A finger joint is also known by its other name as comb joint. It is a result of cutting and joining short complementary pieces of wood. It is one of the cheapest forms of woodworking joint that offers strength to a woodworking project. The interlocking profiles of two wood pieces make them strong enough against heavy pressure.
If you look at the cross-section of finger joints, you will notice that the shapes look like several networks of fingers of two hands with wide sides for gluing. In comparison with butt joints, finger joints are not visually attractive yet more robust than their butt counterparts.
Uses & Applications of Finger Joints
Finger joints have existed for over a century, but their popularity remains unfazed. Advanced countries like Japan, Europe, and the United States use finger joints to construct boxes. These joints work best in natural woods and boards, such as MDF and plywood. Mahogany is the best wood choice for this type of joinery.
Home interiors look appealing with the application of wood in their living spaces. Finger joints on wood tiles and wall paneling exude a natural and calm spirit. They are ideal for creating floorboards, doors, molding, trim, and baseboards.
How To Make Finger Joints
Woodworkers create two identical profiles to form finger joints. They use a finger router or spindle molder to cut the profiles and rotate the tool to develop complementary profiles. It would be best to use a tool to cut the shapes, as manual cutting takes longer, and errors are inevitable.
They bond the short pieces of wood together to form longer boards with the help of structural adhesives. Wood joint technology balances the internal stress of the wood plank through the fusion of various pieces of wood.
This method leads to the stability of the finished product. A single wood plank is subject to warping and twisting during prolonged exposure to humidity and heat caused by the multiple fiber densities on the wood’s length.
Finger-Joined Lumber vs. Finger-Joint Board
Finger-joined lumber uses scarfed or tapered finger joints from solid boards to shape them into long pieces. This joint finger technique is proper in structural and non-structural projects. Some uses of structural products are horizontal plates and vertical studs in constructing platform frames in house buildings.
This method is beneficial in the manufacturing of both glue and cross-laminated timbers. The non-structural uses of finger-joined lumber include trim and molding.
Finger joint boards result from leftover wood lengths too short for other uses. Wood manufacturers cut the ends of the leftover wood to form a finger joint profile. It is easy to make using a finger joint router bit.
The purpose of this construction is to extend the length of the wood by adding more pieces to reach the desired length and reinforces it with structural adhesive or wood glue before clamping together to adhere well.
After curing the glue, the manufacturer takes out the clamps. They assemble the leftover wood to form moldings or trims. The final touches are optional, such as sanding or planing the surface to fit the joints perfectly. This technology can save a lot of dollars as the manufacturer utilizes those wood rejects.
Usually, the wood pieces are two to five centimeters wide. The staves of the leftover wood can have the same length as the board, known as the entire stave board, which is about 20 over 39 centimeters long. The manufacturer connects the end to end of the wood with finger joints to reach the desired length.
Finger-joint board is advantageous in making expansive solid wood panels which a single log cannot do. It offers broader dimensional stability as they comprise small wood planks. It requires fewer tools to make them. The downside of finger-joint boards is that they are a candidate for warping and twisting as they are prone to moisture exposure. The type of wood you are using may have a different reaction to humidity and moisture.
Advantages of Finger Joint
- Easy to make: Finger joint is affordable as you can assemble small pieces of wood materials to extend their lengths. Leftover wood with lengths too small to use for a solid panel is recycled, joining the joints to form a continuous board.
- Strong & Resilient: These characteristics make finger joints useful in many applications as their strength is more robust than single lumber. The joints can withstand vertical loads. Twisting and warping seldom occur in finger joints, mainly if you use a good quality wood type like mahogany.
- Straight & Stable– Bowing down of wood is lesser in finger joints as the joint wood absorbs them. The finger joints offer a more linear structure due to the small pieces of enduring wood materials, ensuring good performance.
Disadvantages of Finger Joint
- Not So Durable: Although fingerboard furniture can save you a lot of money, it offers little longevity. Since it comprises several short pieces of wood, its durability relies only on the finger joints bonded with adhesive or glue.
- Bow-Down Issues: The finished product tends to bow down in the long run because it is not solid wood compared to traditional solid wood. Most finger joint products use raw wood materials that are low quality, such as cypress and pine.
- Less Appealing: It is less appealing due to the visibility of short wood pieces added end-to-end to reach their desired length.
- Single-layer Finger is Quite Weak: Joint fingers consist of single-layer finger joint boards and three-layer finger joint boards. The single-layer version is weaker, so choose it only if you want a sturdy finished product. Only the three-layer finger joint board can provide stability to your woodworking project.
Conclusion
Finger joint wood may be an affordable wood board, but it is not durable. Solid wood is much cheaper than finger joints in the long run. Experts say finger joint is unsuitable for constructing structural products, especially when exposed to the elements. But, if you are on a budget, you can opt for this joint, ensuring that you take care of your furniture by not exposing them to humidity, moisture, and extreme condition.