Abstract: At 11:00 p.m. on February 1, 2020, a crew of four employees (Employee #1 and three coworkers) was engaged in the replacement of knives of an east mill tandem hammer. The operation was done during second shift (4:00 p.m. to 12:00 a.m.). The employees had only one shaft left to remove all the knives, and three knives out of another shaft. There were two mechanics, a welder, and a mechanic helper doing the operation. One of the mechanics was using a square metal bar for a hammering rod, and the welder was taking in/out the rod as it was aligned with the shaft. Every time the rod was hammered, blades knocked down to the floor from the shaft. The other two employees were picking up knives as they fell down. Employee #1 was aligning the rod with the shaft. Employee #1 was inserting his finger to assess how secure was the last blade left hanging from the shaft. Employee #1 started using his finger after a blade fell off the shaft, while the coworkers were picking up blades from the floor. As Employee #1 was having his middle finger of his left hand inserted, a coworker hammered the rod inadvertently. Employee #1 got his finger partially amputated down to his nail. Employee #1 was treated without hospitalization. A CSHO documented that Employee #1 was wearing gloves at the time of the incident.