The Ultimate Guide to Finger Joints in Woodworking

Finger joints are one of the most common and stable types of wood-length joints used in woodworking. It has interlocking fingers with angled profiles and enables the perpendicular joining of two boards.

Mastering this joinery technique can help you make big progress in your DIY journey. In this guide, we are going to take a look at what a finger joint is and how to make perfect finger joints.

What is a Finger Joint?

Finger joints are also called comb joints, whose fingers resemble the teeth of a comb, giving it the name. They are created by cutting complementary interlocking profiles into the wood pieces, which provides a large surface for gluing, resulting in a strong and seamless structure.

The most common type is a tapered or scarfed finger joint. It is used to create long lumber pieces from solid boards, which can be used in producing baseboards, doors, molding, trim, and floor.

Finger joints can be used in various woodworking tasks. And they can be categorized into two types: non-structural and structural. Non-structural finger joints feature shorter fingers, used in making furniture, while structural finger joints feature longer and pointed fingers, used in flooring, roofing, etc.

Box Joint & Finger Joint

The box joint (square joint) is used on the corners of boxes or box-like constructions to join two pieces of wood together at a right angle, hence the name. It seems like the dovetail joint, but different from it, the dovetail joint has angled tails and pins, while the box joint features meshed straight fingers.

Box joints are regularly confused with finger joints. Like we mentioned above, finger joints are used for joining wood pieces longitudinally and at a right angle for longer lengths, while box joints are typically used on boxes, cabinets, frames, etc.

Why Choose a Finger Joint?

One advantage of finger joints is the use of smaller wood pieces. They can connect individual pieces of wood to a finger-jointed board, which can exhibit strength compared to solid wood. But its usage depends on the wood types, the adhesive used, and the dimensions of the fingers.

Interlocking fingers make it easy to assemble, and the substantial glue surface area can ensure the strength. In addition, this joint also offers a visually appealing symmetrical design.

But every coin has two sides, and finger joints are no exception. The initial investment for woodworking beginners or small workshops might be higher. They need some other tools, like specialized jigs and tools, including a router with a finger joint bit and a table saw with a dado blade, which might not be available to all woodworkers.

How to Make Finger Joints?

Having a router table with a properly positioned fence and router bit is the first and key step to making the finger joint. Now, here is the step-by-step guide on how to make a finger joint.

Step one: Set up the router table

To begin, mount your finger joint bit on a router table so that the bearing and fence are aligned. This increases safety, especially when routing end pieces, and provides the finest support for your board. Position the router table fence so that the front of the router bit’s cutting edge is aligned to the face of the fence. Using a straight edge or ruler to verify this alignment will ensure accurate finger profiles.

Step two: Make test cuts

Perform test cuts on two scrapboards. Perform a cutting test on the first board and make an adjacent cut on the second board. If the two boards do not fit together precisely, adjust the blade height and retest until they fit together perfectly.

Step three: Make final cuts

Make any final adjustments to the cutter if the test cuts are not perfect. Once the setup is correct, proceed with cutting your final wood pieces. Ensure each pair of boards interlocks with flush top and bottom edges when the fingers are interlocked. Once cutting has been done, test the fit of the joints. They should fit snugly without any gaps, and the glue ensures that they are practically durable.

Step four: Gluing and assembling the pieces

Here we finish cutting the grooves and fingers before it is glued together. The fingers are lined up with each other, and they should slide and interlock together. Once satisfied with the fit, apply wood glue to all the mating surfaces of the fingers. Interlock the fingers of the two pieces, ensuring that the edges are flush and the joint is tight.

What do You Need for Finger Joints?

Usually, a router table-mounted router bit is used to create this kind of joint. What would be your best choice for a bit to make the finger joints? While there are no hard rules, bit selection is based first on board thickness. When boards of different thicknesses are joined together, the selected bits must have sufficient cutting depth to accommodate the thickest board. Simultaneously, choose the bit that best suits your needs and budget.

A finger joint router bit is the most widely used and optimal tool for joining wood both end-to-end and edge-to-edge. Findbuytool provides a full selection of industrial-grade finger joint router bits with high-grade welding technology, stable quality, and high efficiency. These bits can be used to make wooden planks’ edge styling of wooden planks precise, resulting in smooth and detailed cuts. Ideal for projects of any level of complexity, they are the preferred choice of professionals and hobbyists alike.

A straight router bit or a spiral upcut router bit also works well. Both make a square cut, with the spiral bit doing the cleanest cut. The spiral upcut design routs cleaner and faster, leaves a smoother finish, and dramatically reduces tear-out.

If you still have any problems with this joint, you can leave a comment, and we will reply to you via email ASAP!

FAQ about Finger Joints in Woodworking

#1 What is a finger joint in woodworking?

A finger joint is a wood joint that is used to interlock two boards for a longer board, creating a strong and stable connection.

#2 What is the difference between a finger joint and a box joint?

Finger joints are used for joining wood pieces longitudinally and at a right angle for longer lengths, while box joints are used on the corners of boxes or box-like constructions to join two pieces of wood together at a right angle, typically used on boxes, cabinets, frames, etc.