How to Make Biscuit Joints

What You'll Need
Biscuit joiner
Wood glue
Tape measure
Safety glasses

Biscuits joints are often used for joining wood because they tend to be very strong. Making biscuits joints with a biscuit joiner is quite easy once you’ve mastered to tool and it cuts the slots you need to perfection. Also known as a plate joiner, it helps make your biscuit joints accurate.

Step 1 - Size

The first thing to do is decide on the size of biscuit for the joint. In most instances, you’ll find that a #20 biscuit will be quite adequate. However, if the wood you’re working with is very thin, then you’ll need to go smaller on the biscuit size. The biscuit is the piece of wood that fits in the holes you make and joins the two pieces of wood.

Step 2 - Setting the Biscuit Joiner

The size of biscuit will determine how you set the depth adjustment on the biscuit joiner. From there you’ll have to set the height adjustment so the biscuit is in the middle of the stock. You need to be aware that if you’re using double biscuits-that is, two biscuit joints side by side-then you have to leave a gap of 3/16 inch or more between the biscuit joints, and also between the joint and the edge of any board.

Step 3 - Marking

Now you need to prepare the wood to be cut by the biscuit joiner. Place it in the position you’ll be using for cutting, and with your tape measure and pencil, mark out where you’ll be cutting the slits on each board.

Step 4 - Cutting

You need to be aware of how a biscuit joiner works before you begin using it. Wear safety glasses before you use it, to keep your eyes well protected. To make the cuts in the wood, you need to press the biscuit joiner against the board. When you do this, the blade, which is 4 inches long, emerges. As you release the pressure on the tool, the blade contracts again.

To make sure you’re cutting in exactly the right place, you need to have the cutting guide completely aligned with the pencil marks you’ve made on the board, and the fencing guide perpendicular to the edge of the wood.

To make the cut, push the biscuit joiner firmly against the wood, keeping on going until the blade will go no further. Release the pressure and let the blade retract, and you will have your cut. Repeat this on the other board. Make sure the cuts are clean and full enough to accept the biscuit, and blow and debris out of them. Make sure you store the biscuit joiner safely, under no pressure so that the blade is fully retracted.

Step 5 - Glue

To fix the biscuit joints properly, take your wood glue and apply a little into one of the slots. Insert the biscuit, making sure it’s the way in. Now put glue in the other slot, line up the boards and push the biscuit into the second board.

Now you need to clamp the two boards together. Beware, however, that you don’t clamp too tightly. If you do that, you risk losing all the glue from the joint. There will inevitably be some excess glue that leaks, and use a damp cloth to wipe it off before it has a chance to dry.