The standard (normal) design for external thread undercuts. It is typically used for general engineering applications.
Instructions:
In the technical diagrams found in these PDFs,
If your drawing calls for "DIN 76-A", you must comply with the German standard. Using ISO 3508 dimensions could lead to rejected parts, especially in German automotive or industrial machinery contracts.
When a designer wants an external thread undercut according to DIN 76‑1, Form A, the drawing will typically include a note such as:
On a 2D engineering blueprint, this feature is typically annotated with a simple leader line pointing to the groove, reading: . Finding and Downloading a Legit DIN 76-A PDF
| Standard | Description | |----------|-------------| | | Metric thread run-outs and undercuts (German/European standard) | | ISO 3508 | Thread run-outs for ISO metric threads (withdrawn, merged into ISO 4755) | | ISO 4755 | Thread run-outs and undercuts (similar but less detailed) | | ANSI B1.3M | Unified screw threads – run-outs and undercuts (inch/Unified system) |
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.
I can provide the exact target dimensions or machining tolerances you need for your project.
: Most engineering handbooks offer authorized reproductions of the DIN 76-A dimensional tables for quick workshop reference.
If you need the actual , you must buy it from a standards distributor. For a quick reference table, search for "DIN 76-1 summary chart" in reputable engineering forums or tooling catalogs.
