Tongue and groove joints are one of the most solid and stable ways to secure two pieces of wood together. Whether for furniture or flooring, panels or toys, using tongue and groove construction to join your pieces will result in the most solid fabrication possible. There are two ways to create tongue and groove joints easily, with a router and matched bits or with a table saw and a dado blade set.
Things You'll Need
- Safety goggles
- Stacked dado blade set
- Jointer or table saw jointer jig
- Wood glue
Measure and cut the wood you want to use in your tongue and groove joint at least 1 inch longer than the final length. You can do this with your table saw, a mitre saw or circular saw.
Create a joint on the connecting side of each piece of wood using the jointer or jointer jig. Jointing creates a flat, smooth edge at a perfect angle to the board edges to make clean and seamless joints.
Repeat the process on the opposite side, creating perfectly parallel edges which are flat to each other and the boards you are joining.
Line your boards up to make certain they sit flush with each other before cutting the tongue and grooves. Label them in order, such as 1-2-3 or A-B-C, so you can make certain to cut them in the right order. Each board will have a tongue side and groove side.
Create the groove on each board before creating the tongues. Place the stacked dado blade set at 1/4-inch width, which should be the two outer blades. Using your table saw, cut a groove 1/3 inch from the edge of the board, by running the flat edge along the table, perpendicular to the guide.
Turn the board and run it back through the saw to ensure a centered groove. Repeat the groove cutting process with all of the boards you will be joining.
Cut the tongue side of your boards. Set the blade set to 1/2 inch wide, and make the depth of cut 3/16 inch. Using a spare board (not one you will need later) move the saw guard over enough that it is barely touching the blade, and clamp the spare board to the table.
Place the tongue side of your board against the spare board and run it along the saw the entire length of the board. Turn the board over and repeat this to create a tongue. Repeat this process for all boards being joined.
Remove excess wood if your tongue is a little too thick for the groove. It is by far easier to remove excess wood than try to reattach it if you cut too much off. Raise your blade a little and run the board through again, and test it against the groove, repeating as necessary until the tongue and groove fit snugly together.
Dry fit the joints to ensure smooth connections once all the boards are cut. After you are certain they fit together properly, join them with wood glue and clamp them together until dry.
Tips & Warnings
- You do not want the joint to be so tight you have to force the tongue and groove edges together. By the same token, it should not wiggle once it is joined.