Knock down joints, often called KD joints, are mechanical connectors designed to join timber panels without traditional woodworking skills. Unlike mortise and tenon joints that demand precise chisel work, knock down joints rely on purpose-made brackets, cams, bolts and blocks that anyone can install with basic tools. These fittings form the backbone of modern flatpack furniture, kitchen cabinets, shelving units and ready-to-assemble furniture found in homes worldwide. Their defining feature is that they can be assembled and disassembled multiple times without damaging components, making them ideal for shipping, home moves and reconfiguration. This guide examines the most common types of knock down joints, their specific applications, and the techniques needed for strong, durable results.
What Are Knock Down Joints and Why Use Them?
A knock down joint is any timber joint that uses a separate bracket, fitting or mechanical connector to hold two or more pieces of material together. The term “knock down” describes how furniture built with these joints can be reduced to flat components for transport and reassembled at the destination. This approach transformed the furniture industry by allowing manufacturers to ship products in compact flat boxes rather than bulky assembled items.
The advantages over traditional methods are significant. They eliminate the need for advanced carpentry skills, reduce assembly time, and allow furniture to be dismantled for relocation. Most fittings are hidden inside the cabinet or panel, keeping the finished appearance clean. Modern KD fittings have evolved to support impressive loads, with some types capable of handling bookshelves and bed frames. Understanding the different types of wood joints and their specific fittings is the first step toward professional results in any self-assembly project.
Plastic Corner Blocks and Square Section Battens
Plastic corner blocks, also called fixit blocks, are among the simplest knock down joints. These moulded plastic brackets press into the internal corner where two panels meet, with screws driven through pre-drilled holes into the adjoining panels. They are common in modern kitchen cabinets and bathroom vanity units where the joint must hold the cabinet square during daily use without bearing extreme loads.
The installation process for plastic corner blocks is straightforward:
- Position the two panels at a right angle in their final orientation.
- Press the corner block into the internal corner so it contacts both panels evenly.
- Drive screws through the block’s guide holes into the panels using a screwdriver or cordless drill.
- Check the squareness of the joint with a try square before final tightening.
- Tighten all screws evenly to avoid twisting the joint out of alignment.
Square section battens offer a more budget-friendly alternative. A softwood batten such as pine is drilled with clearance holes, and screws pass through these into the adjoining panels. The screws are countersunk so the batten sits flush. This method works well for workshop shelving, simple storage units and utility spaces where appearance matters less. Square section battens provide an effective knock down joint using offcuts of timber construction materials already on hand.
Two Block Fittings and Rigid Joints
Two block fittings, marketed as lok-joints, represent a step forward in strength and engineering. They consist of two separate plastic or nylon blocks. A bolt passes through a hole in the first block and threads into the second. As the bolt tightens, the blocks draw together, pulling the panels into firm alignment. Small guide pins keep the fitting straight during tensioning to prevent skewing. These joints are used in cabinet carcases, wardrobe frames and entertainment units where the connection experiences regular stress. They can be disassembled and reassembled multiple times without losing holding power, ideal for furniture moved between rooms or houses.
Rigid joints are moulded from dense plastic with four screw holes in a square pattern. These brackets reinforce cabinet corners by holding adjacent sides firmly together. The rigid bracket itself provides alignment, so the installer simply drives screws through all four holes. They are common in heavy-duty shelving, workshop cabinets and storage racking. Many such components are machined from engineered industrial timber products such as MDF or particle board, which hold screws well with correct pilot holes.
| Joint Type | Strength Rating | Dismantlable | Typical Use |
|---|---|---|---|
| Plastic Corner Block | Moderate | Yes | Kitchen cabinets, vanity units |
| Square Section Batten | Moderate | Yes | Workshop shelving, utility units |
| Two Block Fitting | High | Yes | Wardrobes, entertainment units |
| Rigid Joint Bracket | Very High | Limited | Heavy shelving, workshop cabinets |
| Scan Fitting | High | Yes | Flatpack furniture, bed frames |
| Cam Lock | High | Yes | Flatpack wardrobes, office furniture |
| Table Plate | Very High | Yes | Table legs, desk frames |
Scan Fittings for Flatpack Furniture
Scan fittings are among the most common knock down joints in flatpack furniture. The system has two parts: a metal or nylon cylinder that fits into a pre-drilled hole on the inner face of one panel, and a machine screw that passes through a corresponding hole on the adjoining panel and threads into the cylinder. When tightened with a screwdriver, it draws the panels together with considerable force, creating a tight, rattle-free connection. These fittings serve as either permanent or temporary joints and are extensively used in bed frames where the joint must support both mattress weight and dynamic loads.
