On Sun, 21 Dec 2008 13:14:20 +0900, "K Ludger"
wrote:

I've got a job coming up to drill around 300 x 25mm diameter holes in some
powder coated steel electrical enclosures. The metal is 1mm thick, probably
30 - 35 thou. Punching is out, I need to do this using my drill press.

I've done a bunch of holes in the past using a step drill, and then spent
almost as much time again deburring the holes. I'de very much like to avoid
using coolant or Trefolex due to the cleanup involved with the enclosures.

I'd like to drill the holes in one go (ie not pilot then change & drill) any
recommendations as to the best approach or tool that I should use?

thanks

If the enclosures are built, I don't have any advice, although
personally I'd punch them. If they are not built, design your
enclosures carefully, locating all holes, square round, large small,
doesn't matter. Send the drawing (I use email) to an enclosure
fabricator near you, and they'll plasma cut the holes in the flat
sheet, bend up, weld, and powder coat the boxes. Saves a lot of money
and hassle, plus hole edges are powder coated. That's about the only
way I'll do enclosures of any complexity any more. I've also done it
in 4X.

Pete Keillor