Better 3D-Printed Bridges Are Possible, With The Right Settings

The header image above shows a completely unsupported 3D-printed bridge, believe it or not. You’re looking at the bottom of the print. [Make Wonderful Things] wondered whether unsightly unsupported bridges could be improved, and has been busy nailing down remarkably high-quality results by exhaustive testing of different settings.

It all started when they thought that unsupported bridges looked a lot as though they were made from ropes stretched between two points. Unlike normal layers, these stretched extrusions didn’t adhere to their neighbors. They are too far apart from one another, and there’s no “squish” to them. But could this be overcome?

His experiments centered mainly around bridge printing speed, temperature, and bridge flow. That last setting affects how much the extrusion from the hot end is adjusted when printing a bridge. He accidentally increased it past 1.0 and thought the results were interesting enough to follow up on; it seemed that a higher flow rate when printing a bridge gave the nudge that was needed to get better inter-line adhesion. What followed was a lot of testing, finally settling on something that provided markedly better results than the stock slicer settings. Markedly better on his test pieces, anyway.

BF = Bridge flow, BS = Bridge printing speed (in mm/sec)

The best results seem to come from tweaking the Bridge Flow rate high enough that extrusions attach to their neighbors, printing slowly (he used 10 mm/sec), and ensuring the bridged area is as consistent as possible. There are still open questions, like some residual sagging at corners he hasn’t been able to eliminate, but the results otherwise look great. And it doesn’t even require laying one’s printer on its side!

All the latest is on the project page where you can download his test models, so if you’re of a mind to give it a try be sure to check it out and share your results. Watch a short video demonstrating everything, embedded just under the page break.

Thanks to [Hari] for the tip!

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X-wing Aircraft Are Trickier Than They Look

The iconic X-wing ship design from Star Wars is something many a hobbyist have tried to recreate, and not always with success. While [German engineer] succeeded in re-imagining an FPV quadcopter as an X-wing fighter, the process also highlighted why there have been more failures than successes when it comes to DIY X-wing aircraft.

For one thing, the X-wing shape is not particularly aerodynamic. It doesn’t make a very good airplane. Quadcopters on the other hand rely entirely on precise motor control to defy gravity in a controlled way. It occurred to [German engineer] that if one tilts their head just so, an X-wing fighter bears a passing resemblance to a rocket-style quadcopter layout, so he set out to CAD up a workable design.

When flying at speed, the aircraft goes nearly horizontal and the resemblance to an X-wing fighter is complete.

One idea that seemed ideal but ultimately didn’t work was using four EDF (electric ducted fan) motors mounted in the same locations as the four cylindrical engines on an X-wing. Motors large enough to fly simply wouldn’t fit without ruining the whole look. A workable alternative ended up being the four props and brushless motors mounted on the ends of the wings, like you see here.

The unit still needed a lot of fine tuning to get to a properly workable state, but it got there. It takes off and lands vertically, like a classical quadcopter, but when flying at speed it levels out almost completely and looks just like an X-wing as it screams by. It’s in sharp contrast to the slow, methodical movements of this Imperial Shuttle drone.

There are also a couple design elements in [German engineer]’s build we thought were notable. The spring-loaded battery door (all 3D-printed, including the spring) looks handy and keeps the lines of the aircraft clean. And since it’s intended to be flown as an FPV (first person view) aircraft, the tilting camera mount in the nose swings the camera 90 degrees during takeoff and landing to make things a little easier on the pilot.

3D models for the frame (along with a parts list) are up for anyone who wants to give it a shot. Check it out in the video, embedded below.

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Does 3D-Printed Foam Make Good Custom Tires?

Wouldn’t it be nice to 3D print an entire custom tire for small robots? It sure would, so [Angus] of [Maker’s Muse] decided to investigate whether nifty new filaments like expanding TPU offer anything new in this area. He did more than just print out a variety of smooth tires; he tested each with a motorized platform attached to a load cell, driving on a dusty sheet of MDF to simulate the average shop floor, or ant weight combat robot arena.

Why bother making your own wheels? As [Angus] points out, when one is designing their own robots from scratch, it’s actually quite difficult to find something off the shelf that is just the right size. And even if one does find a wheel that is just right, there’s still the matter of fitting it to the shaft. Things would be so much easier if one could simply 3D print both wheel and tire in a material that performs well.

Like TPU, but squishier.

Here’s what he found: Siraya Tech’s TPU air filament (about 70A on the Shore hardness scale) performed the best. This is TPU plus a heat-activated additive that foams up during extrusion, resulting in a flexible print that looks and feels more like foam than usual TPU. It makes a promising tire that performs as well as it looks. Another expanding filament, PEBA air (also from Siraya Tech) didn’t look or perform as well, but was roughly in the same ballpark.

Both performed better than the classic DIY options of 3D-printed plain TPU, or laser-cut EVA foam. It’s certainly a lot less work than casting custom tires.

What about adding a tread pattern? [Angus] gave it a try. Perhaps unsurprisingly, a knobby tire has worse traction compared to a smooth tire on smooth MDF. But sometimes treads are appropriate, and as [Angus] points out, if one is 3D printing tires then adding treads comes at essentially zero cost. That’s a powerful ability.

Even if you are not interested in custom wheels, that foaming TPU filament looks pretty nifty. See for yourself in the video, embedded just below. If you find yourself finding a good use for it, be sure to drop us a tip!

