3D Printing Hailstone Molds for Science

Hollywood would have you believe that tornadoes are prevalent in the Midwest. We’re much more likely to see hail in the springtime—balls of slushy ice that pelt our roofs and dimple our cars. [Dr. Ian Giammanco] and his wife and fellow scientist [Tanya Brown-Giammanco] have been studying hail at the Insurance Institute for Business and Home Safety’s research lab since 2012. In 2013, their team created over 9,000 artificial hailstones and fired them at a mock-up of  a house in the first indoor full-scale hailstorm.

As fun as it sounds to shoot balls of ice at different things, they did it to better understand the humble hailstone and the damage it can do to insurable goods. Those hailstones from a few years ago were created manually by injecting molds and freezing them. Recently, [the Giammancos] and  have taken a more advanced approach to creating artificial hail so they can study the physical characteristics. They scan actual hailstones in order to create models of them. Then they make a 3D-printed mold and use it in a hail-making machine that uses diffused carbon dioxide to mimic the layering that occurs when natural hailstones are formed.

While it would be nice to be able to control hail, the next best thing is mitigating the damage it causes. The better that scientists understand hail, the better materials will become that can withstand its impact. Perhaps someone can perfect a shape-shifting building material and make it resistant to hail.

Wooden Antikythera Mechanism is Geared for Greatness

[Dave] builds custom wooden orreries, which are mechanical models of the solar system. It’s no surprise then that he’s interested in the Antikythera Mechanism—a small geared device discovered off the coast of the Greece in 1900 that is believed to be the first analog computer and one of the oldest known geared systems, built partly to predict the positions of celestial bodies in the solar system as it was understood in ancient Greece.

wooden-antikythera-mechanism[Dave] decided to build a wooden version of the Antikythera Mechanism as a proof of concept that it can be done in wood rather than the brass of the original. He also sought to incorporate all the modern theories of the device’s gear train. The entire system is made out of 6mm birch plywood that [Dave] cut by hand on a scroll saw. That’s right — no CNC or lasers here. This has as much to do with replicating the craftsmanship of the original as it does with practicality. Besides, the pitch of the gear teeth is too small to be effectively cut with a laser.

There are no motors, either. The gears are centrally connected to nested brass tubing and the mechanism is actuated with a hand crank. The six pages of forum discussion are worth combing through just to see the pictures of [Dave]’s progress and all of those meticulously hand-cut gears.

It took [Dave] the better part of two years to complete this work of art, and you can see it in motion after the break. With the first version complete, he has begun Mk. II which will feature all of the spiral dials and pointers of the original. If you’re interested in exploring the Antikythera Mechanism further, here is Hackaday’s own in-depth look at it.

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Retro Rotary Raspi Phone Rings Alexa

[MisterM] is a man after our own heart. He loves to combine the aesthetic of vintage equipment with the utility of new technologies. His latest venture is AlexaPhone, which marries the nearly instantaneous retrieval and computation power of Amazon’s Alexa voice service with the look and feel of a 1970s rotary phone. Best of all, there’s no need to spin the dial and wait for it to go whirring back around. AlexaPhone is ready to take questions as soon as the handset is lifted.

Questions are transmitted through a salvaged USB VOIP phone plugged into the Pi. The user must hang up the receiver in order to trigger the search. Once Alexa has an answer, the audio comes back through a small external amplified speaker with a USB-rechargeable battery. Since the hardware is a bit atypical for Alexa, [MisterM] had a bit of trouble at first trying to query the service with a physical button until he came across this AlexaPi code.

This phone is actually a reproduction of a classic BT Trimphone, which explains the asterisk and octothorpe on the dial.  The modern internals meant that [MisterM] could take advantage of the ribbon cable coming off of the receiver hook to trigger the Pi to send the query. Watch [MisterM]’s kids put Alexa through her paces after the break.

If this has you feeling nostalgic, check out this vintage Chromecast TV we covered recently or this old Russian radio reborn as a Bluetooth speaker.

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Are Powdered Metal Fuels Just a Flash in the Pan?

