Din 76a Pdf ~upd~ Jun 2026

Because the required measurements change depending on the diameter and pitch (e.g., M10 1.5 vs M20

Thread undercuts are essential engineering features that ensure parts screw together perfectly. Without a proper undercut, the unthreaded runout of a bolt can prevent a mating component from seating flush against the surface.

: The undercut's width and depth are strictly calculated based on the thread pitch (P) Comparison

Among the globally recognized standards for these geometries, is the premier specification for external thread undercuts for metric ISO threads. What is DIN 76-A? din 76a pdf

According to the Technical Data for DIN 76-1 , Form A is the standard default used unless otherwise specified on technical drawings.

DIN 76-A is a specific form of thread undercut defined under the German industrial standard , which governs the dimensions and design of thread run-outs and undercuts for fasteners and threaded components. This standard ensures that threads terminate cleanly, allowing mating parts like nuts or bolts to sit perfectly flush against a shoulder or collar. What is Form A in DIN 76?

) : The curvature radius linking the undercut to the unthreaded shaft to prevent stress risers. Standard DIN 76-A Dimension Table Reference Because the required measurements change depending on the

outlines the geometry for a standard, long external undercut. It is widely used because it provides ample clearance for threading tools (such as chasers, dies, or single-point CNC cutting inserts) to safely back out without colliding with a shoulder. 2. Technical Functions of an Undercut (Thread Relief)

: Clearly call out "Undercut DIN 76-A" on your 2D manufacturing prints. This tells the machine shop exactly what standard tool geometry to use, saving space on the blueprint from manual dimensioning. Conclusion

The current standard is – Thread run-outs and thread undercuts for metric ISO threads according to DIN 13 . If you meant DIN 76-2 , that covers thread run-outs and undercuts for fine pitch threads. What is DIN 76-A

Below is a reference guide mapping standard metric thread pitches to their corresponding DIN 76 Form A undercut dimensions (typically found in official PDF data sheets): Thread Pitch ( Undercut Diameter ( Undercut Width ( (e.g., M3) 0.7 (e.g., M4) 0.8 (e.g., M5) 1.0 (e.g., M6) 1.25 (e.g., M8) 1.5 (e.g., M10) 1.75 (e.g., M12) 2.0 (e.g., M16) 2.5 (e.g., M20) Note: " " represents the nominal major diameter of the thread. How to Read a DIN 76-A Technical Drawing

Sites like Accuris Standards Store or GlobalSpec provide access to this standard. Usage in CAD and Technical Drawings

| Feature | ISO 3508 / ISO 4755 | DIN 76-1 | | --- | --- | --- | | External thread undercut length | One type only: | Form A: 3.5P (normal) Form B: 2.5P (short) | | Internal thread specifications | Not covered | Fully specified (Form C) |

| Thread Pitch P | Radius r (min) | Width of Undercut g (approx) | Diameter of Undercut d₃ (max) | | :--- | :--- | :--- | :--- | | 0.5 | 0.2 | 1.5 | d - 0.8 | | 0.6 | 0.2 | 1.5 | d - 1.0 | | 0.7 | 0.4 | 2.0 | d - 1.1 | | | 0.4 | 2.0 | d - 1.3 | | 1.0 | 0.6 | 2.5 | d - 1.6 | | 1.25 | 0.6 | 3.0 | d - 2.0 | | 1.5 | 0.8 | 3.5 | d - 2.3 | | 1.75 | 1.0 | 4.0 | d - 2.6 | | 2.0 | 1.0 | 5.0 | d - 3.0 | | 2.5 | 1.2 | 6.0 | d - 3.8 | | 3.0 | 1.6 | 7.0 | d - 4.4 | | 3.5 | 2.0 | 8.0 | d - 5.0 | | 4.0 | 2.0 | 9.0 | d - 5.7 | | 4.5 | 2.5 | 10.0 | d - 6.4 | | 5.0 | 2.5 | 11.0 | d - 7.0 |