Primary Breakdown Headrig
Prepared logs are fed into the headrig. This is a computerized saw which makes a number of measurements using laser scanners to determine the logs size and shape. Then the computer decides the best location to place the saw to maximize the yield. The log is moved into the proper position, and the log is cut.
Placing the headrig cut in the right place is very important: a sawline misplaced by only one-tenth of an inch can result in a loss of 25% or more of a log's potential yield. This kind of inefficiency in today's high-priced log market would be disastrous for any mill.
The primary breakdown machine uses either two saw blades (twin bandmills) or four-saw (quad bandmills) depending on the size of the log. The most common pattern for cutting is illustrated here.
Next step: gang sawing