Introduction to Basic Manufacturing Processes and ... - always yours

9.8 FACTORS INFLUENCING TIMBER SELECTION
Carpentry 159
The factors influencing the selection of timber involve the quality of timber in terms of its
durability, workability, weight, hardness, cohesiveness, elasticity, type of texture, type of
grains, resistance to fire, resistance to various stresses, ability to retain shape, suitability for
polishing and painting.
9.9 PLYWOOD AND APPLICATIONS
For the last so many years, the use of the plywood and other manufactured boards has, in
varying degrees have replaced the use of solid timber in the making of furniture, fittings,
paneling and many forms of constructional work. Plywood is generally made of three or more
sheets of veneer glued together, with the grain of successive plys laid cross-wise. Since the
strength of timber lies along the grain, when plys of veneer are bonded in opposing grain
direction, strength is distributed to both length and breadth of the piece. The plywood can be
obtained in much larger sizes without shrinkage and warping in comparison to plain wood.
The molded plywood boats, television and radio cabinets can be formed from plywood. The
plywood can withstand easily against humid condition. Plywood is lighter in weight and
stronger across the grain than even the toughest hardwoods. Screws and nails can be driven
close to the edge of plywood without any danger of splitting. High class surface finish can be
are easily obtained on plywood.
The development of moisture and heat-resistant adhesives have contributed to the use
of laminated members for heavy truss construction, to the gluing together of narrow boards
to make wider ones, and to the making of finger joints by which short lengths are joined to
make longer pieces. Plywood is used for many forms of construction, including sheathing,
interior finish, sub flooring, under-roofing, paneling, flooring, cabinets, furniture, shelving,
partitions, ceilings, containers such as baskets, boxes, crates, trunks into boats, toys, tables,
woodenware and repair work in garages and basements.
9.10. MISCELLANEOUS MATERIAL USED IN CARPENTRY SHOP
There are a number of other materials used in carpentry shop besides timber. The main
materials are dowels, nails, screws, adhesives, paints and varnishes. A brief description of
such material is given as under.
Dowels
Dowels are wooden pieces of special nails kind generally made out from bamboos or
other similar wood by the carpenter himself. They are used for fastening different wood
structural components. Hole is initially drilled through the two pieces or parts to be joined
together. After assembling of in proper position of the parts to be joined, the dowel is then
driven through the parts.
Nails
Nails in wood work are made out of drawn wire of brass or copper or low carbon steel
or malleable iron rods. Nails made from drawn wires are termed as wire nails and are
produced from rods as clasp nails. The clasp nails possess a better holding capacity than wire
nails. According to the use, the wire nails are subjected to light and medium work while the
clasp nails are commonly used for heavy work. Nails are mainly used for reinforcing glued