Watch The World Spin With The Earth Clock

June 18, 2018 by Sven Gregori 9 Comments

With the June solstice right around the corner, it’s a perfect time to witness first hand the effects of Earth’s axial tilt on the day’s length above and beyond 60 degrees latitude. But if you can’t make it there, or otherwise prefer a more regular, less deprived sleep pattern, you can always resort to simulations to demonstrate the phenomenon. [SimonRob] for example built a clock with a real time rotating model of Earth to visualize its exposure to the sun over the year.

The daily rotating cycle, as well as Earth’s rotation within one year, are simulated with a hand painted plastic ball attached to a rotating axis and mounted on a rotating plate. The hand painting was done with a neat trick; placing printed slivers of an atlas inside the transparent orb to serve as guides. Movement for both axes are driven by a pair of stepper motors and a ring of LEDs in the same diameter as the Earth model is used to represent the Sun. You can of course wait a whole year to observe it all in real time, or then make use of a set of buttons that lets you fast forward and reverse time.

Earth’s rotation, and especially countering it, is a regular concept in astrophotography, so it’s a nice change of perspective to use it to look onto Earth itself from the outside. And who knows, if [SimonRob] ever feels like extending his clock with an aurora borealis simulation, he might find inspiration in this northern lights tracking light show.

This is a spectacular showpiece and a great project you can do with common tools already in your workshop. Once you’ve mastered earth, put on your machinists hat and give the solar system a try.

3D Printer Tech Cuts Paper

June 16, 2018 by Al Williams 19 Comments

While 3D printing has been a great thing all by itself, it has also made electromechanical hardware a commodity item. Instead of raiding an old printer for motors and rods of unknown provenance, you can now buy everything very inexpensively due to the economy of scale and offshore manufacturing.

[Mr. Innovation] proves this point with his recent paper cutting machine which feeds and slices paper strips with user-selected width and quantity. He did steal one roller assembly from an old printer, but most of it is straight out of a 3D printer build. There’s NEMA stepper motors, modular motor driver boards, smooth rods, belts, and pulleys.

The blade of the cutter is just a standard snap off box cutter blade. It is angled so it doesn’t drag when the motor pulls it back to the home position after a cut. Honestly, we might have made the paper mechanism retract the paper a bit at that point, but that would be simple to add to the device’s firmware.

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Jeremy Cook's strandbeest kit RC conversion

Stepper Motor And Key Fob Controlled Strandbeest

May 12, 2018 by Steven Dufresne 7 Comments

We never tire of watching Strandbeests with their multitude of legs walking around, and especially enjoy the RC ones. [Jeremy Cook], prolific Strandbeest maker, just made one by motorizing and adding remote control to a small, plastic wind-powered kit.

We’ve seen a Strandbeest kit conversion like this before, such as this DC motor one but it’s always interesting to see how it can be done differently. In [Jeremy’s], he’s gone with two inexpensive $2.00 stepper motors. The RC is done using a keyfob transmitter with a receiver board wired into an Arduino Nano’s analog pins. He tried driving it directly off the LiPo batteries but had issues which he solved by adding a 5-volt regulator. Check out his build and the modified Strandbeest walking around in the video below.

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Glow In The Dark Globe On A Spherical Screen

May 6, 2018 by James Hobson 18 Comments

Terrestrial globes are almost a thing of the past in an era of Google Earth, but they can still be an exciting object worth hacking together, as [Ivan Miranda] shows with his glow-in-the-dark globe. It’s a globe, it’s a display, and it’s a great use of glow in the dark filament.

For the mechanical part of this build, [Miranda] used glow in the dark filament to 3D print a sphere and a reinforcing ring that hides inside. A threaded rod through the middle secured with screws and bearings make an appropriate spindle, and is attached to a stepper motor in the 3D printed stand. So far, it’s a sphere made of glowey plastic. Where’s the ‘globe’ part coming from?

To project a globe onto this sphere, [Miranda] used a strip of WS2812B LEDs stuck to the inside of the stand’s arc are programmed to selectively illuminate the globe as it rotates on its axis. After a brief hiccup with getting the proper power supply, he was ready to test out his new….. giant light ball.

It turns out, the filament was a bit more transparent than he was expecting so he had to pull it all apart and cover the interior with aluminium tape. [Miranda] also took the chance to clean up the wiring, code, and upgrade to a Teensy 3.1 before another test.

Despite the resulting continental projection being upside-down, it worked! [Miranda] added a USB cable before he closed it up again in case he wanted to reprogram it and display any number of images down the line.

