Disco Ain’t Dead: Blinky Ball Makes You Solder Inside A Dome

November 22, 2018 by Mike Szczys 10 Comments

Disco balls take a zillion mirrors glued to a sphere and shine a spotlight on them. But what if the ball itself was the light source? Here’s a modern version that uses addressable LEDs in a 3D-printed sphere that also hides the electronics inside the ball itself.

Check out the video below to see the fantastic results. It’s a Teensy 3.6 driving a whopping 130 WS2812 LEDs to make this happen. (Even though the sphere has the lowest surface area to volume ratio.) There’s even a microphone and an accelerometer to make the orb interactive. Hidden inside is a 4400 mAh battery pack that handles recharging and feeds 5 V to the project.

For us, it’s the fabrication that really makes this even more impressive. The sphere itself is 3D printed as four rings that combine to form a sphere. This makes perfect spacing for the LEDs a snap, but you’re going to spend some time soldering the voltage, ground, and data connections from pixel to pixel. In this case that’s greatly simplified because the LEDs were sourced from AliExpress already hosted on a little circle of PCB so you’re not trying to solder on the component itself. Still, that’s something like 390 wires requiring 780 solder joints!

We love seeing an LED ball you can hold in your hand. But if you do want something bigger, try this 540 LED sphere built from triangular PCBs.

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PLA Foils Homemade Tachometer

November 22, 2018 by Al Williams 19 Comments

[Integza] built a Tesla turbine and wanted to know how fast it was spinning. However, he didn’t have a tachometer, and didn’t want to buy one. After a false start of trying to analyze the audio to measure the speed, he decided to use a tried-and-true method. Let the wheel break an infrared (IR) optointerruptor and count the spokes of the wheel as they go by. If you know the spacing between the spokes, you can compute the speed. There was only one problem: it didn’t work.

Turns out, PLA is at least somewhat transparent to IR. Knowing that it was a simple matter to fix some tape to the wheel that would block IR and that made things work much better. If you missed the video where he built the turbine, you might want to watch it first.

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3D Printer Warning: Heating Plastic To High Temps Is Not Healthy

November 21, 2018 by Bryan Cockfield 42 Comments

If you’ve ever tried to cut a piece of acrylic with a tool designed to cut wood or metal, you know that the plastic doesn’t cut in the same way that either of the other materials would. It melts at the cutting location, often gumming up the tool but always releasing a terrible smell that will encourage anyone who has tried this to get the proper plastic cutting tools instead of taking shortcuts. Other tools that heat up plastic also have this problem, as Gizmodo reported recently, and it turns out that the plastic particles aren’t just smelly, they’re toxic.

The report released recently in Aerosol Science and Technology (first part and second part) focuses on 3D printers which heat plastic of some form or other in order to make it malleable and form to the specifications of the print. Similar to cutting plastic with the wrong tool, this releases vaporized plastic particles into the air which are incredibly small and can cause health issues when inhaled. They are too small to be seen, and can enter the bloodstream through the lungs. The study found 200 different compounds that were emitted by the printers, some of which are known to be harmful, including several carcinogens. The worst of the emissions seem to be released when the prints are first initiated, but they are continuously released throuhgout the print session as well.

Perhaps it’s not surprising that aerosolized plastic is harmful to breathe, but the sheer magnitude of particles detected in this study is worth taking note of. If you don’t already, it might be good to run your 3D printer in the garage or at least in a room that isn’t used as living space. If that’s not possible, you might want to look at other options to keep your work area safe.

Thanks to [Michael] for the tip!

Generative Design Algorithms Prepare For Space

November 17, 2018 by Roger Cheng 14 Comments

NASA is famously risk-averse, taking cautious approaches because billions of taxpayer dollars are at stake and each failure receives far more political attention than their many successes. So while moving the final frontier outward requires adopting new ideas, those ideas must first prove themselves through a lengthy process of risk-reduction. Autodesk’s research into generative design algorithms has just taken a significant step on this long journey with a planetary lander concept.

It was built jointly with a research division of NASA’s Jet Propulsion Laboratory, the birthplace of many successful interplanetary space probes. This project got a foot in the door by promising 30% weight savings over conventional design techniques. Large reduction in launch mass is always a good way to get a space engineer’s attention! Mimicking mother nature’s evolutionary process, these algorithms output very organic looking shapes. This is a relatively new approach to design optimization under exploration by multiple engineering software vendors. Not just Autodesk’s “Generative Design” but also “Topology Optimization” in SolidWorks, plus others. Though these shapes appear ideally suited to 3D printing, Autodesk also had to prove their algorithm could work with more traditional fabrication techniques like 5-axis CNC mills.

This is leading-edge research technology though some less specialized, customer-ready versions are starting to trickle out of research labs. Starting with an exclusive circle: People with right tiers of SolidWorks license, the paid (not free) tier of Autodesk Fusion 360, etc. We’ve looked at another recent project with nontraditional organic shapes, and we’ve looked at generative designs used for their form as well as their function. This category of CAD tools hold a lot of promise, and we’re optimistic they’ll soon become widely accessible so we can all put them to good use in our earthbound projects.

