Sharpeners with exposed belts will create metal "dust" as they remove material, so you should do it on a surface that is easy to clean or in an area where the dust won't get on food. I use an old box underneath them to catch the shavings on the off side of the belt, and they only make it a few inches from the sharpener. The Chef's Choice 15XV keeps all shavings internal and has a clean-out port on the bottom, which is great for the kitchen.