This is a guide for sharpening your knives to a 20% angle on a 6" Ryobi bench grinder using paper sharpening wheels.
I purchased a Ryobi 6" Bench Grinder (BG612G) From Home Depot to sharpen knives using The Razer Sharp Edgemaking System (see: http://nextgen.sharpeningwheels.com). The system is great, but I found that I had trouble getting a consistent edge when free handing the grind. So I turned the wheels around (top of wheel spinning away) and chose to sharpen my blades by holding the flat side level with the ground. In order to know where on the wheel to hold the blade I made these edge-sharpening guides. They screw in place onto the grinder and have an indicator at 20% and 45%. I line up the tip of the arrow with the center of the shaft and hold my blade level with the ground and grind on the wheel on that line. (pictures added) Works like a champ!