This Big, Bright Seven-Segment Display is 3D-Printable

Seven-segment LED displays have been around forever, it seems, and the design is pretty optimized by now. Off-the-shelf units are readily available in all sorts of sizes and colors, but if you want a really big display, you might have to roll your own. Scaling up the size doesn’t necessarily mean you have to scale up the complexity, though, if this light-pipeless jumbo seven-segment LED display is any indication.

It’s clear that [Fran Blanche] has a thing for collecting and building oddball numeric displays, like this cathode ray tube Nixie knockoff or her Apollo DSKY electroluminescent display. Her plus-size seven-segment display is far less complicated than either of those, and that’s by design; [Fran] wanted something that was 3D-printable as a single part, rather than an assembly with light pipes and diffusers. To that end, the display is just a pair of X-shaped dividers stacked on top of each other behind the display’s face. They dividers form six triangular compartments and a diamond shaped one, with each compartment opening into a segment-shaped window. One LED goes in each triangular compartment, while the double-sized diamond space gets two. That’s it — the LEDs light up the inside of each compartment to turn on the appropriate segments. Watch it in action below.

The display still needs some tweaking, but it’s big and bright and has a large acceptance angle. What’s more, it’s scalable — imagine a display the size of a sheet of plywood using LED light bulbs. We’re looking forward to [Fran]’s improvements and her next display project, which appears to use hot glue as a light pipe.

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3D Printed Stethoscope Makes the Grade

On the off chance that initiatives like the Hackaday Prize didn’t make it abundantly clear, we believe strongly that open designs can change the world. Putting technology into the hands of the people is a very powerful thing, and depending on where you are or your station in life, can quite literally mean the difference between life and death. So when we saw that not only had a team of researchers developed a 3D printable stethoscope, but released everything as open source on GitHub, it’s fair to say we were pretty interested.

The stethoscope has been in development for several years now, but has just recently completed a round of testing that clinically validated its performance against premium brand models. Not only does this 3D printed stethoscope work, it works well: tests showed its acoustic performance to be on par with the gold standard in medical stethoscopes, the Littmann Cardiology III. Not bad for something the researchers estimate can be manufactured for as little as $3 each.

All of the 3D printed parts were designed in OpenSCAD (in addition to a Ruby framework called CrystalSCAD), which means the design can be evaluated, modified, and compiled into STLs with completely free and open source tools. A huge advantage for underfunded institutions, and in many ways the benchmark by which other open source 3D-printable projects should be measured. As for the non-printed parts, there’s a complete Bill of Materials which even includes links to where you can purchase each item.

The documentation for the project is also exceptional. It not only breaks down exactly how to print and assemble the stethoscope, it even includes multi-lingual instructions which can be printed out and distributed with kits so they can be assembled in the field by those who need them most.

From low-cost ultrasounds to truly personalized prosthetics, the future of open source medical devices is looking exceptionally bright.

[Thanks to Qes for the tip]

Gamecube Dock For Switch Mods Nintendo with More Nintendo

[Dorison Hugo] let us know about a project he just completed that not only mods Nintendo with more Nintendo, but highlights some of the challenges that come from having to work with and around existing hardware. The project is a Gamecube Dock for the Nintendo Switch, complete with working Gamecube controller ports. It looks like a Gamecube with a big slice out of it, into which the Nintendo Switch docks seamlessly. Not only that, but thanks to an embedded adapter, original Gamecube controllers can plug into the ports and work with the Switch. The original orange LED on the top of the Gamecube even lights up when the Switch is docked. It was made mostly with parts left over from other mods.

The interesting parts of this project are not just the attention to detail in the whole build, but the process [Dorison] used to get everything just right. Integrating existing hardware means accepting design constraints that are out of one’s control, such as the size and shape of circuit boards, length of wires, and often inconvenient locations of plugs and connectors. On top of it all, [Dorison] wanted this mod to be non-destructive and reversible with regards to the Nintendo Switch dock itself.

To accomplish that, the dock was modeled in CAD and 3D printed. The rest of the mods were all done using the 3D printed dock as a stand-in for the real unit. Since the finished unit won’t be painted or post-processed in any way, any scratches on both the expensive dock and the Gamecube case must be avoided. There’s a lot of under-cutting and patient sanding to get the cuts right as a result. The video (embedded below) steps through every part of the process. The final screws holding everything together had to go in at an odd angle, but in the end everything fit.

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Gramazon Gives Your Echo Dot a 1920’s Makeover

Unless you’re particularly fond of hockey pucks, you probably aren’t really keen on the aesthetics of the NSA’s Amazon’s diminutive listening device, the Echo Dot. It’s not exactly ugly, but if anyone at Amazon spent more than ten minutes considering the visual design of the thing when it was being developed, we’d be shocked.

