This 3D Printer Is Soft On Robots

It always seems to us that the best robots mimic things that are alive. For an example look no further than the 3D printed mesh structures from researchers at North Carolina State University. External magnetic fields make the mesh-like “robot” flex and move while floating in water. The mechanism can grab small objects and carry something as delicate as a water droplet.

The key is a viscous toothpaste-like ink made from silicone microbeads, iron carbonyl particles, and liquid silicone. The resulting paste is amenable to 3D printing before being cured in an oven. Of course, the iron is the element that makes the thing sensitive to magnetic fields. You can see several videos of it in action, below.

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Cloning Knobs For Vintage Testing Equipment

Knobs! Shiny candy-colored knobs! The last stand of skeuomorphism is smart light switches! Everyone loves knobs, but when you’re dealing with vintage equipment with a missing knob, the odds of replacing it are slim to none. That’s what happened to [Wesley Treat] when he picked up a vintage Philco tube tester. The tester looked great, but a single knob for a rotary switch was missing. What to do? Clone some knobs! You only need some resin and a little bit of silicone.

The process of copying little bits of plastic or bakelite is fairly standard and well-tread territory. Go to Michaels or Hobby Lobby, grab some silicone and resin, make a box, put your parts down, cover them in silicone, remove the parts, then put resin in. For simple parts, and parts with flat bottoms like knobs, this works great. However, there’s something weird about the knob on this old Philco tube tester. Firstly, it doesn’t fit a standard 1/4″ shaft — it’s a bit bigger. There’s also no set screw. Instead, this knob has a stamped spring aligning it with the flat part of the D-shaft in this rotary switch. This means a copy of this knob wouldn’t be useful to anyone else, and that no other knob would work with this tube tester.

However, a bit of clever engineering would make a copy of this knob fit the existing switch. Once the resin was cured, [Wesley] drilled out the hole, then sanded a dowel down to fit into the flat of the D-shaft. It took a little kergiggering, but the knob eventually fit onto one of the rotary switches. Not bad for a few bucks in silicone and resin.

You can check out the entire build process below.

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Soft Silicone Pneumatics Are 3D-printed In A Tub Of Gel

We’ve seen our fair share of soft silicone robots around here. Typically they are produced through a casting process, where molds are printed and then filled with liquid silicone to form the robot parts. These parts are subsequently removed from the molds and made to wiggle, grip, and swim through the use of pneumatic or hydraulic pumps and valves. MIT’s Self-Assembly Lab has found a way to print the parts directly instead, by extruding silicone, layer by layer, into a gel-filled tank.

The Self-Assembly Lab’s site is unfortunately light on details, but there is a related academic paper (behind a paywall, alas) that documents the process. From the abstract, it seems the printing process is intended for more general purpose printing needs, and is able to print any “photo or chemically cured” material, including two-part mixtures. Additionally, because of the gel-filled tank, the material need not be deposited in flat layers like a traditional 3D-printer. More interesting shapes and material properties could be created by using the full 3d-volume to do 3D extrusion paths.

To see some of the creative shapes and mechanisms developed by MIT using this process, check out the two aesthetically pleasing videos of pulsating soft white silicone shapes after the break.

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Lessons in Disposable Design from a Cheap Blinky Ball

Planned obsolescence, as annoying as it is when you’re its victim, still has to be admired. You can’t help but stand in awe of the designer who somehow managed to optimize a product to live one day longer than its warranty period. Seriously, why is it always the next day?

The design of products that are never intended to live long enough to go obsolete must be similarly challenging, and [electronupdate] did a teardown of a cheap LED blinky toy to see what’s involved. You’ve no doubt seen these seizure-triggering silicone balls before, mostly at checkout counters and the like where they’re sold at prices many hundreds of times what it took to make them. This particular device, which seems representative of the species, has two bright LEDs, a small controller chip, a trio of button cells for power, and a springy switch to activate it. All this is mounted to a cheap scrap of phenolic resin PCB, with the controller chip and one of the LEDs covered by a blob of clear epoxy.

This teardown one-ups most others, as [electronupdate] disrobes the chip and points a microscope at the die; the video below shows just how few transistors are employed and proposes a likely circuit. Everything about this ball just oozes cheapness, and it’s likely these things cost essentially nothing to build. Which makes sense for something destined for the landfill within a week or so.

