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.
Most Bona-Fide manufacturers have spent large sums of money and countless hours of their time perfecting their product before offering it to the open market, and can also provide genuine facts and figures relating to their product.
The portable sawmill of today is reliable and because of competition with various brands, reasonably priced. They operate well within the accuracy tolerances required.
They are not as cumbersome as earlier models and can offer more reliable componentry.
Well designed portable coconut sawmills include components that may require replacement. If designed with this fact in view, spare parts can often be procured from local retail hardware or engineering shops, and fitted by the sawmill team.
Designers of portable sawmilling equipment are aware of the need to have the unit sturdy yet light, be able to be transported. easily and have a very short down time between sawmilling sites or plantations.
Portable sawmills have the ability to go right into the plantation to the raw materials and after processing these raw materials, be ready to move on within half an hour.
The simplicity of the portable mill is another advantage as it can be operated successfully, after a short training period by local unskilled labour who soon become enthusiastic and proficient at their job.
Being quick to relocate and set up, it is therefore the most economical method for selective logging activities, where logs are scattered.
Moving to a long dump of say 100 logs and setting up takes a very short time and transportation of cocostems to the mill need not have to be any great distance.
In fact, if the number of logs warrant it in an area, the transportation of raw materials need not be half a kilometer radius from the sawmill.
The advantages of the portable sawmill are: 1) Lower capital cost
2) Simplicity of operation
3) Can be operated by unskilled personnel
4) Creates employment
5) Unskilled labour quickly become skilled
6) No land acquisition required.
7) Most appropriate sawmill for selective, logging
8) Low maintenance and overheads
9) Can be operated by a variety of power sources
10) Financial rewards
Most of these types of sawmills are equipped with their own permanently fixed axles and wheels and towing eye.
The power to the saw blade is entirely the owner's choice, but a tractor of suitable horsepower is mostly favoured owing to the many uses that it could be put to when not actually milling timber.
For instance, after the coconut plantation has been cut over, horticulture could be carried out with the possibility of potential export crops, or for local consumption, grown in soil prepared and cultivated by the tractor.
A sawmill owner-operator with a tractor could carry out agricultural contract work during non-milling periods.
Processing sawn lumber
After milling the cocologs into manageable and stock-sized timber, the timber is generally chemically treated with anti-sapstain solutions.
Cocowood offers more challenges than native timbers as it is hard and extremely abrasive requiring special machines to further process it.
Planing Machinery
All planers are designed to dress the timber to whatever profiles that are required. They should have a variable feed speed to accommodate different densities from hard to soft. Too fast a feed speed into the planer, on hard portions of the timber will result in stalling the unit or jamming it.
Too slow a feed speed will tend to burn the planer knives, causing rapid dulling and more frequent sharpenings, putting the planer out of commission until resharpened knives; can be fitted. Regular unnecessary sharpenings shorten the life of planer blades.
Planers come in varying sizes and models and new machines are very expensive. Reconditioned secondhand machines are available at a far lesser cost, and if maintained properly will perform and last well.
Thicknessers
These machines are designed to dress one side of the piece of timber at a time, the finished sizes being determined by a simple adjusting mechnism. They should also be equipped with provision for variable feed speeds.
Dressing cocowood green is an advantage over hard dry timber, as it is softer and more manageable.
Some difficulty may be experienced with the feed mechanism with wet or green timber but this is of minor concern and can be overcome.
SAWBLADES
Types used for Cocowood Processing
Bandsaws
As mentioned previously, bandsaws are favoured, mainly for their clean cutting and thin kerf. They are recommended only for clean cutting logs and would not be suitable for cocopalm logs.
If it is decided to use bandsaws on cocologs, they would have to be tipped with either tungsten carbide tips or stellite. Maintenance is extremely high and requires expert attention to servicing.
Circular Ripping Saws
The circular saw is the traditional and most inexpensive saw used in sawmilling operations. General purpose plate saws have been cutting timber for many years. They have proved to be the most versatile saw in the sawmilling industry, their main features being the vast array of sizes and types available. They are easy to maintain and service.
To cut coconut wood with these plate saws, experience has proved that fitted with stellite or tungsten carbide tips and suitably ground, they are well suited.
A special grinding wheel is required to sharpen and shape saws fitted with tungsten carbide teeth.
Inserted toothed saw blades
These are circular saws fitted with a special type of removable tooth (or bit), held in place by a specially designed holder. They are more expensive initially to purchase than plate saws, but require less maintenance.
A variety of special bits are available that can be fitted to suit particular species of timber, or muddy, abrasive raw materials.
