BSI - BS 3409-1
Specification for The tapping of holes to receive wire thread inserts (UNC and UNF threads) - Part 1: Diameters 1/4 in and over
|Publication Date:||16 August 1961|
|ICS Code (Taps and threading dies):||25.100.50|
Specifies limits of size for tapped holes to accommodate wire thread inserts to provide thread sizes from 1⁄4 in to 11⁄2 in UNC inclusive and from 1⁄4 in to 1 in UNF inclusive. It includes recommendations for general dimensions and limits of size on the threaded portion of screwing taps intended to produce holes to the limits specified, together with details of a recommended gauging system for checking them.