Disclaimer: This post is for informational purposes. Always refer to the latest official DIN ISO 13715 standard document for absolute compliance.
![Example symbol structure: A triangle-like figure with a line pointing to the edge, plus a numeric value.] din iso 13715
If you have ever looked at a technical drawing and wondered, "Is that edge supposed to be sharp? How sharp is 'sharp'?" — you are not alone. Disclaimer: This post is for informational purposes
For sharp edges that must cut (e.g., cutting tools, scrapers), write: "Edge max R 0.05" or "Sharp edge permitted – handle with care" (though the latter is rare in modern standards). The Most Common Mistake Do not write: "Break all sharp edges." This is subjective. Does "break" mean 0.1 mm or 1.0 mm? It depends on who is reading. How sharp is 'sharp'
Here is what the symbols mean:
Enter . This standard is the universal language for defining the condition of undefined edges on technical drawings.
Simply put: It tells the machinist how to treat the "leftover" edges—those small intersections between two surfaces where no specific radius or chamfer is called out.