I've been thinking about buying one of these but I don't know if they are just a gimmick. Also, if they genuinely work well how good do your bits need to be in the first place to be worth sharpening?

Up until recently, though, my collection of drill bit sets was so large that I had duplicates and often triplicates of all the bit sizes I commonly used because my older bits were worn out, and in ...

How long drill bits last depends on the bit type, material drilled, drilling speed, heat, sharpening, lubrication, and ...