads is essential.

The Whitworth thread form was introduced in 1841 by Sir Joseph Whitworth and became the first nationally standardised screw thread in the world. Its rounded crests and 55° angle were designed for strength and ease of manufacture using the machinery of the time. Whitworth threads remain important today in restoration and heritage engineering.