Lesson One: Introduction
Provides course learning objectives, student expectations, available resources, and explanation of the structured online learning format.
Lesson Two: Structure of Woods
Wood is a unique building material as it is a once-living substance. This gives it properties no other building material contends with.
3. Lesson Three: Characteristics of Woods
The living characteristics of wood fuse with lumber cuts to create unique grain patterns.
Lesson Four: Beautiful Woods
Let's take a look at a sampler of beautiful woods you may one day work with.
This is the end of course quiz.
Inspirational / Aspirational - Optional Learning
Optional learning; These videos showcase advanced woodworking skills used in building one-of-a-kind furniture pieces. You will have mastered these skills by completion of your woodworking program.
In this lesson we’ll cover the standard for testing the hardness of wood, one of the more important wood properties. Wood hardness is defined as the resistance of a sample of wood to denting and wear. The most commonly referenced standard is the The Janka hardness test, named after Austrian-born emigrant Gabriel Janka. A common use of Janka hardness ratings is to determine whether a species is suitable for use as flooring, but there are other wood applications where this hardness value is important. The higher the value, the harder the wood.
The test measures the force required to embed an 11.28 millimeters (0.444 in) diameter steel ball halfway into a sample of wood. In the United States, the Janka Hardness test is referenced by the American Society for Testing and Materials (ASTM) standard D1037.50 (ASTM.D1037.50). This video demonstrates how this test is conducted.
This Video Duration – 1:18 Minutes
The Janka hardness test results hardness numbers are an average. There is a standard deviation associated with each species, but these values are typically not given for commercial work. Numerous factors associated with tree growth means that the Janka Hardness value can vary from one piece of lumber to another even if the lumber is of the same species of wood. The Janka hardness in North America is typically represented by a number representing newton pounds forces, and woods are shown on a comparative scale.
Example Janka hardness Chart