Inserted toothed sawblades can be serviced on site in the forest using minimum equipment by semi-skilled labour.
Consequently, this type of saw is most favoured where maintenance facilities are limited. They are confined mainly as rip saws. Warn bits can be rebuiltand returned to service with either stellite or tungsten retipping.
Retipped with tungsten carbide, worn inserted bits, owing to the lower cost of materials and the longer periods of cutting between resharpenings, is another advantage.
The principal advantages of inserted toothed saws are:
1) Longer life at a constant diameter.
2) Longer intervals between resharpening because the teeth, being separate from the saw body, can be manufactured of harder special steel alloys that are more wear resistant than ordinary saw steel.
3) Less servicing of the saw is required since tension is not destroyed by continual gulletting and welding needed on tungsten or stellite tipped plate saws.
4) Teeth are readily replaced with spare or over-hauled teeth held in stock so there is no delay when replacement is necessary.
5) Teeth are easier to sharpen.
6) An ideal hook angle and gullett area is permanently maintained to chamber sawdust correctly, essential on high speed saws.
7) The style of tooth, as well as width of kerf can readily be changed to suit different applications.
8) Inserted toothed saws have a good heat dissipation and are ideal for sawmills operating in tropical climates. Cross cut sawblades
The difference between rip saws and cross cutting sawblades is the hook angle, whereas ripping sawblades have a hook angle of around 450, cross cut blades have a negative hook angle. This means that the cutting face of the tooth is square with the saw arbor.
This type of blade is used mainly for cut-off sawing square across the grain, giving a good smooth finish to the cut.
Power units to power sawmills designed for small scale sawing operation's
Units designed to power sawmills should be fitted with diesel engines with sufficient horsepower to adequately do the job. An engine working on its extreme limit of power required will use more fuel and often encounter early component failure.
Engines should have plenty of power in reserve and it will be found that fuel consumption is generally less and machinery runs smoothly and vibration free.
For example, if a horsepower of 60 horsepower is recommended to operate a 40" sawblade efficiently, it must be remembered that other power losses occur through "V" belt drives and other ancillary equipment such as sawdust removal systems, hydraulic equipment, etc., and these should be taken into consideration when choosing an engine.
Unfortunately, the costs of building up a power unit, equipped with hydraulic services, "V" belt and pulley drives, etc. often exceeds the cost of the sawmill, then 'the whole unit comprising power unit and sawmill becomes cost prohibitive for small scale coconut wood processing.
Somewhere around the milling operation, a tractor is going to be needed and this is considered the cheapest option. For instance, a tractor fitted with a front-end loader can shift logs, waste wood and sawn timber as well as hauling logs to the sawmill site, relocating the operation to new milling sites, besides powering the sawmill.
Inventive operators have adapted 2nd hand truck engines and some of these have worked very well.
There are several other methods of powering sawmills. Electricity is the most reliable and available at the touch of a button but is limited to permanent situations.
Water power and steam turbines are also used but these would be inappropriate for requirements of sawmills previously described.
Sawdoctor training
There are few places where a potential, sawdoctor can receive training, apart from apprenticeships of which a limited opportunity exists.
In New Zealand, courses are available for 2 or 3 weeks throughout the year covering all aspects of sawdoctorin-g. sawing and machinery.
For the sawmilling enterprise requiring sawdoctoring tuition, these courses are well worthwhile. It could mean the difference between a sawmill successfully run or a sawmill failing through ignorance of basic saw maintenance.
The Timber Industry Training Centre is a national training centre, supporting the New Zealand sawmilling and wood processing sector, improving productivity and standards, increasing efficiencies and opportunities, by providing skilled and knowledgeable personnel.
For further information:
The Manager Timber Industry Training Centre P.O. Box. 2242 Rotorua, New Zealand.
Phone : 73-487457 Fax : 73-468786
Basic Sawdoctoring equipment
The basic sawdoctoring equipment required to service and maintain saws for small scale milling operations is quite simple if using inserted toothed sawblades.
To remove and replace bits, a simple wrench, which is generally supplied with the saws, is used.
A grinding machine for resharpening is also available with most sawmills and depending on whether tungsten carbide or stellite bits are being used a diamond grit grinding wheel is necessary.
There are several variations, of grinding equipment, the most popular being one that will sharpen the saw teeth without removing the sawblade from the arbor.
If the sawblade requires further servicing such as tensioning or hammering, a good anvil is required along with an assortment of straight edges and tensioning hammers.
