The History of Furniture Construction

Characteristic of Skeletal Furniture

Skeletal furniture is the products of linear and surface structure, in which elements

do not close a space. Like in the group of case furniture, we distinguish:

• main element, forming the function and construction of the furniture piece (leg, backrest board, seat frame, top panel—usually the worktop of the table),

• complementary element, providing only the function of furniture piece (insert of worktop, armrest) and

• compensatory element, which can improve satisfactory stiffness, strength, durability and reliability of construction (support, bar).

Each of these elements can be made as:

• beam or rod element derived from wood, or any profile made of metal or plastic,

• element in the form of a board made of wood or fitting made of metal or plastic and

• panel element, obtained from an MDF board, HDF board, composite board with the addition of lignocellulosic particles, plywood, etc.

Usually, skeletal furniture consists of a frame (i. e. a skeletal bearing structure), the seat and the backrest (in the case of chairs), as well as of the top panel (in the case of a table, it is usually a worktop). Characteristic surfaces of these parts significantly affect diversity of finish and workmanship. Distinguished here are (Fig. 2.29):

• external surfaces, visible in the furniture piece at a position of use. This includes all surfaces of beam, rod, board and panel elements and

• invisible surfaces, those that are invisible in the furniture piece during its use in accordance with the intended purpose. This includes bottom surfaces of seats, worktops, invisible surfaces of rails, frames and runners.

The most characteristic representative of skeletal furniture is the chair. Usually, frame elements (of bearing structure) of chairs are connected using inseparable connections, which provide greater stiffness and strength of the construction compared to connections using metal joints (bolts and screws for wood) (Fig. 2.30).

The seats of chairs usually constitute a separate subassemblage, but they may well be a constituent element of the frame. Depending on the purpose, the seats of chairs are made in upholstered form, from plywood and plastic mouldings, flat or profiled boards, leather, wicker or rattan weaves (Fig. 2.31).

The backrest of a chair, similarly to the backrest of an armchair, ensures addi­tional transfer of the human body’s weight. It usually constitutes the form of connection of backrest legs. There are also backrests that are an independent ele­ment or subassemblage fitted to the seat (in stools), frames (in bent furniture) or to

the rails (in carpentry furniture) (Fig. 2.32). As in the seat, depending on the purpose of the chair, the filling between the vertical elements of the backrest are made in upholstered form, made of plywood and plastic mouldings, flat or profiles boards, leather, wicker or rattan weaves.

Tabourets and benches are a kind of skeletal furniture mostly used in kitchens and public buildings. These are usually constructions without a backrest; however, due to ergonomic reasons, for benches for waiting rooms in public offices, backrests are designed which support the entire back or only a portion at the height of the loin (Fig. 2.33). Like with chairs, the seats of tabourets and benches can be hard or upholstered.

The shape and detailed features of tables depend on the place of use. For each specific group of users in kindergarten, school, office, laboratory, computer labo­ratory, dining room, kitchen, restaurant, etc., often personalised parameters are defined, which decide on the shapes, dimensions and construction solutions. In tables intended for flats, the height of the top surface is adapted to users sitting on chairs. In places of recreation and leisure, low tables are designed, called occasional tables, tailored to people sitting in armchairs.

Bearing structures of high tables occur mainly in rail forms (Fig. 2.34), with the legs of the following cross sections: polygonal, rectangular, triangular, circular, oval and irregular. In longitudinal cross sections, the legs have rectangular or trapezoidal shape, usually converging downwards. For transport reasons, it is rec­ommended that the legs are attached to the rails in a disjoint manner.

Depending on the purpose and functions of the designed table, the top boards can have a regular form of squares, rectangles, ellipses, ovals and circles, or in the

form of irregular surfaces limited by a polygon, splain or polyline. In employee table for offices, designers search for shapes of top surfaces which allow their connection into new usable forms (Fig. 2.35).

Each of the shapes of the top surface should enable its pivoting, rotating, pulling out and disassembling. In addition, in school and office furniture, it is important to provide the possibility of step or stepless height adjustment of their position.

