The mortice latch is normally set to the centre position of the door height, so that it corresponds to the lock block of the hollow core door. Before the latch can be fitted, measurements must be taken, and the door marked accordingly. Begin by measuring down from the top of the door to its mid point, and using a square, draw a short horizontal line at this position, and squared lines onto both faces of the door from this mark as shown in the drawing on the right. With a solid panel door, measure the same distances, but avoid contact with cross members such as door rails.
Now measure the distance from the forend of the mortice latch to the centre of the spindle hole, and transfer this distance onto both horizontal lines on the door face as shown below. This can also be done using the marking gauge if preferred.
At the point of this mark on the horizontal lines, define the position by drawing vertical lines. At this point where the two lines cross will be the position where the door will be bored out to receive the spindle. The spindle is the short square metal bar that is provided with the door handles, and makes the connection between the handles and the mortice latch. Pushing down the door handle causes the spindle to revolve within the mortice latch, so that the spring loaded latch retracts into the body of the mortice latch.
The mortice latch is normally set to the centre position of the door height, so that it corresponds to the lock block of the hollow core door. Before the latch can be fitted, measurements must be taken, and the door marked accordingly. Begin by measuring down from the top of the door to its mid point, and using a square, draw a short horizontal line at this 
