Abstract: A board positioner operationally cooperates with a radial arm saw with a workpiece fence to measure a board to be cut by the saw. The positioner comprises a support structure, a slide bar supported by the structure and a slide mounted on the slide bar. The slide is selectively rotatable with respect to the bar and infinitely positionable therealong. The slide includes a bridge which allows the slide to arc the fence when in operational position to assist an operator in cutting a board from a workpiece.