During thread cutting (whether by lathe, die, or rolling), the cutting tool requires a small groove or decreasing depth to exit the workpiece. Without a proper run-out, the tool may crash into the shoulder of the part, breaking the tool or damaging the part.
When you open a DIN 76-A PDF table, you will see that the dimensions are entirely dependent on the , rather than the nominal diameter of the screw.
The letter specifically designates the type of thread undercut (Gewindefreistich) intended for external threads (bolts and screws). Key Differences Within the Standard: DIN 76-A : Standard undercut for external metric threads. din 76-a pdf
Legally, no. DIN standards are copyrighted technical documents. However, many reputable engineering reference handbooks (e.g., Machinery's Handbook , Roloff/Matek Maschinenelemente ) summarize the critical tables of DIN 76-A. For quick workshop reference, laminated summary charts are often available from third-party vendors. But for legally binding design work, you must purchase the official PDF.
Most reputable mechanical engineering handbooks reproduce the DIN 76-A tables legally in their fasteners and threading sections. During thread cutting (whether by lathe, die, or
To help you get the exact data you need, could you specify if you are working with ? If you have a specific thread size in mind (like M8 or M12 ), let me know and I can provide its precise geometric tolerances. Share public link
The Definitive Guide to DIN 76-A: Understanding Thread Undercuts and Run-outs The letter specifically designates the type of thread
The diameter of the undercut groove must be smaller than the minor diameter of the thread to ensure the mating part clears it easily. is the nominal thread diameter and is the thread pitch). 2. Undercut Width (
Programs like SolidWorks, Autodesk Inventor, and PTC Creo have the DIN 76-A standard built directly into their "Hole Wizard" or "Thread/Groove" features.
Since you need the data now , here are the standard undercut widths for metric threads (P = Pitch):
The official DIN 76‑1 PDF includes : Table 1 for external threads (Forms A and B) and Table 2 for internal threads (Forms C and D). The tables are organized by thread pitch ( P ), not by nominal diameter. Once you know the pitch, you can read the corresponding ( g_2 ), ( r ), and diameter dimensions directly.