Thread run‑outs are the transitional zones where a full‑form thread gradually disappears at the end of a threaded portion. Thread undercuts are narrow, recessed grooves cut at the end of a thread, often used to provide clearance for a threading tool or to ensure that a mating part can seat flush against a shoulder. By standardising these features, DIN 76‑1 guarantees interchangeability, predictable strength, and reliable assembly of threaded components.
The use of DIN 76A offers several benefits, including: din 76a pdf
DIN 76-1 is the German standard that specifies dimensions for and thread undercuts for ISO metric threads. It ensures that when a bolt is tightened into a tapped hole, it doesn’t bottom out or experience stress concentrations due to the transition between the threaded and unthreaded portion of the shank. Key Forms of DIN 76 Thread run‑outs are the transitional zones where a
: The undercut's width and depth are strictly calculated based on the thread pitch (P) Comparison The use of DIN 76A offers several benefits,
| Topic | Key Point | | --- | --- | | | DIN 76‑1: Thread run‑outs and thread undercuts — Part 1: For ISO metric threads in accordance with DIN 13‑1 | | Main purpose | Standardizes dimensions for thread run‑outs and undercuts on external and internal ISO metric threads | | Three forms | A (external, normal length – g₂ ₘₐₓ = 3.5 P) B (external, short design – g₂ ₘₐₓ = 2.5 P, special tools) C (internal) | | Comparison with ISO | DIN 76‑1 adds Form B and covers internal threads; ISO 3508/4755 do not cover internal threads | | Latest edition | DIN 76‑1:2025‑07 (includes correction for P = 5.5 mm radius value) | | CAD/CNC support | Integrated in PTC Creo, HEIDENHAIN, AutoCAD Mechanical, and many standard parts libraries | | How to obtain | Purchase official PDF from Beuth Verlag, DIN Media, Intertek Inform, ANSI, or NSAI |
Now that you understand the importance of this standard, locate a legitimate , print the thread undercut table, and pin it up in your workshop. Your bolts—and your machines—will last much longer.