Tongue and groove is just one of the many joints available to a woodworker. The tongue component refers to a strip of wood extending along the side of block of wood that fits snugly into a groove on a second block of wood. Tongue and groove joints are very easy to make with a table saw.
This example will set the dado head to cut a ¼ inch wide joint using ¾ inch wood blocks. Set the blade height of your table saw at 3/8 inch, and set the fence at ¼ inch for the first cut.
First you will make the groove cut. To make sure the groove is completely centered on the block of wood make the first pass as evenly as possible, then turn the block around 180 degrees and make a second pass through the table saw. This will affect the width of the joint, especially if your first pass was far off center, but this is not very important so early in the process.
Once the groove component of the joint has been cut, you will need to readjust the saw to make the tongue. Set the fence at ½ inches wide for the first pass. Again, you will flip the block of wood 180 degrees and make a second pass. This should shave off the edges of the block, leaving a neat tongue along the center.
Check the fit of your tongue and groove. If you can’t fit the joint together by hand, you will have a hard time connecting the two pieces later when you glue them. However, if the tongue is too loose in the groove, the joint’s strength will be compromised. At this point, it is better to have too snug of a fit than too loose.
Adjust the table saw’s fence to create a snug fit in the joint. Remember that while you don’t want to force the pieces together, glue cannot fill the gaps between two loose pieces of wood- a loose joint is not dependable.
No matter how simple the process, creating a good tongue and groove joint on the first try takes practice. Experiment with scrap wood before moving on to bigger projects.