HSS Hexagon Die Nuts for External Thread Repair & Restoration
Explore our range of High Speed Steel (HSS) Hexagon Die Nuts, designed for cleaning, chasing, repairing and restoring existing external threads on bolts, studs, threaded rods and other engineering components.
Our range includes Metric Coarse, UNC, UNF, UNEF, UNJF, UNS, BSW, BSF, BA, BSP, BSPT and NPT thread forms, together with specialist left-hand threading die nuts.
Manufactured from High Speed Steel, these hexagonal dies are suitable for general engineering, automotive maintenance, machinery repairs, fabrication and restoration applications.
Unlike adjustable round split dies, hexagon die nuts feature a fixed, non-adjustable design and can generally be driven using a suitable spanner or hexagonal die holder. They are primarily intended for chasing and restoring existing threads rather than cutting completely new threads into unthreaded material.
Whether you are cleaning damaged bolt threads, removing burrs or restoring existing threaded components, our selection of metric and imperial hexagon die nuts provides solutions for a wide range of engineering applications.
Available Hexagon Die Nut Thread Types
Metric Hexagon Die Nuts
Metric Coarse (M)
Metric Coarse hexagon die nuts are designed for cleaning and restoring standard ISO metric external threads. Featuring a 60° thread profile, they are widely used for general engineering, automotive repairs, machinery maintenance and industrial applications.
Metric Coarse threads are commonly found on standard metric bolts, studs and threaded fasteners.
Unified Thread Hexagon Die Nuts
UNC – Unified National Coarse
UNC hexagon die nuts are designed for chasing and repairing Unified National Coarse external threads. Featuring a 60° thread profile, UNC threads are commonly used in general engineering, machinery and industrial equipment.
UNF – Unified National Fine
UNF hexagon die nuts are suitable for cleaning and restoring Unified National Fine threads, commonly found in automotive engineering, machinery and precision mechanical components.
UNEF – Unified National Extra Fine
UNEF hexagon die nuts are designed for repairing extra-fine Unified threads used in specialist engineering applications requiring finer thread pitches.
UNJF – Unified National J-Series Fine
UNJF hexagon die nuts are intended for the specialist Unified J-Series Fine thread form, which incorporates a controlled external root radius to reduce stress concentrations. These threads are used in aerospace and other high-performance engineering applications. Any thread restoration must comply with the applicable component specification.
UNS – Unified National Special
UNS hexagon die nuts are designed for special Unified thread diameter and pitch combinations outside the standard UNC, UNF and UNEF series.
British Standard & Whitworth Hexagon Die Nuts
BSW – British Standard Whitworth
BSW hexagon die nuts feature a 55° Whitworth thread profile with rounded crests and roots. Commonly used for repairing threaded components on older British machinery, vintage vehicles and traditional engineering equipment.
BSF – British Standard Fine
BSF hexagon die nuts use a finer-pitch Whitworth thread form and are particularly useful for classic vehicle restoration, machinery maintenance and traditional British engineering applications.
BA – British Association
BA hexagon die nuts feature a distinctive 47.5° thread profile and are available in numbered thread sizes. They are particularly useful for model engineering, electrical equipment, scientific instruments and small precision components.
Pipe Thread Hexagon Die Nuts
BSP – British Standard Pipe Parallel
BSP hexagon die nuts are designed for cleaning and restoring parallel external pipe threads with a 55° Whitworth thread profile. Commonly used for hydraulic fittings, pneumatic equipment, pipe connections and industrial machinery.
BSPT – British Standard Pipe Taper
BSPT hexagon die nuts are designed for restoring tapered British Standard Pipe threads. Featuring a 55° Whitworth thread profile, BSPT threads are commonly used in pipework and fittings where a pressure-tight threaded connection is required.
NPT – National Pipe Taper
NPT hexagon die nuts are designed for repairing American National Pipe Taper external threads. Featuring a 60° thread profile and tapered thread geometry, NPT threads are commonly found on American pipe fittings, hydraulic equipment, pneumatic systems and industrial machinery.
Left Hand Hexagon Die Nuts
Our range also includes specialist Left Hand Hexagon Die Nuts, designed for cleaning and restoring external threads that tighten anticlockwise rather than clockwise.
Available thread forms include:
Left-hand threads are commonly specified for rotating assemblies, specialist machinery, reverse-threaded fasteners and applications where the equipment design requires an opposite thread direction.
Why Choose HSS Hexagon Die Nuts?
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High Speed Steel Construction – Suitable for thread repair and maintenance across a range of machinable engineering materials.
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Hexagonal Design – Can generally be driven using a suitable spanner or hexagonal die holder.
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Thread Chasing & Restoration – Designed for cleaning and repairing existing external threads.
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Fixed Thread Dimensions – Non-adjustable construction for the specified thread size and pitch.
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Metric & Imperial Options – A selection of common and specialist thread forms.
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Right Hand & Left Hand Threads – Options for standard and reverse-threaded applications.
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Workshop Versatility – Suitable for engineering, maintenance, automotive repairs and restoration.
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Multiple Thread Sizes – Choose the correct diameter and pitch for the existing thread.
Hexagon Die Nuts vs Split Dies – What's the Difference?
Hexagon Die Nuts
Hexagon die nuts, also known as hex dies or thread chasers, are primarily used for cleaning, chasing and restoring existing external threads.
Their fixed, non-adjustable design makes them particularly convenient for removing burrs, cleaning damaged threads and maintaining threaded fasteners.
Round Split Dies
Round adjustable split dies are primarily designed for cutting new external threads. Their split construction allows minor adjustment of the thread fit when used with a compatible die stock.
For producing completely new threads on unthreaded material, an appropriately specified round split die is generally the preferred option.
Choosing the Correct Hexagon Die Nut
When selecting a hexagon die nut, it is important to identify the correct:
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Thread Type – Metric, UNC, UNF, BSW, BSF, BA, BSP, BSPT, NPT or another thread series.
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Thread Diameter – The nominal diameter of the existing thread.
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Thread Pitch – Specified in millimetres for metric threads or threads per inch (TPI) for imperial threads.
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Thread Direction – Right hand or left hand.
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Thread Geometry – Parallel or tapered, where applicable.
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Hexagon Outside Size – The external dimensions of the die nut, particularly when using a dedicated die holder.
Different thread forms are not necessarily interchangeable, even when their nominal diameters or thread pitches appear similar.
For best results, ensure the existing thread is correctly identified, use suitable cutting lubricant where appropriate and start the die nut squarely to avoid cross-threading.
Where a threaded component is severely damaged, worn beyond tolerance or safety-critical, replacement may be necessary rather than thread restoration.
Shop HSS Hexagon Die Nuts at Rennie Tool
Browse our selection of HSS hexagon die nuts for metric, imperial, British Standard, Unified and specialist thread repair applications.
Whether you are restoring damaged bolt threads, maintaining industrial machinery or repairing vintage equipment, find the correct thread form, diameter and pitch for your application.
