Wiseman HSS BSB Split Dies – British Standard Brass Right Hand Thread

Wiseman HSS BSB Split Dies are manufactured from High Speed Steel (HSS) and designed for cutting new external BSB (British Standard Brass) threads, as well as repairing, cleaning and restoring damaged or worn existing threads.

These round split dies feature an adjustable design, allowing minor adjustments to the thread fit when used with a suitable die stock. They are suitable for precision engineering, instrument making, restoration and general workshop applications.

British Standard Brass threads feature a 55° Whitworth thread profile with rounded crests and roots. Unlike BSW and BSF threads, which use different pitches depending on the nominal diameter, the BSB thread series uses a constant pitch of 26 threads per inch (TPI) across its standard range of sizes.

BSB threads are traditionally associated with brass components, electrical fittings, instruments, model engineering and specialist threaded parts. Although commonly used with brass, the BSB designation refers to the thread form and dimensions rather than restricting the thread to a particular material.

Designed for right-hand thread cutting, these split dies are suitable for producing and restoring BSB threads on rods, studs, fittings and other externally threaded components.

Key Features

• High Speed Steel (HSS) – Durable construction for reliable thread cutting and maintenance.

• BSB Thread Form – Designed for British Standard Brass external threads.

• Right Hand Thread – Standard clockwise tightening thread direction.

• Adjustable Split Design – Allows minor adjustment of the thread fit when used with a suitable die stock.

• Round Die Construction – Designed for use with compatible die stocks and die holders.

• 26 TPI Thread Pitch – Constant 26 threads per inch across the standard BSB thread series.

• 55° Whitworth Thread Profile – Features rounded crests and roots.

• Thread Cutting & Restoration – Suitable for producing new threads and restoring existing threads.

• Specialist Engineering Applications – Suitable for instrument making, model engineering and restoration work.

Applications

Suitable for:

• Cutting new BSB external threads on rods, studs and fittings.

• Repairing damaged or worn British Standard Brass threads.

• Cleaning and restoring existing external threads.

• Brass fittings and threaded components.

• Electrical fittings and traditional equipment.

• Instrument making and precision engineering.

• Model engineering and miniature machinery.

• Restoration of vintage equipment and specialist components.

• General engineering and workshop machining.

Recommended Use

Select the correct BSB split die diameter to match the required external thread. Standard British Standard Brass threads use a pitch of 26 TPI.

Secure the die in a compatible die stock or holder, ensuring the adjustment screws are correctly positioned. Prepare the workpiece to the appropriate diameter and apply a suitable chamfer to help the die start squarely.

Apply a cutting lubricant appropriate to the workpiece material and rotate the die clockwise to cut the thread. Periodically reverse the die slightly to break and clear chips where appropriate for the material and cutting conditions.

The adjustable split design allows minor adjustments to the thread fit. Check the finished thread using a suitable BSB thread gauge or correctly specified mating component.

Important

• Suitable for BSB (British Standard Brass) right-hand external threads only.

• Standard BSB threads use 26 TPI regardless of nominal thread diameter.

• Features a 55° Whitworth thread profile.

• Not interchangeable with BSW, BSF, BSP, metric or Unified threads solely because the nominal diameter or pitch appears similar.

• Adjustable round split die for cutting and restoring external threads.

• Requires a compatible die stock or die holder.

• Select the correct nominal thread diameter before use.