Originally Posted by
rootboy
I think it's too late for that, Jolly_Ross. That said, I'm curious what you mean.
Drilling a hole straight through flat metal leaves a right angle on the hole edge (when viewed in cross section). The tiniest fault on the tip of the angle can start a crack. Holes in high stress places should be radiused (sometimes called chamfering) as a curved surface is a great deal stronger.
This is done on the holes of high performance disk rotors too - albeit for reasons of preventing high heat build up on the tip of the angle. The only picture I could quickly find is from a disk brake page:
http://www.sp-performance.com/Cross_Drilled/imag025.jpg