I thought I was done with the armoire, but as it turned out I made a mistake in my design. The mistake turns out to be obvious enough in hind sight, and it was easily remedied. This is more a matter of jotting it down so I remember for the next time this situation arrives.
The problem had everything to do with the drawers. They are large, solid wood doors made of maple, cherry and cedar on the bottoms. The shear size of them (nearly 3 1/2 feet wide and 2 feet deep) necessitated larger dimensions on all of the pieces, including the bottom which I made 3/8″ thick. The larger pieces means more weight, even before they get loaded up with whatever.
The drawers are mounted on Blum invisible drawer slides. These slides mount to the sides of the cabinet, but then hook under the drawer so when the drawer is pulled out the slides themselves are not seen.
To support the runners attached to the cabinet, I fashioned rails for attaching the slides. Those rails were mortised into the posts at the front and rear of the lower cabinet space. And that’s where the problem occurred. The glue holding those rails in place in their mortises let go under the combination of the weight of the drawers and the active, day-to-day usage of them. Because they let go, the drawers sagged and would hit the rails on the front that defined the drawer openings. The problem got so bad that one of the clips that attaches to the drawer itself, and then to the drawer slide, was knocked off of the drawer and made using the drawer basically impossible.
So, the fix was simple. First, I used a single screw in each end of the rails to reattach them to the post. Now, there’s not way for the rail to fail short of it actually breaking. Next, to make sure there is enough clearance, I reattached the drawers slide a little higher. The combination of fixes took care of the problem and the drawers work like new again.
The mistake I made was in not using the proper mechanical joint for attaching the rails. I should have used a sliding dovetail design instead of a straight up mortise. My assumption was I just need joint strength in the vertical direction. As it turned out, there was also a moment that I had to account for due to the drawer activity. A sliding dovetail would have handled the problem splendidly, pinning the rail into the post with no chance of it breaking out. Something for me to keep in mind for the next project I work on.