twist drill bits, hole saws and annular cutters. 1. Twist drill bits. Especially in steel thicker than ¼", twist drill bits will require extra pressure, lots of lubrication for cooling and some ...

What our tester says: “These proved to be very durable heavy-duty bits: After drilling 10 holes with each, I saw virtually no softening of the blades or dulling. As I drilled an additional 30 ...