A guy at the local hardware store spent 15 minutes showing me how to sharpen my chisels with a simple jig he made from scrap wood. | DIY Home Projects - Pinecone Attack
Honestly, that guy was spot on. Tried making a jig out of an old piece of 2x4 and a couple screws after watching a YouTube video. Works better than my expensive guide for flat chisels. The trick is getting the angle right, maybe 25 degrees for most work. Once you mark the blade with a Sharpie and adjust the jig until it hits all the way across, it's dead simple. Mirror finish in minutes.