This is a jig I threw together from things in my shop that makes it easy to create hollow-ground knife bevels. I would have made an instructable out of it, but I don't have any pictures of the process and it's pretty easy to see how the thing goes together any way. The metal widget with the springs is there just to make sure the work rest (the piece of cherry with the c-clamp on top) doesn't move around and change the distance of the knife to the wheel. The c-clamp itself is cut down so I have a better view and control of the knife while grinding. I can also move it around to accommodate blades of different widths and thicknesses.
This jig could also work for with a bench grinder with a hard wheel. The roller that makes my hollow edge only has a 4-inch diameter, which is a little small for single edges...but it's the best I've got right now. And the blades end up devilishly sharp.
The last few images are of a knife I recently made with this jig, what I'm calling a "camp seax." Straight edges are easier. If you've seen my knifemaking Instructable, you can tell that I've greatly improved in a couple years.