MAKING THE JIG
This jig is made from 3/4” material that you may have in the cutoff bin. This is, more or less, a project specific jig. If you do a lot of boxes then adding hold downs, removable and replaceable inserts are possible if you want a more versatile jig. Also making a jig for more than one key per corner is possible by laying out each key in a couple of steps. I cover this later on. But this one is pretty basic and took just 20 minutes to put together. Layout begins by finding the center on the vertical panel portion of this jig and scribe a line. From the center point scribe two opposing 45 degree lines. Attach the legs to the vertical panel with cleats, rechecking your angles as you go.
ROUTER BIT SET UP
Setting up the bit is first. The diameter and degree of the bit is arbitrary. Choose one that suits your box and your design. I chose a 14 degree 3/4” dovetail bit for my project.
1.) Determine the depth of the dovetail key (or keys) onto your box by scribing a line across the miter. The depth of cut, I think, should be about 2/3rds up from the outside corner. That depth will give you a key that is of nice proportion.
2.) Place the box into the jig and transfer the scribe line to the legs of the jig. Raise the bit in your table to that line.
3.) In the picture above you can see that in the jig I have a set up piece glued together from cutoffs of the project. I will use that later to verify my set up before I commit myself to routing the actual box
ROUTER FENCE SET UP
Setting the fence is next. Placement of the keys, depending on your design, may call for more than one fence setting. I chose to place one dovetail key perfectly centered across the width of the box which meant just one fence setting.
1.) Scribe lines where you want the dovetail key (or keys) onto the end of a piece of scrap that is exactly the same width as your box (preferably cutoffs from you box). For my project I used a 3/4” dovetail bit, so I first scribed the center of the board and then scribed lines 3/8” on each side of center onto the scrap.
2.) To set the fence, place another scrap piece that is the same thickness as the vertical panel of the jig against the fence. Adjust the fence to align the bit with the scribe lines (or set of scribe lines) on the scrap you made in step one. To make it easier, get the fence in an approximate location and tighten one end securely. Fine tune the alignment with the other end of the fence, then once aligned tighten it down. It doesn’t matter if the fence is set askew from the front edge of your router table or miter slot.
3.) Bump cut your scrap piece into the bit far enough that you get the full width of the cutter routed into the wood. Double check your layout.
4.) Once satisfied, place the jig onto the router table and carefully make a pass cutting a profile into the legs. Make sure the jig lies flat on the table and is up against the fence as you cut. It’s important to make a clean pass over the bit. A clean entry and exit through the legs of the jig will support the grain of the box and prevent tear out.
5.) Place your box into the jig and secure with clamps. Again, my preference is to route a mitered sample piece before committing to routing the actual box. Be sure you have the box orientated correctly, and that orientation is consistent with each pass on all four sides of each box. Carefully make a pass cutting the profile onto the box. Be sure the jig lies flat on the table and is up against the fence as you cut.
6.) Route all slots needed before changing the fence. Placement of any additional keys can be made easy enough by just repeating steps 2-5.
CUTTING THE KEYS
After all the dovetail slots are routed on the boxes, the next step is to make the keys. The use of contrasting woods is a personal preference. Using the same species also has a great effect. To make the keys, you use the same bit already in your router table. This assures the keys matches exact to the corresponding slot.
1.) Prep the wood for the keys. Select a piece long enough to make multiple keys and wide enough to safely route and rip on the table saw in a later step. The thickness of the material should start out a bit thicker than the width of your dovetail slots. In my case I milled 5/4 S2S cherry down to 7/8” for the 3/4” dovetailed slots
2.) Raise the bit about a 1/16” or so higher than what was set cutting the slots. That 1/16” or so is to increase the size of the key in relationship to the depth of the slot. This ensures a key will fit along the entire tapered portion of the slot. The extra will be removed after they are glued into place later on.
3.) Adjust router fence so bit will just make a full cut without leaving a flat spot but not so much that you remove a lot of wood. The idea is that you maintain as much of the thickness as possible. Route both edges.
4.) Now you have an oversized tail that is too wide to fit the slots. Adjust the router fence in very small increments making more passes along both edges until the tail just fits snugly in the slot
5.) Now the fence is set to route more edges of the work piece if a lot of keys are needed.
6.) Set up you table saw to rip free the long tail piece from the wide board. I like to rip the piece to leave a “handle.” This handle makes applying glue to the tapered surfaces easier.
7.) Crosscut into short pieces but oversized when fitted in the slot.
8.) Repeat steps 5 through 7 if more keys are needed
9.) Because you routed these to be snug, some could be too snug so a light
sanding on the tapers may be required to fit each into a slot.
10.) Apply a light coat of glue to each tapered face. No clamps are necessary
11.) Once glue has set, its time to remove the excess material. This can be done with a band saw, flush cut saw, or even a belt sander. Careful not to cut into the box. By leaving the tail a little proud is the best approach. Flushing the tails perfectly with the box can achieved with a hand plane or sanding block.
In this picture is my project boxes in progress. I wiped it down with a little mineral spirits to highlight the keys
Finished Project posted below
-- Measure "at least" twice and cut once