Tungsten tipped sawblades require a welding plant with oxy acetylene welding equipment, to remove the old tips and replace them with new ones.
A special holder to hold the tungsten tips in place when welding is used.
After the tips have been applied, special grinding equipment is required to shape them and to grind the edges at precise angles that are necessary.
These grinding machines are very expensive. Simplified grinders can be built up at a fraction of the cost of manufactured grinders that are designed to cover all aspects of tungsten carbide tooling.
A 300mm. smooth cut Bastard file is also an asset around the sawshop or sawmill. Chainsaw files too have to be considered that will suit the type and size of chainsaw chains.
Bench vices, clamps, gauges, etc. can all be accumulated as demand warrants and it will be found that very soon an efficient sawdoctoring tool kit is soon available.
END USES FOR COCOWOOD
Woodturing
There are many articles with many uses turned from wood, such as wooden bowls, staircase balustrades, tool handles, goblets, drawer handles, door knobs, table and chair legs etc.
Also replicas of ships steering wheels and other objects fitted with clocks or weather barometers. These could be sold to tourists or exported.
The machinery required is simple. A small woodturning lathe and a few well chosen chisels. This could well be established as a cottage type industry by individual villages, and the competition between them would assure a good quality product. It would also assist in stimulating the imagination so that further ideas and prospects are produced.
Paneling and cladding for housing
Coconut timber is an extremely attractive timber and when properly dressed to its required profiles, (ship lap, square edged, tongue and grooved etc.), and stained or varnished, makes a pleasing feature inside or outside of a house.
It is used as a sarking under roofs and if fitted at a 450 angle is extremely attractive and a strong bracing. Shiplapped panelling is generally used on exterior walls and should be treated accordingly. A board and batten verticle weatherboard external cladding also is a good exterior wall cladding.
Tongue and groove panelling is used for interior walls and partitions, including f looring. Properly treated and stained with polyurethane varnish, it makes a good floor that not only looks attractive but is easy to keep clean.
Parquet floor tiling
The more dense and hard portions of the coconut palm make good hard wearing parquet floor tiles. To produce these as a cottage industry using offcuts of cocopalm, a small thicknesser or planer and an accurate cut off saw would be required. A linisher and belt sander would also be advantageous.
Laminated Beams
Beams made from 100 x 50 medium density timber in random lengths make good strong laminated beams and can be made to, the depth required. Long beams made, this way could be pre-tensioned to counteract sag.
House building materials – framing etc.
Cocowood is a good strong building material when using the medium density grade. It could be used for framing, roof trusses, floor joists, etc. with the harder grades being used for piles if properly treated.
Although the cocowood is a little harder to machine and work, the low cost of the material makes it most suitable for low cost house construction.
Construction of dwellings can be on site, pre-cut, or pre-built in sections and transported to their permanent site as required. The latter would assist greatly victims of hurricanes who have been made homeless.
Pre-built housing could be a lucrative business manufacturing low cost coconut timbered houses.
UTILIZING THE WASTE: FROM COCOPALM
Slabwood and softwood
This material is mainly made up of the soft inner ortion well up from the butt log or slabwood left over from the milling and processing operations. It can be either chipped, burnt as firewood or converted to charcoal, all of which would be saleable items.
Sawdust
A by-product that has, many uses. It makes excellent mulch around newly planted cocopalms when creating new plantations. It has the ability to hold moisture and discourage insects. It eventually will break down and create a good humus. Sandy, wet, or clay types of soil are more readily worked when mixed with sawdust which will also increase the natural fertility and improve soil structure. If spread around the sawmill working areas, it creates a dry mudfree working area.
CONCLUSION
In this paper I have attempted to give an easily understood indication of machinery required to start a small scale cocowood manufacturing enterprise, converting raw materials into a finished useful article.
Having been involved directly in the sawmilling and sawmill manufacturing business for 30 years and actively involved in manufacturing and operating coconut sawmills specially designed by ourselves, for the past 15 years, I have acquired a large store of knowledge.
It has enabled me to understand the characteristics of many forest timber species, including coconut and the problems associated with its utilization.
I have also listened to knowledgeable people who have volunteered valuable information and suggestions.
This has enabled my company to create the Varteg "Little Tiger" Sawmill, the newest sawmill in the Varteg sawmill range, which I feel confident will benefit future projects, and which has already proved an excellent cocowood sawmill.
But, men like me grow old and they seek promising young men to tutor for fear that his lifetime of knowledge may be lost, and pass on this knowledge so that they may carry on the work that has benefited others less fortunate, work that may just be beginning.