Abstract: An orbital rotary blade sharpener for sharpening rotary cutter blades and other rotary blades includes a bottom blade holding portion having a center and a perimeter edge, a top blade holding portion rotatably connectable to said bottom blade holding portion, having a perimeter and a center, a central shaft portion extending from said bottom blade holding portion through said top blade holding portion over which a rotary blade can be fitted, a radial shaft portion extending through said top blade holding portion positioned between the perimeter and the center of the top blade holding portion, and grinding portion connected to said radial shaft portion, and within said top blade holding portion, positioned to be orbitally revolvable around said bottom blade holding portion center and contactable with a blade held between said top and bottom blade holding portions.