Pin knot clusters—unacceptable, if they produce large effect on grain direction. Spike knots—knots running completely through the depth of a beam perpendicular to the annual rings and appear most frequently in quarter-sawed lumber.

Pin knot clusters in a piece of aircraft structural wood are permitted if they are small clusters and produce only a small effect on grain direction.

beam and are not closer than 20 inches to another knot or other defect (pertains to 3/8 inch knots—smaller knots may be proportionately closer). Knots greater than 1/4 inch must be used with caution. d. Pin knot clusters. Small clusters are acceptable providing they produce only a small effect on grain dire c-tion. e. Pitch pockets.

Pin knot clusters are permitted in wood aircraft structure provided a) they produce a small effect on grain direction. b) they have no mineral streaks. c) no pitch pocket are within 12 inches.

they are in the center third of the beam and not closer than 20-inches to another knot or other defect (pertains to 3 ⁄8-inch knots; smaller knots may be proportionately closer). Knots greater than 1⁄4-inch must be used with caution.

c. Hard knots. Not acceptable, unless within limitations noted in 1c. d. Pin knot clusters. Not acceptable, if they produce large effect on grain direction. e. Spike knots. These are knots running completely through the depth of a beam perpendicular to the annual rings and appear most frequently in quarter-sawed lumber. Reject wood containing ...

2025年2月18日 · Below are 3 examples of knot clusters in Timbers that I had received from my sawyer. The timbers are 8" x 10" x 20' northern white pine. These timbers are to be used as rafters and collar ties The cut list specified #2 or better and small to medium knots.

Pin knot clusters in a piece of aircraft structural wood are permitted if they are small clusters and produce only a small effect on grain direction.

12. Pin knot clusters are acceptable if they produce only a small effect on _____.