One of the side effects of the rise of 3D printers has been the increased availability and low cost of 3D printer components, which are use fill for range of applications. [How To Mechatronics] capitalized on this and built a SCARA robot arm using 3D-printed parts and common 3D-printer components.

The basic SCARA mechanism is a two-link arm, similar to a human arm. The end of the second joint can move through the XY-plane by rotating at the base and elbow of the mechanism. [How To Mechatronics] added Z-motion by moving the base of the first arm on four vertical linear rods with a lead screw. A combination of thrust bearings and ball bearings allow for smooth rotation of each of the joints, which are belt-driven with NEMA17 stepper motors. Each joint has a microswitch at a certain position in its rotation to give it a home position. The jaws of the gripper slide on two parallel linear rods, and are actuated with a servo. For controlling the motors, an Arduino Uno and CNC stepper shield was used.

The arm is operated from a computer with a GUI written in Processing, which sends instructions to the Arduino over serial. The GUI allows for both direct forward kinematic control of the joints, and inverse kinematic control,  which will automatically move the gripper to a specified coordinate. The GUI can also save positions, and then string them together to do complete tasks autonomously.

The base joint is a bit wobbly due to the weight of the rest of the arm, but this could be fixed by using a frame to support it at the top as well. We really like the fact that commonly available components were used, and the link in the first paragraph has detailed instructions and source files for building your own. If the remaining backlash can be solved, it could be a decent light duty CNC platform, especially with the small footprint and large travel area. This is very similar to a wooden SCARA robots we’ve seen before, except that one put the Z-axis at the gripper. We’ve also seen a few 3D printers and pen plotters that used this layout.

The variety of ways that people find to show the passage of time never ceases to amaze us. Just when you think you’ve seen them all, someone comes up with something new and unusual, like the concentric rings of this automated perpetual calendar.

What we really like about the design that [tomatoskins] came up with is both its simplicity and its mystery. By hiding the mechanism, which is just a 3D-printed internal ring gear attached to the back of each ring, it invites people in to check it out closely and discover more. Doing so reveals that each ring is hanging from a pinion gear on a small stepper motor, which rotates it to the right point once a day or once a month. Most of the clock is made from wood, with the rings themselves made using the same technique that woodturners use to create blanks for turning bowls — or a Death Star. We love the look the method yields, although it could be even cooler with contrasting colors and grains for each segment. And there’s nothing stopping someone from reproducing this with laser-cut parts, or adding rings to display the time too.

Another nice tip in this write up is the trick [tomatoskins] used to label the rings, by transferring laser-printed characters from paper to wood using nothing but water-based polyurethane wood finish. That’s one to file away for another day.

You don’t have to be an extinct mammal or a Millennial to enjoy the smooth, buttery taste of an avocado. Being psychic on the other hand is definitely an advantage to catch that small, perfect window between raw and rotten of this divaesque fruit. But don’t worry, as modern problems require modern solutions, [Eden Bar-Tov], [Elan Goldberg], and [Mizpe Ramon] built the AvoRipe, a device to notify you when your next avocado has reached that window.

Taking both the firmness and color of an avocado as indicators of its ripeness into account, the team built a dome holding a TCS3200 color sensor as stand for the avocado itself, and 3D printed a servo-controlled gripper with a force sensor attached to it. Closing the gripper’s arms step by step and reading the force sensor’s value will determine the softness the avocado has reached. Using an ESP8266 as centerpiece, the AvoRipe is turned into a full-blown IoT device, reporting the sensor readings to a smartphone app, and collecting the avocado’s data history on an Adafruit.IO dashboard.

There is unfortunately one big drawback: to calibrate the sensors, a set of nicely, ripe avocados are required, turning the device into somewhat of a chicken and egg situation. Nevertheless, it’s a nice showcase of tying together different platforms available for widescale hobbyist projects. Sure, it doesn’t hurt to know how to do each part from scratch on your own, but on the other hand, why not use the shortcuts that are at our disposal to remove some obstacles — which sometimes might include programming itself.