A common issue is the cylinder spinning inside its hole when the screw is driven in. Many scan cylinders have serrated edges or a hexagonal profile that bites into the chipboard as the screw tightens. If a cylinder spins freely, a dab of wood glue around it before re-tightening can help, or a specialised jointer tool designed for furniture assembly may be used. Always follow torque guidance, as overtightening can strip the thread inside the cylinder or crack the panel.
- Ensure scan cylinders are fully seated in their holes before inserting screws.
- Use the correct screwdriver bit to avoid cam-out and damage to the screw head.
- Tighten screws in a cross pattern when multiple fittings join the same panel.
- Apply light pressure to the joint while tightening to encourage even closure.
- For load-bearing furniture such as beds, consider thread-locking fluid to prevent screws loosening over time.
Cam Lock Fittings Explained
Cam lock fittings, also called cam dowels, are the most recognisable knock down joint in modern furniture. The system has two components: a circular metal or plastic cam disc that sits in a recess on one panel surface, and a metal dowel pin that screws into the adjoining panel. The dowel pin has a wide collar near its head that fits into a slot on the cam disc.
To engage the cam lock, insert a screwdriver into the slot on the cam disc and rotate it 180 degrees clockwise. The slot captures the dowel collar and pulls it inward, drawing the panels tightly together. When fully rotated, the cam locks in position and holds the joint secure. The mechanism is hidden within the panel thickness, with only the cam disc visible on the interior surface. Cam locks are the standard for flatpack wardrobes, chests of drawers, office desks and bookcases. They require only a screwdriver to operate and provide consistent clamping force across the joint.
A limitation is that the cam depends on the particle board holding the dowel pin securely. If the dowel hole is stripped, the joint loses clamping power. Many designs combine cam locks with wooden dowels for better alignment. For projects using natural timber rather than engineered board, ensure the cam lock recess is routed to the correct depth so the cam sits flush. If a cam lock feels loose after full rotation, check that the dowel pin is at the correct depth, as misalignment prevents proper engagement. For additional guidance on furniture assembly hardware, read this flatpack assembly guide from leading DIY sources.
Table Plate Fittings for Larger Furniture
Table plate fittings are designed for joining table legs to table tops. Traditional tables use mortise and tenon joints that are strong but permanent and difficult to transport. The table plate fitting solves this with a metal bracket that screws into both the table top and the leg, creating a rigid connection that can be undone with a spanner and screwdriver.
A typical fitting consists of a flat metal plate with screw holes attached to the underside of the table top, with a separate bracket connecting to the table leg. Some designs use a central bolt passing through the plate into a threaded insert in the leg, while others use a two-piece bracket that slides together and locks with a grub screw. Key installation considerations include:
- Centre alignment: Plates must be centred on the leg position to distribute weight evenly.
- Screw depth: Use screws long enough for good bite without penetrating the upper surface. A 25 mm to 30 mm length works for standard 18 mm tops.
- Pre-drilling: Always drill pilot holes in hardwood to prevent splitting.
- Sequential tightening: Loosely attach all legs first, then tighten in sequence so the table stands level.
- Cross-bracing: For larger tables, add an apron or cross-brace between legs using timber roof truss connector plates to prevent lateral wobble.
Table plate fittings are also used for desk frames, workbench legs, side tables and console units. The ability to dismantle legs makes these pieces easier to move through doorways and into vehicles. Choose zinc-plated or stainless steel fittings for corrosion resistance in kitchens and bathrooms. The combination of a well-designed plate fitting and sound masonry joint techniques may seem unrelated, but the same principles of accurate alignment and proper fastener selection apply across all joint types in construction and furniture making.
Whichever knock down joint you choose, the same principles apply: ensure panels are cut square, drill accurate pilot holes, use the correct bit to avoid damaging fittings, and tighten all fixings evenly. Well-assembled knock down furniture using quality fittings is every bit as strong as traditionally built pieces, with the significant advantage of portability and easy maintenance.