What you do is place your material under the edge guide and tighten it down. Mark around the edge guide. Then lay the blade on top of the material in the position you want it in as you sharpen it and mark the shape of the spine of that knife. Remove the material and cut out what was under the edge guide and what was under the blade. When you use it place it in front and around the edge guide, place the knife spine in the outline of it, position the edge just in front of the edge table and tighten it down. Now the blade will stay perfectly still as you sharpen it. When you flip the blade over just flip the EGB over as well. It will hold the blade still for the other side. If you have any questions ask if you are interested in this. You do need one for each knife you have with a differnt spine shape.