See This Mesmerizing 3D Printed Water Droplet Automaton

Water Experiment No. 33 by [Dean O’Callaghan]
Most modern automata are hand-cranked kinetic sculptures typically made from wood, and [videohead118] was inspired by a video of one simulating a wave pattern from a drop of liquid. As a result, they made a 3D printed version of their own and shared the files on Thingiverse.

In this piece, a hand crank turns a bunch of cams that raise and lower a series of rings in a simulated wave pattern, apparently in response to the motion of a sphere on a central shaft. The original (shown in the animation to the right) was made from wood by a fellow named [Dean O’Callaghan], and a video of it in its entirety is embedded below the break.

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3D Prints That Fold Themselves

3D printing technologies have come a long way, not only in terms of machine construction and affordability but also in the availability of the diverse range of different printing materials at our disposal. The common consumer might already be familiar with the usual PLA, ABS but there are other more exotic offerings such as PVA based dissolvable filaments and even carbon fiber and wood infused materials. Researchers at MIT allude to yet another possibility in a paper titled “3D-Printed Self-Folding Electronics” also dubbed the “Peel and Go” material.

The crux of the publication is the ability to print structures that are ultimately intended to be intricately folded, in a more convenient planar arrangement. As the material is taken off the build platform it immediately starts to morph into the intended shape. The key to this behavior is the use of a special polymer as a filler for joint-like structures, made out of more traditional but flexible filament. This special polymer, rather atypically, expands after printing serving almost like a muscle to contort the printed joint.

Existing filaments that can achieve similar results, albeit after some manual post-processing such as immersion in water or exposure to heat are not ideal for electronic circuits. The researchers focus on this new materials potential use in manufacturing electronic circuits and sensors for the ever miniaturizing consumer electronics.

If you want to experiment printing extremely intricate structures, check out how [_primoz_] brilliant technique revolutionized how the 3D printing community prints thin fibers, bristles, and lion sculptures.

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Automatically 3D Print Infinite Number of Parts

We’ve seen 3D printers coming out with infinite build volumes, including some attempts at patenting that may or may not stall their development. One way around the controversy is to do it in a completely different way. [Aad van der Geest]’s solution may not give you the ability to print an infinitely long part, but it will allow you to print an infinite number of the same, or different, parts, at least until your spool runs out.

[Aad]’s solution is to have a blade automatically remove each part from the print bed before going on to the next. For that he put together a rail system that sits on the bed of his Ultimaker 2, but out of the way on the periphery. A servo at one end pulls a blade along the rails, sweeping over the bed and moving any parts on the bed to one end where they fall away. This is all done by a combination of special G-code and a circuit built around a PIC12F629.

One of many things that we think is pretty clever, as well as fun to watch, is that after the part is finished, the extruder moves to the top corner of the printer and presses a micro switch to tell the PIC12F629 to start the part removal process. You can see this in the first video below. The G-code takes over again after a configurable pause.

But [Aad]’s put in more features than just that. As the second video below shows, after the parts have been scraped from the build plate, a pin on the extruder is used to lift and drop the blade a few times to remove small parts that tend to stay on the blade. Also, the extruder is purged between prints by being moved over a small ridge a few times. This of course is also in that special G-code.

How do you produce the special G-code, since obviously it also has to include the parts to print? For that [Aad]’s written a Windows program called gcmerge. It reads a configuration file, which you edit, that contains: a list of files containing the G-code for your parts, how many to print, whether or not you want the extruder to be purged between prints, various extruder temperatures, cooling times, and so on. You can find all this, as well as source for the gcmerge program, packaged up on a hackaday.io page. Incidentally, you can find the PIC12F629 code there too.

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3D Printed Ribs For Not 3D Printed Planes

A few months ago, [Tom] built a few RC planes. The first was completely 3D printed, but the resulting print — and plane — came in a bit overweight, making it a terrible plane. The second plane was a VTOL tilt rotor, using aluminum box section for the wing spar. This plane was a lot of fun to fly, but again, a bit overweight and the airfoil was never quite right.

