Abstract: A guide assembly for sawing an elongate member accurately to length to form the sides of a picture frame comprises two saw-guide units which are adjustably clamped to two guide roads by means of screws. The picture frame glass is placed between reference surfaces of blocks on the saw-guide units to determine the required distance apart of the two saw-guide units. Each saw-guide unit has two pairs of posts defining slots therebetween for the blade of a saw, to hold the saw-blade accurately at 45.degree. to the direction of elongation of the wooden member, for the eventual formation of mitred joints between the sides of the picture frame. Each saw-guide unit includes a special ridge to abut that surface of the wooden member which is to surround the edge of the glass.