Drilling diecast aluminium boxes (Hammond 1550 series)

[mekanik]

If i was doing it i would clamp some stops on your drill table to locate your box for the first hole, grind the drill flat bottomish so the drill cuts initially on two points (each flute) use parafin as a lubricant and don't go silly with the revs, just cozz you can cut ally at a fast speed doesn't mean you have too, drill your 25 off @ 7mm. reset your stops and do the 8mm.
Simples

[EddyCurrent]

Flat bottomish drills are great for brass. Recently I bought a set of Heller cobolt drills, not that I'm drilling hard stuff, I just find they drill a neater hole in half the time as jobber drills, maybe worth a try ?

[Saracen]

Thanks all.

Good to know I'm not doing anything too dumb :)

Guess I'll just have to persevere and keep the bits clean as I go.

Thanks for the pointer about the drills. I don't have a grinder, so I'll have a hunt for some ready made drill bits.

Adrian.