Finger joints are an excellent joint for boxes, as they provide a great amount of surface area for glue. And this is the key to what happened with the storage box I made to store the guides for the FMT Pro and for the Super FMT: I failed to apply sufficient glue to the top-most finger joint in one of the corners; as a result, it failed where the arrow points:
Fortunately, I was able to inspect the joint; that is how I learned I did not apply enough glue. Carefully I pried open the joint, applied glue, and clamped it with a small C clamp and allowed it to set for several hours. It now awaits the last two coats of Waterlox varnish.
On the other hand, the box body finger joints are nice and tight:
hope to will pay better attention next time I make a new box with finger joints. I do not want to fail again.
— Al Navas