[jcprintnplay] has challenged himself to making Raspberry Pi cases in different ways, and his Fold-a-Pi enclosure tries for a “less is more” approach while also leveraging the strong points of 3D printing. The enclosure prints as a single piece in about 3 hours, and requires no additional hardware whatsoever.
The design requires no screws or other fasteners, and provides a mounting hole for a fan as well as some holes for mounting the enclosure itself to something. All the ports and headers are accessible, and the folding one-piece design is not just a gimmick; in a workshop situation where the Pi needs to be switched out or handled a lot, it takes no time at all to pop the Raspberry Pi in and out of the enclosure.
[James] points out that the trick with a print-in-place hinge like this is leaving enough space between the parts so that the two pieces aren’t fused together, but not so much space that the print fails. He doesn’t go into detail about how much space worked or didn’t work, but an examination of the downloadable model shows that the clearance used looks like 0.30 mm, intended to be printed with a 0.4 mm nozzle.
[James] also demonstrates the value of being able to do quick iterations on a design when prototyping. In a video (embedded below) The first prototype had the hinge not quite right. In the second prototype there was a lack of clearance when closing. The third one solved both and shows the final design.
As the world grapples with the spectre of the so-called “hockey stick” graph of climate change, there have been a variety of solutions proposed to the problem of carbon emissions from sectors such as transport which have become inseparable from the maintenance of 21st century life. Sometimes these are blue-sky ideas that may just be a little bit barmy, while other times they make you stop and think: “That could just work!”.
One thing that should be obvious to all is that moving our long-distance freight around by means of an individual fossil-fuel-powered diesel engine for every 38 tonne or so freight container may be convenient, but it is hardly either fuel-efficient or environmentally friendly The most efficient diesel engines on the road are said to have a 43% efficiency, and when hauling an single load they take none of the economies of scale afforded to the diesel engines that haul for example a freight train. Similarly they spread any pollution they emit across the entirety of their route, and yet again fail to benefit from the economies of scale present in for example a power station exhaust scrubber. However much I have a weakness for the sight of a big rig at full stretch, even I have to admit that its day has passed.
The battery technology being pursued for passenger cars is a tempting alternative, as we’ve seen with Tesla Semi. But for all its technology that vehicle still walks the knife-edge between the gain in cost-effectiveness versus the cost of hauling around enough batteries to transport that quantity of freight. Against that the overhead wire truck seems to offer the best of both worlds, the lightness and easy refueling of a diesel versus the lack of emissions from an electric. In the idealised world of a brochure it runs on renewable wind, sun, and water power, so all our problems are solved, right? But does it really stack up?
These days, if you’ve got a TV that’s a little too old to directly access streaming services, you’ve got plenty of options. Apple TV, Chromecast, and a cavalcade of Android boxes are available to help get content on your screen. However, if you’re really stuck in the past, ESPFLIX might just be for you.
Yes, that’s right – it’s an online streaming service running on an ESP32. [rossumur] has achieved this feat through a careful use of codecs, and some efficient coding strategies to make it all come together. Video is MPEG1, at just 352×192 resolution. Audio is via the SBC codec, originally intended for use with Bluetooth devices. It’s chosen here for its tiny sample buffers, making it easier to decode in the limited RAM of the ESP32. Output is via composite video, generated on the ESP32 itself.
The titles themselves consist of public domain content, running off an Amazon Web Services instance. With limited RAM on the ESP32, there’s not much buffering to be had, so [rossumur] is bankrolling an AWS Cloudfront instance which should make it possible to use ESPFLIX from most places around the world with a solid internet connection.
Time may bring change, but kinematic couplings don’t. This handy kinematic couplings resource by [nickw] was for a design contest a few years ago, but what’s great is that it includes ready-to-use models intended for 3D printing, complete with a bill of materials (and McMaster-Carr part numbers) for hardware. The short document is well written and illustrated with assembly diagrams and concise, practical theory. The accompanying 3D models are ready to be copied and pasted anywhere one might find them useful.
What are kinematic couplings? They are a way to ensure that two parts physically connect, detach, and re-connect in a precise and repeatable way. The download has ready-to-use designs for both a Kelvin and Maxwell system kinematic coupling, and a more advanced design for an optomechanical mount like one would find in a laser system.
The download from Pinshape requires a free account, but the models and document are licensed under CC – Attribution and ready to use in designs (so long as the attribution part of the license is satisfied, of course.) Embedded below is a short video demonstrating the coupling using the Maxwell system. The Kelvin system is similar.