[Thanks for the tip, olivekrystal!]

Pi Zero Gives Telescope Hands Free Focus

February 12, 2018 by Tom Nardi 7 Comments

It seems like [Jason Bowling] never gets tired of finding new ways to combine the Raspberry Pi with his love of the cosmos. This time he’s come up with a very straightforward way of focusing his Celestron 127SLT with everyone’s favorite Linux SBC. He found the focus mechanism on the scope to be a bit fiddly, and operating it by hand was becoming a chore. With the Pi Zero and a stepper motor, he’s now able to focus the telescope with more accuracy and repeatability than clumsy human fingers will be able to replicate.

On this particular type of telescope, the focus knob is a small knob on the back of the scope (rather than on the eyepiece), which just so happens to be the perfect size to slide a 15mm bore pulley over. With a pulley on the focus knob, he just needed to mount a stepper motor with matching toothed pulley next to it and find a small enough belt to link them together. Through the magic of Amazon and McMaster-Carr he was able to find all the parts without having to make anything himself, beyond the bent piece of aluminum he’s using as a stepper mount.

To control the stepper, [Jason] is using an EasyDriver connected up to the Pi’s GPIO, which along with a 5V regulator (which appears to be a UBEC from the RC world) is held in a tidy weather proof box mounted to the telescope’s tripod. The regulator is necessary because the whole setup is powered by a 12V portable “jump start” battery pack for portability. Handy when you’re stargazing in the middle of a field somewhere.

[Jason] promises a future blog post where he details how he used Flask to create a web-based control for the hardware, which we’ll be keeping an eye out for. In the meantime, he reports that his automated focus system is working perfectly and keeps the image stable in the eyepiece even while moving (something he was never able to do by hand).

Last year this same scope had a Raspberry Pi camera mounted to it to deliver some very impressive pictures without breaking the bank. We’re interested in seeing how [Jason] ties these systems together going forward.

Making Prints More Resilient With Fibre-Filled Filament

January 23, 2018 by James Hobson 14 Comments

For all that we love 3D printers, sometimes the final print doesn’t turn out as durable as we might want it to be.

Aiming to mimic the properties of natural structures such as wood, bone, and shells, a research team lead by [Jennifer A. Lewis] at Harvard John A. Paulson School of Engineering and Applied Sciences’ Lewis Lab have developed a new combined filament and printing technique which they call rotational 3D printing.

Minuscule fibres are mixed in with the epoxy filament and their controlled orientation within the print can reinforce the overall structure or specific points that will undergo constant stresses. To do so the print head is fitted with a stepper motor, and its precisely programmed spin controls the weaving of the fibres into the print. The team suggests that they would be able to adapt this tech to many different 3D printing methods and materials, as well as use different materials and printed patterns to focus on thermal, electrical, or optical properties.

Be it adding carbon nano-tubes or enlisting the expertise of spiders to refine our printed materials, we’re looking forward to the future of ever stronger prints. However, that doesn’t mean that existing methods are entirely lacking in endurance.

[Thanks for the tip, Qes!]

Stepper Motor Robot Arm Has Smooth Moves

January 22, 2018 by Steven Dufresne 17 Comments

[Tobias Kuhn] had watched a YouTube video about a robot arm which used servo motors, and wanted to try making one himself. But he found it hard to get slow or smooth movements out of the servos. Even removing the microcontroller and trying to work with the servo’s driver-IC and potentiometer from an Arduino Nano didn’t get him satisfaction.

Then he found the very affordable 28BYJ-48 stepper motor. After some experimenting, he came up with a smooth moving robot arm with four steppers controlled from an Arduino Mega and A4988 stepper motor drivers. Rather than write a bunch of stepper motor code himself, he installed and ran a four-axis fork of grbl on the Arduino, turning it into a stepper motor controller. One minor hitch was that the A4988 motor drivers are for bipolar stepper motors but 28BYJ-48 steppers are unipolar. Luckily he knew of a very simple hack which our [Brian Benchoff] wrote about for turning a unipolar motor into a bipolar motor.

To tell the robot arm what to do, he built a replica arm with potentiometers in place of the stepper motors. As he manipulates the replica, the values of the potentiometers are read by a Raspberry Pi and some custom Python code which sends the appropriate G-code to the Arduino/grbl controlled robot arm. There’s a bit of a lag but when he moves the replica arm, the robot arm does the same move. See it in action in the video below.

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