Wiseman HSS BSP Split Dies – British Standard Pipe Parallel Right Hand Thread

Wiseman HSS BSP Split Dies are manufactured from High Speed Steel (HSS) and designed for cutting new external BSP (British Standard Pipe) parallel 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 particularly useful for pipe fitting, general engineering, machinery maintenance and workshop applications.

BSP parallel threads, also known as BSPP or G threads, feature a 55° Whitworth thread profile with rounded crests and roots. Unlike BSPT (British Standard Pipe Taper) threads, BSP parallel threads maintain a constant diameter along the threaded section.

BSP parallel threads are widely used in plumbing, hydraulic systems, pneumatic equipment, industrial machinery and mechanical fittings. They are commonly used where a sealing washer, O-ring, gasket or other suitable sealing arrangement provides the seal rather than the thread itself.

Designed for right-hand thread cutting, these split dies are suitable for producing and restoring BSP parallel external threads on suitable pipes, fittings, adapters and other threaded components.

Key Features

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

• BSP Parallel Thread Form – Designed for British Standard Pipe Parallel external threads.

• Right Hand Thread – Standard clockwise tightening thread direction.

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

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

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

• Parallel Thread Design – Produces threads with a constant nominal major diameter along their length.

• Thread Cutting & Restoration – Suitable for cutting new external threads and repairing existing threads.

• Engineering & Pipe Fitting Applications – Suitable for hydraulic, pneumatic and general mechanical fittings.

Applications

Suitable for:

• Cutting new BSP parallel external threads.

• Repairing damaged or worn BSPP threads.

• Cleaning and restoring existing external threads.

• Plumbing and pipe fitting applications.

• Hydraulic fittings and adapters.

• Pneumatic equipment and compressed air fittings.

• Industrial machinery and maintenance.

• General engineering and workshop machining.

• Manufacturing replacement threaded fittings and adapters.

Recommended Use

Select the correct BSP split die size and thread pitch to match the required external thread.

BSP sizes are designated by nominal pipe sizes rather than the actual outside diameter of the thread. For example, a 1/2" BSP thread has an external major diameter of approximately 20.96mm, not 12.7mm.

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 an appropriate cutting lubricant 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 BSP parallel thread gauge or correctly specified mating component.

Where the threaded connection is required to seal against pressure, ensure that the appropriate sealing method is used and that the complete connection is suitable for the intended application.

Important

• Suitable for BSP (British Standard Pipe Parallel / BSPP) right-hand external threads.

• Also commonly identified by the G thread designation.

• Features a 55° Whitworth thread profile.

• Produces parallel threads, not tapered threads.

• Not interchangeable with BSPT or NPT dies.

• BSP nominal thread sizes do not correspond directly to the measured external thread diameter.

• BSP parallel threads generally require a separate sealing arrangement where a pressure-tight connection is needed.

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

• Requires a compatible die stock or die holder.

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