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?

A workman is only as good as his tools. At least that's how the saying goes. When it comes to such workmanship, nothing kills a workflow like a dull drill bit. They are cornerstones of any good garage ...