The flat dowel , also form spring , wood connection plate or LFF [from "lamella form spring"], is an approximately lens-shaped connection element in wood processing . In the southern German and Austrian language areas, flat anchors are also known as "Fischerl", and the name with the brand name "Lamello" is also common.
The flat dowels, mostly made of beech wood, are available in several sizes, they have pressed-in grooves and bevelled edges. They are suitable for all types of connections in solid wood and wood-based materials , especially for body and frame corner connections, butt and mitred .
To make the connection, short grooves are milled into each of the components to be connected with a flat dowel cutter , into which the flat dowels are glued with wood glue . When the glue is used, they swell up and create a very firm connection. The connection can be moved slightly in the direction of the groove, which must be taken into account when pressing the components and corrected if necessary.
Flat dowel connections enable an efficient production for individual production and small quantities. Compared with a dowel connection , the effort involved in marking and setting up is lower. With higher quantities and series, the use of wooden dowels with the use of automatic dowel machines or machining centers is usually more economical.
Chipboard came onto the market in Switzerland around the middle of the 20th century . Herman Steiner, founder of Lamello AG, was looking for a way to connect this new material without any problems, as connections with a continuous groove produced weak edges on the chipboard.
In 1956 Steiner launched the flat dowel under the brand name Lamello, which has since been widely used in professional and semi-professional woodworking. After the expiry of patent protection, there is a greater variety of devices, which has led to hardware stores offering inexpensive milling cutters in their range and as a result this wood connection is popular with do-it-yourselfers.
There are now flat dowels made of plastic and aluminum. A new generation of flat anchors has been on the market since 2005, which are no longer made of solid wood but of a wood-based material based on fibers. As an alternative to a firmly glued flat dowel connection, there are now releasable flat dowel connections. Some variants are form-fitting and can be dismantled without tools, other variants require a hexagon wrench to release the locking pin again.
- Wolfgang Nutsch and others: Expertise for carpenters 12th edition, Europa-Lehrmittel, Wuppertal 1980, ISBN 3-8085-4011-7 , p. 175.
- Authors' community: Book of tables for wood occupations Bildungsverlag EINS, Troisdorf 2002, ISBN 3-441-92350-2 , pp. 130-131.
- History of Lamello AG. In: Lamello AG website. Retrieved October 6, 2018 .
- Lamello system - connector overview. (PDF) Retrieved October 6, 2018 .