Being spent my young days in Saw Mill, I have seen manual sawmill processing to convert wooden timber logs into its first shape of wooden planks and blocks. Saw Mill is a place where hard work needs to be combined with the equal amount of skills to handle any size of timber logs.
Moving huge bulk timber log or multiple small bulk timber logs requires unique skill to bring them right from forest to sawmill cutting bed. The journey of Timber starts from converting them from fully grown tree to sizeable logs. Conversion of a tree to timber logs is a skill which needs to be viewed with the end product in mind. For in-house fully grown plantations, timber is made to grow to a reasonable size which gets into a plantation cycle. For tree’s grown in a forest, timber conversion usually happens based on several deciding factors. Characteristic & Structure of wood also plays a key role in determining right time of converting the tree into a log.
Timber logs usually bought to sizeable length by using chain saws which are been used in multiple shape and size. Automated machines are used to convert those timber logs to a sizeable length. Skilled labors are used to ensure maximum returns are leveraged from available full-length timber log to sizeable timber logs. The sizeable timber logs are being bought to Saw Mill bed to convert those timber into wooden planks and wooden blocks.
When it comes to cutting lumber, things really get interesting. The vertical and horizontal Bandsaws are being used to covert logs into planks and blocks. These equipment’s are being preferred over circular saw at initial stage because they can accommodate large diameter timber and because of their smaller kerf resulting in less waste. In a full-size sawmill, the blades are mounted on wheels with a diameter large enough not to cause metal fatigue due to flexing when the blade repeatedly changes from a circular to a straight profile. It is stretched very tight (with fatigue strength of the saw metal being the limiting factor). Bandsaws of this size need to have a deformation worked into them that counteracts the forces and heating of operation. This is called “benching”. They also need to be removed and serviced at regular intervals. Saw filers or saw doctors are the craftsmen responsible for this work.
If the belt managed to stay on the pulleys, the 52″ circle saw blade spun at a terrifying speed. With no guards or safety devices, we stayed well clear of it. The objective of horizontal sawing machine is to make an initial cut called a ‘’slab cut’’ to get log flat. Loading, turning, and clamping the log—as well as setting the board thickness and pushing the carriage as the blade—relies on a combination of muscle power. Few of the other features of the mill that impressed me were its rigid frame, smooth feel while cutting, and the availability of track extensions for longer logs, if I need them. And If I get tired of manhandling the logs, I can add hydraulic sawmill attachments to load, turn, and clamp them.
The timber logs conversion happens into sizeable wooden planks or blocks. As in other work areas, running timber saw mill requires optimal utilization of resources which start from technical skills to end state vision of final products. Technical skills largely embark on using sawing blades to maintaining vertical as well as horizontal sawing machines. Usual traditional sawing machines come with a 2.5-inch-wide blade. The shape of the tooth gullet is highly optimized and designed by the sawyer and sawfiler. It varies according to the mill, as well as the type and condition of the wood. The shape of the tooth gullet is created when the blade is manufactured and its shape is automatically maintained with each sharpening. The sawfiler will need to maintain the grinding wheel’s profile with periodic dressing of the wheel.
Proper tracking of the blade is crucial to accurate cutting and considerably reduces blade breakage. The first step to ensuring good tracking is to check that the two band wheels or flywheels are co-planar. This can be done by placing a straightedge across the front of the wheels and adjusting until each wheel touches. Rotate the wheels with the blade in position and properly tensioned and check that the tracking is correct. Now install the blade guide rollers and leave a gap of about 1 mm between the back of the blade and the guide flange. The teeth of blades that have become narrow through repeated sharpening will foul the front edge of the guide rollers due to their kerf set and force the blade out of alignment. This can be remedied by cutting of a small step on the rollers’ front edges to accommodate the protruding teeth. Ideally the rollers should be crowned, (see belt_and_pulley_systems) a configuration that assists in the proper tracking of bands and belts, at the same time allowing clearance for the set of the teeth.
The timber logs conversion happens into sizeable wooden planks or blocks. As in other work areas, running timber saw mill requires optimal utilization of resources which start from technical skills to end state vision of final products. Technical skills largely embark on using sawing blades to maintaining vertical as well as horizontal sawing machines. Usual traditional sawing machines come with a 2.5-inch-wide blade.
Automated sawing operations have been developed to assist the sawyer in maximizing the yield from each piece of wood. The process involves using optical, infrared or laser scanner to determine the configuration of each piece of wood just before it goes into sawing station. The information is sent to a computer, which uses software incorporating models of wood configurations and instructions on the best way to cut a piece to maximize yield. The computer compares the configuration of scanned wood with the models in its memory, and select the cutting pattern that best fits the piece of wood that has been scanned.
Computer cutting decisions can be fully automated in the system that is available where the wood is scanned on its way to the saw, and put into proper sawing position by hydraulic or pneumatic controls, as the saw blades are adjusted automatically. Then the wood is fed into the saw. In a fully automated system, the operator has manual override control. In less automated systems the computer provides an operator the data on how to cut the wood, sometimes by the display on a TV-like screen in the Sawyer cubicle, but by more often by focusing laser guide beams in front of saw blades. The operator aligns the wood according to the guides and feeds it into the saw.
Computerized sawing is used most frequently on a mill’s head saw. This is where a log first cut, the most complex sawing operation in the mill. Many new and renowned mills use computerized sawing operations on their head saw. Other sawing operations – bucking, edging, trimming etc. are less frequently automated although this is changing rapidly.
Machine learning and internet of things will be the next opportunity to build the automated models which will help this industry to operate in an automated environment.