3D Printering: Will A Resin Printer Retire Your Filament-based One?

April 30, 2020 by Donald Papp 25 Comments

Adding a resin printer to one’s workbench has never looked so attractive, nor been so affordable. Complex shapes with effortlessly great detail and surface finish? Yes, please! Well, photos make the results look effortless, anyway. Since filament-based printers using fused deposition modeling (FDM) get solid “could be better” ratings when it comes to surface finish and small detail resolution, will a trusty FDM printer end up retired if one buys a resin printer?

The short answer is this: for users who already use FDM, a resin-based stereolithography (SLA) printer is not likely to take over. What is more likely to happen is that the filament printer continues to do the same jobs it is good at, while the resin printer opens some wonderful new doors. This is partly because those great SLA prints will come at a cost that may not always justify the extra work.

Let’s go through what makes SLA good, what it needs in return, and how it does and doesn’t fit in with FDM.

Continue reading “3D Printering: Will A Resin Printer Retire Your Filament-based One?” →

Giving Surfaces Their Own Antiviral Coating To Fight Infection

April 30, 2020 by Maya Posch 15 Comments

The use of disinfectants is not a new thing, but a major disadvantage with most common disinfectants is that they are only effective in the short term. After applying bleach, alcohol or other disinfectant to the surface, the disinfectant’s effect quickly fades as the liquid evaporates. Ideally the disinfectant would remain on the surface, ready to disinfect when needed.

According to researchers at the Hong Kong University of Science and Technology (HKUST), the solution may lie in a heat-sensitive coating that releases disinfectant when it’s needed. This Multilevel Antimicrobial Polymer (MAP-1) can remain effective for as long as 90 days, depending on how often the surface is touched or otherwise used.

MAP-1 consists out of polymer strands of a material that prevents viruses and bacteria from attaching to its surface, while disrupting its outside surface. Effectively this has the potential to inactivate (kill) most viruses and harmful bacteria that come into contact with it.

MAP-1 is currently being deployed in Hong Kong, where public places such as schools, malls and sport facilities have had the coating applied. It costs between US $2,600 and US $50,000 to treat an area, which is not cheap, but would be cheaper than shutting down such a facility for regular surface disinfecting.

Although it still has to be determined that MAP-1 is as effective as hoped, it is another example of an antimicrobial surface, a material that is designed to be as incompatible with sustaining viruses and bacteria as possible. In the past copper and its alloys have been commonly used for this purpose, but a polymer coating is obviously more versatile. From the point of view of today’s pandemic, making surfaces incapable of hosting viruses definitely can be regarded as highly necessary.

(Pictured: a MAP-1 coating on a surface, courtesy of HKUST)

Ultrasonic Sound Gun Precisely Aims Your Music

April 30, 2020 by Moritz v. Sivers 25 Comments

When listening to music you sometimes cannot avoid the situation where other people get annoyed because they feel it disrupts their important doings or they do not share your taste in avant-garde doom metal. Of course one could just use headphones. But a hackier way would be to build a parametric speaker that focuses soundwaves into a narrow beam like [Shane] did with this ultrasonic sound gun.

As the directivity of a soundwave depends on the size of the source and its frequency, a directed beam can practically only be achieved with ultrasound. Even though we are not able to perceive frequencies above ~20 kHz, the nonlinear properties of air make it possible to hear the audio modulated onto an ultrasonic carrier signal. For his sound gun [Shane] was inspired by another parametric speaker project. It took him some time to get the 555 timer circuit oscillating at the right frequency and he fried a cheap Bluetooth audio module while trying to increase the output volume but in the end, he managed to get everything working. As the project name suggests, he also 3D printed a gun-shaped enclosure. The video below shows that the sound from the gun behaves really similar to a beam of light and can, for example, be bounced off other objects.

If you are looking for other inspiration there is a whole list of cool ultrasonic projects from distance sensors to acoustic levitation.

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Classic 8-Bit Computing The Atari Way

April 29, 2020 by Bryan Cockfield 9 Comments

In the classic gaming world, even before the NES arrived on the scene, there was no name more ubiquitous than Atari. Their famous 2600 console sold almost as many units as the Nintendo 64, but was released nearly 20 years prior. In many ways, despite making mistakes that led to the video game crash of the early 80s, Atari was the first to make a path in the video game industry. If you want to explore what the era of 8-bit computing was like in the Atari age, a new resource is compiling all kinds of Atari-based projects.

This site has everything, from assembling Atari 8-bit computers based on the 6502 chip, to programming them in BASIC and assembly, to running official and homebrew games on the hardware itself. This was put together by [Jason H. Moore] who grew up around Atari systems and later, their home computers. He even puts his biomedical experience to use here by designing a game for the 2600 called Gene Medic which can be found at the site as well.

