What Are Biscuit Joints? A Beginner’s Introduction

If you’re just getting into woodworking, you might be wondering: How do woodworkers get boards to line up so perfectly? The answer, in many cases, is biscuit joints. These simple connectors help create strong, long-lasting bonds between pieces of wood, without needing years of experience or complicated tools.

In this guide, we’ll cover what biscuit joints are, when to use them, and how they compare to other woodworking methods. You’ll also learn the pros and cons so you can decide if biscuit joinery is right for your next project.

What Is a Biscuit Joint?

Small, oval pieces of compressed wood called biscuits are used in the carpentry process known as a biscuit joint to unite two pieces of lumber. It is comparable to fitting a piece of a jigsaw puzzle into each of the two identical holes on a board.

Here's how it works: With a biscuit joiner, sometimes called a plate joiner, you make slots in both pieces of wood that match. You insert the biscuits into the slots after putting adhesive on them. The biscuit absorbs the glue that ties the two boards together, and then it extends up.

Why Woodworkers Like Biscuit Joints

Woodworkers use biscuit joints because of their efficiency and simplicity of use. You don't need years of experience to get good results; you just need the right tools and a little practice.

Additionally, biscuit joints make it easier to position boards when they are being glued together. Without biscuits, boards could slip and produce uneven edges. During the glue's drying process, the biscuits maintain their level and flatness.

They also add strength. While some old-school joints may be even stronger, biscuit joints are plenty strong for most furniture and cabinet projects. Biscuits are made from tough, compressed beech wood that locks tightly in place once glued.

Where You’ll Find Biscuit Joints

Many woodworking projects employ biscuit joints. They can be found on shelves, tables, cabinets, furniture, and more.

One of the most common uses for edge-to-edge glueing is combining many boards to form a larger surface (like a tabletop). Using biscuits to keep the boards aligned during glue-up will save you hours of sanding uneven edges.

Furthermore, biscuit joints are perfect for light-duty corners, such as those seen in picture frames or small boxes. However, for extremely strong corner joints, traditional methods may be more effective.

Tools You Need

The main tool for this type of joint is a biscuit joiner. It looks a bit like a small circular saw but is designed to cut the curved slots that the biscuits fit into.

Biscuit joiners usually let you adjust the depth of the cut and the position of the slot. Some popular brands are Porter-Cable, DeWalt, and Lamello.

You’ll also need biscuits. They come in three common sizes:

• #0 (small)
  
  
• #10 (medium)
  
  
• #20 (large)
  
  

The size you use depends on how thick your wood is and how strong you need the joint to be.

How to Make a Biscuit Joint

Making a biscuit joint is pretty simple. Here’s a basic process:

1. Mark your boards where you want the biscuits to go. Most woodworkers space them about 6–8 inches apart.
   
   
2. Set up your biscuit joiner according to the instructions, adjusting it for the thickness of your wood.
   
   
3. Cut the slots in both pieces of wood. Keep the tool steady and let it do the work.
   
   
4. Test the fit. The biscuits should fit snugly in the slots but still slide in easily.
   
   
5. Apply glue to the slots and the biscuits, then assemble the boards. Work quickly, because the biscuits will start expanding as soon as they touch the glue.

Pros and Cons of Biscuit Joints

Like all woodworking techniques, biscuit joints have advantages and disadvantages of their own. You can determine when they're the best option for your project by being aware of both.

Pros

• Simple to learn, even for beginners
  
  
• Speeds up the joining process
  
  
• Keeps boards aligned during glue-ups
  
  
• Strong enough for most furniture and cabinet work
  
  
• Works well in many types of builds with just a few tools

Cons

• Not ideal for heavy-duty or structural joints
  
  
• Depends on the glue, moisture can weaken the bond.
  
  
• Best for boards at least 3/4 inch thick
  
  
• Joints are permanent, not easy to undo
  
  
• Less effective when joining boards with different grain directions

Things to Keep in Mind

Not every circumstance calls for biscuit joints. Boards at least 3/4 inch thick are ideal for these. The joints may get weaker since thinner boards don't have adequate space for the slots.

Moreover, biscuit joints are broadly strengthened by glue. If you intend to disassemble the item later, you would be better off using screws or other detachable fasteners.

Finally, wood grain matters. Biscuit joints work best when the pieces of wood have similar grain direction. If the grain runs in opposite directions, the joint may not hold up as well over time.

Balancing Old and New Woodworking Techniques

Biscuit joints are a great modern invention. But there’s still value in learning traditional joinery techniques, too. At Bay & Bent, we’ve spent years restoring historic timber frames built with joints like mortise and tenon connections that have lasted for centuries without nails or modern fasteners.

When we restore old barns and timber structures, we respect the original craftsmanship. Sometimes we repair the old joints, and other times we use modern techniques like biscuit joints for new additions or hidden parts of the structure.

Blending old and new methods allows us to preserve the beauty of these historic buildings while making them useful for today.

Try It Yourself

Start with a basic project, such as a picture frame or tiny shelf, if you wish to try biscuit joints. To become familiar with your tool, start by cutting slots in scrap wood.

Biscuit joinery requires practice, just like any other woodworking technique. Although your initial joints may not be flawless, you will rapidly get better. Due to its speed, strength, and ease of use, biscuit joints are frequently used by woodworkers.



You can choose the finest alternative for each project and create stunning, long-lasting pieces of your own by learning both traditional and modern techniques, such as biscuit joints.