If everything goes according to plan, Elon Musk says the first generation of SpaceX’s massive Starship will make an orbital flight before the end of 2020. That’s a pretty bold claim, but when you’ve made landing rockets on their tails as in the old science fiction pulp magazines seem routine, we suppose you’ve earned the right to a bit of bravado. We’re excited to see the vehicle evolve over the next several months, but even if the real one stays grounded, we’ll gladly take this “flying” Starship model from [Chris Chimienti] as a consolation prize.

Feeling a bit let down by the 3D printable models of the Starship he found online, [Chris] set out to build his own. But it wasn’t enough to just make his bigger, stronger, and more accurate to Starship’s current design; he also wanted to make it a bit more exciting. Some RGB LEDs an Arduino embedded in the “cloud” stand the rocket sits on was a good start, and the landing pad inspired by SpaceX’s real autonomous spaceport drone ship Just Read the Instructions looks great all lit up.

But this is Starship we’re talking about, a vehicle that could literally push humanity towards being a multi-planet species. To do it justice, you’ve really got to knock it out of the park. So [Chris] found a magnetic levitation module online that could support a few hundred grams, and set to work on making his plastic Starship actually hover over the landing pad.

As you might imagine, it was a bit tricky. The first versions of the rocket looked great but came out too heavy, so he switched over to printing the model in so-called “spiral vase mode” which made it entirely hollow. Now far lighter and with a magnetic plate fit into the bottom, it was stable enough to float on its own. For the final touch, [Chris] added some red LEDs and a coin cell battery to the base of the Starship so it looks like the sleek craft is performing a last-second landing burn with its “impossible” full-flow staged combustion engines.

This isn’t the first time we’ve seen a model rocket with an electronic glowing cloud under it, but it’s certainly the first one we’ve seen that could levitate in mid-air. While this little rocket might not make it all the way to Mars, we wouldn’t be surprised to see it touching down on the desks of other hackers and makers in the near future.

In concept, an everyday sewing machine could make embroidery a snap: the operator would move the fabric around in any direction they wish while the sewing machine would take care of slapping down stitches of colored thread to create designs and filled areas. In practice though, getting good results in this way is quite a bit more complex. To aid and automate this process, [sausagePaws] has been using CNC to take care of all the necessary motion control. The result is the DIY Embroidery Machine V2 which leverages 3D printed parts and common components such as an Arduino and stepper drivers for an economical DIY solution.

It’s not shown in the photo here, but we particularly like the 3D printed sockets that are screwed into the tabletop. These hold the sewing machine’s “feet”, and allow it to be treated like a modular component that can easily be removed and used normally when needed.

The system consists of a UI running on an Android tablet, communicating over Bluetooth to an Arduino. The Arduino controls the gantry which moves the hoop (a frame that holds a section of fabric taut while it is being embroidered), while the sewing machine lays down the stitches.

[sausagePaws]’s first version worked well, but this new design really takes advantage of 3D printing as well as the increased availability of cheap and effective CNC components. It’s still a work in progress that is a bit light on design details, but you can see it all in action in the video embedded below.

Anansi in African folktale is a trickster and god of stories, usually taking physical form of a spider. Anansi’s adventures through oral tradition have adapted to the situation of people telling those stories, everything ranging from unseasonable weather to living a life in slavery. How might Anansi adapt to the twenty-first century? [odd_jayy] imagined the form of a cyborg spider, and created Asi the robot companion to perch on his shoulder. Anyone who desire their own are invited to visit Asi’s project page.

Asi was inspired by [Alex Glow]’s Archimedes, who also has a project page for anyone to build their own. According to [Alex] at Superconference 2018, she knew of several who have done so, some with their own individual customization. [odd_jayy] loved the idea of a robot companion perched on his shoulder but decided to draw from a different pool of cultural folklore for Asi. Accompanying him to various events like Sparklecon 2019, Asi is always a crowd pleaser wherever they go.

