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.

Behold The Track-Twisting Möbius Tank

November 18, 2023 by Donald Papp 17 Comments

It started with someone asking [James Bruton] about using a Möbius strip as a tank tread. He wasn’t sure what the point would be, but he was willing to make one and see what happened. Turns out it works reasonably well!

The grey plates are responsible for tensioning the tracks. Designing them as separate pieces means rework for fine-tuning avoids having to re-print structural parts.

The main design challenge was creating a tread system that would allow for the required rotation. [James] designed in the ability for each link to rotate about 18 degrees, and ensured plenty of open space on the upper side of the drive train to accommodate a full 180 degree twist. It took a little fine-tuning and looks a bit trippy, but in the end works about as well as a regular tread system.

[James] shows off a good technique to keep in mind when constructing big assemblies like this tank. It takes a lot of time and material to print large pieces, and in such cases it’s especially important to minimize rework. [James] therefore designs smaller, separate pieces as interfaces to other parts. This way, if changes are needed down the line (for example, to adjust motor placement or change tension on parts), only a smaller interface piece needs to be redone instead of having to re-print a huge part.

The unit uses an Arduino Mega, two 24 V gearmotors to drive each tread independently, an RC radio receiver, and some beefy BTS7960 DC motor drivers to drive the motors.

[James]’ unit is pretty big, but we’ve also seen 3D printed tanks capable of carrying a human driver. It’s clear that build plate size doesn’t seem to limit tank designs. Watch the Möbius tank get built and drive around in the video, just below the page break.

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It’s A Marble Clock, But Not As We Know It

November 6, 2023 by Donald Papp 28 Comments

[Ivan Miranda] is taking a very interesting approach to a marble clock. His design is a huge assembly that uses black and white marbles to create a (sort of) dot matrix display. It’s part kinetic art and part digital clock, all driven by marbles.

Here’s how it works: black and white marbles feed into a big elevator. This elevator lifts marbles to the top of the curved runs that make up the biggest part of the device. The horizontal area at the bottom is where the time is shown, with white and black marbles making up the numerical display. But how to make sure the white marbles and black marbles go in the right order?

The solution to that is simple. Marbles feed into the elevator in an unpredictable order. An array of sensors detects the color of each marble. Solenoids simply eject any marble that isn’t in the right place. For example, if the next marble for track n needs to be white, then simply kick out any black marbles in that position until there’s a white one. Simple, effective, and guarantees plenty of mesmerizing moving parts.

Of course, this means that marble ejection and marble color sensing need to be utterly reliable, and [Ivan] ran into problems with both. Marble ejection took some careful component testing and selection to get the right solenoids. Color sensing (as well as detecting empty spaces) settled on IR-based sensors commonly used in line-following robots.

You can watch the clock in action in the video embedded below just under the page break. We recommend giving it a look, because [Ivan] does a great job of showing all of the little challenges that reared their heads, and how he addressed them. There are still a few things to address, but he expects to have those licked by the next video. In the meantime, [Ivan] asks that if anyone knows a source for high quality glass marbles in bulk, please let him know. Low quality ones vary in size and tend to get stuck.

Marble clocks are great expressions of creativity, especially now that 3D printing is common. We love clock hacks, so if you ever create or run across a good one, let us know about it!

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Micromanipulator Touches The Tiny Things, Cheaply

October 11, 2023 by Donald Papp 12 Comments

Some things are small and fragile enough that they cannot be held or touched by even the steadiest of hands. Such cases call for a micromanipulator, and [BYU CMR]’s DIY micromanipulator design can be 3D printed and assembled with the help of some common hardware, and a little CA glue.

You may recall an ultra-tiny Nerf-like blaster recently; clearly such a tiny mechanical device cannot be handled directly, yet needed to be loaded and have its trigger pressed. A micromanipulator is exactly the tool for such a job. This design is in fact the very same one used to move and manipulate that tiny blaster at a microscopic level.

The design doesn’t include any end effectors — those depend on one’s application — but there is a mount point for them and the manipulator can effectively move it in X, Y, and Z axes by turning three different knobs. In addition, because the structural parts can be 3D printed and the hardware is just some common nuts and screws, it’s remarkably economical which is always a welcome thing for a workshop.