The IoT (Internet of Teeth)

Get ready for another step towards our dystopian future as scientists have invented a way to track and monitor what we eat. This 2mm x 2mm wireless sensor can be mounted on to teeth and can track everything that goes into your mouth. Currently it can monitor salt, glucose, and alcohol intake. The sensor then communicates wirelessly to a mobile device that tracks the data. Future revisions are predicted to monitor a wide range of nutrients and chemicals that can get ingested.

It uses an interesting method to both sense the target chemicals and communicate its data. It consists of a sandwich of three layers with the central layer being a biosensor that reacts to certain chemicals. The complete sandwich forms a tiny RFID antenna and when RF signals are transmitted to the device, some of the signal gets absorbed by the antenna and the rest reflected back.

The mechanism is similar to how chromatography works for chemical analysis where certain chemicals absorb light wavelengths of specific frequencies. Passing a calibrated light source through a gas column and observing the parts of the spectrum that get absorbed allows researchers to identify certain chemicals inside the column.

This technology is based on previous research with”tooth tatoos” that could be used by dentists to monitor your oral health. Now this tiny wireless sensor has evolved to monitoring the dietary intake of people for health purposes but we’re pretty sure Facebook is eyeing it for more nefarious purposes too.

Mechanisms: Gears

Even before the Industrial Revolution, gears of one kind or another have been put to work both for and against us. From ancient water wheels and windmills that ground grain and pounded flax, to the drive trains that power machines of war from siege engines to main battle tanks, gears have been essential parts of almost every mechanical device ever built. The next installment of our series on Mechanisms will take a brief look at gears and their applications.

Continue reading “Mechanisms: Gears”

Repairs You Can Print: Broken Glue Gun Triggers Replacement

Picture this: you need to buy a simple tool like a glue gun. There’s usually not a whole lot going on in that particular piece of technology, so you base your decision on the power rating and whether it looks like it will last. And it does last, at least for a few years—just long enough to grow attached to it and get upset when it breaks. Sound familiar?

[pixelk] bought a glue gun a few years ago for its power rating and its claims of strength. Lo and behold, the trigger mechanism has proven to be weak around the screws. The part that pushes the glue stick into the hot end snapped in two.

It didn’t take much to create a replacement. [pixelk] got most of the measurements with calipers and then got to work in OpenSCAD. After printing a few iterations, it fit well enough, but [pixelk] saw a chance to improve on the original design and added a few teeth where the part touches the glue stick. The new part has been going strong for three months.

We think this entry into our Repairs You Can Print contest is a perfect example of the everyday utility of 3D printers. Small reproducible plastic parts are all around us, just waiting to fail. The ability to not only replace them but to improve on them is one of the brightest sides of our increasingly disposable culture.

Still haven’t found a glue gun you can stick to? Try building your own.

Mechanisms: Ode to the Zipper

Look around yourself right now and chances are pretty good that you’ll quickly lay eyes on a zipper. Zippers are incredibly commonplace artifacts, a commodity item produced by the mile that we rarely give a second thought to until they break or get stuck. But zippers are a fairly modern convenience, and the story of their invention is one that shows even the best ideas can be delayed by overly complicated designs and lack of a practical method for manufacturing.

Try and Try Again

US Patent #504,307. One of the many iterations of Judson’s design. Like the others, it didn’t work.

Ideas for fasteners to replace buttons and laces have been kicking around since the mid-19th century. The first patent for a zipper-like fastener was issued to Elias Howe, inventor of the sewing machine. Though he was no slouch at engineering intricate mechanisms, Howe was never able to make his “Automatic, Continuous Clothing Closure” a workable product, and Howe shifted his inventive energies to other projects.

The world would wait another forty years for further development of a hookless fastener, when a Chicago-born inventor of little prior success named Whitcomb Judson began work on a “Clasp Locker or Unlocker.” Intended for the shoe and boot market, Judson’s device has all the recognizable parts of a modern zipper — rows of interlocking teeth with a slide mechanism to mesh and unmesh the two sides. The device was debuted at the Chicago World’s Fair in 1893 and was met with almost no commercial interest.

Judson went through several iterations of designs for his clasp locker, looking for the right combination of ideas that would result in a workable fastener that was easy enough to manufacture profitably. He lined up backers, formed a company, and marketed various versions of his improved products. But everything he tried seemed to have one or more serious drawbacks. When his fasteners were used in shoes, unexpected failure was a mere inconvenience. If a fastener on a lady’s dress opened unexpectedly, it could have been a social catastrophe. Coupled with a price tag that was exorbitantly high to cover the manual labor needed to assemble them, almost every version of Judson’s invention flopped.

