Civil Engineering - Building Materials - Discussion

Medullary rings are the rings which ties all annular rings while annular rings are the rings which are formed every year spreading outside or inside depending on the type of trees.

Sawing of timber mean?

What is the difference between medullary rings and annular rings?

Ordinary Sawing.

It is the most economical, cheapest and is widely used method of sawing. In it only long parallel planks are cut. Because the inner portion is heartwood which is hard and outer portion is sapwood which is soft thus after dryness there will be unequal shrinkage, thus the planks are liable to wrap and twist.

In Quarter sawing, the logs are cut or sawn in a quarter and is then cut in such a way so as to bend in a transverse direction. This method is adopted when no distinct medullary rays are present and gives very fine figure wood.

In this method, logs are sawn parallel to modular rays and perpendicular to annual rings. This method gives the least shrinkage but most wasteful. This method gives most decorative works in which medullary rays are marked, and least shrinkage is because of the property of medullary rays to resist shrinkage.

Tangential Sawing.

If annual rings are well formed and medullary rays are not well formed than tangential sawing is used. In this method, cuts are made tangent to the annual rings. Planks obtained by this method wraps too much and must not be used for costly works. Such planks are not suitable for flooring.

Sawing? please difine it for me.

Sawing timber?