JAPAN SKC ROUND DIE - No: 822 BSW

More info

The SKC Japan Round Die No. 822 (BSW variant) is a high-quality threading tool designed for cutting external threads on cylindrical rods or repairing damaged threads.¹ SKC is a well-regarded Japanese brand specializing in hand-threading tools, and the "822" series specifically identifies their Adjustable Round Split Dies.²

Key Specifications

Thread Standard: BSW (British Standard Whitworth).³ This is a 55° thread angle standard widely used in older machinery and British engineering.
Series Number: 822 (Indicates the adjustable round split die model).⁴
Material: Alloy Tool Steel (often referred to as SKS or Carbon Steel).⁵ It is hardened and tempered, making it ideal for general-purpose threading in mild steel, brass, copper, and aluminum.⁶
Feature: Adjustable (Split).⁷ There is a small slit in the side of the die. When placed in a die stock, the set screws allow you to slightly expand or compress the die to achieve a tighter or looser fit for the bolt.⁸

Common BSW Sizes & Dimensions

The No. 822 series comes in various sizes.⁹ The Outside Diameter (OD) of the die determines which Die Stock (handle) you need:

Thread Size (inch)	Threads Per Inch (TPI)	Common Outside Diameter (OD)
1/4"	20	1" (25mm) or 1-1/2" (38mm)
5/16"	18	1" (25mm) or 1-1/2" (38mm)
3/8"	16	1-5/16" (35mm)
1/2"	12	1-1/2" (38mm)
5/8"	11	1-1/2" (38mm)
3/4"	10	1-1/2" (38mm) or 2" (50mm)

Usage Tips

Chamfer the Rod: Before starting, file a slight taper (chamfer) onto the end of the rod. This helps the die "bite" into the metal more easily.
Use Lubrication: Always use cutting oil (or a light machine oil) to reduce friction and clear away metal chips.¹⁰
The "Back-and-Forth" Method: Turn the die half a turn forward, then a quarter turn back. This breaks the metal chips and prevents the die from jamming or breaking.
Check Alignment: Ensure the die is perfectly perpendicular to the rod at the start to avoid "drunken" (crooked) threads.