Abstract: Shredder hammers include a hammer pin opening in which at least some portion of the interior surface is curved in a direction moving from one major surface of the shredder hammer to the other. This interior surface may be smoothly formed as an arc of a circle, as a parabola, as a hyperbola, or as another curved surface, with the local extrema within the interior of the hole (e.g., at or near the center). Providing the curved interior surface helps vary and disperse the locations where force is absorbed due to contact between the hammer pin and the walls defining the hammer pin opening when the shredding hammer blade contacts the material to be shredded. Other structures include engagement between the hammer pin and the hammer as part of a bushing member, a spool or sleeve member, or a ball swivel member.