I have a landpride model WC 1504 chipper with four double sided blades, each about 6 inches long, 2 inches wide and 1/2 inch thick. I have been sharpening these blades manually as no attachment I can find will hold the blade. Which leads to an inconsistent edge/sharpness. The planer blade jig is not big enough to hold the landpride blades. Can't see to modify the planer blade jib because it would entail damaged to the jig. Any suggestions?