Since this blanket chest has frame-and-panel construction, the next step was to make the grooves to hold the panels. As I mentioned in the post on cutting the tenons they, and their corresponding grooves are not centered, but offset to the inside face of the chest. This means that the old tablesaw trick of running a board through, then flipping it end-for-end and running it through again to get a centered groove won’t work. However, there’s an excellent way to get a groove without having to dig out the dado set.
A plow plane is an excellent alternative for grooves. While not as fast as a dado, it can be set once and left on the shelf (much like a marking gauge), to be picked up as needed. This leaves the tablesaw with its combination blade in place for such other jobs as may arise as the project progresses. And, once set up and adjusted, the plow plane isn’t as slow as you might think.
With the 1/4″ blade installed, I set the plow plane’s fence to plow a groove in line with the tenons, and 1/4″ deep. Notice in the photo above, the letter “I” near the tenon shoulder. This stands for “inside”, and marks the face with the 1/4″ shoulder. On the opposite side of the shoulder is an “O”, which stands for (you guesssed it) “outside”. Placing these marks on every joint affords me a much better chance of staying oriented with all this asymmetrical joinery.
Another trick, as shown above, is the use of a cabinetmaker’s handscrew to keep the board vertically oriented. I use this same configuration later when boring mortise starter holes. Handscrews are generally underutilized by modern woodworkers, but this is just one of many uses they have in anyone’s workshop.
Once the grooves were plowed, it was time to layout for the mortises. By gang-clamping matching pieces together and marking all of them at once, I was able to cut down on error.
The pieces shown above are four of the corner stiles, and the markings require a bit of explanation. On the right, you see two lines. The one on the outside marks the edge of the mating rail, while the inside one marks the end of the mortise. On the left, there is a single line that marks the start of the mortise, but no line for the edge of the rail. This edge is flush with the end of the stile, and the long gap indicates the haunch that will fill the groove to the edge. It’s wider than usual due to the fact that these mortises will be hand-chopped, and I allowed extra wood on the outside of the mortise to help prevent any blow-outs of the end grain.
One of the beauties of grooved rails is that all of your mortising guides are already in place. Just place your auger bit or mortising chisel in the groove, and you’re ready to go. Of course, you still have to stay vertical. As usual, I bored multiple clearance holes for each mortise to make the chisel work easier. This step is especially important on mortises near the end of the board, as this helps to reduce the dreaded blow-out of the unsupported endgrain.
The next step will be to start bringing these various chunks of wood together. Stay tuned!