Producing A Prop Gun That Actually Ejects Cases

July 31, 2020 by Lewin Day 34 Comments

With the movie Man of War shooting in Cyprus, there was a problem. They needed prop guns that looked realistic and ejected cases when fired, but that were also allowed under the country’s firearm laws. The task fell on [Paradym’s] shoulders, and he set to work producing a prop capable of doing the job.

With the laws in Cyprus, using anything off-the-shelf like an Airsoft pistol was simply not allowed. Instead, he had to start from scratch, creating a design outwardly similar to the Colt 1911 to suit the era of the film. Using green gas canisters for power, the first focus was on getting a realistic semi-automatic firing cycle happening. With that done, the next goal was to get the cases to eject from the weapon on each shot. To achieve this, a lever was used, actuated by the slide moving back after a shot, pushing the “spent” cartridge out of the port.

[Paradym] goes into great deal, covering the design of the 3D printed parts, the machining of springs, as well as the final assembly of the prop. We’ve seen other prop gun builds before, too. Video after the break.

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An Open-Source Microfluidic Pump For Your Science Needs

July 29, 2020 by Lewin Day 8 Comments

When it comes to research in fields such as chemistry or biology, historically these are things that have taken place in well-financed labs in commercial settings or academic institutions. However, with the wealth of technology available to the average person today, a movement has sprung up of those that run advanced experiments in the comfort of their own home laboratory. For those needing to work with very tiny amounts of liquid, [Josh’s] microfluidics pump may be just the ticket.

Consisting of a series of stepper-motor driven pumps, the hardware is inspired by modern 3D printer designs. The motors used are all common NEMA items, and the whole system is driven by the popular Marlin firmware. The reported performance is impressive, delivering up to 15 mL/min with accuracy to 0.1uL/min. That’s a truly tiny amount of fluid, and the device could prove highly useful to those exploring genetics or biology at home.

The great thing about this build is that it’s open source. [Josh] took the time to ensure that it was easily moddable to work with different tubing and materials, such that others could spin up a copy using whatever was readily available in their area. Performance will naturally vary, but if you’re experienced enough to build a microfluidic pump, you’re experienced enough to calibrate it, too. Design files are on Github for those keen to build their own.

We’ve seen other builds in this area before, too. We look forward to seeing some fun science done with [Josh]’s build, and look forward to seeing more DIY science gear in the future!

3D Printing Latex Is Now Possible

July 27, 2020 by Lewin Day 14 Comments

For those getting started with 3D printers, thermoplastics such as ABS and PLA are the norm. For those looking to produce parts with some give, materials like Ninjaflex are most commonly chosen, using thermoplastic polyeurethane. Until recently, it hasn’t been possible to 3D print latex rubber. However, a team at Virginia Tech have managed the feat through the combination of advanced printer hardware and some serious chemistry.

Sample cubes printed with the new process. Note the clarity of the sample at the top right.

The work was primarily a collaboration between [Phil Scott] and [Viswanath Meenakshisundaram]. After initial experiments to formulate a custom liquid latex failed, [Scott] looked to modify a commercially available product to suit the project. Liquid latexes are difficult to work with, with even slight alterations to the formula leading the solution to become unstable. Through the use of a molecular scaffold, it became possible to modify the liquid latex to become photocurable, and thus 3D printable using UV exposure techniques.

The printer side of things took plenty of work, too. After creating a high-resolution UV printer, [Meenakshisundaram] had to contend with the liquid latex resin scattering light, causing parts to be misshapen. To solve this, a camera was added to the system, which visualises the exposure process and self-corrects the exposure patterns to account for the scattering.

It’s an incredibly advanced project that has produced latex rubber parts with advanced geometries and impressive mechanical properties. We suspect this technology could be developed quickly in the coming years to produce custom rubber parts with significant strength. In the meantime, replicating flexible parts is still possible with available filaments on the market.

[via phys.org]

Breadboarding Console Has The Power

July 26, 2020 by Al Williams 18 Comments

It is hard to remember how expensive an electronic hobby used to be. It wasn’t long ago, for example, that a solderless breadboard was reasonably expensive and was likely to have some sort of baseboard. The nicer ones even had a power supply or some simple test instruments. While you can still buy that sort of thing today, the low cost of bare breadboards have made them much more common. [Sebastian] decided to use his 3D printer to give those cheap breadboards a nice home.

The design looks great, and frankly isn’t much of a technical triumph, but it is useful and clean looking. The build uses some banana jacks, a switch, an LED, a 9V battery, and a common small power supply module. Of course, you also need a few breadboards.

