Abstract: A grinder for sharpening saw chain cutting teeth includes a base, an arcuate guide arranged on the base, a power-driven rotary grinding wheel mounted on a pivotal motor arm movable with a mounting bracket along the arcuate guide and a releasable, self-centering clamp for holding a segment of a saw chain in position beneath the grinding wheel. The clamp includes laterally opposed elongate bars which support a saw chain and which are each simultaneously displaceable at equal rates toward a preselected datum line. The preselected datum line intersects a fixed, reference axis about which the mounting bracket is angularly displaced. Because the elongate bars are movable equally with respect to the preselected datum line, the lengthwise centerline of a saw chain will always be maintained substantially aligned on the preselected datum line regardless of the width of the chain. The arcuate guide is an elongate bar having an arcuate guide track which receives the motor arm mounting bracket.