Abstract: A form tool holder having a dovetail slot for mounting a form tool cutter, a clamping rod for exerting concentrated clamping pressure laterally against the dovetail portion of the cutter adjacent one end of the slot, and a back-up block for exerting a holding force against the inner end of the cutter all in combination with a detachable tool base having a transverse key having provision for angular adjustment to align the cutting edge of the cutter precisely with respect to a workpiece, all of the actuators for the clamping rod, the back-up block, and the key being readily accessible for quick and easy actuation and adjustment of the parts referred to when the holder is mounted on a machine tool.