Yes, this annoying blinky-thing is low-end garbage, but there are still design lessons to be learned from it. Anything that’s built for a broad market has to be built to a price point, and understanding those constraints is important to understanding how planned obsolescence works.

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H2gO Keeps Us from Drying Out

The scientific community cannot always agree on how much water a person needs in a day, and since we are not Fremen, we should give it more thought than we do. For many people, remembering to take a sip now and then is all we need and the H2gO is built to remind [Angeliki Beyko] when to reach for the water bottle. A kitchen timer would probably get the job done, but we can assure you, that is not how we do things around here.

A cast silicone droplet lights up to show how much water you have drunk and pressing the center of the device means you have taken a drink. Under the hood, you find a twelve-node NeoPixel ring, a twelve millimeter momentary switch, and an Arduino Pro Mini holding it all together. A GitHub repo is linked in the article where you can find Arduino code, the droplet model, and links to all the parts. I do not think we will need a device to remind us when to use the bathroom after all this water.

Another intrepid hacker seeks to measure a person’s intake while another measures output.

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This 3D Printed Syringe Static Mixer Does It All

One trick for getting the bubbles out of freshly mixed 2-part epoxy, aka degassing, is to go over it gently with the flame from a propane torch. But both the mixing and degassing take time. [Gianteye] came up with a 3D printed dual-syringe static mixing system which speeds up the process. He used it with silicone to get the difficult steps out of the way quickly for his hands-on soft robotics class, allowing the students to focus more on the matter at hand. But we figure most readers might use it for epoxy.

Mixing tube interior
Mixing tube interior

If you’ve bought those 2-part epoxy syringes available in stores before then you’ll know that they usually come with two syringes, each filled with one of the two parts to be mixed. Depressing the syringes causes each part to come out of its own tube. It’s then your job to mix them together and degas the result.

[Gianteye’s] system consists of 3D printed parts and two syringes.  Models for the 3D printing are available on his Thingiverse page and the syringes can be found online. Some of the 3D printed parts help you first fill and degas the syringes. You then attach a 3D printed mixing tube to the ends of the syringes. This tube serves two purposes. When the syringe’s plungers are depressed, both parts of the material are forced through the tube and extruded out. But on their way through, both parts pass through eight helices which form 180° turns and mix the parts together. Out comes the portioned, mixed and degassed material which can go straight into a mold or to wherever you need it.

The mixing tube was designed for one-time use but [Gianteye] discovered during an evaluation that it can be reused if you pull out any cured material and purge it. The evaluation involved silicone though. With hardened epoxy, you’ll probably have to use a new tube each time.

Check out the full details of his system in the video below, including both assembly and usage.

If you’re looking for a metallic look for something without wanting to cast metal than have a look at our own [Gerrit Coetzee’s] article about cold casting wherein he makes some very nice looking parts.

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Custom Buttons For Your Game Controller

Console gamers have relatively few options when it comes to hardware hacking, unless they wish to partake of some extreme modifications that threaten the very integrity of their machines. So without reaching for a Dremel, how can you insert a little individuality into the same standard components all your friends have?

It seems one answer is to customise your controller with some different buttons. There are commercial outfits that will supply your needs in this direction, but they aren’t always cheap, and plenty of older machines have no products available. This isn’t  a problem for [RockerGaming] though, who shows us how to cast your own set of custom buttons using a silicone mold taken from the originals.

The video is a step-by-step walkthrough of the molding process that could just as easily be applied to any other small plastic parts and is not unique to console buttons. The subjects come from a Sega Saturn controller, in the video a beige model, which raises a passing interest among European Hackaday scribes who remember the Saturn as a black console.

We see the preparation of the original buttons and mold. An acrylic golf ball trophy display case is pressed into service. (Who knew those were even a thing!) A dye is added to the two-part silicone to provide a visual mixing aid, and once the cast mold is separated from the buttons the final resin is poured into it. The cloned buttons are tidied up underneath with a Dremel, and the controller is reassembled.

A set of custom buttons will not improve your gaming, but underlying this is the fact that resin casting is a useful skill. It’s somewhere we’ve been before in depth, so it’s worth reading our guide from back in 2016.

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