How to Use a Biscuit Joiner

5 min readJul 4, 2018

How to Use a Biscuit Joiner | A Complete Tutorial with Tips & Recommendations

As intimidating as a biscuit joiner may seem, it’s one of the best options for getting a seamless joint. In particular, they are the preferred tool for joining parallel pieces of wood together as often done with a table top. Unlike a hand drill. a biscuit joiner offers a stable base and several points of contact with the board. They are nimbler than a drill press and operate with fewer size limitations. Additionally, biscuits are much stronger than dowels and they work on narrower cuts of wood. For perpendicular joints as seen in a cabinet shelf, smaller biscuits allow for thinner materials to be used. As with a parallel joint like the example below, larger biscuits improve the strength of the seam. In this tutorial, we are going to show you some of the most important tips for getting perfect wood joints.

Prepping the Lumber

In order to get a perfect joint, we recommend squaring your lumber while you’re first learning. At the very least, the two sides that will face each other need to be flat. Also, the two slabs will need to be the exact same height for both the top and the bottom to sit flush. If you don’t have the means to square up the sides of your lumber, you can always purchase manufactured pieces of wood at stores like Home Depot or Lowe’s. With that being said, be sure to check that your manufactured materials aren’t warped in any way. For this example, I’m using two pine stair treads that I purchased from Lowe’s (both stores are okay for pine treads, but Home Depot uses a veneer on their hardwood treads whereas Lowe’s uses solid oak).

Setting Up the Work Station

Having the correct work space is just as important as using the right materials. You’ll need to make sure that the top of your workbench is flat and that the base isn’t wobbly or sitting on uneven ground. Next, a stable back is necessary for the board to push up against while you’re cutting the biscuit holes.

If your work surface doesn’t have a back or a fence to push up against, you can always clamp a flat piece of wood to the top of it.

Placement of the Biscuits

The number of biscuits is largely dependent on the size of the boards that you’re planning to joint. At a minimum, you’ll need two biscuits at each end for any two pieces over 12 inches in length. For boards that extend beyond two or three feet, a third biscuit is recommended in the center. This will ensure that boards keep their vertical alignment in the middle. In my example, I opted for 7 biscuits in total because this platform needs to be able to hold up to one ton. When marking the lines for your cuts on the board, the exact distance between two biscuit holes is less important than making sure that the holes align horizontally.

Perfect Horizontal Alignment with Biscuit Joiner

To ensure horizontal alignment, I recommend folding the two pieces of wood on top of each other. Then, you will running the marker across the two boards at the appropriate location.

Cutting the Biscuit Holes

When cutting a biscuit hole in your board, you need to ensure that the side of the wood that’s facing downward is completely flush with your work surface. If you want the sure-easy way of doing this successfully, consider just clamping the board down. Using clamps to secure the board to your work surface will also keep the board from sliding horizontally. Next, place your biscuit joiner against the face of the side that you will be cutting. If you have an adjustable fence, it’s optional to use when cutting into the wood at a 90-degree angle. You’ll then line the mark on the biscuit joiner that indicates the center of the blade with the line that you drew on the board. Next, we are going to make the actual hole. While pushing down on the biscuit joiner with your front hand, you will steadily push the blade into the board. Once the blade is fully extended, you can retract the blade with control. Unlike a power drill, you will keep the button on until the blade has returned to its original position.

Adhering the Two Pieces of Wood

You will want to start with a dry fit before applying any amount of glue. Before doing this, be sure to check that each biscuit hole lines up both horizontally & vertically with its respective mate. Otherwise, you risk snapping the biscuit, which will render both holes useless. In the event that any two holes don’t line up, you may need to relocate the placement of that given biscuit altogether. Once the boards connect well in the dry fit, you can start applying glue. It’s important to get small amounts of glue into each of the holes to keep the biscuits in place. To make the bond as seamless as possible, we suggest using at least two clamps to hold the boards together. When adjusting the clamps, you’ll want them to be as tight as possible.

Next Steps…

After the glue has fully cured (check bottle for time frame), you can remove the clamps and continue forward. If you have a drum sander, the smoothing process is easy. In the case that you’re like me, you’ll need to use a random orbit sander to clean up the top. When using a hand-held sander, be sure not to focus only on the glue seam. Otherwise, you’ll end up with a concavity straight down the center of your platform. As with sanding any piece of wood, softening the edges will hide imperfections. If you need help with sanding, keep an eye out for future tutorials.