Formful Wood. Explorative Furniture

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GRAIN ORIENTATION, GROWN AND SHAPED FIGURE 1 Oak outer string timbers required for shipbuilding FIGURE 2 Structure of a wood cell FIGURE 3 Stress distribution in curved wood FIGURE 4 and 5 Hay sled
SEBASTIAN KRAFT the material does not have to stretch or compact. By placing a metal bending rail on the outer (pull) side, the tensile component can be completely removed from the wood. Metal has a considerably higher tensile modulus (and a higher tensile strength) than wood and takes over the tensile stress. As a result, the wood “only” has to compress—on the inside now several times over. According to a rule of thumb, hardwoods such as beech, oak, ash and elm can be bent by a minimum radius of three to four times the thickness of the piece in question. Conifers, on the other hand, only allow 18 times the radius. 1 [→ FIGURE 3] DAMPNESS In preparation, the air-dry wood is moistened with water. When moisture is supplied, the cells swell and the properties of the cell building blocks change. E-modulus and strength decrease. Moistening beyond the fibre saturation point does not further soften the wood, contents are washed out if necessary and cell cavities filled with water can lead to breaking outwards on the pressure side during bending. TEMPERATURE Temperature has a great influence on the mechanical properties of the wood. In combination with wood moisture, an increase in temperature leads to a loosening of the fiber composition and to plastic deformation (in contrast to elastic deformation, in which the object returns to its original state after loading/bending). Elongation now causes much less stress than with dry, unheated wood. The deformability of the cell walls allows for strong compression. <strong>Wood</strong> should be continuously warmed to 80° C and moistened up to the fiber saturation point. GROWTH RINGS A load in the tangential direction is advantageous, i.e. the cross-section to be bent should preferably have standing growth rings (90° to the bending direction). Grain orientation should be parallel to the longitudinal axis. Cut fibers break outwards during bending, the piece has a reduced load-bearing capacity. METHODS The wood is steamed or boiled in a closed container, then bent and fixed as quickly as possible over a press mold or several points. After cooling it is loosened and can be further processed. Since the wood springs back a little after forming, the bending form must be 10–20 % beyond the target geometry. Additional fixation over several days or weeks—e. g. with a clamping set or nailed strips—prevents slow resetting further. Each wooden part takes on an individual shape after bending, therefore it is important for parts that are in a series production that they are fastened at several points (at least three) when installed. 167
Page 1 and 2: MARIO RINKE, FLORIAN HAUSWIRTH [EDS
Page 3 and 4: FORMFUL WOOD EXPLORATIVE FURNITURE
Page 5 and 6: Can there be a more enticing and ch
Page 7 and 8: A TEACHING PROJECT TRANSCENDS DISCI
Page 9 and 10: CHRISTOPH SCHINDLER HISTORY Histori
Page 11 and 12: FLORIAN HAUSWIRTH ing or CNC millin
Page 13 and 14: RAOUL DUBOIS [GALLERY] → 82 45
Page 15 and 16: MANON ZIMMERLI [GALLERY] → 96 55
Page 17 and 18: ILGHAR DADGOSTARI [GALLERY] → 112
Page 19 and 20: MELINA MICHAELIDES [GALLERY] → 12
Page 21 and 22: RAOUL DUBOIS [PROGRESS] ← 44 83
Page 23 and 24: MANON ZIMMERLI [PROGRESS] ← 54 97
Page 25 and 26: NICOLAS HARTER [PROGRESS] ← 60 10
Page 27 and 28: LEA BISSIG [PROGRESS] ← 70 115
Page 29 and 30: MERET TRÖSCH [PROGRESS] → 146 12
Page 31 and 32: OLEKSANDRA MEDVEDEVA [PROGRESS] →
Page 33 and 34: NATALIE AGREDA [GALLERY] ← 130 15
Page 35: URSINA HASLEBACHER [GALLERY] ← 13
Page 39 and 40: MARIO RINKE itself in England as a
Page 41: NICOLAI DE GIER Technique prepares
Page 44 and 45: TABLE OF FIGURES NICOLAI DE GIER: T
Page 46: Design and construct a plywood seat

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