Zipping up. Source: Dominique Toussaint (Wikipedia)

It would take another decade, a change of company name, a cross-country move, and the hiring of a bright young engineer before the world would have what we would recognize as the first modern zipper. Judson hired Gideon Sundback in 1901, and by 1913 he was head designer at the Fastener Manufacturing and Machine Company, newly relocated to Meadville, Pennsylvania after a stop in Hoboken, New Jersey. Sundback’s design called for rows of identical teeth with cups on the underside and nibs on the upper, set on fabric tapes. A slide with a Y-shaped channel bent the tapes to open the gap between teeth, allowing the cups to nest on the nibs and mesh the teeth together strongly.

Sundback’s design had significant advantages over any of Judson’s attempts. First, it worked, and it was reliable enough to start quickly making inroads into fashionable apparel beyond its initial marketing toward more utilitarian products like tobacco pouches. Secondly, and perhaps more importantly, Sundback invented machinery that could make hundreds of feet of the fasteners in a day. This gave the invention an economy of scale that none of Judson’s fasteners could ever have achieved.

Putting Some Teeth into It

Continuous process for forming metal zippers. Source: How Products Are Made

The machinery that Sundback invented to make his “Separable Fastener” has been much improved since the early 1900s, but the current process still looks similar, at least for metal zippers. Stringers, which are the fabric tapes with teeth attached, are formed in a continuous process by a multi-step punching and crimping machine. For metal stringers, a coil of flat metal is fed into a punch and die to form hollow scoops. The strip is then punched again to form a Y-shape around the scoop and cut it free from the web. The legs of the Y straddle the edge of the fabric tape, and a set of dies then crimps the legs to the tape. A modern zipper machine can make stringers at a rate of 2000 teeth per minute.

Plastic zippers are common these days, too, and manufacturing methods vary by zipper style. One method has the fabric tapes squeezed between the halves of a die while teeth are injection molded around the tape to form two parallel stringers. A sprue connected the stringers by the teeth breaks free after molding, and the completed stringers are assembled later.

Zippers have come a long way since Sundback’s first successful design, with manufacturing improvements that have eliminated many of the manual operations once required. Specialized zippers have made it from the depths of the oceans to the surface of the Moon, and chances are pretty good that if we ever get to Mars, one way or another, zippers will go with us.

Hacker Straightens Own Teeth

So you say your wonky smile has you feeling a bit self-conscious? And that your parents didn’t sock away a king’s ransom for orthodontia? Well, if you have access to some fairly common fab-lab tools, and you have the guts to experiment on yourself, why not try hacking your smile with DIY braces?

First of all: just – don’t. Really. But if you’re curious about how [Amos Dudley] open-sourced his face, this is one to sink your teeth into. A little research showed [Amos] how conventional “invisible” braces work: a 3D model is made of your mouth, each tooth is isolated in the model, and a route from the current position to the desired position is plotted. Clear plastic trays that exert forces on the teeth are then 3D printed, and after a few months of nudging teeth around, you’ve got a new smile. [Amos] replicated this hideously expensive process by creating a cast of his teeth, laser scanning it, manipulating the teeth in 3D modeling software, and 3D printing a series of intermediate choppers. The prints were used to vacuum mold clear plastic trays, and with a little Dremel action they were ready to wear. After 16 weeks of night and day wear, the results are pretty amazing – a nicely aligned smile, and whiter teeth to boot, since the braces make great whitening trays.

Considering how badly this could have turned out, we’ve got to hand it to [Amos] for having the guts to try this. And maybe he’s onto something – after all, we’ve advocated for preemptive 3D scanning of our bodies recently, and what [Amos] did with this hack is a step beyond that.

[LupusMechanicus], thanks for the tip!

Box Maker extension for Inkscape

If you use Inkscape to lay out your laser cutter designs you might want to look into this box maker extension. Inscape is [Elliot’s] drawing software of choice since it’s easy to use, and it’s open source. After having to lay out the tabs for a box he decided it was worth his effort to develop a tool to do this automatically. The extension works inside of Inkscape, letting you start your projects with a set of automatically generated box sides.

The input window for the extension leaves you plenty of options for the joint design. In addition to the size of the box (inside or outside measurements can be selected), you need to enter the thickness of the material, the kerf size (how wide the cut will be), and how much clearance you want between the teeth. The width of the teeth is also configurable.

Our feature of a laser cut replacement case is what prompted [Elliot] to tip us off about his extension. That project used a web-based parts generator to do the joint design.