Top surfaces of tables can be made entirely from solid wood, chipboard, car­pentry boards, cellular and MDF boards, boards veneered with natural veneer, decorative paper, HPL, CPL laminate, as well as metal and plastics. There are also boards made of plastic, marble, glass or a few materials simultaneously, e. g. metal

and glass, wood and ceramic tiles, wood and glass, etc. Depending on the purpose, worktop surfaces should be finished with materials of varying durability and resistance to the impact of fluids, temperatures, UV radiation, mechanical damage, etc.

From the point of view of use, tables of variable surface of the worktop are favoured. According to Swaczyna and Swaczyna (1993), they can be divided into three groups:

• with an increased working surface,

• with a lifted working surface (board) and

• unfolding or connected tables.

Among tables with an increased worktop, Swaczyna and Swaczyna (1993) dis­tinguish tables with:

• moving boards supported after being unfolded on pulled out legs,

• moving boards supported on extended rails,

• sideboards supported on additional supports and

• boards enlarged using auxiliary boards (inserts).

Tables with movable boards supported after extended on pulled out legs are characterised by the mobility of the structure of the frame, generally thanks to fitting wheels. Legs with a pull-out function are attached to the rails by hinges. Worktops of these tables can be divided into two or three parts and also joined by hinges from the bottom surface. The worktop divided into two parts leans on a turntable set on the rails. In order to increase the usable area, the legs must be pulled out (usually at an angle of less than 90°), the worktop turned by 90°, and one wing of the worktop spread out (Fig. 2.36a). If the worktop is divided into three parts, then its vertical parts should be raised to a horizontal position and the legs pulled

out (Fig. 2.36b). These types of constructions are applied to kitchen tables and small dining rooms.

Tables with movable boards supported on extended rails can have divided worktops and ones connected with hinges, as well as inserts. A characteristic fea­ture of this group of furniture is the extended construction of the rails.

In divided worktops, they rest directly on rails or on the turntable fitted to the rails. Tables with inserts are distinguished by two worktops secured to the extended rails. In order to increase the usable area of the table with an unfolded worktop, the frame must be extended and the board spread out by turning the top element 180° (Fig. 2.37a) or by turning and spreading out the upper wing (Fig. 2.37b). If the worktop of the table is assembled of two parts and fixed to the rails, user should spread out of the worktop, take out inserts and the stabilising elements from a pocket and slide worktop back again. (Fig. 2.37c). These types of constructions are applied to kitchen furniture and dining rooms.

Tables with sideboards supported on additional supports are characterised by external invariability of the geometry of the frame. Increasing the usable surface of the worktop usually occurs through the elevation of its vertical parts to the

horizontal position and extending the vertical supports being movable elements of the rails (Fig. 2.38a) or extending additional worktops resting under the surface of the main board (Fig. 2.38b). With this construction solution, auxiliary worktops are fixed to supports which are also runners enabling to hide and pull them out.

Tables with worktops enlarged by inserts are distinguished by: two equal sliding worktops and usually geometrically unchangeable frame. Enlarging the surface of the worktop takes place by sliding out worktop that is fixed to runners (wooden or metal) and inserting into the gap inserts in the shape of a rectangle. Inserts can be placed loosely in a magazine created in the space between the lower surfaces of the worktop and the transverse skirtings fastening the longitudinal rails (Fig. 2.39a). An interesting solution is also the eccentric fastening of the insert (Fig. 2.39b). After extending the worktops, the insert rotates 180° in the rails and again connects the

worktops. At the eccentric embedding of the insert, it is recommended also to install a turntable which enables to install an insert divided into two parts, thus signifi­cantly increasing the work surface (Fig. 2.39c). With this construction solution, after extending the boards, the insert should be rotated once 180° and then the upper element of the board unfolded 180°, after which the worktops should be connected together.

Tables with an unfolded worktop are rare today. Worktops of these tables are one piece and rotationally fixed to the column or one edge of the frame (Fig. 2.40).

