Author: haroonkhan

This is the method adopted for sawing hardwood. This method of sawing produces planks, which do not shrink much. Because of the interplay of grains, it gives a decorative finish. However, maximum wastage occurs by this method of sawing.

The disadvantage mentioned in ordinary sawing is to some extent avoided in quarter sawing. This method of sawing produces fine timber when the wood has no distinct medullary rays. However, timber cut by this method has a tendency to get bent in the transverse direction (Fig. 10.7(a)). Figure 10.7 Ordinary and quarter sawing

In this method of sawing the log is simply sawed along the diameter. This is the quickest and commonly adopted method. This approach is more economical as wastage of useful timber is minimum. Each cut plank has an outer portion of sapwood and an inner portion of heartwood. But there will be differential shrinkage and…

After felling trees, the branches are removed and the trunk is cut into logs. Conversion is the process of cutting and sawing logs into suitable sections of timber. In earlier days, it was done manually using saws. Now-a-days, cutting is done by band and circular saws run by machines. Sawing is done by four methods,…

As discussed earlier sapwood is less durable than heartwood and hence its presence should be avoided. The presence of sapwood can be identified by the colour, which is much lighter than that of heartwood. Further, it does not take good polish as compared to heartwood. Apart from the natural causes discussed above there may be…

The cells in living trees do not always grow perfectly vertical or straight and parallel to the length of the truck but in a sloping manner. Such an action causes the grains to slope when the timber is sawn parallel to the pitch. Such sloping grains are considered to be a defect.

The exterior surface of a tree shrinks when it is exposed to atmospheric agencies. Such a shrinkage results in cracks known as wind cracks (Fig. 10.6). Figure 10.6 Typical wind cracks of timber

These are also known as twisted grains or wandering hearts. They are caused by the twisting of young trees by fast-blowing winds. The fibres of the wood are twisted in one direction only which causes problems while sawing. However, they may be used as poles or posts without any planing (Fig. 10.4). Figure 10.4 Typical twisted…

Different kinds of defects are found in timber. Generally, they are caused by the nature of the soil on which the tree is grown, the fertility it gained during growth and changes occurred in the environment during its growth. The defects to be generally looked into while selecting timber for woodwork are discussed below. Knots…

Good timber should produce a clear ringing sound when struck. Decayed timber produces a dull and heavy sound.