The Time a Customer Asked for the Impossible
A customer called me on a Tuesday afternoon. They had a part redesign on their hands and needed a 1mm diameter hole drilled through 400mm of Inconel 718. I asked them to repeat those numbers because I thought I had misheard. They had not misheard. A 1mm hole through 400mm of material gives a length-to-diameter ratio of 400 to 1. For context, a standard gun drill with a 1mm diameter has a flute length of roughly 150mm before the brazed joint at the shank. Going 400mm deep means the drill would need to cut 250mm past the end of its own flute support. ...