Installing molding on solid wood cases

I don't remember where I found this particular tip... I think it was an old Fine Wood Working magazine.

Because the case is so wide, there's going to be a fairly significant amount of wood movement, so brad nails won't cut it here. The case will likely expand and contract by as much as 3/16" over the course of the passing seasons here in New England, so it needs to be able to do so independently of the molding.

So, to hold the molding to the case, I cut a dovetail groove in the back of the molding, and cut matching splines that were glued and nailed to the case. Once the splines were attached, I slid the molding into place. The front molding I glued on completely. Because it's long-grain to long-grain, it doesn't need the splines, but they certainly help with alignment. The side moldings were glued onto the front-most spline, and the first few inches of the case. The rest is only held on with the splines.

Cutting the splines doesn't have to be a nerve-wracking exercise in precision. If they're a smidge loose when you make them, you can take a shaving or two off of the mating surface, and it will tighten up the final joint. Because they're not going to be regularly visible, it's not a big deal.

In the picture below, there are two gauge lines. Originally, I thought it would be good to use a gauge line for the nails, which were set up in pre-drilled holes in the splines. Bad plan, minor discrepancies made a mess. So, there's the second gauge line, which is simply for placement of the upper edge of the spline, which worked much better.