my best drilling is done with ICE CUBES. i push them into the bit where it makes contact. It improves the life of the bit tremendously. The drilll doctor is also a big help as sharper bit cut better. also lower your drill speed to reduce heat. seriously though. try ice cubes. I did 29 plates, 2 holes in each plate with 3x 1/8" inch bits and 2 step down bits