A biscuit joiner, also called a plate joiner, is a woodworking tool used to join two boards together. I love mine, made by Skil. You do need to wear a mask and goggles as there is a lot of saw dust expelled quickly. Most joiners are corded, but you almost always use them in an environment where electricity is available.
To join two boards together, to make a wider surface, you simply align them together and make short marks, across both boards, where you’d like the two attached. Set the biscuit size, 0 small – 10 medium 20 – large), height of the board (so it will cut in the center) and align the mark on the joiner against one of the boards. Turn it on the push to plunge the joiner, inward, to cut the slot, repeating on that same board, for the other slots.
Then do this same procedure for the other board. now test you work by inserting the biscuits and making sure your boards align properly. Once satisfied, remove the biscuits and apply wood glue in all the cut slots and along the board joining surfaces. Re-join the two, clean off the expelled glue and clamp for drying. A good rule of thumb is to use a biscuit every 6 to 12 inches.
The biscuit joiner was invented in 1956 in Liestal, Switzerland by Hermann Steiner. One of the most important things to look for in a joiner is the amperage, you’ll want 5-7 amps. The next factor is speed so look for 8000 to 10,000 rpm ratings. It is nice if you can get one that comes in a hardened case that will store the joiner, some biscuits, the instructions and maybe a spare blade.
The photos above are from a project I was working on.