This report presents the results of the first stage of an investigation into the feasibility of developing a machine capable of automatically tensioning a bandsaw blade. The present work involves an experimental and analytical investigation of the effects of roll tensioning upon the cutting performance of the bandsaw. In order to understand the role of roll tensioning its effects on internal stress distribution, torsional and lateral natural frequencies and stiffness of the blade have been investigated. The results of strain measurements induced during different rolling patterns and with different thickness of plate and differing rolling pressures are presented and an analytical explanation of the results is given. Experimental results showing how the stiffness of the blade and its natural frequencies are affected by the roll tensioning are also presented. An accurate analytical model that relates the rolling pattern to the lateral stiffness has not been found. Cutting tests have been conducted in which the performance of a blade with no tension is compared with a blade with different levels of tensioning. The results of these tests are presented and indicate that the relationship between cutting accuracy and tensioning is very subtle.
New Zealand will soon be in a position to export a large wood surplus, which will compete with Canadian exports. Radiata pine has a natural advantage of being readily treatable. 20% of New Zealand's total lumber production is treated with boron salts, either hot borate or cold thickened borate, followed by a diffusion period of 6-8 weeks for 50 mm thick wood. The lumber is usually sold green. There is an active research program to improve boron treatment. The viability of transferring New Zealand treatment practices to B.C. sawmills will depend on economics, technical and marketing considerations. There are potential world markets for borate treated wood which could be partly filled by western Canadian softwoods such as hem-fir and alpine fir. COFI and Forintek should investigate further and develop these markets. Impediments should be identified and addressed. Forintek should ensure it is up-to-date in knowledge of boron treatments used in New Zealand and elsewhere, and ensure that it has the technical information required to treat western Canadian softwoods