The challenge: The dust cover must be perfectly flush with the top edge of the bottom rail of the front apron, or what I have been calling the drawer frame. The reason: The bottom of the inset drawers will ride on the stiles (the dividers between the panels) of the dust cover. Therefore, the joinery must ensure smooth transition from the drawer frame to the dust cover.
The last time I showed the drawer frame, it looked as follows:
It now looks like this, after completing the tongue & groove joinery – tongue on the dust cover, and groove on the drawer frame:
Doing tongue & groove joinery on the router table normally requires the edge of the board that has the groove to slide on the router table. In this case, with the drawer frame already assembled and glued, I was unable to place this edge on the table.
What to do?
Solution: Test, using scrap wood, and calculate the offset required to make the two surfaces even, carefully adjusting the corresponding router bit height for each cut. The thickness of the drawer frame is 1 inch, and that of the dust cover is 3/4-inch:
In the past I’ve used tongue & groove joinery extensively, when making cabinets using plywood. It also works well here, as the long grain-to long grain joint will glue up nicely, without need for other reinforcement, such as pocket screws. I am happy to report that the dust frame now fits nicely all ’round the side and back aprons, too.
A heads-up on the desk drawers: as I have stated before, the drawers will slide on the surface of the dust cover. This perspective shot gives a better idea how they will ride on the dividers of the frame:
Now I can continue with the rest of the work.