Cam Lock Connectors vs. Dowels — When to Use Which?
A cam lock connector enables a demountable and force-fit furniture construction, whereas a glued wooden dowel creates a permanent, rigid joint.
When building furniture, constructing carcasses, shelving units, or drawers inevitably raises the question of the right joining technique. The decision is usually between traditional wood joints and modern metal fitting systems. Both variants possess specific technical characteristics that make them suitable for different assembly requirements. Anyone looking to join carcass components made from chipboard or MDF at right angles must understand the mechanical differences between both systems.
What is a Dowel in Furniture Construction?
In the context of cabinet making, this term almost always refers to the cylindrical wooden dowel (mostly produced as a fluted dowel). It is usually made from beech wood and inserted into precision-drilled holes. In carcass construction, a diameter of 8 mm has become the established standard, frequently in lengths of 30 mm or 40 mm.
Alongside the standard round dowel, there is the oval flat biscuit dowel, which is machined using a dedicated biscuit jointer. It is primarily used for mitre joints or flat panel joints.
In construction, a plain wooden pin primarily performs two mechanical tasks: it positions the components precisely relative to each other and absorbs occurring shear forces. Without the addition of wood glue, however, a round dowel does not hold components together under tension. Only gluing and subsequent clamping with sash clamps creates a permanent, heavy-duty joint.
What is a Cam Lock Connector?
A cam lock connector is a two-part furniture fitting that operates on the knock-down principle. It consists of a cylindrical casing (the cam itself) made of zinc alloy or plastic, as well as a matching connecting bolt. In technical terminology, this bolt is often referred to as a connecting dowel pin.
The system works via an eccentric curved track inside the casing. The bolt is screwed into the edge of one component, while the casing is inserted into a face-drilled hole (usually 15 mm diameter) in the second component. By turning the casing half a turn with a screwdriver (drive usually PZ or hex key), the cam engages the head of the bolt, pulls it in, and clamps the two panels tightly together.
Depending on the design, panel thickness, and grid system, different bolt lengths are used. A connecting dowel pin 24mm is suitable for standard joints in 16 mm thick panels. For thicker material or deeper drilling, a connecting dowel pin 34mm is often chosen. For central divider panels where shelves are fixed on both sides, fitters use specific special dimensions such as the connecting dowel pin 28mm.
The Technical Differences in Detail
The choice between the two systems depends on several mechanical and practical factors.
1. Demountability and Disassembly
The most significant difference lies in the reversibility of the joint. A glued timber joint is permanent. Any attempt to undo it inevitably destroys the chipboard or the wood. A cam lock system, on the other hand, can be released as many times as needed with a half-turn anti-clockwise. The piece of furniture remains fully demountable and transportable.
2. Load Bearing and Structural Stability
The cam lock fitting actively pulls the components together, generating high tensile strength. A dry wooden pin cannot do this. While a glued wooden pin does withstand tensile forces, the ultimate strength depends heavily on the quality of the gluing, the precision of the drilling, and the clamping force applied while drying. The metal bolt of the cam lock delivers immediate, predictable strength.
3. Drilling Requirements and Precision
For a standard wooden dowel, two simple holes (edge and face) that align precisely are all that is required. The cam lock system requires a more complex drilling pattern. It requires an edge hole for the bolt shaft, a face hole for the bolt thread in the first component, and a precise blind hole (usually 15 mm) for the casing in the second component. These holes must be positioned at exact distances from one another, which is demanding without a drilling jig or CNC machine.
4. Tolerance Compensation
Wooden pins tolerate almost no inaccuracies during drilling. If the hole is off by just 1 mm, an unsightly step appears on the furniture edge. Cam lock systems provide a degree of error tolerance due to the tightening travel of the curved track. Like a zip pulling two pieces of fabric together, the cam pulls the timber panels tightly against each other over the final millimetres, closing minimal gaps.
5. Tools Required
For wooden dowels, a standard lip-and-spur drill bit is sufficient. Installing a cam lock casing strictly requires a Forstner bit or machine drill bit to cut a clean, flat-bottomed 15 mm wide blind hole into the panel without tear-out.
Which Should You Choose?
In trade and industrial practice, one system does not exclude the other. Instead, they complement each other, based on the established System 32, which defines hole spacing at 32 mm intervals.
Dowel-Only Joint (Glued)
This method is suitable for components that never need to be dismantled after assembly. Typical applications include drawer carcasses, small wall shelving units, or fixed plinth bases. The benefits include low material costs and high torsional rigidity once the glue cures.
Cam-Lock-Only Joint
A construction relying solely on connecting bolts is technically possible, but structurally risky. The connecting pin, even in a heavy-duty design like the connecting dowel pin 8mm with metric thread, does not offer sufficient resistance against lateral shear forces on its own. Under lateral loads, the furniture could tear the drill holes out of the chipboard.
The Combination (Best Practice)
The standard in modern, flat-pack furniture making is combining both elements. Two to three wooden pins per edge provide precise alignment of the components and transfer lateral shear forces into the panel (for instance, when the furniture is shifted).
One or two cam lock fittings positioned centrally between the wooden pins take up the tensile force. They pull the components firmly together, eliminating the need for clamps. Because no glue is used with this construction method, the cabinet remains demountable at any time. The metal fittings clamp the structure, while the wood bears the load.
FAQ – Frequently Asked Questions About Furniture Fixings
Can I replace chipboard screws with cam lock connectors? Yes, this is completely possible for carcass components and looks much neater, as no screw heads remain visible on the outside panels. However, it requires specialist drilling tools (Forstner bits) and precise marking out of the drilling centres.
What thread do the connecting bolts have? There are two common variants: bolts with Euro threads are designed for pre-drilled 5 mm holes in System 32. Bolts with wood threads or metric threads (M6) are screwed directly into the timber or require a pre-fitted insert nut.
Why is my cabinet wobbly despite tightened cam locks? If a unit wobbles, the accompanying wooden dowels that absorb shear forces are usually missing, or the back panel has not been secured correctly. The cam lock fitting alone cannot entirely prevent panels from shifting sideways.
How deep should the hole for the cam casing be drilled? That depends on the panel thickness. For a 16 mm thick chipboard, the drilling depth for a standard casing (15 mm diameter) is typically 12 mm to 12.5 mm. Drilling right through the panel must strictly be avoided.
What does the arrow symbol on the cam casing mean? The arrow on top of the casing must point directly towards the edge-drilled hole (towards the approaching bolt) during insertion. Only in this position can the component slide over the head of the bolt before being locked into place by turning.