[UROParts]

Nice work John! As you mentioned, quality drill bits are worth it. Always good to have a set of standard Ti-coated bits for everyday use, and then a set of rarely-used (and thus sharp) cobalt bits on hand for the tough jobs.

Cobalt drills almost anything with lots of cutting oil, care to keep the flutes from packing with chips (reducing friction and heat buildup), and slow drill speed to keep the cutting edges from overheating. Always slow the drill speed just before you punch through the back side, as this is the moment the tip temperature will peak. (You may want to remove the drill from the hole and clean the hole with a shot of compressed air before cutting the final fraction of an inch.) If you have a ring-shaped burr of metal on the back side of a hole, you came through too hot and the cutting edges on the drill may be dulled. A sharp, cool drill cuts a clean hole.