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How Wood Hardness is Measured

Images from USDA Forest Products Laboratory Research Note FPL-RN-0303, "Janka Hardness Using Nonstandard Specimens."

In fact, there are a now a couple of different tests, but the traditional method is known as the Janka hardness test, named for Austrian wood researcher Gabriel Janka, who invented it in 1906. The test measures the force required to embed a standard-sized steel ball (of 0.444in/11.28mm diameter) exactly... Read more »

Nanometer Scale 3D Printer


Researchers Jan Torgersen and Peter Gruber at Vienna University of Technology (TU Vienna) have successfully printed intricately detailed models of various objects at the nanometer scale using a process called “two-photon lithography”. In the process, they also managed to speed things up a bit and have gone from printing in... Read more »

How-To: Extract Your DNA


It's news to me that it's possible to extract the DNA from your own cells with just a few household products such as bottled water, dish soap, food coloring, table salt, and isopropyl alcohol. You can learn how to see your own DNA in this fun video from PBS's NOVA. Read more »

Rock Out Hands Free with Air Guitar Hero

Air Guitar Hero Project from MAKE Volume 29

Biomechanical engineer Robert Armiger and surgical roboticist Carol Reiley, both of Johns Hopkins University, created Air Guitar Hero as a fun rehabilitation exercise for people with amputations. The original version they made was a bit costly, but they wrote up a less expensive DIY version, and shared their build instructions... Read more »