Photo 6- Cutting the dadoes in the desk sides with an overhead bearing flush trim bit. The bearing rides against the wood fence which is attached to a piece of plywood. The plywood is clamped to the desk side and bench with handscrews as shown. You could also use a straight flute bit and template guide in the router for this operation.

Cut dadoes in the insides of the desk sides for the drawer frames and desk top to fit into. Cut these using an overhead bearing flush trim bit in the router, along with a straight edge for the bearing to ride on (photos 6 and 7). Note in the photos that the straight edge is attached to a piece of plywood. This is because the clamps would get in the way of the router's travel if the straight edge were clamped directly to the desk side, and the plywood allows the straight edge to be clamped from behind. Also, the ply gives added spacing which I needed because of the height of my overhead bearing bit.

Photo 7-Your fence height and height of the overhead bearing flush trim bit need to be coordinated so that the bearing hits wood and the bit cuts the dadoes at the correct depth, 1/4". This may be easier to attain with a template guide and straight bit, but such a setup is a little trickier to align due to the offset of the template guide from the bit.

Cut stopped dadoes for the drawer frames, but cut the desk top dado through. This way the desk top has the added support of a through dado, needed because leaning on the desk lid will apply leverage on the top itself. But the drawer frames don't need this added strength and the front looks better with a minimum of through dadoes. Stop the dadoes at 1/2" from the front edge of the sides, and cut the dadoes at 1/4" deep.

Photo 8- Use this setup to put a stopped dado in the front corners of the drawer frames. If you don't have a dado set for your table saw, these cuts can be made with a band saw or by hand.

Cut the front corners of the drawer frames to fit around the stopped dadoes in the sides by setting up a 3/4" dado on the table saw as in photos 8+9. The fence needs to be set against the dado cutter so that it will cut along the full thickness of the drawer frames, so screw a board onto the fence as in the photo so you don't mar the fence itself. Clamp a stop on the fence as you did when cutting the slot mortises in the frame rails. The length of cut only needs to be enough for all surfaces to clear when the frame goes into the dado in the desk side. The depth of cut is critical-make it exactly the same as depth of the dadoes, so that the front rail ends contact the inside face of the desk sides in front of the dado.

Photo 9- A dado set makes the cut fast, easy and accurate since it cuts to a very even line and is easy to adjust for depth. Make test cuts on scrap to be sure you don't cut too deep, making a visible gap on the front of the drawer frame.