It’s no secret that fossil fuels are quickly becoming extinct. As technology charges ever forward, they are disappearing faster and faster. Many of our current dependencies on fossil fuels are associated with high-energy applications like transportation. Since it’s unlikely that global transportation will ever be in decline for any reason other than fuel shortage itself, it’s imperative that we find something that can replicate the high energy density of fossil fuels. Either that, or go back to the drawing board and change the entire scope of global transportation.

Energy, especially solar and wind, cannot be created all over the world. Traditionally, energy is created in situ and shipped to other places that need it. The proposed solutions for zero-carbon energy carriers—batteries and hydrogen—all have their weaknesses. Batteries are a fairly safe option, but their energy density is pretty poor. Hydrogen’s energy density is higher, but its flammability makes it dangerously volatile to store and transport.

Recently, a group of researchers at McGill University in Canada released a paper exploring the use of metal powders as our zero-carbon fuel of the future. Although metal powders could potentially be used as primary energy sources, the transitory solution they propose is to use them as secondary sources powered by wind and solar primaries.

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Colored Filament From a Can

On the last day of MRRF, the guys from Lulzbot were printing a vase with some clear Taulman t-glase on their TAZ 6 prototype. It was probably the third or fourth one they had printed, but I was compelled to go over there because they were painting the filament with a blue Sharpie right before it went into the extruder.

It immediately made me think of this video that hit our tips line last fall and fell through the cracks—a short one from [Angus] at Maker’s Muse about creating your own colored filament by spraying clear PLA with cheap spray paint. This is a neat alternative to painting a finished print because the color isn’t going to rub off. The pigment fuses with the PLA in the hot end, providing consistent coloring.

Disclaimer time: [Angus] ran his spray-painted PLA through a WANHAO i3, which is a cheap, modified Prusa that actually has pretty good reviews. The point is, he doesn’t care if the nozzle gets clogged. But the nozzle didn’t clog. Nothing bad happened at all, and the prints turned out great. As you can see in the video after the break, he tried silver and blue separately on short lengths of filament, and then alternated the colors to make the striped Marvin in the main image. [Angus]’ main concern is that the paint probably affects the strength of the print.

Have you tried spray painting filament? How did it go? Let us know in the comments. If you long to print in any color on the cheap but don’t want to seriously risk clogging your hot end, there’s always the drilled-out Sharpie method.

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ChaiBot: A Tea Robot Steeped in Utility

On the surface, a cup of tea is a simple thing to make. Heat up some water, insert tea leaves, and wait for it to steep. The wait time is a matter of taste, and it is absolutely crucial to remove the bag or infuser before it’s too late. Otherwise, you end up with a liquid that’s almost, but not quite, entirely unlike tea.

[Adrian] and his son would often find themselves lost in conversation during the steeping process and let it go too long. But that was before they built ChaiBot, an automatic tea minder. This fine-looking machine uses an old CD drive to raise and lower the tea bags, which are held by a thin piece of stainless steel mesh. Once the bags are lowered, [Adrian] pours hot water into the cups. The weight of the water is detected by a capacitive sensor under the cup cutouts, and this triggers the timer to start counting down to the perfect cuppa.

One of the coolest features of ChaiBot is the built-in circulation. Every minute, the bags are lifted out briefly and reinserted, disturbing the water so the steeping is more uniform. Since the final step to making great tea is drinking it before it goes cold, ChaiBot sends a push notification to [Adrian]’s phone. Be sure to check out the demo after the break.

Here’s another CD drive-based tea bot we covered a while back. It’s not quite as pretty, but it gets the job done. If you’re not one to wander off while your tea steeps but prefer not to watch a clock, here’s a compact timer that’ll fit in your pocket.

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A Field Guide to the North American Communications Tower

The need for clear and reliable communication has driven technology forward for centuries. The longer communication’s reach, the smaller the world becomes. When it comes to cell phones, seamless network coverage and low power draw are the ideals that continually spawn R&D and the eventual deployment of new equipment.

Almost all of us carry a cell phone these days. It takes a lot of infrastructure to support them, whether or not we use them as phones. The most recognizable part of that infrastructure is the communications tower. But what do you know about them?

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