Line of electromechanical water valves dispensing a pattern of water droplets

Gravity-Defying Water Drop Display Shows Potential

October 23, 2021 by Dave Rowntree 9 Comments

[3DPrintedLife aka Andrew DeGonge] saw that advert for gatorade that shows some slick stop-motion animation using a so-called ‘liquid printer’ and wondered how they built the machine and got it to work so well. The answer, it would seem, involves a lot of hard work and experimentation.

Conceptually it’s not hard to grasp. A water reservoir sits at the top, which gravity-feeds into a a series of electromechanical valves below, which feed into nozzles. From there, the timing of the valve and water pressure dictate the droplet size. The droplets fall under the influence of gravity, to be collected at the bottom. From that point it’s a ‘simple’ matter of timing droplets with respect to a lighting strobe or camera shutter and hey-presto! instant animation.

As will become evident from the video, it’s just not as easy as that. After an initial wobble when [Andrew] realised that cheap “air-only” solenoids actually are for air-only when they rusted up, he took a slight detour to design and 3D print his own valve body. Using a resin printer to produce fine detailed prints, enabled the production of small internal passages including an ‘air spring’ which is just a small chamber of air. After a lot of testing, proved to be a step in the right direction. Whether this could have been achieved with an FDM printer, is open to speculation, but we suspect the superior fine detail capabilities of modern resin printers are a big help here.

In a nice twist, [Andrew] ripped open and dissolved a fluorescent marker pen, and used that in place of plain water, so when illuminated with suitably triggered UV LED strips, discernable animation was achieved, with an eerie green glow which we think looks pretty neat. All he needs to do now is upgrade the hardware to make a 3D array with more resolution, and he can start approaching the capability of the thing that inspired him. Work on some custom electronics to drive it has started, so this is one to watch in the coming months!

We’ve seen many water-based display device before, like this one that projects directly onto a thin stream of water, and this strangely satisfying hack using paraffin and water, but a full 3D Open Source display device seems elusive so far.

All project details can be found on the associated GitHub.

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Testing 3D Printed Cutting Blades Is Scary Work

October 22, 2021 by Lewin Day 15 Comments

[Ivan Miranda] comes from a land where the shops close on Sundays. Thus, when he found himself in need of a cutting blade, he realised he would have to build his own, or simply wait. He elected to do the former, and we get to enjoy the journey. (Video, embedded below.)

His first attempt was to cut a wooden plank with a 3D-printed cutting blade fitted to a mitre saw. After setting up the mitre saw to cut while he was at a safe distance, [Ivan] elected to test the blade. Alas, it simply melted, and the wood was barely scratched, so [Ivan] went back to the drawing board.

His second attempt was to CNC mill an aluminium blade, which was a full 6 mm thick. The saw needed some modifications to the saw to fit properly, but it was able to cut wood without major drama!

Returning to the 3D-printed concept, [Ivan] suspected reducing the surface speed of the cutting disc could reduce friction-induced heating. This would allow the 3D-printed blade to cut wood without melting, in theory. To achieve this, he built his own basic drop saw using a steel frame and a brushless motor. With a little water spray, and careful control of speed and pressure, the blade was able to slowly chew through a plank of wood. Afterwards, the teeth were almost completely worn down.

The fact is, 3D-printed blades are usually going to be too soft to do any real useful work. However, it’s fun to watch, and that’s good enough for us. If you want something more useful though, consider building your own knives.

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3D Printable Scope Probe Adapts To Your Needs

October 21, 2021 by Dave Rowntree 18 Comments

If there’s one this we electronics engineers are precious about, it’s our test gear. The instruments themselves can be obscenely expensive, since all that R&D effort needs to be paid back over a much smaller user base compared to say a DVD player. The test probes themselves can often come with an eye-watering price tag as well. Take the oscilloscope probe, pretty much everyone who tinkers with hardware will be familiar with. It’s great for poking around, looking desperately for inspiration when you’re getting stuck in with some debug, but you’ve only got two hands, and that doesn’t leave any spare for button pushing.

Hands-free probing solutions exist, but they can be pricey, flimsy or just a pain to use. Sometimes you just want to solder a wire and leave the probe attached, hoping the grounding lead doesn’t fall off and short something. We’ve seen many solutions to this, so here’s yet another one you can 3D print yourself, so it’s almost free to make.

The two-part 3D printed assembly embeds a pair of wires with a Molex 0008500113 sprung terminal on one end, which can be terminated with your choice of pins, headers or just a pair of plain ‘ol wires. Once you’ve dropped your wiring of choice inside, simply glue the halves with a little cyanoacrylate and you’re good to go. Designed around the Siglent 200MHz PP215 specifically, it is likely compatible with many other brands. Thingiverse only has STL files (sigh!) so it may be tricky to adapt it to your exact probe dimensions, but the idea is good at least.

There is no shortage of electronics probing solutions out there, and boy have we covered a few over the years, here’s a low-cost current probe, an Open Source 2 GHz scope probe, and if you want to get really hacky, look no further for inspiration than the 2019 Hackaday SuperCon SMD Challenge.

Thanks [daniel] for the tip!

Spinning Threads Put The Bite On Filament In This Novel Extruder Design

October 20, 2021 by Dan Maloney 29 Comments

When it comes to innovation in FDM 3D printing, there doesn’t seem to be much room left to move the needle. Pretty much everything about filament printing has been reduced to practice, with more or less every assembly available off the shelf. Even the business end — the extruder — is so optimized that there’s not much room left for innovation.

