Choosing the Right Screwdriver Bit
What's the best way to match a bit with a screwhead?
When I was installing stainless-steel Phillips-head screws using a cordless drill, I couldn't seem to find a bit that wouldn't strip the screwhead. What's the best way to match a bit with a screwhead?
—Brad MacDowell, Saranac Lake, N.Y.
Kevin O'Connor replies: Kevin Enke, the bit expert at bit and blade manufacturer Vermont American, explained to me that a bit that fits snugly in the screwhead recess is less likely to strip the head. The three common Phillips bit sizes, from smallest to largest, have PH 1, 2, or 3 stamped on their shanks. With all three bits on hand, it's easy to find the one that fits: If it moves in the recess when you turn the screw by hand, try a larger bit.
I also mentioned your problem to Tom Silva. He had these suggestions: Use a drill/ driver and adjust its torque so the bit stops when it meets too much resistance, before it mangles the screwhead. Always drill a pilot hole first, and always keep the bit in line with the screw shank. Tilting a Phillips bit even a few degrees to one side could cause it to lose its grip. With stainless-steel screws, you have to be doubly careful because the metal is soft.
Worn bits are troublemakers, too, Tom says. If a bit's edges start to look or feel rounded over, don't hesitate to toss it.