Complete Technical Guide to DIN 76-A: Thread Undercuts and Run-outs
When looking for an official , it is important to note that the document is officially titled DIN 76-1 ("Tapping holes, thread run-outs and thread undercuts for ISO metric threads"). Tips for Sourcing the Document:
The standard is typically categorized by the type of thread and the specific "form" required for the design: Standard Part Description Covers coarse and fine pitch threads (DIN 13-1). Pipe Threads DIN 76-2 Specifies dimensions for pipe threads (ISO 228 Part 1). Coarse Pitch/Trapezoidal DIN 76-3 Covers trapezoidal, buttress, and knuckle threads. Din 76-1 | PDF | Screw | Metalworking - Scribd din 76-a pdf
: It eliminates sharp corners, distributing mechanical stress more evenly and reducing the risk of fatigue failure.
): The total axial width of the groove. DIN 76 defines both "normal" (Type 1) and "short" (Type 2) widths depending on the space available on the component. DIN 76-A Standard Dimensions Table Complete Technical Guide to DIN 76-A: Thread Undercuts
"Thread: M12 – 6H – DIN 13. Undercut per DIN 76-A – Form F"
If the drawing shows a shaft with a thread ending at a shoulder, the machinist must look up the in the DIN 76-A PDF and machine the undercut to the specified width and depth. DIN 76 defines both "normal" (Type 1) and
Here is a helpful, practical article summarizing the key points of (the current standard: DIN 76-1:2016-11 – "Thread run-outs and thread undercuts for metric ISO threads according to DIN 13").