WOOD- WORKING MACHi: 501 



hints. 



e are constructed similarly to the above-mentioned 

 machines, only there are a number of circular planes fixed 

 close together on a flat ed-_ ier the wood is pressed 



against the planes or the latter against the wood; round 

 rods or threads are produced of the same diameter as the 

 planes, and of the same length as the piece of wood. 



6. Wood-bending Machine*. 



alrea<r I (p. 96) wood becomes pliable when 



moistened and heated. Steamed or boiled wood when dried 

 ins the shape that is given to it. Manual labour suffices 

 to bend small pieces of wood, but large pieces for wheel- 

 felloes or for curved wood used in ships and barges are bent 

 by machines. As in bending wood the fibres on the outer 

 convex side are stretched and may break, precaution is taken 

 to bend the wood rather by shortening the inner fibres than 

 hing the outer ones. The piece of wood is therefore 

 fixed along a thin piece of steel between two strong bent iron 

 clamps at its transverse ends. The wood is then pressed 

 against a cylindrical surface, so that both wood and steel are 

 bent, the steel preventing the stretching and breaking of the 

 wood-fibres. 



'-pressing Machines. 



Cast brazen dies are pressed into wood by a strong iron press, 

 wood is boiled or steamed, or the dies are heated by red- 

 hot irons. Wood can be pressed more easily on its transverse 

 section, than tangentially or radially. A piece of veneer is 

 glued on to the surface of the wood before it is pressed, so that 

 it may be imagined that the wood is curved and not pressed. 

 If pieces of veneer 3 mm. thick are pressed between two 

 slightly undulating iron plates, the undulations in which fit 

 into one another, wavy wood, or curls, may be imitated. When 

 this wood is planed, imitations of mottled wood are produced 

 completely resembling the structure shown in Fig. 



8. Wood-pulping Machines. 



There are two kinds of these machines, one in which the 

 surface of the wood is rubbed or planed away, and th: 



