Now that the door has been tailored to fit the opening we can now proceed to fit the hinges, a task that's equally important if we are to maintain the correct clearances.
Understanding the hinge
Looking at the 75mm hinge it appears at first glance that the two flaps are identical, but on closer examination, a slight difference can be seen between them. The knuckle which is wrapped around the pivot pin is made up of five segments from the two flaps, with one flap forming the top, middle and bottom segments, while the other forms the other two. The flap that forms the two portions also has slight gaps between it and the knuckle at the top middle and bottom. This flap with the two portions wrapped around the pivot pin is the flap that is fitted to the door.
After being correctly fitted the hinge will automatically form the correct gap between the hanging stile of the door and the jamb of the door casing. This is achieved by the fact that the two flaps when set parallel to each other have a gap between them of 2mm, therefore, if one or both flaps are set in too deep into the door or casing, the gap will be reduced and cause the door to bind. If the flaps are not set deep enough, this will increase the required 2mm gap for internal doors.
Place the door on to its edge with the hinge side uppermost and secure in this position.
From the top edge of the door, measure down 150mm and using a square, draw a line about 20mm long, ensuring that the shoulder of the square is placed against the door face (which has been marked) when drawing this line. Next, place the top of the open hinge onto this mark and using a sharp pencil, mark the length of the hinge flap on to the door. Again using the square, extend this mark to the same length as the top mark.
These two horizontal lines will now need to be joined vertically to the width of the hinge flap, and to do this, the marking gauge will be required and set to the correct distance from the face edge of the door. The marking gauge is set to this measurement by resting it against the edge of the hinge flap, and adjusted so that the marking pin is up to the joint (as shown).
This distance is then transferred onto the door edge by marking a line parallel to the door edge between the horizontal two marks that you have already drawn. (Gauge from the door face) Next, set your gauge to the exact thickness of one flap, which is the amount the door needs to be recessed, and transfer this onto the door face (Gauge from the door edge onto the face). I use two making gauges for this job.
Bottom and Extra Hinge
Follow the same procedure for fitting the bottom hinge, the only difference being that you measure up from the bottom of the door 200mm with your first line, this means that your second line will be 275mm from the bottom of the door, assuming you are using the standard 75mm hinges. Heavy doors will require a third hinge, which should be placed in the centre, between the top and bottom hinge.
With your wood chisel held vertically, follow the inside of the lines that you have drawn onto the door edge, striking downwards to the required depth. Next, with the chisel held at an angle, chisel the area to be recessed, working in the same direction as the grain, then remove the loosened timber to the depth that you have gauged working across the grain. Continue to trim the recess until the hinge flaps fit snugly into the door. The top of the hinge flap should finish flush with the door edge when screwed in place.
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