Sawing guidelines for small-scale timber processing

Timber sawing is aimed at producing sized timber from round logs. The process requires skill and the right machinery and equipment Large-scale sawmills as well as small-scale set ups have been used with different levels of success worldwide. In Kenya, while large-scale saw milling found acceptance, small-scale timber processing faced lack of technology and skills. The most common opinion therefore has been that sma1l-scale timber processing methods are wasteful and produce timber with very rough surfaces. These methods may however continue being used on the farms due to their advantages compared to the large-scale saw milling machinery.
Some of the advantages of small-scale timber processing methods are their ability to be used on the same site where the tree falls. This reduces the costs of extracting and moving the logs to a different sawing site. It also greatly reduces the potential environmental damages associated with timber logging practices in the large-scale sector due to the use of heavy logging equipment (Pasiecznik et al, 2006). They are also relatively cheap to buy and maintain. There are three main small-scale timber-sawing methods in Kenya; chain sawing, mobile bench sawing and pit sawing. These are used in different areas in single and some limes in combination.
Timber recovery is the amount of sized timber obtained from a given amount of logs and is sometimes referred to as sawn timber yield. Majority of the small-scale sawyers in Kenya have limited skills in sawing techniques used to increase timber recovery and quality. Thus, the average recovery is as low as 23% for chain saw operators and about 27% and 39% respectively for bench saw and pit saw operators at the sawing stage (Muthike. 2003a). The actual recovery from the available wood can also be controlled at every stage from tree felling to the timber handling before selling. Since about 50 to 80 percent of tota1 saw milling costs are in terms of raw materials, it is important for the sawyer to recover as much of the raw materials as possible. This calls for a good understanding of recovery rates and the factors influencing it. It is therefore important that mobile saw bench millers, chain saw operators and pit sawyers are educated on how to improve timber recovery and quality.
This manual aims at making available useful skills to sawyers and trainers involved in small-scale on-farm timber processing sector. It offers guidelines on the important steps to take during felling and sawing of timber using the sawing methods available to the sawyers. Equipment maintenance and safety have been included due to their direct influence to timber recovery and quality. By following these guidelines, the sawyer is expected to recover more of the available tree resources into quality, merchantable timber. Training sawyers on these sawing guidelines has resulted in improved timber recovery and quality, hence increases financial gains for both the sawyers and tree owners (Muthike, 2004b). The number of trees cut for sawing at any particular time for sawing is also reduced.