Biscuit Dowels and Jointing Biscuits: Sizes, Dimensions & Lamello Alternatives
A biscuit dowel, frequently referred to in joinery as a jointing biscuit or by the well-known manufacturer name Lamello, is an oval connecting plate made from compressed beechwood. It serves to form a positive-locking joint between wooden components and swells upon contact with water-based wood glue inside the routed groove to create an extremely strong anchor.
What Exactly Is a Biscuit Dowel?
The biscuit dowel is an essential element in modern furniture construction. It consists of beechwood cut diagonally to the longitudinal grain, which is compressed mechanically under high pressure. The surface is finished with a fine waffle pattern or embossing. This texture makes insertion into the routed slot easier and ensures an optimal distribution of glue.
The technical principle relies on expansion: much like a dry sponge, the compressed timber absorbs moisture from the applied PVA wood glue. As a result, the jointing biscuit swells by fractions of a millimetre and jams tightly into the cut. Compared to standard wooden dowels, this joining method offers a decisive assembly advantage: the routed slot is slightly wider along its length than the wooden plate itself. This grants the joiner a lateral play of around 2 mm during assembly, allowing components to be aligned perfectly flush before the adhesive sets.
Lamello or Jointing Biscuit: What Is the Difference?
In workshop practice, these terms are often used interchangeably. Strictly speaking, Lamello is the registered brand name of the Swiss company that invented this jointing system. The generic, manufacturer-independent technical term is jointing biscuit or simply biscuit dowel. Technically and dimensionally, standardised jointing biscuits from other manufacturers are identical and fully compatible with the routing tools of the original manufacturer.
Sizes, Dimensions and Technical Specifications
Standardised biscuit dowels are divided into three primary sizes, which correspond to the material thickness of the panels being joined. The thickness of the wooden biscuits across all three standard sizes is exactly 4 mm. The biscuit jointer is accordingly fitted with a 4 mm thick groove cutter.
- Size 0
- Dimensions: 47 x 15 x 4 mm
- Routing depth: 8.0 mm
- Application: For narrow frame joints and thin board materials with a thickness of 8 mm - 12 mm.
- Size 10
- Dimensions: 53 x 19 x 4 mm
- Routing depth: 10.0 mm
- Application: For material thicknesses from 12 mm - 15 mm, commonly used in drawer boxes or delicate small furniture units.
- Size 20
- Dimensions: 56 x 23 x 4 mm
- Routing depth: 12.3 mm
- Application: The absolute standard in cabinet making. Designed for panel thicknesses from 15 mm, ideal for standard 19 mm chipboard or MDF.
Beyond these standard dimensions, special sizes exist such as Size S6 (85 x 30 x 4 mm) for heavy sections or extremely compact variants such as H9 (38 x 12 x 3 mm), which require a reduced slot width of 3 mm.
Usage and Selection During Assembly
Anyone using biscuit dowels in carcase construction requires a dedicated biscuit jointer (groove cutter). The tool is referenced against the workpiece to plunge crescent-shaped slots into edges and faces.
For a sturdy cabinet carcase made from 19 mm panels, Size 20 is always the correct choice. When it comes to positioning, joinery practice relies on the following rule of thumb: the first and last biscuit dowel are placed approximately 50 mm from the outer edge. In between, spacing follows a grid of around 150 mm - 200 mm, depending on the anticipated load on the piece. For mitred corners (e.g. edges cut at 45°), these oval plates provide exceptionally high shear strength because they penetrate deeply into the material of both mitred halves.
Related Terms in Furniture Making
- Wooden dowels: Cylindrical timber pins (usually 8 mm in diameter) that, unlike jointing biscuits, permit no lateral play during gluing and require absolute drilling accuracy.
- Cam lock fittings: A demountable metal connector fitting, frequently used alongside wooden dowels to make flat-pack furniture easy to disassemble.
- Tongue and groove joint: A continuous edge profiling where a machined tongue engages into a full-length groove.
Matching Category
For professional timber joints in furniture and interior fitting, you can find standardised, precision-fit biscuit dowels in various pack sizes for every material thickness.