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Automatically Serving Up Canned Cat Food

If there’s any one benefit to having a cat as a pet instead of a dog, it’s that they’re a bit more independent and able to care for themselves for many days without human intervention. The only thing that’s really needed is a way to make sure they get food and water at regular intervals, but there are plenty of off-the-shelf options for these tasks. Assuming your cat can be fed dry food, that is. [Ben Heck]’s cat has a health problem that requires a special canned wet food, and since there aren’t automatic feeders for this he built his own cat-feeding robot.

Unlike dry food that can dispense a measured amount from a hopper full of food, the wet food needs to be opened and dispensed every day. To accomplish this, his robot has a mechanism that slowly slides a wedge under the pull tab on the can, punctures the can with it, and then pulls it back to remove the lid. From there the food is ejected from the feeder down a ramp to a waiting (and sometimes startled) cat. The cans are loaded into 3D-printed cartridges and then stacked into the machine on top of each other, so the machine can dispense food cans until it runs out. This design has space for six cans.

Although there are many benefits to having pets of any sort, one of the fun side quests of pet ownership is building fun things for them to enjoy or to make caring for them easier. We even had an entire Hackaday contest based on this premise. And, if biological life forms aren’t your cup of tea, there are always virtual pets to care for as well.

Thanks to [Michael C] for the tip!

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Robot Bartender Is The Life Of The Party

As the old saying goes, when the only tool you have is a 6 DOF industrial robotic arm, every problem looks like an opportunity to make it serve up adult beverages. [benkokes] found himself in this familiar predicament and did what any of us would do, but his process wasn’t without a few party fouls as well as a few head-scratchers.

One of the common problems that people who suddenly find themselves with an old industrial robot have is that there’s usually no documentation or instructions. This was true here with the added hiccup of the robot’s UI being set to Chinese. Luckily no one had changed the root password, and eventually he was able to get the robot up and working.

Getting it to make drinks was a different matter altogether. [benkokes] needed a custom tool to hold the cup as well as shake it, and 3D printed a claw-style end effector with a lid. Out of his multi-colored pack of party cups, however, the orange cups were different enough in dimension to cause problems for the shaking lid which was discovered when the robot spilled a drink all over the table.

Eventually, though, the robot was successfully serving drinks at a party. One of [benkokes]’s friends happened to be a puppet maker and was able to outfit it with a tailored tuxedo for the party as well, and he also programmed it to dance in between serving drinks, completing the AI revolution we have all been hoping for. Perhaps unsurprisingly, this is a common project for people who suddenly come to posses a large general-purpose industrial robot, while others build robots specifically for this task alone.

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A Closer Look Inside A Robot’s Typewriter-Inspired Mouth

[Ancient] has a video showing off a fascinating piece of work: a lip-syncing robot whose animated electro-mechanical mouth works like an IBM Selectric typewriter. The mouth rapidly flips between different phonetic positions, creating the appearance of moving lips and mouth. This rapid and high-precision movement is the product of a carefully-planned and executed build. When we featured this project before, we wanted to see under the hood. Now we can.

Behind the face is a ball that, when moving quickly enough, gives the impression of animated mouth and lips. The new video gives a closer look at how it works.

[Ancient] dubs the concept Selectramatronics, because its action is reminiscent of the IBM Selectric typewriter. Instead of each key having a letter on a long arm that would swing up and stamp an ink ribbon, the Selectric used a roughly spherical unit – called a typeball – with letters sticking out of it like a spiky ball.

Hitting the ‘A’ key would rapidly turn the typeball so that the ‘A’ faced forward, then satisfyingly smack it into the ink ribbon at great speed. Here’s a look at how that system worked, by way of designing DIY typeballs from scratch. In this robot, the same concept is used to rapidly flip a ball bristling with lip positions.

We first saw this unusual and fascinating design when its creator showed videos of the end result on social media, pronouncing it complete. We’re delighted to see that there’s now an in-depth look at the internals in the form of a new video (the first link in this post, also embedded below just under the page break.)

The new video is wonderfully wordless, preferring to show rather than tell. It goes all the way from introducing the basic concept to showing off the final product, lip-syncing to audio from an embedded Raspberry Pi.

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Build Your Own Pip-Boy Styled Watch

[Arnov Sharma]’s latest PIP-WATCH version is an homage to Pip-Boys, the multi-function wrist-mounted personal computers of Fallout.

We like the magnetic clasp on the back end.

[Arnov] has created a really clean wearable design with great build instructions, so anyone who wants to make their own should have an easy time. Prefer to put your own spin on it, or feel inspired by the wrist-mounted enclosure? He’s thoughtfully provided the CAD files as well.

Inside the PIP-WATCH is a neat piece of hardware, the Lilygo T-Display-S3 Long. It’s an ESP32-based board with a wide, touch-enabled, color 180 x 640 display attached. That makes it a perfect fit for a project like this, at least in theory. In practice, [Arnov] found the documentation extremely lacking which made the hardware difficult to use, but he provides code and instructions so there’s no need to go through the same hassles he did.

In addition to the Hackaday.io project page, there’s an Instructables walkthrough.

If you put your own spin on a Pip-boy (whether just a project inspired by one, or a no-detail-spared build of dizzying detail) we want to hear about it, so be sure to drop us a tip!

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