Factors such as dryness, density and silica content have a significant impact on the longevity of a sharp cutting edge in the tools being used upon different timbers. Sharpening a plane blade requires a 5 minute interruption in work. These 5 minute interruptions can accumulate to a significant loss of time in the course of a large project. The choice to design in dense, silica rich timbers must be weighed against the added expense of additional sharpenings. The chart below reflects the frequency of sharpening required by woods representing a range of densities.
Species | Density measured as Specific Gravity | Silica Content | Duration of a cutting edge |
Pine | .350 | None | 45 minutes |
Walnut | .63 | None | 15 minutes |
Purpleheart | .750 | High | 2 minutes |
(NCTM Standard: Data Analysis and Probability)
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