BSF Setscrews Grade R

What are BSF hex setscrews?

These are high tensile carbon steel hex setscrews, Grade R, also known as fully threaded BSF bolts. BSF means British Standard Fine. Compared with Whitworth/BSW at the same nominal diameter, it has a finer pitch and more threads per inch (TPI). BSF and BSW fasteners are not interchangeable.

Thread runs along the shaft rather than leaving the plain section found on a part-thread bolt. The hex head is tightened with a suitable spanner or socket.

When would I choose a fully threaded BSF bolt?

Choose this form where the assembly needs thread along the shaft—for example, to engage an existing BSF tapped hole or fasten components with a compatible nut.

For restoration and maintenance of older British vehicles, motorcycles or machinery, match the fixing specified for that particular joint. These setscrews provide a high tensile Grade R option where a fully threaded BSF fastener is required.

Can I use UNF instead of BSF?

No. The names both include “fine”, but BSF and UNF belong to different thread standards. Match the original thread system and diameter rather than choosing a fixing that looks similar. Our imperial thread identification guide helps compare the threads.

How do they differ from BSF part-thread bolts?

Our BSF part-thread hex bolts are also high tensile Grade R, but have an unthreaded section beneath the head. Choose the form required by the joint.

How do I choose the size and finish?

Check diameter and TPI against the receiving nut or tapped hole. Measure length from underneath the head to the tip, allowing for the components and thread engagement required.

Select the finish available for your size. See our fastener coating guide for help comparing finishes.

Is a hex setscrew the same as a grub screw?

No. Here, “setscrew” means a fully threaded bolt with a hex head. A grub screw is headless.

Browse matching BSF nuts and appropriately sized imperial washers to complete the fixing.

All Available Sizes & Types