A grinder has an abrasive belt removably mounted on a wheel for grinding a workpiece. The belt has its ends extend through a transverse slot in the wheel into a recess within the wheel. One end of the belt is attached to a first slider and the other end of the belt is attached to a second slider with the sliders increasing the tension on the ends of the belt through outward movement of the sliders by centrifugal force as the wheel rotates with the tension increasing as the angular velocity of the wheel increases. The sliders may move parallel to each other or along two separate radii extending from the axis of rotation of the wheel. Pivotally mounted pendulums may be employed instead of the sliders to apply tension to each end of the belt with the pendulums increasing the tension on the ends of the belt through outward movement of the pendulums by centrifugal force created by rotation of the wheel.