Measured strains in slow linear veneer cutting: Effects of nosebar form and gap

Abstract

A quantitative study was made of the strain field near the knife and nosebar in a slow linear veneer cutting. A grid of 0.01 in. mesh was printed on the side of the specimen, and measurements on photographs taken before and during cutting were used to calculate strains. Nosebar type (single-faced, double-faced and roller), nosebar gap, and nosebar lubrication were varied. The work-pieces were of regrowth redwood (Sequoia sempervirens Endl.) and plantationgrown douglas fir (Pseudotsuga menziesii (Mirb.) Franco). A “maximum principle strain” criterion appeared to accord with rupture formation. The single-faced nosebar was more effective in reducing maximum principle strain at the knife edge, but produced greater values of that parameter at the nosebar edge, while the roller nosebar had reverse effects. Lubrication with silicone grease had only small, generally favourable effects. Uneven texture of the work-pieces increased variability of results, but provided some insight into control of peeling checks, compression tearing and nosebar tear in cutting veneer from difficult species.