Irwin dropped us a note this week to let us know they’ve updated their Speedbor wood bits. Specifically, they thickened the cutting edge by 40% and expanded the shank by 25%, both changes designed to increase durability and lifespan.
Other features remain the same, like Irwin’s “Blue-Groove” point and cutting edge design, which they claim “provides fast chip removal and cuts quickly through wood” and double cutting spurs that “scribe the outside of the hole, reducing breakout and ensuring clean, true holes.”
Actually, I’m fascinated with the whole idea of how drills work. So often there’s a lot more to the science of drilling than one might suspect. My dad (a machinist and instructor pilot, among many other things) used to give me holy hell about looking up the correct speed for the material before slapping something on the drill press. The short version of his lecture: Don’t think of metal as so solid. Drills (and mill bits) actually cleave off small bits of metal, just like they do with softer materials like wood and plastic. Choosing the perfect bit angle, flute type and number, rotational speed, and feed rate make for a good, clean cut. Just setting the press to high speed and bearing down as hard as you can makes for an ugly mess and worn out/broken bits and gear.
His other drill peeve: push-through around the hole in sheet metal. It’s a real bitch to make holes completely sans push-through bends in 20 gauge, but it’s worth it to avoid the lecture again.
Anyway, we haven’t had a chance to try out these new bits, but it wouldn’t surprise me at all if little changes in the edge and bit shape make a big difference in how they work. Let us know if you’ve tried ’em. Expect to pay around $3 to $20 for various sets.