interesting, and nice workmanship. He gets good results with simple tools.

But that is a good way to ruin a good stone.

My grandpa was a butcher. He taught me how to sharpen tools. Every time you use a stone, you are doing two things, sharpening the tool and at the same time, dressing the stone. Always try to use the entire surface. YES, I know that is not always possible but, for the most part it is. A guide that holds the tool in the same spot on the stone will soon make a groove in the stone.