A Screw Surface of a Board

It seems that a theoretical and accurate method of making a screw surface of a board has not been known yet. Considering the property of an involute helicoid, the author has derived the theory on how to make a screw surface of a board, and succeeded in making a very accurate one by using this theory. This method has many advantageous points in comparison with some other methods which are known as for a work shop. Furthermore, the author thinks that this is only method of making an accurate screw surface of a board, since it is impossible theoretically to make that of a triangular thread and the like, of a board