Why VR As Monitor Replacement Is Likely To Be Terrible For A While Yet

August 9, 2023 by Donald Papp 26 Comments

Putting on a headset and using virtual monitors in VR instead of physical ones is a use case that pops up, but is it really something feasible? [Karl Guttag], who has long experience and a deep understanding of the technical challenges that face such devices, doesn’t seem to think so.

In his writeup [Karl] often focuses on the recently-unveiled high resolution Apple Vision Pro, but the issues he discusses transcend any particular product. His article is worth the read for anyone with an interest in these issues, but we’ll summarize some main points here. Continue reading “Why VR As Monitor Replacement Is Likely To Be Terrible For A While Yet” →

3D Print Your Own Seiko-Style “Magic Lever” Energy Harvester

August 9, 2023 by Donald Papp 20 Comments

Back in 1956, Seiko created their “magic lever” as an integral part of self-winding mechanical watches, which were essentially mechanical energy harvesters. The magic lever is a type of ratcheting arrangement that ensures a main gear only ever advances in a single direction. [Robert Murray-Smith] goes into detail in this video (here’s a link cued up to 1:50 where he begins discussing the magic lever)

There is a lot of naturally-occuring reciprocal motion in our natural world. That is to say, there is plenty of back-and-forth and side-to-side, but not a lot of round-and-round. So, an effective mechanism for a self-winding watch needed a way to convert unpredictable reciprocal motion into a unidirectional rotary one. The magic lever was one way to do so, and it only has three main parts. [Robert] drew these up into 3D models, which he demonstrates in his video, embedded below.

The 3D models for Seiko’s magic lever are available here, and while it’s fun to play with, [Robert] wonders if it could be integrated into something else. We’ve certainly seen plenty of energy harvesting projects, and while they are mostly electrical, we’ve also seen ideas about how to harvest the energy from falling raindrops.

Continue reading “3D Print Your Own Seiko-Style “Magic Lever” Energy Harvester” →

Running DOOM In A Keycap Takes Careful Work

August 9, 2023 by Donald Papp 4 Comments

Shoehorning DOOM into different hardware is a classic hacker’s exercise, and [TheKeebProject] managed to squeeze the 1993 classic into a custom keycap with the help of a Raspberry Pi RP2040, a custom PCB, and a clear resin enclosure. It even has a speaker for sound!

All processing is done inside the keycap, which is a clever feat. There is a USB connection, but it’s only for power and keyboard controls, so it’s completely playable without needing a whole lot of external support. The custom PCB and code are based off an earlier RP2040 DOOM project, and [TheKeebProject] has certainly made it their own by managing to get everything so tightly integrated. There’s a quick video mashup embedded below. There’s still a bit of work to do, but the code and design files are all on GitHub should you wish for a closer look.

Making DOOM physically smaller is a good challenge, but we’d like to remind fans that we’ve also seen DOOM shrink in terms of power consumption, all the way down to 1 mW.

Continue reading “Running DOOM In A Keycap Takes Careful Work” →

Enhance Your Enclosures With A Shadow Line

August 7, 2023 by Donald Papp 15 Comments

Some design techniques and concepts from the injection molding world apply very nicely to 3D printing, despite them being fundamentally different processes. [Teaching Tech] demonstrates designing shadow lines into 3D printed parts whose surfaces are intended to mate up to one another.

This is a feature mainly seen in enclosures, and you’ve definitely seen it in all kinds of off-the-shelf products. Essentially, one half of the part has a slight “underbite” of a rim, and the other half has a slight “overbite”, with a bit of a standoff between the two. When placed together, the combination helps parts self-locate to one another, as well as providing a consistent appearance around the mating surfaces.

Why is this necessary? When a plastic part is made — such as an enclosure in two halves — the resulting surfaces are never truly flat. Without post-processing, the two not-quite-flat surfaces result in an inconsistent line with a varying gap between them.

