This happened at my company a few years ago. I was working on the crew when it happened. The arborist tossed a log into the chipper and it grabbed a hold at an angle causing the log to smash against the right side of the chipper, smashing his thumb in the process. He needed surgery and rehab/ therapy due to nerve damage. His thumb looked like a split hot dog when you cook it on the grill. He admitted he was only using one hand to load the log and not paying close attention when this happened. Nobody blamed him for the accident or anything, it was a very bad injury. Another guy I work with said the same thing happened to him when someone else loaded a limb when he was standing nearby and the limb nailed him in the mouth breaking his front tooth in half.