Unfolding or connected tables are usually marked by a fixed geometry of worktops and frames, and they are distinguished by low weight and mobility by fixing wheels to the legs. Such a construction of tables enables the quick and efficient completion of furniture and adapting rooms (usually offices) to the user’s needs.

The following elements are distinguished in skeletal furniture, chairs and tables

(Fig. 2.41):

• backrest board, an element of skeletal furniture for sitting, constituting the backrest or base for upholstering in the backrest,

• seat board, an element of skeletal furniture for sitting, constituting the seat or base for upholstering in the seat,

• hanger head, a rolled or sharp-edged element, constituting the co-axial extension of the hanger post,

• hanger hook, an element, usually formed in the shape of the letter J or S, constituting the basic functional part of the hanger,

• block, an element which is the strengthening of the main structural nodes

• and fulfils functions, e. g. of slider and resistance,

• connector, a type of curve-shaped bar in bent furniture,

• bar, an element constituting additional strengthening of structural connections, and depending on the location in the furniture piece, the bar may be longitu­dinal, transverse, etc.,

• leg, bearing element of the base of the furniture piece, and depending on the location in the furniture, it can be the back or front leg,

• support leg, an element fulfilling the function of a back leg and support of the backrest simultaneously in skeletal furniture for sitting,

• support legs, an bent element in the shape of an inverted U, and these are two support legs connected from the top in bent furniture for sitting,

• rim, a bent element with a closed circumference, usually constituting additional strengthening of construction connections in the base of skeletal bent furniture,

• rail, an element constituting the primary horizontal structure of the base in skeletal furniture, and depending on the location in the furniture, the rail may be frontal, side, rear, longitudinal or transverse,

• arch, a bent element in one or a few planes of an open circumference, usually constituting strengthening of connections at the base of bent skeletal furniture,

• worktop, the element or subassemblage that constitutes the usable, top plane of the furniture,

• support, an element supporting the armrest in skeletal furniture for sitting,

• armrest, an element constituting the support of arms in skeletal and upholstered furniture for sitting,

• semi-rim, a bent element with an open circumference, in the shape of the letter U, usually constituting the strengthening of connections at the base of bent skeletal furniture,

• rail, the component element of the frame, and depending on the location, there are longitudinal, transverse, central rails etc.,

• column, a vertical bearing element, e. g. of a free-standing hanger,

• muntin, an element for filling a particular space in an openwork manner

• in skeletal furniture,

• insert, a movable element for increasing the dimension of the worktop (Fig. 2.39) and

• inset, an element that fills the space between the rails and other external limi­tations of the backrest, side, etc., in an openwork manner, and depending on the location, there are backrest insets, side insets, etc., and in special cases, it can be a subassemblage.

Subassemblages and assemblages of skeletal furniture include (Fig. 2.42):

• side, subassemblage constituting the side limitation, and depending on the type of furniture distinguished are chair sides and armchair sides,

• backrest, an assemblage or subassemblage, upholstered or not, serving as a backrest,

• rail module, an assemblage of several rails joined together,

• base, an assemblage or subassemblage that has a bearing function for the fur­niture piece or assemblage,

• armrest module, in skeletal furniture usually built from an armrest and support,

• frame, subassemblage consisting of connected rails, fulfilling the bearing function for the upholstery pillow, also in the base or body of the furniture, and in bent furniture, it can constitute a bent element with a closed circumference, and depending on the function, there are upholstery frames, door frames, etc.,

• seat frame, a bent element with a closed circumference or U-shaped, which constitutes the main structural connection of the seat,

• seat, an upholstered assemblage or subassemblage for sitting,

• frame, subcomponent of a skeletal structure which is a kind of base

• in case furniture and skeletal furniture,

• skeleton, an assemblage or subassemblage composed of structurally bound beam elements, rod elements, pipe elements, etc., which constitutes the bearing structure of the skeletal furniture or its part, e. g. upholstered.