The next part in the process is to form the grooves in the two cross rails. These rails receive the raised panel and line up with the grooves in the side pieces. The grooves therefore remain 3/8’ wide and are cut to the same 5/16” depth. These grooves are situated exactly in the centre of the rails and so the fence is set at 1/4” from either face of the rails.
With all of the grooves now cut, I focus on the main housing dado joints in the top and bottom pieces. With all the surfaces planed smooth and all marks removed, I place the top and bottom pieces inside face to inside face in the vise with the back edges facing uppermost as shown. this is a traditional practice and the best way to align the exact alignment of housing dadoes in both pieces of wood.
I measure in 1 3/4” from each end and square the line across the back edge of both pieces. I then place one of the side pieces on the line, between the end and the first line. You could also use the thickness of the board to mark the distance in from the end and then make the second mark using the same board.
I square the lines onto the inner faces using the pencil and square. these lines are temporary and will be replaced by more exact knife lines shortly. The pencil lines serve as guide lines for more permanent knife and gauge lines. We use the pencil lines to prevent marring the wood with cut lines.
It’s important to lay out all of the marks to help visualize exactly what the housing will look like and where it begins and ends.
On the inside lines; the ones marked with a knife mark, I establish the first knifewall using the square and knife. My first pass is light and careful. That way, subsequent knife cuts are deepened and exactly on the initial cut line.
We establish the second knifewall after we have deepened the first knifewall. This ensures accuracy and exactness to the parallel walls.
Using the knife mark I used to get the exact position on the inside line, I square my first knifewall across the board from the front pencil line. My first pass is light and then, applying more pressure, I make the cut line deeper, taking care not to stray from the beam of the square.
Using the side piece I will use in that recess, placing tight up against the newly formed knifewall, I mark the position of the second knifewall with a small knife mark. I try to reach as if underneath the corner slightly. That way the joint will be tight but not overly so.
I deepen the cuts as I alternate between vertical and horizontal cuts .
A double-handed stabbing action removes the bulk of the waste wood. I take care not to cut below my depth gauge lines.
With all of the housing dadoes cut, I assemble the four parts together to check for assembly coordination.