During lumber drying and seasoning, differential shrinkage across growth rings can cause various forms of dimensional warping. Match each specific type of lumber defect to its precise geometric distortion profile.
- CupCurvature across the transverse width of the board from edge to edge, creating a concave face
- BowCurvature along the length of the wide flat face of the board from end to end
- CrookCurvature along the length of the narrow edge of the board from end to end
- TwistSpiral or rotational distortion where the four corners of the board no longer rest in the same flat plane
Answer
Cup matches curvature across the transverse width from edge to edge; Bow matches curvature along the length of the wide flat face; Crook matches curvature along the length of the narrow edge; Twist matches spiral or rotational distortion where the four corners no longer rest in the same flat plane.
Each type of warp in solid dimensional lumber is defined by its specific geometric axis: Cup is a widthwise hollow across the face; Bow is a lengthwise bend on the flat face; Crook is a lengthwise bend along the edge; and Twist is a torsional deformation lifting the corners out of plane.
Step-by-Step Solution
Key Concept
Geometric classification of dimensional lumber warping defects based on the axis and plane of distortion
Estimated Time:1m 15s