Obviously, there are improvements to be made in the field of 3D printed aeronautics, and [Tom]’s recent experiments with 3D printed ribs hit it out of the park.

If you’re unfamiliar, a wing spar is a very long member that goes from wingtip to wingtip, or from the fuselage to each wingtip, and effectively supports the entire weight of the plane. The ribs run perpendicular to the spar and provide support for the wing covering, whether it’s aluminum, foam board, or monokote.

For this build, [Tom] is relying on the old standby, a square piece of balsa. The ribs, though, are 3D printed. They’re basically a single-wall vase in the shape of a wing rib, and are attached to the covering (foam board) with Gorilla glue.

Did the 3D printed ribs work? Yes, of course, you can strap a motor to a toaster and get it to fly. What’s interesting here is how good the resulting wing looked. It’s not quite up to the quality of fancy fiberglass wings, but it’s on par with any other foam board construction.

The takeaway, though, is how much lighter this construction was when compared to the completely 3D printed plane. With similar electronics, the plane with the 3D printed ribs weighed in at 312 grams. The completely 3D printed plane was a hefty 468 grams. That’s a lot of weight saved, and that translates into more flying time.

You can check out the build video below.

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I’ve Seen the Future and It’s Full of Freakin’ Huge Bricks

“Did you know you can 3D-print LEGO bricks that can actually be used as regular LEGO?”–me, in 2009

Those magical words made real to me the wonder that was 3D printing. It was a magical time! Everyone was 3D printing everything, though most of it wasn’t very good because the technology wasn’t there. But just as every technology goes through an evolution, the goalposts of coolness move on past what used to be remarkable to the new thing everyone’s talking about.

These days, no one is going to be more than mildly curious about your 3D-printed LEGO brick. Still, when you look at that uneven lump of plastic as being just one step in an evolution, it’s pretty momentous. What I’m saying is that we’re looking at a future that can be described in three words: Freakin’ Huge Bricks.

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Polyurethane, Meet 3D Printing

3D printing makes prototyping wonderful. But what do you do when your plastics of choice just aren’t strong enough? For [Michael Memeteau], the answer was to combine the strength of a vacuum-poured polyurethane part with the ease of 3D-printed molds. The write-up is a fantastic walk through of a particular problem and all of the false steps along the way to a solution.

The prototype is a connected scale for LPG canisters, so the frame would have to support 80 kg and survive an outdoor environment. Lego or MDF lattice were considered and abandoned as options early on. 3D printing at 100% infill might have worked, but because of the frame’s size, it would have to be assembled in pieces and took far too long anyway.

The next approach was to make a mold with the 3D printer and pour the chosen polyurethane resin in, but a simple hollow mold didn’t work because the polyurethane heats as it cures. The combined weight and heat deformed the PLA mold. Worse, their polyurethane of choice was viscous and cured too quickly.

The solution, in the end, was a PET filament that deforms less with heat, clever choice of internal support structures to hold the stress in while being permeable, and finally pouring the polyurethane in a vacuum bag to help it fill and degas. The 3D-printed hull is part of the final product, but the strength comes from the polyurethane.

Mold-making is one of the killer apps of 3D printing. We’ve seen 3D prints used as molds for spin-casting hollow parts, and used as a sacrificial shell for otherwise epoxy parts. But for really complex shapes, strength, and ease of fabrication, we have to say that [Michael]’s approach looks promising.

How Low-Power Can You Go?

[lasersaber] has a passion: low-power motors. In a bid to challenge himself and inspired by betavoltaic cells, he has 3D printed and built a small nuclear powered motor!

This photovoltaic battery uses fragile glass vials of tritium extracted from keychains and a small section of a solar panel to absorb the light, generating power. After experimenting with numerous designs, [lasersaber] went with a 3D printed pyramid that houses six coils and three magnets, encapsulated in a glass cloche and accompanied by a suitably ominous green glow.

Can you guess how much power and current are coursing through this thing? Guess again. Lower. Lower.

Under 200mV and 20nA!

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