Scanning for biological defects is fairly new in this industry, as evidenced by the number of mills that do not yet have a system. This is because the technology was not available until just recently to support typical planer mill production speeds. That means that the technology is still new and will improve quickly in the next few years. So the only way to compensate for and then move beyond the human brain’s advantage over machines is to play to the computer’s data processing strengths and have a system flexible enough to support future sensor changes to gather more information from the fiber.
A transverse scanner might seem to be a simple “cookie cutter” solution because it only has a couple of sensor technologies and they are “off the shelf.” But it is very costly to add additional sensors to a transverse system; a prime example being density. Adding the hardware for x-ray or other technology clear across the width of a lug chain is expensive and could take up a lot of space. Additionally, high resolution tracheid and grain angle sensing technologies require that the board move in the lineal direction because the energy follows the grain. And consider that the higher your piece count, the faster the board moves sideways, reducing the resolution you get – in the most critical direction across the width of the board. The lineal scanner resolution in the width direction doesn’t change with speed and contrary to the popular myth, there is actually 4x less time to capture all the data from a board traveling transverse!
There are other differences, including transverse chain races can block surface areas, board movement reducing accuracy, lower sensor resolution in the most important direction (board width), and speed limitations. IF there were more advantages to scanning lumber transverse than lineally, Lucidyne would offer such a solution. The company’s owner, George Carman, used to design transverse scanners for USNR before he founded Lucidyne, and he certainly knows their limitations. Talk to mills who have had transverse scanners for more than a couple years and they will tell you that at first the scanner appeared to work well and did better than manual grading, but it wasn’t until a year down the road that they discovered that the limitations of a transverse scanner keeps them from doing any better, while the lineal scanner still offers a growth path through adding new technologies.