Kinetic Clock Is A Clean Modern Way To Tell Time

January 16, 2024 by Lewin Day 11 Comments

Hackers and makers aren’t usually too interested in basic round analog clocks. They tend to prefer building altogether more arcane and complicated contraptions to display numbers for the telling of time. [alstroemeria] did just that with this nifty kinetic clock build.

The basic concept of the kinetic clock is to have a flat plate, which individual segments raise out of to create a physical (instead of illuminated) 7-segment display. This is achieved with servos which push the segments in and out using a small rack mechanism. It’s not a sophisticated build; it simply uses 30 servos to handle all the segments needed to tell time. Thus, the Arduino Mega was the perfect tool for the job. With a sensor shield added on, it has an abundance of IO, driving a ton of servos is a cinch. There’s also a DS3231 real time clock to help it keep accurate time.

Incidentally, it’s a hefty thing to print, according to YouTuber [Lukas Deem] who replicated the project. It took around 85 hours to print, and a total of 655 grams of filament – not counting mistakes and trashed parts.

And if you think you’re having deja-vu, you might well be. We’ve seen a take on this exquisite design before. We liked it then, and we like it now.

Overall, it’s a stylish build that looks as good as your 3D printer’s output will allow. A resin printer would be a massive boon in this regard. Video after the break.

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Möbius Tank’s Twisty Treads Became Bendy

January 14, 2024 by Donald Papp 14 Comments

[James Bruton]’s unusual Möbius Tank has gotten a little more unusual with the ability to bend itself, which allows it to perform turns even though it is a single-track vehicle.

The turning radius isn’t great, but three-point turns are perfectly feasible.

The Möbius Tank was a wild idea that started as a “what if” question: what if a tank tread was a Möbius strip? We saw how [James] showed it could be done, and he demonstrated smart design and assembly techniques in the process.

He’s since modified the design to a single-track, and added a flex point in the center of the body. Two linear actuators work together to make the vehicle bend, and therefore give it the ability to steer and turn. A normal tread would be unable to bend in this way, but the twist in the Möbius tread accommodates this pivot point perfectly well.

It works, but it’s not exactly an ideal vehicle. With the tread doing a 90-degree twist on the bottom, there isn’t a lot of ground clearance. In addition, since the long vehicle has only a single tread, it is much taller than it is wide. Neither does it any real favors when it comes to stability over uneven terrain, but it’s sure neat to try.

Even if it’s not practical, Möbius Tank is wild to look at. Check it out in the video, embedded just under the page break.

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Tips For 3D Printing Watertight Test Tubes

January 13, 2024 by Donald Papp 12 Comments

[DaveMakesStuff] uses 3D printed test tubes for plants and similar purposes, and he’s shared how to make them on a 3D printer, complete with different models each optimized for different nozzle sizes.

The slots in the model are a means of manipulating how the slicer creates a toolpath when printing in spiral vase mode. These areas end up denser and stronger than they otherwise would be.

It’s not too hard to get clear-looking prints in spiral vase mode by using a transparent filament, but the real value in his design is that it comes out reliably watertight, with an extra-strong base and rim.

How is this accomplished when using spiral vase mode, which extrudes only a single wall perimeter? By using fancy geometry on the part, which makes the nozzle follow a high-density path that turns back onto itself multiple times, in concept a little like a switchback trail. The result is extra-dense areas on both the rim and the bottom of the tubes. This helps make them not only watertight, but far stronger than a single wall.

This technique is reminiscent of an earlier method we saw of enhancing the strength of vase mode prints by modeling thin slots into an object. After slicing, the model still consists of a single unbroken spiral extrusion. But in practice, the extruded plastic forms what resemble structural ribs. Why? Because those technically-adjacent extruded lines are so close to one another that they end up sticking together. Something similar is being done here by [DaveMakesStuff] to ensure that the bottom and top of the tubes are extra strong.

You can see a short video (embedded below) that showcases the tubes, as well as some modular 3D-printable racks that [DaveMakesStuff] also makes. And should you want some tips on getting better transparency from your 3D prints, the essentials boil down to printing with transparent filament, slightly hotter, and with a slightly higher extrusion rate.

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Telescope Rides On 3D Printed Equatorial Table

January 4, 2024 by Bryan Cockfield 25 Comments

In the realm of amateur astronomy, enthusiasts find themselves navigating a cosmos in perpetual motion. Planets revolve around stars, which, in turn, orbit within galaxies. But the axial rotation of the Earth and the fact that its axis is tilted is the thing that tends to get in the way of viewing celestial bodies for any appreciable amount of time.