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3D Printed Doggie Braces

July 25, 2020 by Orlando Hoilett 2 Comments

[Tye’s] dog Lucifur unfortunately has degenerative arthritis causing her a lot of pain in her feet. The vet suggested orthotic carpal braces to help alleviate the pain, but they come at a price tag of at least $1600. Given her current budgetary limitations, [Tye] decided to try the DIY route.

The first task was to cast Lucifur’s paws in plaster to make a mold of her feet in both the weight-bearing and non-weight-bearing orientations. According to [Tye], the non-weight-bearing orientation is more representative of the shape of a “normal” paw, but she also needed to model the weight-bearing orientation to better design the braces for walking.

Then it was time to print a PLA-based dog splint from a design she found on Thingiverse. Since PLA softens when it’s in boiling water, the splint can be easily molded to Lucifur’s paw. This is where the paw molds [Tye] made earlier come in handy, since nobody would want Lucifur wearing a PLA splint fresh out of boiling water. Finally, she added a bit of super glue to the heel of the splint in hopes that it will hold up better over time.

We certainly can’t recommend DIY solutions to medical problems and [Tye] made sure she stressed the importance of following the recommendations of your vet if you’re ever in her position. Either way, we hope Lucifur finds some momentary reprieve, and that she can eventually receive those $1600 braces she desperately needs.

3D Printed Speaker Uses DSP For Ultimate Performance

July 25, 2020 by Lewin Day 17 Comments

Speaker design used to be as much about woodwork as it was about advanced acoustic mathematics. In recent decades, technologies such as digital signal processing and 3D printing have changed the game significantly. Leaning heavily on these techniques, [ssashton] developed a design called Mr. Speaker.

The speaker contains a 3″ woofer for good bass response, and twin tweeters to deliver stereo audio. Using WinISD to help do the requisite calculations on porting and volume, [ssashton] designed a swooping 3D printed enclosure with a striking design. Sound comes into the unit through an off-the-shelf Bluetooth module, before being passed to an ADAU1401 digital signal processing unit. From there, it’s passed to a mono amp to drive the woofer and a stereo one for the tweeters.

To get the flattest frequency response possible and maintain linear phase, it’s all about DSP in this case. RePhase software was used to design a DSP filter to achieve these goals, helping the speaker to produce the desired output. The ADAU1401 DSP was then programmed using Sigma Studio, which also allows the designer to do things such as split outputs for seperate woofer and tweeter drives.

[ssashton] does a great job of explaining both DSP principles and old-school speaker design tricks, from phase plugs to reflections. The use of 3D printed parts to rapidly iterate the design is impressive, too. We’d love to see the final enclsoure get an acetone smoothing treatment to really take it over the edge.

If you’re into serious speaker design and want more, be sure to check out this advanced transmission line design. For those of you with your own builds with some nifty tricks, drop us a note on the tipline.

Appeasing Chicken Tastes With 3D Printing

July 23, 2020 by Erin Pinheiro 4 Comments

Like most of us, [Hunter] and his partner [Katyrose] have been in quarantine for the past few months. Unlike most of us, they spun a 3D printed chicken playground design hackathon out of their self-isolation. The idea is simple: to build a playground full of toys custom-tailored to appease each chicken’s distinctive taste. The execution, however, can be proven a little tricky given that chickens are very unpredictable.

For each of the four select chickens in their coop, the couple designed separate toys based on their perceived interests. One, showing a fondness for worms, inspired the construction of a tree adorned with rice noodles in place of the living article, and moss to top it off. For late-night entertainment, the tree is printed in glow-in-the-dark filament. The others were presented with a print-in-place rotating mirror disguised as a flower, and a pecking post covered in peanut butter and corn. As a finishing piece, the fourth toy is designed as a jungle gym post with a reward of bread at the top for the chicken who dares climb it. Since none of the chickens seemed interested in it, they were eventually hand-fed the bread.

With no other entries to their hackathon, [Hunter] declared themselves as the winners. The 3D files for their designs are available for their patrons to print, should they have their own chicken coops they want to adorn. While the hackathon might’ve been a success for them, their chickens in particular seemed unimpressed with their new toys, only going to show that the only difference between science and messing around is writing it down, or in this case, filming the process. If you’re looking for other ways to integrate your chickens into the maker world, check out this Twitch-enabled chicken feeder, or this home automation IoT chicken coop door. Meanwhile, check out the video about their findings after the break.

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