Abstract: An adjustable fly cutter tool for cutting and forming blanks of metal, wood, plastic, glass, etc. The tool can be used on a conventional lathe or milling machine, and enables the operator to continuously change the depth of the cut into the blank without slowing or stopping the tool operation. The cutting tool is mounted on a threaded bar movable in the x and/or y direction and is axially received in a threaded advancement gear which is actuated by a ratchet assembly that extends or retracts the position of the threaded bar holding the cutter as the main gear is rotated. A non-rotating lever journalled around the cutter drive shaft activates the assembly.