Luckily for us, there are hackers and makers who not only have the artistic chops to come up with visually appealing designs, but are kind enough to share them with those of us who are a few crayons short of a full box in that department. Such is the case with the jaw-dropping Gramazon by [Bård Fleistad], a 3D printed acoustic amplifier for the Echo Dot that converts the ho-hum looking device into a classic 1920’s style “horn” speaker.

[Bård] has wanted a horn speaker for awhile, but the prices on a real one in decent condition are getting pretty high. If he couldn’t have the real deal he figured the next best thing would be to 3D print his own version, but he’d still need electronics to put into it. Since the Echo is readily available and works as a Bluetooth speaker (not to mention plays audio from various online sources), it made sense to use it as the heart of his faux-horn.

The design he came up with is very slick, but the finish work on the printed parts is really what puts this project over the edge. [Bård] used Bondo and multiple primer coats to smooth the outside of the horn, and XTC-3D for the hard-to-reach internal curves. Plus sanding. Lots, and lots, of sanding.

If you’re looking for more information on putting high quality finishes on your 3D printed parts like this, check out our Visual 3D Print Finishing Guide. Or if you’d rather just find a swanky home for your always-listening hockey puck, we’ve got plenty of inspiration for you there as well.

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Single Motor, Single Piece 3D Printed Hovercraft

RC hovercrafts offer all sorts of design options which make them interesting projects to explore. There are dual-motor ones where one motor provides lift while the other does the thrust. For steering, the thrust motor can swivel or you can place a rudder behind it. And there are single-motor ones where one motor does all the work. In that case, the airflow from the motor blades has to be redirected to under the hovercraft somehow, while also being vectored out the back and steered.

[Tom Stanton] decided to make a single-motor hovercraft using only a single 3D printed piece for the main structure. His goals were to keep it as simple as possible, lightweight, and inexpensive. Some of the air from the blades is directed via ducting printed into the structure to the underside while the remainder flows backward past a steering rudder. He even managed to share a bolt between the rudder’s servo and the motor mount. Another goal was to need no support structure for the printing, though he did get some stringing which he cleaned up easily by blasting them with a heat gun.

From initial testing, he found that it didn’t steer well. He suspected the rudder wasn’t redirecting the air to enough of a sideways angle. The solution he came up with was pretty ingenious, switching to a wedge-shaped rudder. In the video below he gives a the side-by-side comparison of the two rudders which shows a huge difference in the angle at which the air should be redirected, and further testing proved that it now steered great.

Another issue he attacks in the video below was a tendency for the hovercraft to dip to one side. He solves this with some iterative changes to the skirt, but we’ll leave it to you to watch the video for the details. The ease of assembly and the figure-eight drift course he demonstrates at the end shows that he succeeded wonderfully with his design goals.

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3D Printering: Print Smoothing Tests with UV Resin

Smoothing the layer lines out of filament-based 3D prints is a common desire, and there are various methods for doing it. Besides good old sanding, another method is to apply a liquid coating of some kind that fills in irregularities and creates a smooth surface. There’s even a product specifically for this purpose: XTC-3D by Smooth-on. However, I happened to have access to the syrup-thick UV resin from an SLA printer and it occurred to me to see whether I could smooth a 3D print by brushing the resin on, then curing it. I didn’t see any reason it shouldn’t work, and it might even bring its own advantages. Filament printers and resin-based printers don’t normally have anything to do with one another, but since I had access to both I decided to cross the streams a little.

The UV-curable resin I tested is Clear Standard resin from a Formlabs printer. Other UV resins should work similarly from what I understand, but I haven’t tested them.

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Customizing STLs for Off-Brand Devices

[Rob Clarke] needed a mount for his off-brand action camera, but it’s not exactly the kind of thing with a bustling accessory market. To make matters worse, it turns out the camera is so low-key that he couldn’t find a 3D printable mount for it either. Luckily, a check with his calipers confirmed his camera is just about the same size as an old GoPro Hero 3, so all he had to do was modify an existing design to fit his needs.

As anyone who’s worked with STL files will tell you, they are a pain to modify. An STL is essentially a completed solid model, and not really meant to be fiddled around with. It’s a bit like trying to take an edited image and get back to the layers that were used to create it in Photoshop or GIMP. The final output has been “flattened”, so that granular control is lost.

That being said, [Rob] got rather lucky in this case. He found a GoPro mount that was about 90% there, he just needed to adjust the depth and change the positioning of the holes on the side. He loaded the STL into SketchUp, deleted the two sides, and replaced them with new surfaces. This gave him a clean slate to add the appropriate openings for his camera’s USB port and microSD card. To adjust the depth of the mount, he simply stretched the model out on the Z axis.

[Rob] event went ahead and released his modified STLs as a remix of the original case he found on Thingiverse for anyone else that has the same camera. That’s what we love to see.

If you’re interested in learning more about using SketchUp for designing 3D printed parts, check out this excellent guide by our very own [Brian Benchoff].

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