A guide bush apparatus that supports a rod-shaped workpiece so that the workpiece is free to slide in the axis direction of the workpiece includes a guide bush sleeve, a guide bush that is disposed inside the guide bush sleeve, has a bush screw formed thereon, and has an inner diameter that changes in accordance with the relative position thereof relative to the guide bush sleeve in the axis direction, a retraction sleeve which is disposed inside the guide bush sleeve and on which a first screw that engages with the bush screw and a second screw having a different thread pitch from the first screw are formed, and a differential attachment/detachment body on which a differential screw that engages with the second screw is formed, and which can be fixed to and released from the guide bush sleeve.

An arrangement for forming grooves in a board element. The arrangement includes a support member for supporting the board element during the forming and cutting elements arranged on a spindle member configured to rotate around a rotational axis. The cutting elements are configured to form the grooves by removing material from the board element. The spindle member is arranged in a pivot body configured to be pivoted with respect to the support member. The arrangement includes a driving device configured to drive the pivot body, wherein the driving device is configured to rotate in a single direction during a groove forming cycle.