I have never had good luck with the sharpeners that are basically carbides that scrape across the edge. I have used paper wheels, fine wet sandpaper, or a Worksharp belt sharpener to sharpen all types of auger blades. The key is to never bevel the ice side of the blade. If there is a ding, you can carefully stone that out, but then sharpen only the off- ice side, and leave the burr. It goes away with the first hole. Have not bought blades or paid for sharpening the last dozen years, and have sharpened Mora, Lazer, and Nils type blades.