Whitworth (BSW) UNF UNC BSF BA

BA Imperial Machine Screws

Slotted Cheese Head Screws

Slotted Cheese Head Screws

BA - Mild Steel Zinc Plated

Length8BA6BA4BA2BA
1 1/2" ✔
2 3/8" ✔
2 3/4" ✔
2 7/8" ✔

BA - Mild Steel Unplated

Length8BA6BA4BA2BA
2 3/4" ✔
3 1/4" ✔
Slotted Mushroom Head Screws

Slotted Mushroom Head Screws

BA - Brass

Length8BA6BA4BA2BA
5/16" ✔
Pozi Pan Head Screws

Pozi Pan Head Screws

BA - Mild Steel Zinc Plated

Length8BA6BA4BA2BA
7/8" ✔
2 3/8" ✔
4" ✔

BA - Mild Steel Unplated

Length8BA6BA4BA2BA
2 7/8" ✔
3" ✔
Slotted Round Head Screws

Slotted Round Head Screws

BA - Mild Steel Zinc Plated

Length8BA6BA4BA2BA
3" ✔
3 1/2" ✔

BA - Mild Steel Unplated

Length8BA6BA4BA2BA
2 1/4" ✔
2 1/2" ✔
3 1/8" ✔
3 1/2" ✔

BA - Brass

Length8BA6BA4BA2BA
5/8" ✔
1 1/2" ✔
3" ✔
Hex Head Setscrews

Hex Head Setscrews

BA - Mild Steel Zinc Plated

Length8BA6BA4BA2BA
1/2" ✔
5/8" ✔

BA - Mild Steel Unplated

Length8BA6BA4BA2BA
5/8" ✔
1 1/2" ✔

BA - A2 Stainless

Length8BA6BA4BA2BA
1/2" ✔

BA - Brass

Length8BA6BA4BA2BA
7/16" ✔
1/2" ✔

Related Technical Resources

More information

BA (British Association) machine screws are widely used in electronics, instruments, model engineering, clocks, scientific equipment and precision mechanisms. Their fine thread form and small diameters make them ideal for delicate assemblies where accuracy and reliability are essential.

Typical uses include electrical terminals, control panels, gauges, meters, optical equipment, model engineering projects and restoration of vintage instruments. BA screws remain a standard choice in many precision engineering fields due to their consistent sizing and well‑defined thread geometry.

The British Association thread system was introduced in 1903 for small screw threads used in electrical and scientific instruments. BA threads use a 47.5° thread angle and a logarithmic pitch series, giving excellent performance in miniature engineering applications. They continue to be important in electronics, instrumentation and restoration work.