i just bought a cheap chicago electric chain sharpener from harbor freight and told some buddies to give me some old chains to sharpen for practice,and i got one that cant be sharpened with the grinder,ive never seen one like this,it has cutters that has an edge on 3 sides,oregon chain .354, 91 on the driver and a engraving of a diamond on the tie straps,oregon didnt have anything on their site about this...the top of the cutter is not angled its straight forward..ill try and post a pic later.
