I bought a 120mm (4.72") saw to cut some fan holes in 3/16" sheet aluminum. I was hoping I could use a hand drill and move slowly to get through and make some holes. But even with the drill in low gear and holding on with all my might (Very Mighty Man), I couldn't hold her when she decided to grab. Both center drills broke in less than 60 seconds, replaced with a 1/4" screw. as a centering guide as it is not as brittle as HSS center drills. Strong pressure pierces and breaks wrist immediately. Gentle pressure works 3-5 seconds long then sticks hard and breaks wrist it barely scratches works for 10 seconds then bites and breaks your wrist an hour later, with two burly men weighing nearly 600 pounds carrying this bronco with the extra side grip Holding the drill bit we finally cut a hole....I'm sure it would work wonders with wood, thin steel or sheet metal but the aluminum is soft and the teeth are so sharp it's a bear with a so was large in diameter.