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Build a Woodworking Jig for Better Boxes
Tools and Materials
Learn how to build a simple woodworking jig that allows you to cut spline slots in the corners of your boxes.
Perhaps one of the easiest boxes for a beginner woodworker to make is one with mitered corners. If cut accurately, mitered corners glue-up easy without the use of clamps. That's right, you heard me--no clamps. In fact, the secret to putting together mitered boxes is using packing tape to hold the entire assembly together during glue-up. You can learn how to use this jig in a post on building a beautiful recipe box. For now however, we'll need to turn our attention to building this specialized tablesaw jig that will allow you to cut spline slots in the corners of your box.
For small boxes like the recipe box we'll be building in a future post--or the box at left, you could just rely on glue to keep the joinery together however, inserting splines offers excellent joint reinforcement and will allow you to build larger boxes without the worry that the joints might come apart a few years down the road. The wood in a miter joint is an odd breed. It's not quite end grain (which doesn't yield very good glue joints) and it isn't quite face or edge grain--it's somewhere in between. You'll notice that the wood facing you in a miter or end grain cut is rather porous (think of a bunch of straws bundled together). This means that the wood really sucks up glue and doesn't bond very well. By using splines in your joinery, you're introducing face grain, and using the strong glue bond that that particular type of grain offers. An added bonus is that by using wood of a contrasting color, your splines will stand out and add beauty to your project. Arkansas woodworker Doug Stowe is a big proponent of this technique and his books and articles are a must-read for anyone who wishes to delve into serious box-building. In fact, this little jig is one he uses regularly.
So without further ado, lets get to work building a spline jig and put it to work building beautiful boxes.
How to Make
Step 1: Gather and Cut Materials to Size: The jig is composed of a hardwood board (mine was ash, but you could use maple or any other hardwood scrap) that not only acts as the backer block for the jig, but also, as the runner which will fit into your tablesaw's miter gauge slot. You'll want a piece that measures in at about 17.25-in. long by 5.5-in. wide. Those are the exact measurements for my jig but anything in the ball park is just fine. Just be sure it's thickness allows it to fit snugly (it should be snug but glide freely) in your miter gauge slot. The other two pieces are plywood scraps measuring in at 6.5-in. x 10.25-in.
Step 2: Prepare the Hardwood Runner: Notice how the hardwood backer block fits perfectly in my tablesaw's miter gauge slot. I used my jointer and planer to hone in the size however, most miter gauge slots are about 3/4-in wide and you can use that thickness stock, paring it down with a handlplane if necessary.
Step 3: Cut a 45-degree Angle Along One Edge: Next, I cut a 45-degree angle along one of the long edges on one of my plywood pieces. This angle will eventually ride along the tablesaw's table--you'll see a detailed photo showing the angle in the "Cradle-to-Hardwood Runner Detail" photo further down in this post.
Step 4: Glue and Nail the Jig's Cradle Assembly: Next, I glued and nailed the assembly together using some brads. Take care not to use nails anywhere near the center of the cradle assembly, where your saw blade will eventually cut through the mating corner of the assembly. You'll ruin your blade!
Cradle Assembly Detail: Here's what that cradle assembly should look like once your glue has dried. Notice that the 45-degree angle is on the OUTSIDE corner.
Step 5: Glue and Screw the Cradle Assembly to the Hardwood Runner: Now you'll need to glue and screw your cradle assembly to the hardwood backer block/runner. The bottom of my cradle assembly (where the 45-degree angle was cut earlier) is set up above the bottom of the hardwood runner board by about 3/8-in. This allows the runner board to seat inside the tablesaw's miter gauge slot. See the next step for a detailed photo showing the placement. Also note that the two cradle pieces each come off the bottom of the hardwood runner board at a 45-degree angle (see plan download for more details).
Cradle-to-Hardwood Runner Detail: Notice how the 45-degree angle is facing down - where the it will eventually meet with the tablesaw table. Also, notice that the bottom of the cradle assembly is mounted 3/8-in. above the bottom of the hardwood runner block.
Step 6: Mount the Jig and Cut your Saw Kerf: The last step is to cut a saw kerf straight through the bottom of the cradle assembly. Simply mount the hardwood runner block into your tablesaw's miter gauge slot, and with the blade raised up a bit so that it will cut right through the assembly, simply run the jig through the blade. That's it! Your jig is now ready to use.