How many RPM's are your blades running? Hustlers like me I will estimate in the 18K range....so my question to you is this.....at that RPM ....how much of the 8 inch plus blade that you are sharpening is actually ever going to see a blade of grass? My guess less that 4 inches. The first 4 inches of the blade is all you should have to be concerned about. If it is not cut by then, I am not sure what to tell you.