Portable Sawmill - Our Guide to an Economic and Practical Approach to Forest Utilization
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PORTABLE SAWMILL - OUR GUIDE TO AN ECONOMIC AND PRACTICAL APPROACH TO FOREST UTILIZATION By L.S.T. (Stan) Griffiths1 Abstract For many years the coconut palm has been to many the tree of life. Not only has it provided food and drink, but, shelter and heat. It is therefore understandable the reasons why there is some reluctance to destroy this commodity that, has served them so well, howev'er senile and unproductive. In this modern world with its rapidly diminishing lumber supplies due to indiscriminate logging, overcutting, slash and burn cultivation and the creeping sprawl of cities into rural areas where trees make way for roads and progress, it is little wonder that conservationists have taken up the cause to halt or control further diminishing of native forests. The shortage that has been created of millable timber has increased costs for building materials so alternatives have to be sought. Throughout tropical territories, an abundance of timber is available in the form of the coconut palm, that has many properties that can fill many of our lumber needs. Being a relatively new product compared with traditional timbers, new methods have to be discovered to process, market and use cocowood to its best advantage. I have attempted to put together a comprehensive paper outlining basic machinery to process coconut palm, from the standing tree to a finished product suitable for everyday needs. Cocowood Felling and Processing The felling of coconut palm stems is sometimes very difficult, as many plantations have young or producing trees in the immediate vicinity requiring care to be taken not to damage them. Therefore, bushmen felling unwanted or senile stems must have reasonable experience in determining his line of fall. Also, the risk of falling nuts and debris make it hazardous to these workers when chainsawing and felling. Bushmen should wear the standard safety equipment, including boots and a recommended type of safety hat. In the tropics bushmen often ignore these basic safety requirements. It is far better to feel uncomfortable than to suffer serious injury from chainsaw cuts or falling trees so -common with this type of occupation. After the stem has been felled, it must be then decided as to the length of each log that is required. A good straight stem presents no problems and can be cut to order, but bent or swept stems do present some problems. 1 Managing Director, Stan Griffith Engineering Ltd. Silverdale, New Zealand. For example, depending on the amount of sweep, to eliminate excess wastage, logs could be cut down to as short as two meters in length, recovering more higher density wood than if left in a longer length of five meters. Machinery required to fell the stems is, simple. A good chainsaw of suitable C.C. rating. It is advisable to have a good tool kit and spare parts on hand to carry out field maintenance and repairs. If a nut or bolt becomes loose it can be retightened immediately but if left may fall out and be lost, putting the chainsaw out of operation, resulting in lost time and extra expense. Fuel for chainsaw should be correctly mixed to the makers recommendations, kept in clean containers and filtered or strained when refueling. If the makers' recommendations are closely adhered to, few problems should be encountered. Operators should be well versed in the maintenance and operation of their machines. A good operator is an asset, a poor one a liability. There are many brands, of chainsaws available and individuals do have their preferences. When choosing a chainsaw, choose a well known brand with local agents that can supply off the shelf spare parts and can offer a good repair service that is prompt and efficient. Breaking Out Roundwood From the Plantation Several methods are employed to do this. The simplest operation is to tow the logs to a central point to be then loaded onto a truck, and delivered to the sawmill. This method is slow and creates double handling. A tractor with rear mounted forks loading direct onto a truck is another method but in adverse weather the truck cannot leave formed roads for fear of getting stuck. A simple method to do both operations of loading and delivering roundwood to the sawmill is a 4 wheeled tractor of 50 H.P. fitted with a hydraulic loader similar to a Hiab loader, and fitted with log tongs. The loader can lift the logs onto a trailer which it also tows and delivers them direct to the milling site. A tractor in the bush can. negotiate many adverse conditions and terrain and can operate on wet or unstable ground. For smaller types of sawmilling operations, a tractor fitted with a towing bar is adequate with an added bonus being a front end loader fitted permanently to the machine. A standard agricultural tractor is ideal. Sawmills - Different Types - Their Advantages and Disadvantages a) Bandsaws Bandsaws have grown in popularity over the last decade mainly because of their thin kerf. They are mostly used on exotic and hardwoods that are clean and free cutting, and little timber is wasted through sawdust. The disadvantage of bandsaw mills is their high maintenance requirements. Bandsaw blades require specialist attention for tensioning and gulleting by well trained and expert saw doctors to maintain them, along with sophisticated grinding and tensioning machinery. They also require more regular sharpening. The tipping of bandsaw blades with either tungsten carbide or stellite is a professional job and is very expensive, both to apply and to acquire the necessary materials. Maintaining bandsaw blades also have a high labour content. To mill coconut, the general opinion is that a bandsaw mill would not take the abrasiveness or density of cocowood unless tipped with either stellite or tungsten. carbide. b) Stationary Circular Sawmills Permanently Sited There are many types and designs of these units. The stationary sawmill is located in a permanent position in a large building, depending on raw materials being delivered by whatever means possible. This means that as the cutting areas extend out from the mill, transport of logs become a problem with eventually long distances to travel for vehicles supplying the sawmill with logs. Soon, the long hauls will prove uneconomic and the mill will either be faced with closing down or shifting. Relocating is a great expense. In such situations, the mill can either be sold at a very low price, be cannibalised for spares or simply left to deteriorate into a useless pile of junk. c) Relocatable Sawmills The relocatable sawmill is generally constructed in a modular form for simpler transportation, and is made up of many heavy pieces. These are very heavy so will require heavy lifting machinery and trucking equipment to relocate the mill in its new position. The relocatable sawmill is designed to be covered from the elements by a large building and this would also have to be shifted when relocating. The whole job takes many days and man-hours to move it to its new site with an added inconvenience of having to rebuild the building. New foundations must be created and machinery reinstalled and re-aligned. Being of a semi-permanent nature, there has to be roads and other facilities completed before any timber can be processed. It is a most frustrating time for both workers and management to have the sawmill unproductive and out of commission. Relocatable sawmills have a higher throughput compared with portable units, as they have machinery incorporated in their design to move and handle sawn timber wastewood and sawdust automatically clear of milling operations. It also employs more labour, creating employment. Other facilities such as drying kilns, saw doctors and maintenance workshops could be assembled around the sawmill if they too are relocatable. Pressure treating plants and chemicals are a problem in many countries. Relocatable chemical treating plants can only be established under strict official controls, with possibly long delays with officialdom and the choice of site. Conservationists will also possibly be involved. d) Portable Sawmills The original portable sawmills were heavy cumbersome affairs, constructed from any material available, and sometimes built around a tractor or truck which not only provided the motive power but also power to drive the sawmill. These units have long been retired from their valuable contribution to the sawmilling industry, and have been replaced with far superior designs that have improved over the decades. Today, these sawmills are found everywhere in plantation type situations and are owned by contractors, farmers or even the part-time sawmilling enthusiast, milling timber that is of good quality and an acceptable degree of accuracy. Of course there is, the odd inexperienced "cowboy" who has no pride in his product, triest to do everything on the cheap, and only after the fast dollar, then disappears leaving his clients disallustioned as to the worth or capabilities of the portable sawmill. Then there is the fly-by-night manufacturer to be aware of, who with little knowledge, jumps on the band-wagon and designs and builds a sawmill that is inferior in both its design and performance. Often these units are made up of second-hand machinery components that would be irreplaceable if replacement was required. At all costs, select sawmilling equipment that has been proven, is reliable, and manufactured by a reputable company with many years of experience behind them. Consider a company that can produce spare parts quickly on demand, and offer a genuine guarantee of good workmanship. Sawmill machinery, like all machinery, should be selected. on their reputation of having the ability to do the job for which they were originally intended.