If you grew up in the 70s and 80s and are looking for a bit of Atari nostalgia this site is the place to go. It’s even worth a visit from younger folks as well since the 8-bit world is a lot easier to get immersed in and learn the fundamentals of computer science. Of course, if you want to take it the other direction, it’s possible to modify the old Atari to add a few modern conveniences.

Photo via Evan-Amos

Make It Easier For Your Software Project To Accept Contributions

April 29, 2020 by Donald Papp 30 Comments

[Flameeyes] has heard complaints (and at times, he admits, has complained himself) about big companies not contributing improvements to projects they seem to find useful, or rolling their own implementation rather than use and contribute to an existing code base. Having recently left Google after seven years, he has some insights into some of the reasons big corporations (at least Google, anyway) may sometimes seem to eschew making code contributions, and some of the reasons might come as a surprise.

There are things a corporation can do differently, but there are also some things that can be done on the project’s end to make accepting contributions easier. [Flameeyes] took some time to write out a few pointers on how to make it easier for others (particularly large corporations) to contribute code to a software project.

The biggest issue is the software license. Without one, there is no legal structure to use, distribute, or contribute to the code, and no corporate entity will want to touch it. Google specifically forbids creating patches for projects with either no license, or incompatible licenses. An example of an incompatible license is one that forbids commercial use, because everything a corporation like Google does — even research –is considered a commercial endeavor. In addition, on the corporate side making contributions might trigger a code review process of some kind for some licenses, but not for others. [Flameeyes] suggests the MIT license as one that is acceptable to pretty much everyone with a minimum of fuss. Another caution: if a project’s code resides in an online repository, make sure the repository is licensed as well.

A few other small suggestions (such as maintaining an AUTHORS file to track contributors in a tidy way) rounds out the advice. It sounds simple, but software licensing is so critical to the whole affair that it’s important to get it right — he suggests the REUSE tool for anyone wanting to make sure a project’s licensing is tidy.

[Flameeyes] makes a point that none of this guidance is based on secret or institutional knowledge. Google has a public document detailing exactly how they use and deal with open source, and it’s a solid guide for how to make your project more accepting of contributions from a corporate entity like Google. (Or, if you prefer, a guide on how to set up as many barriers as possible for your project.)

In case you missed it, we just want to remind you that our favorite recent open source project from Google is definitely Pigweed.

Giant Scale RC A350 Airliner Using Carbon Fibre And 3D Printing

April 29, 2020 by Danie Conradie 16 Comments

Large scale RC aircraft are pleasure to see on the ground and in the air, but putting in the months of effort required to build them requires special dedication. Especially since there is a real possibility it could end up in pieces on the ground at some point. [Ramy RC] is one of those dedicated craftsman, and he has a thing for RC airliners. His latest project is a large Airbus A350, and the painstaking build process is something to behold.

The outer skin of the aircraft is mostly carbon fibre, with wood internal framing to keep everything rigid. The fuselage and winglets are moulded using 3D printed moulds. These were printed in pieces on a large format 3D printer, and painstakingly glued together and prepared to give a perfect surface finish. The wing surfaces are moulded in flat section and then glued onto the frames. [Ramy RC]’s attention to detail is excellent, making all the control surfaces close as possible to the real thing, and retractable landing gear with servo actuated hatches. Thrust comes from a pair of powerful EDF motors, housed in carbon fibre nacelles.

This project has been in the works for almost 5 months so far and it looks spectacular. We’re looking forward to the first flight, and will be holding thumbs that is remains in one piece for a long time. See the video after the break for final assembly of this beast.

For the next step up from RC aircraft, you can always build your own full size aircraft in your basement. If you have very very deep pockets, get yourself a private hangar/workshop and build a turbine powered bush plane.

Thanks for the tip [tayken]! Continue reading “Giant Scale RC A350 Airliner Using Carbon Fibre And 3D Printing” →

A DIY 10-bit Relay Adder

April 29, 2020 by Rich Hawkes 14 Comments

When it comes to understanding computers, sometimes it’s best to get a good understanding of the basics. How is data stored? How does the machine process this information? In order to answer these questions a bit more and start learning programming, [Nakazoto] built a 10-bit binary adder with relays.

The build is designed from the ground up, including the PCBs, which are milled using a CNC machine. There are six boards: the input board, sequencer board, 2 sum register boards, a carry register board and a 1-bit ALU board. The input board has 32 LEDs on it along with the switches to turn on each bit on or off. In total, 96 relays are used and you can hear them clacking on and off in the videos on the page. Finally, there is a separate switch that sets the adder into subtraction mode.

Usually, [Nakazoto]’s website is mostly about cars, but this is a nice diversion. The article has a lot of detail about both the design and build as well as the theory behind the adder. Other articles on binary adders on the site include this one which uses bigger relays, and this 2-bit adder which uses 555 timers.

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