Choosing the right wood species for your woodworking project
Species surface hardness
When working with various woods, there is always the consideration whether we can substitute a less expensive wood for the species we are using and still get the same performance. When looking at a potential substitute, cost, availability, color and density can certainly be important factors.
The importance of density
Density is very important because this property is related closely to strength, stiffness and nail, screw and staple holding power. We can often offset low-density effects. If the strength is low, we can perhaps make the piece a little larger. If the fastener holding power is low, we can increase the fastener size or number of fasteners to achieve the required performance.
One additional variable that is hard to compensate for by changing the design or manufacturing process is surface hardness. A low hardness, or softer woods, means that the surface is easy to dent; a dent can damage the wood fibers and give a brittle finishing coating. Crushed fibers can often be restored by steaming the damaged area briefly, finish repair is much more difficult. Softer woods, although they machine easier, are also harder to sand to a smooth, fuzz-less surface.
Comparing hardness
Surface hardness in the wood industry is measured by the load or force required to embed a steel ball, 0.444 inch in diameter, to a depth of one-half its diameter. The hardness of end grain is different from the two surfaces.
Special note: Soft maple, a lumber trade name, includes both red and silver maple. Note the difference in hardness between the two species that make this grouping. Also note the large differences between the pine, spruce and oak species. ^
Wood density or hardness also varies by location grown. Typically wood grown in a warmer climate with a longer growing season will be softer. Wood grown in a cooler climate with a shorter growing season will be harder. Condition of the soil and rainfall also influence the condition of the wood. Many tropical woods, for example, are described as being “full of sand” because of the high mineral content.
Tip: Cutting hard woods or woods with a higher acidic composition can cause your cutting tools to get dull more quickly. Try using a cermet tipped blade in place of carbide tipped blades to increase service life and bet better cuts.
Tags: hard woods, soft woods, wood species
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