BS 3409-1:1961

Specification for the tapping of holes to receive wire thread inserts (UNC and UNF threads). Diameters ¼ in and over | Status: Current, Confirmed

1 Scope This British Standard comprises three sections: Section 1, which specifies limits of size for tapped holes to accommodate wire thread inserts to provide thread sizes from ¼ in to 1½ in UNC inclusive and from ½ in to1in UNF inclusive; Section 2, which recommends screwing taps intended to produce holes to the limits of size specified in Section 1; Section 3, which gives a recommended gauging system for checking the tapped holes. Figure 1 — Basic form of Unified insert assembly