Abstract: A saw attachment for supporting and moving a workpiece when forming circles or other arcuate shapes is provided which is characterized by the relative ease of its operation and the degree of precision which may be achieved through its use particularly in fashioning circles from workpieces of disparate dimensions. The attachment includes a frame, a movable carriage mounting a centering pin, means mounting the carriage on the frame for moving the carriage along a path of travel, and actuating means for moving the carriage in predetermined increments along a path of travel. The means mounting the carriage defines a path of travel for the carriage which may be constrained through the use of stop means for further enhancing the precision and reproducibility achievable with an attachment of this type.