Amateur astronomy is filled with solutions to problems like these that don’t cost an arm and a leg, though, like this 3D printed equatorial table built by [aeropic]. An equatorial table is a device used to compensate for the Earth’s rotation, enabling telescopes to track celestial objects accurately. It aligns with the Earth’s axis, allowing the telescope to follow the apparent motion of stars and planets across the night sky.

Equatorial tables are specific to a location on the Earth, though, so [aeropic] designed this one to be usable for anyone between around 30° and 50° latitude. An OpenSCAD script generates the parts that are latitude-specific, which can then be 3D printed.

From there, the table is assembled, mounted on ball bearings, and powered by a small stepper motor controlled by an ESP32. The microcontroller allows a telescope, in this case a Newtonian SkyWatcher telescope, to track objects in the sky over long periods of time without any expensive commercially-available mounting systems.

Equatorial tables like these are indispensable for a number of reasons, such as long-exposure astrophotography, time lapse imaging, gathering a large amount of observational detail for scientific purposes, or simply as an educational tool to allow more viewing of objects in the sky and less fussing with the telescope. They’re also comparatively low-cost which is a major key in a hobby whose costs can get high quickly, but not even the telescope needs to be that expensive. A Dobsonian telescope can be put together fairly quickly sometimes using off-the-shelf parts from IKEA.

DIY Pneumatic Actuator Does Great In Action

December 23, 2023 by Lewin Day 5 Comments

Pneumatic actuators can be powerful and fast, making them very useful for all kinds of mechanical jobs. [Michael Rechtin] decided that while he could buy them off-the-shelf, he preferred to see if he could make his own via 3D printing. Despite the challenges, he succeeded!

Part of his success is because he knew when to take advantage of the strengths of 3D printed parts, and where they wouldn’t perform so well. To that end, the main body of the cylinder is actually a piece of PVC pipe. That’s because manufactured PVC pipe is far smoother and more regular than what you could reasonably achieve with a most 3D printers. The end caps, however, were printed and tapped to take standard air fittings. The piston was printed too, fitted with a steel cylinder rod and O-rings for sealing.

The double-acting cylinder performed remarkably well in testing, easily skewering an orange. The initial version did leak a touch, but later revisions performed better. Springs were also fitted for damping hits at either end which improved longevity, with a test rig racking up over 10,000 cycles without failure.

We love a design that is both easy to build at home and capable of great performance. We’ve featured some neat open-source pneumatic builds before, too.

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Intentional Filament Stringing Helps Santa Soar

December 7, 2023 by Donald Papp 3 Comments

Stringing is when a 3D printer’s hot end moves through open air and drags a wisp of melted plastic along with it. This is normally undesirable, but has in the past been done intentionally to create some unconventional prints. Moonlight Santa from [3dprintbunny] shows considerable refinement in the technique, complete with color changes that really make the result pop.

Using a 3D printer’s stringing in a constructive way is something that has been leveraged really well. We remember seeing a lion with a fantastic mane by combining this method with a little post-processing and a blast from a heat gun. The technique has also been applied to make brush bristles (the printer strings filament across two handles, and after printing it is cut in half to make two brushes.)

This isn’t [3dprintbunny]’s first rodeo, either. We loved seeing her show what kind of objects were possible by using clever design, with no reliance on custom G-code or weird slicer tricks. The color changes by filament swaps really make this new one stand out.

Come For The PCB Holder, Stay For The Tour Of FreeCAD

November 26, 2023 by Donald Papp 10 Comments

PCB holders are great tools. Not only is the PCB Solder Fren from [PistonPin] a nice DIY design, it offers some insight into the parts design process with FreeCAD.

This design nicely demonstrates FreeCAD’s workflow for designing parts.

The PCB holder uses 3D-printed parts, M5 hardware, a length of 2020 aluminum extrusion, and one spring to create a handy and adjustable design that accommodates a variety of PCB sizes and shapes. If the ends of the extrusion are threaded, the end caps can be screwed in. Otherwise, a little glue ought to do the trick.

Want a little more insight into what making a part like this involves? [Jo Hinchliffe] at FreeCAD reached out to [PistonPin] for more detail and has a blog post explaining the workflow and steps involved in this part. As a bonus, STEP files and the FreeCAD project file are all included!

Not only is FreeCAD simple to use, but it’s also flexible enough to accommodate custom, niche extensions like a Rocketry workbench, so be sure to give it a look for your open-source CAD needs.