By designing in a shadow line, the two parts will not only self-locate to each other for assembly, but will appear as a much more consistent fit. There will be a clear line between the two parts, but no actual visible gaps between them. Watch the whole thing explained in the video, embedded below.

This isn’t the only time design techniques from the world of injection molding have migrated to 3D printing. Crush ribs have been adapted to the world of 3D printed parts and are a tried-and-true solution to the problem of reliably obtaining a tight fit between plastic parts and hardware inserts.

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Got Fireflies? Try Talking To Them With A Green LED

August 6, 2023 by Donald Papp 25 Comments

[ChrisMentrek] shares a design for a simple green LED signal light intended for experiments in “talking” to fireflies. The device uses simple components like PVC piping and connectors to make something that resembles a signal flashlight with a momentary switch — a device simple enough to make in time for a little weekend experimenting.

Observe and repeat flashing patterns, and see if any fireflies get curious enough to investigate.

Did you know that fireflies, a type of beetle whose lower abdomen can light up thanks to a chemical reaction, flash in patterns? Many creatures, fireflies included, are quite curious under the right circumstances. The idea is to observe some fireflies and attempt to flash the same patterns (or different ones!) with a green LED to see if any come and investigate.

[ChrisMentrek] recommends using a green LED that outputs 565 nm, because that is very close to the colors emitted by most fireflies in North America. There’s also a handy link about firefly flashing patterns from the Massachusetts Audubon society’s Firefly Watch program, which is a great resource for budding scientists.

If staying up and learning more about nocturnal nightlife is your thing, then in between trying to talk to fireflies we recommend listening for bats as another fun activity, although it requires a bit more than just a green LED. Intrigued? Good news, because we can tell you all about the different kinds of bat detectors and what you can expect from them.

Browser-Based Robot Dog Simulator In ~800 Lines Of Code

August 5, 2023 by Donald Papp 9 Comments

[Sergii] has been learning about robot simulation and wrote up a basic simulator for a robodog platform: the Unitree A1. It only took about 800 lines of code to do so, which probably makes it a good place to start if one is headed in a similar direction.

Right now, [Sergii]’s simulator is an interactive physics model than runs in the browser. Software-wise, once the model of the robot exists the Rapier JavaScript physics engine takes care of the physics simulation. The robot’s physical layout comes from the manufacturer’s repository, so it doesn’t need to be created from scratch.

To make the tool useful, the application has two models of the robot, side by side. The one on the left is the control model, and has interactive sliders for limb positions. All movements on the control model are transmitted to the model on the right, which is the simulation model, setting the pose. The simulation model is the one that actually models the physics and gravity of all the desired motions and positions. [Sergii]’s next step is to use the simulator to design and implement a simple walking gait controller, and we look forward to how that turns out.

If Unitree sounds familiar to you, it might be because we recently covered how an unofficial SDK was able to open up some otherwise-unavailable features on the robodogs, so check that out if you want to get a little more out of what you paid for.

Making A Kid-Scale Apollo 11 Lunar Lander

August 5, 2023 by Donald Papp 21 Comments

If you’d like to see what goes into making a 1/3-scale Apollo 11 Lunar Module, [Plasanator]’s photos and build details will show off how he constructed one for a kid’s event that was a hit!

The photo gallery gives plenty of ideas about how one would approach a project like this, and readers will surely appreciate the use of an old frying pan as a concrete mold to create the lander’s “feet”. Later, a little paint makes the frying pan become a pseudo-antenna mounted on the lander’s exterior.

Inside, the lander has a control panel with a lot of arcade-style buttons and LED lighting. It’s pretty simple stuff, but livens things up a lot. Bright red lighting for the engine combined with a couple of slow strobe lights really makes it come alive in the dark. The gold foil? Emergency thermal blankets wrapped around the frame.

We happen to have the perfect chaser for this kid-scale lunar module: the Apollo 11 moon landing, recreated with animatronics and LEGO.

Continue reading “Making A Kid-Scale Apollo 11 Lunar Lander” →