The standard defines the dimensions and design specifications for thread run-outs and thread undercuts for ISO metric threads. It ensures that threads terminate cleanly, preventing assembly issues like burrs or incomplete fits.
If you are looking for specific measurements for your CAD models or shop floor specs, these guides are the gold standard: din 76-a pdf
Without an undercut, a nut or mating part cannot sit directly against the "heel" or shoulder of a bolt. Standardization: The official current version is
(Undercut Diameter): The diameter of the recessed portion. It is always smaller than the minor diameter of the thread. (Undercut Width): The longitudinal width of the recess. din 76-a pdf
The official current version is . You can access or purchase technical guides and tables from these sources:
Covers specialized profiles like trapezoidal , buttress, and knuckle threads. Technical Specifications for Engineers
Typically, you do not need to draw the exact geometry if you call out the standard. Use a note such as: 📥 How to Find a DIN 76-A PDF