JAPAN SKC HAND TAPES - No: 801 MM (SPECIAL SIZE)

More info

Japan's SKC No. 801 is a widely recognized series of high-grade carbon steel (SKS) hand taps.¹ While "Normal" sizes follow standard ISO/JIS coarse thread pitches, the "Special Size" designation refers to metric taps with fine pitches or non-standard diameters used in specialized automotive and industrial machinery.

Key Features of SKC No. 801

Material: High-grade Carbon Steel (SKS).²
Set Composition: Usually sold as a 3-piece set consisting of:
1. Taper (1st): 8–10 threads chamfered for easy starting.³
2. Plug (2nd): 3–5 threads chamfered for general use.
3. Bottoming (3rd): 1.5 threads chamfered for tapping to the bottom of a hole.⁴
Application: Suitable for heavy-duty hand tapping in steel, brass, aluminum, and cast iron.⁵

Special Sizes (Metric Fine/Non-Standard)

The "Special Size" range typically covers diameters from M3 to M30 but with pitches that differ from standard hardware store stock. Common special sizes in the 801 series include:

Nominal Size	Pitch (MM) - Special/Fine	Normal (Coarse) for Comparison
M6	0.75	1.0
M8	0.75, 1.0	1.25
M10	0.75, 1.0, 1.25	1.5
M12	1.0, 1.25, 1.5	1.75
M14	1.25, 1.5	2.0
M16	1.0, 1.5	2.0
M20	1.0, 1.5, 2.0	2.5