The latest Table 2 of the 2025 edition presents the (dimensions for thread run‑out and thread undercut for internal threads). For internal threads, design values for length and relief diameter depend both on thread pitch and on the nominal diameter of the hole.
Understanding the precise dimensions of a undercut is essential for preventing tool breakage, reducing stress concentrations, and ensuring that mating parts can thread seamlessly together up to their intended limit. din 76a pdf
Always obtain the standard from an authorized source to ensure you have the complete, correct, and legally usable document. The latest Table 2 of the 2025 edition
: Centers on ISO metric threads (both coarse and fine pitches) in accordance with DIN 13-1. It defines Forms A and B for external applications. Always obtain the standard from an authorized source
: The radius of the transition between the shank and the undercut. Standard Dimensions (Metric ISO Threads)