Or is there? The way [David Leitner] sees it, there is, which is why he built this rolling-screw extruder (if you can get to the Thingiverse link, [David] cross-posted on reddit, too). Standard extruders work on the pinch-roller principle, where the relatively soft filament is fed past a spring-loaded gear attached to a stepper motor. The stepper rotates the gear, which either advances the filament into or retracts it from the hot end. [David]’s design instead uses a trio of threaded rods mounted between two rings. The rods are at an angle relative to the central axis of the rings, forming a passage that’s just the right size for the filament to fit in. When the rings spin, the threads on the rods engage with the filament, gripping it around its whole circumference and advancing or retracting it depending on which way it’s spinning. The video below shows it working; we have to admit it’s pretty mesmerizing to watch.

[David] himself admits there’s not much advantage to it, perhaps other than a lower tendency to skip since the force is spread over the entire surface of the filament rather than just a small pinch point. Regardless, we like the kind of thinking that leads to something like this, and we’ll bet there are probably unseen benefits to it. And maybe the extruder actually is a place for innovation after all; witness this modular nozzle swapping system.

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Resin Printing Hack Chat

October 11, 2021 by Dan Maloney 6 Comments

Join us on Wednesday, October 13 at noon Pacific for the Resin Printing Hack Chat with Andrew Sink!

At its heart, 3D printing is such a simple idea that it’s a wonder nobody thought of it sooner. Granted, fused deposition modeling does go back to the 80s, and the relatively recent explosion in cheap, mass-market FDM printers has more to do with cheap components than anything else. But really, at the end of the day, commodity 3D printers are really not much more than glorified hot-glue guns, and while they’re still a foundational technology of the maker movement, they’ve gotten a bit dull.

So it’s natural that we in this community would look for other ways to push the 3D printing envelope, and stereolithography has become the new hotness. And with good reason — messy though it may be, the ability to gradually pull a model from a tank of goo by selective photopolymerization looks magical, and the fine level of detail resin printers are capable of is just as enchanting. So too are the prices of resin printers, which are quickly becoming competitive with commodity FDM printers.

If there’s a resin printer in your future, then you’ll want to swing by the Hack Chat when Andrew Sink visits us. Andrew has been doing a lot of 3D printing stuff in general, and resin printing in particular, over on his YouTube channel lately. We’ve featured a couple of his tricks and hacks for getting the most from a resin printer, and he’ll be sharing some of what he has learned lately. Join us as we discuss the ins and outs of resin printing, what’s involved in taking the dive, and the pros and cons of SLA versus FDM.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, October 13 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

How Good Are The Head(amame) 3D Printed Headphones?

September 27, 2021 by Lewin Day 25 Comments

3D printing lets the average maker tackle building anything their heart desires, really, and many have taken to using the technology for audio projects. Printable speaker and headphone designs abound. The Head(amame) headphones from [Vector Finesse] are a design that combines 3D printed parts with hi-fi grade components to create a high-end listening experience. [Angus] of Maker’s Muse decided to try printing a set at home and has shared his thoughts on the hardware.

Printing the parts has to be done carefully, with things like the infill settings crucial to the eventual sound quality of the final product. Using a properly equipped slicer like CURA is key to getting the parts printed properly so the finer settings can be appropriately controlled. The recommendation is to print the pieces in PETG, which [Angus] notes can be difficult to work with, and several prints were required to get all the parts made correctly.

Assembly is straightforward enough with kits available with all the fasteners and electronic parts included. Subjectively, [Angus] found the sound quality to be impressive, with plenty of full bass and clearly defined highs. Overall, it’s a positive review in the areas of comfort and sound quality.

Detractors will note that the kit of parts costs over $100 USD alone, and that after hours of work and printing, the user is left with a set of headphones made out of obviously 3D-printed parts. It seems destined to be a product aimed at the 3D printing fanbase. If you want a set of headphones you can customise endlessly in form and color, these are ideal. If you prefer the fit and finish of a consumer-grade product, they may not be for you.

It’s a good look at a design sure to appeal to a wide set of makers out there. We’ve seen 3D printing put to good use in this realm before, too. Video after the break.

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3D Printed Research Robotics Platform Runs Remotely

September 27, 2021 by Dave Rowntree 8 Comments

The Open Dynamic Robot Initiative Group is a collaboration between five robotics-oriented research groups, based in three countries, with the aim to build an Open Source robotics platform based around the torque-control method. Leveraging 3D printing, a few custom PCBs, and off-the-shelf parts, there is a low-barrier to entry and much lower cost compared to similar robots.

The eagle-eyed will note that this is only a development platform, and all of the higher level control is off-machine, hosted by a separate PC. What’s interesting here, is just how low-level the robot actually is. The motion hardware is purely a few BLDC motors driven by field-orientated control (FOC) driver units, a wireless controller and some batteries. The FOC method enables very efficient motor commutation, giving excellent efficiency and maximum torque. A delve into the maths of how this method operates will be an eye opener for the uninitiated. Optical encoders attached to the motors give positional feedback for the control loop.

It is this control loop that’s kinda weird, in that operates over Wi-Fi! Normally one would do all the position, torque and speed sensing locally within the leg unit, with local control loops, as well as running all the limb kinematics and motion planning. This would need some considerable local processing grunt, which can make development more difficult.

This project side-steps this, by first leveraging the ESPNOW protocol, initially aimed at the ESP8266 and friends. By patching Ubuntu Linux, and enabling preemptive multitasking for real-time scheduling, as well as carefully selecting Wi-Fi drivers, it was possible to get raw packets out to robot in about 1 ms, enabling control loop bandwidths of around 1 Khz. And, that, was fast enough to run at least sixteen motors in parallel.

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