With the face frames slightly wider than the cabinetry bodies, I chiseled about 3/16ths off the last 3/4” of the millwork piece.

The moulding piece then swung in and fixed my problem, but the gap made me think I could use some triplicate paper. There are a few tricks like that which I have learned and since forgotten.

Previous to the joinery in the picture above, I’d thought I could caulk the space (not pictured) in the cut and also where the piece was held away from the cabinetry body by the face frame. That problem was solved by the chisel work when I clamped the piece to the layout table before employing the chisel and hammer.

After installation, a froe mallet and a block of wood failed to get the joint tighter. I had chisel shaved perhaps a few 16’ths off the inside of the joint, and that fixed the millwork to cabinetry gap, and yet the mitre faces of the final cuts joined with an acute wedge of space downward along the vertical axis of the mitre. This, as shown in the third photograph, I have determined, makes paintable caulk both utile and requisite for the finished product.

Additionally, I made three corner space pieces before finding I needed the length to be about 2/8ths.

Pictured above, the state of the job as of this morning.

Finally, I’d like to cite the double bevel mitre saw jig that I suspect I may have invented. I attribute my teaching myself crown moulding joinery to this jig. Now, I no longer use it.