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.
In order to develop long term performance data on the ability of pressure treated wood currently being produced in Canada to resist termite attack, a test plot has been established at Kincardine, Ontario in an area of known termite activity. This particular location, where termites were first reported in 1954, was selected after an extensive evaluation of potential test sites in southwestern Ontario. Material for evaluation in the test plot was either supplied directly by the wood treating industry or purchased at local lumber retailers. This material consisted of incised and non-incised commodities, ie: 2x4 (50x150mm), 2x6 (50x150mm), 4x4 (100x100mm) and 6x6(150x150mm), of four species (red pine, jack pine, lodgepole pine, eastern spruce) treated with either copper chrome arsenate (CCA-C) or ammoniacal copper arsenate (ACA) preservatives to the requirements of the CSA 080 Wood Presevation standard. Some additional PWF grade pressure treated plywood and a number of untreated controls were also installed. Treatment penetration and assay retention determinations were carried out on all test material prior to installation in the test plot. After one year in service, almost half of the untreated controls showed signs of attack, indicating extensive termite foraging activity in the test plot area. While most of the pressure treated material was rated as sound, there were several individual pieces that showed superficial signs of termite attack. However, all of this particular material was known to be very poorly treated. In a separate test at the site, commercial copper naphthenate field cut preservative was found to be very effective in protecting untreated wood surfaces from termite attack.
A national questionnaire survey of home owners was conducted to assess the performance of preserved wood foundations (PWF) in service. The results were then used to select units for site inspections. This report summarizes the results of the questionnaire survey.
The phenotypic correlation between wood density and stem growth (tree height and diameter) was examined in young interior spruce. The sample trees represented 40 half-sib families in two progeny test sites in British Columbia. In general, the relationship was found to be negative and weak. There were individual trees and families that showed fast growth and above-average wood density. If genetic correlations are equal to or weaker than the phenotypic correlations, and if the correlations persist in mature trees, it would be possible to select individual trees and families for fast growth without reducing wood density.
1088 single-nail tension tests were carried out on 109 spruce double-shear specimens in order to analyze variation of load-slip behaviour of non-predrilled nailed connections. The following load-slip parameters were determined from each test: maximum load, elastic slip modulus, initial slip modulus and slip modulus according to ISO 6891 as well as the three parameters of a function fitted to the load-slip relationship. Tests with nails penetrating a knot in the main or a side member resulted in a 20% increase in maximum load and elastic slip modulus. The autocorrelation of the parameters of the load-slip behaviour as well as their mutual correlation are independent of nail distance in the range of 73 mm to 657 mm.