Product Description
3/8"-20 BSF Grade R zinc-plated steel hexagon-head set screws, fully threaded and manufactured to the traditional BS 1083 British Standard Fine fastener pattern.
These high-tensile imperial set screws feature a conventional external hexagon head and a full BSF thread extending along the usable fastener length. They are suitable for classic vehicles, vintage motorcycles, agricultural machinery, heritage equipment and engineering assemblies that retain traditional British threads.
- Thread size: 3/8" BSF
- Threads per inch: 20 TPI
- Thread series: BSF – British Standard Fine
- Thread form: 55-degree Whitworth form
- Threading: Fully threaded set screw
- Selectable lengths: 3/4", 1" and 1 1/4"
- Approximate metric lengths: 19.05mm, 25.4mm and 31.75mm
- Head style: External hexagon head
- Width across flats: Approximately 19/32" / 15.08mm
- Head height: Approximately 1/4" / 6.35mm
- 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, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 50, 100, 250, 500 and 1000
These 3/8" BSF hexagon set screws are commonly used on classic British cars, vintage motorcycles, tractors, agricultural machinery, heritage equipment, restoration projects and older engineering assemblies.
The 20 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 3/8"-20 BSF thread. BSF, BSW, UNC, UNF and metric threads are not interchangeable.
The fully threaded set-screw design provides thread engagement along the usable length of the fastener. 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, SAE grades or metric property-class markings.
The 19/32" width across flats is the actual measured hexagon size. Traditional BSF spanners may be marked according to the nominal thread diameter rather than the measured width across flats, so always confirm correct tool fit before applying torque.
The zinc-plated finish provides a degree of corrosion resistance for general indoor use and sheltered outdoor applications. It is not normally recommended for prolonged exposure to marine, coastal or highly corrosive environments.
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 reference for this traditional BSF hexagon set-screw pattern, while BS 84 defines the BSF thread series and 55-degree thread form. The dimensional table also contains a 1 1/2" length, but this size is not currently shown in the selectable options. Specifications are intended as a guide only; please check availability and dimensions where critical.
| A | B | C | D | E |
| 3/8" | 1 1/4" | 19/32" | 1/4" | 20 |
| 3/8" | 1" | 19/32" | 1/4" | 20 |
| 3/8" | 3/4" | 19/32" | 1/4" | 20 |
| 3/8" | 1 1/2" | 19./32" | 1/4" | 20 |
Please Note: Specifications given are intended as a guide only. If critical to your project please check with us first.
