Dies: thread, type & material
Start from the thread, because it defines the die; the type, material and coating follow. A die cuts an external (male) thread onto round bar, with every edge at once and high torque, which is why the right bar diameter matters as much as the tool itself.
THE THREAD8
The first thing you choose. The thread defines the die; everything else (type, material, coating) follows from it. Click a standard to see only its dies.
The standard thread in Europe, 60° flank angle. Named by diameter and pitch in millimetres: M8 x 1.25. Coarse pitch is the default for general use.
A parallel pipe thread (55°) for hydraulic and pneumatic connections. It does not seal on its own: sealing is done with a washer or PTFE tape.
Same diameter as metric, but a finer pitch (M8 x 1 instead of 1.25). It holds better under vibration, works in thin walls and allows finer adjustment.
The American fine thread (Unified Fine). More threads per inch than UNC, so it holds better under vibration and adjusts more precisely.
The American coarse thread (Unified Coarse), 60° flank angle. Named by diameter in inches and threads per inch: 1/4" x 20.
British Whitworth, with a 55° flank angle instead of 60°. An older standard found on British machinery and old work. It is not interchangeable with UNC.
The American tapered pipe thread (60°). It seals on the thread itself as it tightens, which is why it needs a tapered tap and the correct depth.
British Standard Fine: the Whitworth form with a 55° flank angle, but a finer pitch than BSW. The same system as BSW, in a fine version.
THE TYPE OF DIE3
The shape of the die tells you what job it does: the round one cuts a new thread and adjusts; the hex one is for cleaning up and repairing an existing thread with an ordinary spanner.
The classic die: round, usually adjustable (split, with adjusting screws). It goes in a die stock and is the choice for cutting a new thread from scratch. The adjustment lets you take a first, looser pass and a final one at the right fit.
A hexagonal die ("die nut") turned with an ordinary spanner, no die stock needed. Mainly for cleaning up or repairing a damaged or rusted thread, not for cutting from scratch, since it does not adjust and will not give as clean a result.
A set of dies in a case with the most common sizes together, often with the die stock. The economical way to cover a range of sizes from the start.
THE MATERIAL YOU ARE CUTTING3
Start here. Pick the material you are cutting and the collection filters down to only the tools that work it. The letters P/M/K/N/S/H are the ISO 513 standard, used by every manufacturer; the same letter means the same material in any catalogue.
In detail, per group: [P] Steel · [M] Stainless · [H] Hardened.
Plain and alloy steels: the largest and most forgiving group. They give a long, continuous chip, so chip control is what matters.
Stainless steels. They work-harden locally as you cut them, weld to the edge, and do not carry heat away. They want cobalt, a steady feed with no dwelling, and plenty of coolant.
Hardened materials, typically above 45 HRC. They demand carbide and a thermally stable coating; plain HSS simply dulls immediately.
THE TOOL MATERIAL2
Click a material to filter the collection. For a detailed description of the grades see the Cutting Tool Materials article.
THE COATINGS1
The coating you will find on our dies. Click to see only those.