All in all, a species known to have marked growth stresses will generally yield more veneer by flat-slicing than by quarter-slicing. Ring Shake Ring shake is another undesirable characteristic in logs to be used for veneer. Shake is accentuated by heating in water or steam, and there is no way of eliminating it. To prevent additional damage, plastic clips are sometimes driven across the ring shake to help hold the bolt together during rotary cutting.
The plastic can be cut without damaging the knife edge. Use of a roller bar rather than a fixed nosebar is reported to permit an operator to come closer to shake without having the bolt break out. The roller bar exerts less drag on the bolt, so there is less shear force to cause the wood to break at the ring shake. Shake is much more common in old growth than in young trees.
Knots Knots are one of the most common and important imperfections in veneer logs. Knots may be sound and intergrown, encased, or decayed. Most encased or decayed knots fall out during the drying of veneer. Knot holes are more limiting defects in standard veneer grades than intergrown knots of the same diameter.
In general, there are fewer knots on logs of large diameter, on logs from trees grown in fully stocked stands, and on butt logs. FreM 87667 F Figure 8.—Knot sequence from the indicator on the bark of Douglas-fir (1) to bolt diameters of 38 inches (2) ; 35 inches (3) ; 30 inches (4) ; 21 inches (5) ; and 17 inches (6). quency of knots is also related to species.
The plastic can be cut without damaging the knife edge. Use of a roller bar rather than a fixed nosebar is reported to permit an operator to come closer to shake without having the bolt break out. The roller bar exerts less drag on the bolt, so there is less shear force to cause the wood to break at the ring shake. Shake is much more common in old growth than in young trees.
Knots Knots are one of the most common and important imperfections in veneer logs. Knots may be sound and intergrown, encased, or decayed. Most encased or decayed knots fall out during the drying of veneer. Knot holes are more limiting defects in standard veneer grades than intergrown knots of the same diameter.
In general, there are fewer knots on logs of large diameter, on logs from trees grown in fully stocked stands, and on butt logs. FreM 87667 F Figure 8.—Knot sequence from the indicator on the bark of Douglas-fir (1) to bolt diameters of 38 inches (2) ; 35 inches (3) ; 30 inches (4) ; 21 inches (5) ; and 17 inches (6). quency of knots is also related to species.
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