Join Date: Mar 2009
Location: Bucks County, PA
Like C-Man and Woodnthings said, high speed steel twist bits (marked HS) are all you need for CI. And like Woodnthings said, drill a pilot hole first (3/32" would do it) and drill with no lubricant. Center punch a dimple first so your drill bit doesn't walk on you.
When you saw your angle iron, you can squirt a little oil on the cut to help keep the saw sharp and the heat down. Use the same HS drills when drilling the steel angle, except use oil then.