3.3
Lumber
Lumber is derived from logs which are harvested, debarked, and processed into long pieces with a rectangular cross-section. The transformation of logs…
Long, rectangular pieces of wood used in construction are called lumber.
Logs harvested from trees are debarked and repeatedly fed through an automated saw.
Each time the log is sliced, the slabs are transported by conveyor belt to smaller saws. Here, the slabs are cut into square-edged lumber of the required widths.
At this stage, the cut pieces have rough surfaces, and their dimensions may slightly differ from one end to the other.
Lumber is obtained either by plainsawing or quartersawing. Plainsawn lumber portrays the growth rings of trees flat on the board's wider face and is typically used as structural lumber.
In quartersawn lumber, the growth rings align at roughly 45 degrees or more in softwoods and at 60 degrees or more in hardwoods to the board's wider face. Quartersawn softwood is used for flooring, trim, and siding.
Riftsawing is also used for hardwoods, with the growth rings in riftsawn hardwood aligning at a 30 to 60-degree angle to the board's wide face and used where appearance and durability are essential.
View the full transcript and gain access to JoVE Core videos
Q1: What is the basic process for converting logs into lumber?
Logs are harvested from trees, debarked, and fed through an automated saw that slices them into slabs. These slabs travel via conveyor belt to smaller saws, where they are cut into square-edged lumber of specific widths. The resulting pieces have rough surfaces and may vary slightly in dimensions from end to end.
Q2: How does plainsawing differ from quartersawing in lumber production?
Plainsawn lumber displays growth rings nearly flat on the board's wider face and is used primarily for structural applications due to cost-effectiveness. Quartersawn lumber aligns growth rings at approximately 45 degrees in softwoods and 60 degrees in hardwoods to the board's wider face, offering enhanced stability and appearance for flooring, trim, and siding applications.
Q3: What are the characteristics and uses of quartersawn lumber?
Quartersawn lumber features growth rings aligned at 45 degrees or more in softwoods and 60 degrees or more in hardwoods relative to the board's wider face. This cutting method produces lumber with enhanced stability and superior appearance, making it ideal for flooring, trim, and siding where durability and aesthetic appeal are important.
Q4: When is riftsawing used, and what advantages does it provide?
Riftsawing is primarily applied to hardwoods, aligning growth rings at 30 to 60-degree angles to the board's wide face. This technique optimizes both aesthetic appeal and durability, making riftsawn lumber ideal for high-quality furnishings and decorative applications where appearance and durability are essential.
Q5: Why do different lumber cutting methods affect wood quality and applications?
The cutting method significantly influences lumber's characteristics, stability, and appearance. Plainsawing maximizes efficiency and cost-effectiveness for structural use, while quartersawing and riftsawing enhance stability and aesthetics for specialized applications. Each technique caters to different construction and woodworking industry needs and requirements.
Q6: What happens to lumber immediately after it is cut from logs?
After cutting, lumber pieces have rough surfaces and their dimensions may vary slightly from one end to the other. The pieces require further processing, including surfacing and potentially seasoning, before they meet final specifications for construction or woodworking applications and use.
Q7: How do softwoods and hardwoods differ in their quartersawing angles?
In quartersawn lumber, softwoods have growth rings aligned at approximately 45 degrees to the board's wider face, while hardwoods require alignment at 60 degrees or more. This difference in angle requirements reflects the distinct structural properties and dimensions lumber must meet for different applications.