My buddy, who has a stump grinding business, asked me if I would sharpen a few chains for him with my grinder. I said sure just bring them by. Little did I know he had 28 full chisel chains for a 24in bar. My buddy doesnt cut wood and only uses his 395xp for sawing stumps as low to the ground as possible before grinding them. After seeing the type chains he was using, my first suggestion was to stop buying full chisel chains for stump work, semi chisel will stay sharp longer for that type of saw work. That doesnt solve the problem of the 28 full chisel chains I have to sharpen. Knowing that these 28 chains are mostly never been sharpen, but all are rock bit to some degree or other, I am just wondering what angles might work best to allow these chains to stay sharp longer knowing that sooner more than later, they will probably see some dirt and rock work while sawing off stumps. Normally, for a full chisel, I grind at 30* and 10* angles, and use a sthil filling system to set the rakers and this method works extremely well bucking clean firewood, but not so much in dirty wood. I am pretty sure these angles arnt going to last long sawing dirty stumps so looking for suggestions before I set my grinder up.