Welcome to the Internet of Swords

As has been made abundantly clear by the advertising department of essentially every consumer electronics manufacturer on the planet: everything is improved by the addition of sensors and a smartphone companion app. Doesn’t matter if it’s your thermostat or your toilet, you absolutely must know at all times that it’s operating at peak efficiency. But why stop at household gadgets? What better to induct into the Internet of Things than 600 year old samurai weaponry?

Introducing the eKatana by [Carlos Justiniano]: by adding a microcontroller and accelerometer to the handle of a practice sword, it provides data on the motion of the blade as it’s swung. When accuracy and precision counts in competitive Katana exhibitions, a sword that can give you real time feedback on your performance could be a valuable training aid.

The eKatana is powered by an Adafruit Feather 32u4 Bluefruit LE and LSM9DS0 accelerometer module along with a tiny 110 mAh LiPo battery. Bundled together, it makes for a small and unobtrusive package at the base of the sword’s handle. [Carlos] mentions a 3D printed enclosure of some type would be a logical future improvement, though a practice sword that has a hollow handle to hold the electronics is probably the most ideal solution.

A real-time output of sword rotation, pitch, and heading is sent out by the Adafruit Feather over BLE for analysis by a companion smartphone application. For now he just has a running output of the raw data, but [Carlos] envisions a fully realized application that could provide the user with motions to perform and give feedback on their form.

Incidentally this isn’t the first motion-detecting sword we’ve ever covered, but we think this particular incarnation of the concept might have more practical applications.

The making of a katana hand guard


Even though the handmade portion of Hackaday is still in its infancy, we expected to put up a post on traditional japanese sword making by now. What [Kelvin] sent in to the tip line far surpases the artistry of forging a katana by hand. It’s a tsuba, the hand guard for a katana, and over the course of two videos (one and two), you can see this masterpiece of traditional metalworking techniques take shape.

Tsubas usually come in a matched set, one for the katana, or long sword, and another for the wakizashi, a slightly shorter sword. [Ford Hallam] was asked to construct the tsuba for a katana that had been lost to the sands of time. Fortunately, a black and white photograph of the original as well as the matching wakizashi tsuba were available for reference, making the design of this tsuba an exercise in replication.

The piece of metal this tsuba was constructed from is made out of a slightly modified traditional alloy of 75% copper and 25% silver. After the blank was cast, many, many hours of scraping, filing and hammering began before the design was laid out.

The craftsmanship in this tsuba is, quite simply, insane. There are about 100 different pieces of metal inlaid into the tsuba to emulate the tiger’s stripes, and hundreds of hours of work in hand carving every leaf and every bit of fur.

Even more, no power tools were used in the creation of this hand guard; everything was crafted using the same methods, tools, and materials as the original tsuba. A masterful piece of craftsmanship, indeed.

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