Possibly even before they fly to another planet.

[via Engadget]

Expanding 3D Printer Bed Stays True Under Fire

November 16, 2018 by Sonya Vasquez 9 Comments

It’s hard to pass up another lesson in good machine design brought to us by [Mark Rehorst]. This time, [Mark] combats the relentless forces of bed deformation due to thermal expansion.

Did you think your printer stayed the same size when it heated up? Well, think again! According to [Mark’s] calculations, when heated, the bed can expand by as much as half a millimeter in the x/y direction. While x/y deformation seems like something we can ignore, that’s not always true. If our bed is rigidly fixed in place, then that change in dimension will only result in a warped bed as it tries to make space for itself.

Don’t give up yet though. As sinister as this problem may seem, [Mark] introduces a classic-but-well-implemented solution: and adjustable kinematic coupling. The kinematic coupling holds the bed at the minimum number of points to keep it rigid while exposing thumbscrews to dial in a level bed. What’s special about this technique is that the coupling holds the bed perfectly rigid whilst allowing it to thermally expand!

This is the beauty of “exact constraint” design. Parts are held together only by the minimum number of points needed to guarantee a specific relationship. Here that relationship is coplanarity between the the nozzle’s x/y plane and the bed. Even when the bed expands this relationship holds. Now that is magic.

With such a flood of 3D printed parts on the market, building a printer has never been easier! Nevertheless, it’s easy to pin ourselves into a corner re-tuning a poor design that skips a foundation on the base principles. If you’re curious about more of these principles behind 3D printer design, check out [Mark’s] thorough walkthrough on the CoreXY design.

Turning A Rotary Tool Into A CNC

November 16, 2018 by Brian Benchoff 32 Comments

Now that 3D printers are everywhere, electronics are cheap, and open source software is extremely capable, just about anyone can build a CNC machine. That’s exactly what [Nikodem] did by turning a Dremel tool into an extremely capable CNC machine that’s able to cut MDF and acrylic and can engrave aluminum.

The electronics for the build are just an Arduino Uno, a motor driver sheld running GRBL, a relay for the Dremel, a few motor drivers, and a big ‘ol 30 A power supply. The build uses NEMA 17 motors, two on the Y-axis and one each on the X and Z. The CNC has a fantastically strong frame despite the 3D printed parts. It is constructed out of aluminum extrusion, with the carriages riding on some nice straight rods.

As for how well this CNC machine works, it’s pretty good. With the Gcode to cut an 80mm diameter circle out of MDF, this machine managed to cut a circle that was 80.02 mm in diameter. That’s pretty good, and getting into the territory that the error is probably in the cheap set of calipers, not the finished part itself. It’s an awesome build, and [Nikodem] has everything documented in his four-part video series. You can check the end of that out below.

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3D Print Springs With Hacked GCode

November 14, 2018 by Tom Nardi 36 Comments

If you’ve used a desktop 3D printer in the past, you’re almost certainly done battle with “strings”. These are the wispy bits of filament that harden in the air, usually as the printer’s nozzle moves quickly between points in open air. Depending on the severity and the material you’re printing with, these stringy interlopers can range from being an unsightly annoyance to triggering a heartbreaking failed print. But where most see an annoying reality of pushing melted plastic around, [Adam Kumpf] of Makefast Workshop sees inspiration.

Noticing that the nozzle of their printer left strings behind, [Adam] wondered if it would be possible to induce these mid-air printing artifacts on demand. Even better, would it be possible to tame them into producing a useful object? As it turns out it is, and now we’ve got the web-based tool to prove it.

As [Adam] explains, you can’t just load up a 3D model of a spring in your normal slicer and expect your printer to churn out a useful object. The software will, as it’s designed to do, recognize the object can’t be printed without extensive support material. Now you could in theory go ahead and print such a spring, but good luck getting the support material out.

The trick is to throw away the traditional slicer entirely, as the layer-by-layer approach simply won’t work here. By manually creating GCode using carefully tuned parameters, [Adam] found it was possible to get the printer to extrude plastic at the precise rate at which the part cooling fan would instantly solidify it. Then it was just a matter of taking that concept and applying it to a slow spiral motion. The end result are functional, albeit not very strong, helical compression springs.

But you don’t have to take their word for it. This research has lead to the creation of an online tool that allows you to plug in the variables for your desired spring (pitch, radius, revolutions, etc), as well as details about your printer such as nozzle diameter and temperature. The result is a custom GCode that (hopefully) will produce the desired spring when loaded up on your printer. We’d love to hear if any readers manage to replicate the effect on their own printers, but we should mention fiddling with your printer’s GCode directly isn’t without its risks: from skipping steps to stripped filament to head crashes.

The results remind us somewhat of the 3D lattice printer we featured a couple of years back, but even that machine didn’t use standard FDM technology. It will be interesting to see what other applications could be found for this particular technique.

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