Product Description
1/4"-26 BSF Grade R zinc-plated steel hexagon-head set screws, fully threaded and manufactured to the BS 1083 imperial hexagon fastener pattern.
These British Standard Fine set screws feature a conventional external hexagon head and a full thread extending along the usable length of the fastener. They are suitable for vintage vehicles, classic motorcycles, machinery, restoration work and engineering assemblies using the traditional BSF thread system.
- Thread size: 1/4" BSF
- Threads per inch: 26 TPI
- Thread series: BSF – British Standard Fine
- Thread form: 55-degree Whitworth form
- Threading: Fully threaded set screw
- Available lengths: 1/2", 5/8", 3/4", 1" and 1 1/2"
- Approximate metric lengths: 12.7mm, 15.88mm, 19.05mm, 25.4mm and 38.1mm
- Head style: External hexagon head
- Width across flats: Approximately 7/16" / 11.11mm
- Head height: Approximately 11/64" / 4.37mm
- Material: High-tensile steel
- Strength grade: Grade R
- Approximate metric comparison: Property class 8.8
- Finish: Zinc plated
- Dimensional standard: BS 1083
- Thread standard: BS 84
- Pack sizes available: 1, 5, 10, 20, 50, 100, 250, 500 and 1000
These 1/4" BSF hexagon set screws are suitable for classic cars, vintage motorcycles, agricultural machinery, heritage equipment, restoration projects, workshop repairs and general engineering applications retaining traditional British threads.
The 26 TPI British Standard Fine thread uses the traditional 55-degree Whitworth thread form. The mating nut, threaded insert or tapped hole must have the corresponding 1/4"-26 BSF thread; UNC, UNF and metric threads are not interchangeable.
The fully threaded set-screw design provides thread engagement along the usable fastener length. This makes the screws suitable for assemblies with varying material thicknesses and applications where a plain unthreaded shank is not required.
Grade R is a traditional British high-tensile fastener designation and is commonly regarded as broadly comparable to metric property class 8.8. It should not be confused with stainless-steel grades or modern imperial SAE grades.
The 7/16" width across flats is the actual hexagon measurement. Traditional BSF spanners may be marked according to the thread diameter rather than the measured width across flats, so always confirm that the tool fits correctly before applying torque.
The zinc-plated finish provides a degree of corrosion resistance for general indoor use and sheltered outdoor environments. It is not normally recommended for prolonged exposure to marine, coastal or highly corrosive conditions.
Hexagon set-screw length is measured from directly beneath the head to the end of the screw. The hexagon head is not included in the stated length.
Please note: BS 1083 is used as the dimensional standard for these precision BSF hexagon set screws, while BS 84 defines the BSF thread series and Whitworth thread form. Specifications are intended as a guide only, and actual dimensions may vary within manufacturing tolerances. Please check the fastener where fit, strength or dimensions are critical.
| A | B | C | D | E |
| 1/4" | 1 1/2" | 7/16" | 11/64" | 26 |
| 1/4" | 1" | 7/16" | 11/64" | 26 |
| 1/4" | 1/2" | 7/16" | 11/64" | 26 |
| 1/4" | 3/4" | 7/16" | 11/64" | 26 |
| 1/4" | 5/8" | 7/16" | 11/64" | 26 |
Please Note: Specifications given are intended as a guide only. If critical to your project please check with us first.
