An Analysis of the Differences among Log Scaling Methods and Actual Log Volume

Log rules estimate the volume of green lumber that can be expected to result from the sawing of a log. As such, this ability to reliably predict lumber recovery forms the foundation of log sales and purchase. The more efficient a sawmill, the less the scaling methods reflect the actual volume recovery and the greater the overrun factor. Using high-resolution scanned log data and the RAYSAW hardwood log sawing simulator, we compared recovery results for a 32-log sample with data from other mills and examined the overrun factors for common log scaling methods. With the sample logs, we saw underruns as low as −31.9 percent and overruns as high as 159.4 percent depending on log rule and log characteristics. Given the measurement accuracy of laser profiling systems and computing speed, it is relatively easy to determine log volume and recovery both quickly and with heretofore unknown accuracy. The log rules commonly in use today were all developed over 100 years ago: Doyle in 1825, Scribner in 1846, and International ¼-Inch in 1906. Both the logs from the forest and processing methods and equipment in the mills have changed since then. As such, the log rules are not as relevant to modern mills and today's timber supply as they once were. Given modern developments in laser measurement systems, mill operators have much better tools available to access log supply.