How to Produce an Edge-to-Edge Biscuit Joint

By Mallory Kramer

To lay a small patch of groundwork, a biscuit joint is wood joint that binds two workpieces together with a disc-like oval-shaped "biscuit" of dried and compressed wood shavings. A slot is cut into the adjoining edges of each of these two workpieces, a biscuit is deposited into one slot, glued, aligned with the corresponding slot on the opposite workpiece, and clamped in place to allow the glue to set. This creates a flush, hidden joint that is very tight and extremely strong. Because the biscuit also expands within the joint with the moisture of the glue, a biscuit joint is uncommonly durable.

Because it is relatively fast and simple to create and because the result is accurate and reliable, biscuit joinery is a very popular method among all walks of woodworker. Accordingly, one of the most widely produced biscuit joints is an edge-to-edge joint, one that is used in framing, box making, table-top making and other common woodworking applications.

An edge to edge joint, then, is exactly what you'd suspect of a thing called an "edge-to-edge joint;" it brings two workpieces together and joins or binds them at their edge. Although this article will focus on joining panels for a tabletop (or something like it), the process is essentially the same for all edge-to-edge biscuit joining applications.

1. First, the edges you're preparing to join should be of the same thickness and should be planed flat to ensure a flush joint. Next, you must determine the biscuit size you intend to use for the project. Typically, the largest biscuit size that will insert without disrupting the edges being joined is the best biscuit to use. Next, simply arrange the pieces you plan to join in the manner you intend to join them. When joining multiple pieces, it is recommended that you stagger the grain direction of each panel being joined; in other words, to enhance the integrity of your final product, the direction of the wood grain should alternate with each board.

2. After satisfactorily arranging your workpieces, mark the cut points for your biscuit slots. Depending upon the length and general bigness of your workpiece (bigness being anything that will contribute to the force that the workpiece applies to the joint), biscuit slots should be cut, approximately, every 4" - 6." After all pieces are marked, separate the workpieces and begin cutting.

3. Adjust your biscuit or plate joiner to the size that corresponds to the biscuit size you're using and place the tool's guide fence perpendicular to the top or cutting edge of the board. Align the tool's cutting guide to your cut marks and, while holding the tool in that position, engage the saw. Allow the tool to reach full RPM before carefully plunging the blade into the workpiece. Push the tool until you cannot plunge the blade any deeper into the material. Remove the tool completely and repeat this process to cut each biscuit slot.

4. After each biscuit slot has been cut, assemble the panels for a quick dry-run (this, of course, means don't yet involve any gluing). Plop a biscuit into each slot, align these to the corresponding slots on the opposite workpiece and ensure the pieces come together flush and proper. If the boards come together as desired, you can finally bust out that glue. If the slots are somehow misaligned or the edges are not meeting flush, isolate and correct the issue before proceeding.

5. Once you are ready to glue, evenly distribute an appropriate amount of glue throughout each slot (on both workpieces). "Appropriate," however, is a difficult term here as the gluing process, too, is a delicate one. Accordingly, use as much glue as you can without using so much that it squeezes out of the joint and onto the surface of your project. If you do have some glue runoff, be sure to wipe it immediately as the residue will affect the finish of the final product.

6. The next step is simply connecting the workpieces. Because you will have a small window of wiggle room before the glue sets, ensure all edges are flush before clamping the pieces in place. Lastly, you need only tightly secure your clamps and allow the piece to set. While the glue sets, the biscuit will expand reinforcing the strength and tightness of the joint.

Ultimately, a biscuit joint is relatively simply to produce and delivers a tight, tough and invisible joint. For more information about biscuits, biscuit joiners (like Makita's new PJ7000 plate joiner ), biscuit joinery, or other woodworking techniques, please visit www.toolsandmachinery.com; your resource for everything woodworking. - With power tools and accessories, woodworking and construction equipment, replacement tool parts, and a power tool and machinery repair center, toolsandmachinery.com keeps your craft kicking. What can we do for you today?