What (e.g., M12, M16) are you utilizing? Are you working with a coarse or fine thread pitch?
) of the metric thread. The standard defines specific values for the undercut diameter ( ), the undercut width ( ), and the transition radius ( 1. Undercut Diameter (
: By providing a smooth radius in the undercut, it helps distribute mechanical stress, reducing the risk of fatigue failure at the thread-to-shank transition. Standardization din 76-a pdf
In modern CAD environments (like SolidWorks, AutoCAD, or Inventor), you do not always need to manually draw every curve of the undercut. Instead, engineers use a standard note or a simplified representation compliant with ISO 13715 or DIN ISO 6410.
While Type A is the most searched, the DIN 76 standard includes several variations: What (e
DIN 76-1 defines the shapes and dimensions of thread undercuts. The "Type A" designation specifically refers to the standard undercut for external metric threads. Why Use an Undercut?
Complete Technical Guide to DIN 76-A: Thread Undercuts and Run-outs The standard defines specific values for the undercut
Note: For exact values, always refer to the official tables in the DIN 76-A PDF, as values vary by thread size (M3 to M100+).
: Typically applied to internal threads (tapped holes).
Do you need the engineering dimensions for instead?
Look into ISO 4755 , which covers thread undercuts for ISO metric external threads and shares highly similar dimensioning principles.