On arrival at the mill's storage yard, logs are sorted and stored according to species, diameter, length and end-use, etc. Sufficient quantities are stockpiled to ensure the sawmill's continuous operation, particularly during adverse weather conditions when log extraction and supply from the forests may be adversely affected.
Transportation and handling of logs vary from mill to mill and largely depend on the capacity of the sawmill operation and the size of the loss received. Manual and animal power, as may be used in small portable sawmill units, through to log-carrying front-end loaders and overhead cranes indicate the wide variety of handling equipment currently in use.
Before the log is presented to the headrig for breakdown, it is cut to the longest permissible straight length with a cut-off saw, whereupon it is loaded onto the headsaw carriage and positioned in such a manner as to allow the operator to achieve a sawing pattern, which will result in the optimum production of saw timber with the minimum of waste. The pattern of cut is largely determined by the dimension and condition of the log, as well as the market requirements for the widths and thicknesses of the lumber. Sawing of the log is achieved by the use of a bandsaw or a circular saw with a second saw mounted vertically above the first in the event of sawing large diameter logs. A log carriage conveys the log through the headsaw on which the log may be clamped and turned, so as to enable it to be presented to the headsaw in order to achieve the best sawing pattern.
Following the headrig, further breakdown of slabs, flitches and cants takes place in the resaw, which enables the wood to be upgraded; thick slabs being sawn into planks and the flitches and cants sawn into planks and boards. The rough round edges of the pieces coming from the headrig and resaws are removed by either a circular saw or chipper edger so as to produce standardized widths as required. On leaving the headrig, resaw or edger, the lumber is cut to standardized lengths, edges squared and defects removed by the use of one or more fixed or moveable trimming saws, whereupon the lumber proceeds to be sorted and graded.
The sawn and trimmed timber is sorted according to thickness, width, length, quality, grade and species depending on the market requirements; such an activity may be undertaken manually or, in the case of mills where low-cost labour is not available, by mechanized sorters. Grading is a means to segregate the lumber according to the overall quality, direction of grain, presence of knots and defects, as well as general appearance, etc. To protect the sawntimber against attack from fungi and insects, as well as to inhibit the tendency of air-dried lumber to check and split, the ends may be brushed either manually or mechanically dipped in a suitably prepared chemical solution. Wax or paint is applied to the end-grain of lumber to be air-dried, either by brush or spraying, so as to act as a sealant in order to bring about a slower drying of the extremities and hence, give rise to a more uniform drying of the lumber.