Spline Miter Joints
“Whatever you can do or dream you can, begin it. Boldness has genius, power and magic in it.”
Goethe…(1749-1832) German writer, Polymath
The Beauty of Spline Miter Joints
Spline miter joints offers strength and elegance. It is a joint that wants to be seen and recognized unlike many other joints that serve a utilitarian purpose and are concealed. Often times spline miter joints are made of contrasting colored woods and that is this case of the species chosen for the joinery of this arts and crafts style picture frame selected for this posting. The frame is made from a Camala, a light toned wood from Peru and the spline miter joints for the joinery is cut from black walnut.
To create the spline miter joints we use a shop made spline miter jig that is simply made from scrap plywood in the woodworking shop. The jig has a 90 degree cradle that seats the picture frame and is held in place with a spring clamp. When cutting spline miter joints a flat tooth saw blade is used so that the walnut spline will fit into the saw kerf without any exposed gaps present. In this instance a 1/8″ dado blade is chosen for the task.
Location of the Spline Miter Joints
It is a good idea to determine the location we want for our spline miter joints to be cut on the picture frame. Once this placement is made we can simply clamp a piece of scrap into the jig and to make a test cut. We will need to adjust the rip fence in or out as we will be sliding the miter jig alongside of it. Also, we need to set the saw blade height as this will represent the depth of the cut for the spline. Once these settings are adjusted it is simply a matter of carefully making a pass through the blade and then repositioning the picture frame for the next miter to be cut.
Once all the cuts have been made for the spline miter joints, we can focus our attention on making the spline material. In this case it is 1/8″. Start by ripping the spline a bit wider than the depth of the miter cut and then dimension the material equal to the width of the joints’ saw kerf. Once we achieve the proper thickness for our splines it is time to cut enough triangular pieces for all joints. This is performed by using the dedicated miter sled for the band saw. It makes for quick work and it is very safe especially for working with smaller sized material.
Gluing the Spline Miter Joints
When all the splines are cut we simply brush white glue onto the spline and press the spline into the saw kerf. Now, it is just a matter of repeating this procedure for all the joints. At this point allow for the glue to set at least an hour before sanding the excess of the splines at the disc sander. (Be careful to just remove the excess of the splines and avoid sanding into the frame. Notice how the miter gauge was used to control the sanding.) When all the spline miter joints are finished with sanding at the disc sander we can then use a block sander to detail the joints in preparation for applying one of my favorite wood finishes.