Button Dies

Button Dies

Button dies (also called round dies or circular dies) are the standard tool for cutting external threads on bar, rod, and studs. Held in a die stock, button dies cut precise helical threads in a single or multi-pass operation and are the practical choice for threading in the workshop, on the lathe, or in the field. AIMS Industrial supplies button dies in a full range of thread forms and sizes for metalworking, maintenance, and engineering applications.

Thread Forms Available

Button dies are manufactured in all major thread forms used in Australian engineering and trade:

• Metric (M): ISO metric threads — the standard for new engineering in Australia. Available in coarse pitch (most common) and fine pitch for vibration-resistant or thin-walled applications.
• UNC (Unified National Coarse): American standard coarse thread. Common in equipment manufactured to American specifications and in automotive and machinery applications.
• UNF (Unified National Fine): American standard fine thread. Used in precision assemblies and where coarse thread engagement is insufficient.
• BSW (British Standard Whitworth): The original British thread form. Still found on older Australian machinery and equipment manufactured prior to metrication.
• BSP (British Standard Pipe): Pipe thread form used for fluid system connections — threaded onto pipe nipples and fittings in pneumatic and plumbing installations.

Material and Grade

Button dies are available in High Speed Steel (HSS) and carbon steel grades. HSS dies are the correct choice for production threading and for harder materials including stainless steel, alloy steel, and hardened steel rod. Carbon steel dies are less expensive and suit occasional use on mild steel and softer metals. For workshop and engineering use, HSS is the recommended grade — the longer tool life makes it more economical over time.

Die Stocks and Holders

Button dies require a die stock to hold the die and provide leverage for threading. Die stocks are sized by the die outside diameter — the three most common button die ODs are 25 mm, 38 mm, and 65 mm. Match the die OD to the die stock you have, or purchase a die and stock as a set. Adjustable die stocks allow the cutting depth to be set for a first roughing pass followed by a finishing pass to achieve the correct thread fit.

Cutting Lubrication

Threading without cutting lubricant on steel produces rough, torn thread flanks and rapidly dulls the die cutting edges. Apply cutting oil to the work before and during threading. Tapping fluid, neat cutting oil, or a dedicated thread cutting compound all work well. For stainless steel, use a sulphurised cutting oil — the sulphur additive prevents the galling that occurs when cutting stainless dry or with an inappropriate lubricant.

Order Button Dies from AIMS Industrial

AIMS Industrial stocks button dies across metric, UNC, UNF, BSW, and BSP thread forms in HSS grade. For help identifying the correct die size or thread pitch, or to order a matching die and stock combination, contact our team.