Two tools for everyday thread work: pick the hole and drill for cutting an internal thread with a tap, and find the bar diameter for cutting an external thread with a die. Covers metric, UNC/UNF inch and pipe G/R/NPT.
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Thread standards
Each page covers the three main standards:
- Metric (M) — ISO 261. The most common standard in machine-building and fasteners.
- UNC/UNF — ASME B1.1. Inch threads: UNC coarse, UNF fine. Used in the US, aerospace and imported equipment.
- Pipe G / R / NPT — ISO 228 (BSPP), ISO 7 (BSPT), ASME B1.20.1 (NPT). For piping and pneumatic / hydraulic fittings.