Cope and Stick Door Joints

In the world of cabinet making the frame-and-panel door dominates the industry. For good reason, it solves the age old problem of warping and cracking caused by wood movement that one sees in solid wood doors. I doubt there is a need to argue the benefits of this method of constructing cabinet doors. What I do want to discuss is the method of jointing the frame.

In modern cabinet making it has become immensly common to use a cope-and-stick joint. A cope-and-stick joint is made by machining a profile into the stile that both trims the edge and accomodates the the panel. A matching reversed profile is cut into the end of the rail. These profiles are generally made with a matched set of router bits or a reversable router bit. Cope-and-stick joints are easy to workwith, assuming you have the appropriate tools. They are quick to cut once you are set up and provide large amounts surface area for gluing. This makes them very popular.

There is a weakness to this joint, however, that is rarely talked about. In the joint the profile edge funtions as a both a short tenon and a mortise wall. The problem is that this tenon has been cut thin and short with the pressure pushing parallel to the grain instead of against it. This creates a weak spot in the joint. I've drawn up a picture to demonstrate this. A door like this, with hard use will eventually fail.

Does that mean that you should never use a cope-and-stick joint? No, of course not. But you should consider reinforcing it in some way. Either, you can use a plywood panel and glue the panel in (which is odd considering the whole reason for the creation of the frame-and-panel door). Or you can reinforce with dowel or some other such device. I find that long dowels when placed well can actually look good - a bit of a stand out feature on the door edge.