Often if the back side of a through hole is at an angle instead of perpendicular, the drill or tap will break when they break through.
Er, I don't know this personally, you understand. A little bird told me. That's my story and I'm sticking to it. And it's worse with carbide than with HSS. [drops a shop rag casually over a small box on the bench]
You can often avoid broken taps or drills by making a small cut or spotface on the back where the tool will break through, so it come out on a perpendicular surface. Then there aren't any asymmetrical loads on the tool.
Er, I don't know this personally, you understand. A little bird told me. That's my story and I'm sticking to it. And it's worse with carbide than with HSS. [drops a shop rag casually over a small box on the bench]
You can often avoid broken taps or drills by making a small cut or spotface on the back where the tool will break through, so it come out on a perpendicular surface. Then there aren't any asymmetrical loads on the tool.