Dutch Toolchest: upper and lower sections

Following the lead of Christopher Schwarz and riding the wave that he induced, I built the Dutch toolchest in the early months of 2015 and by springtime, I was aware of a problem with the drop front. It had expanded beyond the allotted opening, making it nearly impossible to remove it, reinsert it, or use the sliding batten to lock it into place. The drop front required replaning about three times over the course of the following 6 months to make it workable. The drop front of the top section is made of white pine by eye.
I wanted to follow Schwarz' idea of a Dutch toolchest lower section on casters. The casters would give me a bit more flexibility in my new work environment and the lower section would house some of the additional tools I had acquired. I therefore rejected Schwarz's construction detail of a sliding batten that required lifting the top section completely off to remove the batten and thereby gain access to the lower section. He uses the lower section only for storing and transporting materials to offsite locations. I was instead drawn to the variation that he highlighted in a posting referred to as the Canadian Gravity Latch. This would allow me the same degree of access to both sections and to show off my Western woodworking skills!
I roughly followed his dimensions and made up the construction details of the gravity latch as I went along.
I have access to fairly clear Southern Yellow Pine so I chose that for my stock. I cannot yet get anything wider than 2"x10" in either SYP or SPF. I got around this hurdle with the upper section by using German made laminated pine shelving boards for the sides. I laminated SYP stock to create the 11-1/4" boards for the main carcase. These were dovetailed with rabbets on the tail boards to lend rigidity and ease the marking of the pins.

Dovetail joint

There was some twist that has started to develop but I managed to squeeze the four boards together, the dovetail joints pulling the corners in square. The back of the upper section had simple shiplap rabbets; whereas, on the bottom section, I had the wherewithal to make a tongue and groove joint. I used some scrap European Beech for the battens. (There is always a lot of this as scrap in this woodshop.) The gravity latch went together without much trouble as I had already understood the principle from having made the upper section.

Thumbcatch on the gravity latch

I unified the two pieces with the same beading plane and a coat of milk paint covered in BLO.

The DTC: upper and lower sections

And it worked for a while without a glitch. Yet since this is China, nothing is ever so easy. About a month or so after everything was together, I started to have trouble with the drop front. It was apparent that the newly exposed surfaces that had been planed down to 3/4"were cupping noticeably.

Newly ajar and uncloseable

Here is a similar example that occurred much faster when I attempted to dimension a piece for a shaving bench.

Released tension after exposing fresh surfaces

My first solution was to cut a series of relief cuts on the inside surface. This seemed viable and I had a circularsaw to execute this idea. After removing the battens, which had evidently done very little to counteract the released stressed with the SYP, I ran a series of sawcuts as deeply as I dared while avoiding the screw holes.

Seemingly reflattened yet still curved

Ribbed for everybody's pleasure

And then I reassembled the mechanism and crossed my fingers. I could see very little effect from attaching the battens and if there was any change to the curvature, it wasn't enough to bring it back to functionality. I pondered adding more sawcuts but I think I had maxxed out on that solution. It then dawned on me that I could simply removed the wood that was interfering with the fit. The battens proved to be prefectly positioned, built-in guides for this operation. I ran a making knife along both battens and after creating knifewall, then I sawed down a bit. I pared out most of the waste before cleaning up and doing the final fettling with shoulder and block planes.

Rabbeted with ease

The result hardly shows the major surgery that has been inflicted upon it. There remains some shelving or interior attachments to be added to accommodate whatever tools I decide to secure in it.