Like every project ever undertaken, there is no shortage of ideas for Asi’s future and [odd_jayy] listed some of them in an interview with [Alex]. (Video after the break.) Adding sound localization components will let Asi face whoever’s speaking nearby. Mechanical articulation for legs would allow more dynamic behaviors while perched, but if the motors are powerful enough, Asi can walk on a surface when not perched. It’s always great to see open source projects inspire even more projects, and watch them as they all evolve in skill and capability. If they all become independently mobile, we’ll need clarification when discussing the average velocity of an unladen folklore robot companion: African or European folklore?

Sometimes it’s necessary to make do with whatever parts one has on hand, but the results of squashing a square peg into a round hole are not always as elegant as [Juan Gg]’s programmable DC load with rotary encoder. [Juan] took a design for a programmable DC load and made it his own in quite a few different ways, including a slick 3D-printed enclosure and color faceplate.

The first thing to catch one’s eye might be that leftmost seven-segment digit. There is a simple reason it doesn’t match its neighbors: [Juan] had to use what he had available, and that meant a mismatched digit. Fortunately, 3D printing one’s own enclosure meant it could be gracefully worked into the design, instead of getting a Dremel or utility knife involved. The next is a bit less obvious: the display lacked a decimal point in the second digit position, so an LED tucked in underneath does the job. Finally, the knob on the right could reasonably be thought to be a rotary encoder, but it’s actually connected to a small DC motor. By biasing the motor with a small DC voltage applied to one lead and reading the resulting voltage from the other, the knob’s speed and direction can be detected, doing a serviceable job as rotary encoder substitute.

The project’s GitHub repository contains the Arduino code for [Juan]’s project, which has its roots in a design EEVblog detailed for an electronic load. For those of you who prefer your DIY rotary encoders to send discrete clicks and pulses instead of an analog voltage, a 3D printed wheel and two microswitches will do the job.

Digitizing an object usually means firing up a CAD program and keeping the calipers handy, or using a 3D scanner to create a point cloud representing an object’s surfaces. [Dzl] took an entirely different approach with his DIY manual 3D digitizer, a laser-cut and 3D printed assembly that uses rotary encoders to create a turntable with an articulated “probe arm” attached.

Each joint of the arm is also an encoder, and by reading the encoder values and applying a bit of trigonometry, the relative position of the arm’s tip can be known at all times. Manually moving the tip of the arm from point to point on an object therefore creates measurements of that object. [Dzl] successfully created a prototype to test the idea, and the project files are available on GitHub.

We remember the earlier version of this project and it’s great to see how it’s been updated with improvements like the addition of a turntable with an encoder. DIY 3D digitizing takes all kinds of approaches, and one example was this unit that used four Raspberry Pi Zeros and four cameras to generate high quality 3D scans.

Some legged robots end up moving with ponderous deliberation, or wavering in unstable-looking jerks. A few unfortunates manage to do both at once. [MusaW]’s 3D Printed Quadruped Robot, on the other hand, moves in rapid motions that manage to look sharp and insect-like instead of unstable. Based on an earlier design he made for a 3D printable quadruped frame, [MusaW] has now released this step-by-step guide for building your own version. All that’s needed is the STL files and roughly $50 in parts from the usual Chinese resellers to have the makings of a great weekend project.

The robot uses twelve SG90 servos and an Arduino nano with a servo driver board to control them all, but there’s one additional feature: Wi-Fi control is provided thanks to a Wemos D1 Mini (which uses an ESP-8266EX) acting as a wireless access point to serve up a simple web interface through which the robot can be controlled with any web browser.

Embedded below is a brief video. The first half is assembly, and the second half demonstrates the robot’s fast, sharp movements.

We love it when robots show some personality, like this adorable little quadruped robot that can make small jumps.

Thanks to [Baldpower] for the tip!

The first thing to notice about [Bijuo]’s cat-sized quadruped robot designs (link is in Korean, Google translation here) is how slim and sleek the legs are. That’s because unlike most legged robots, the limbs themselves don’t contain any motors. Instead, the motors are in the main body, with one driving a half-circle pulley while another moves the limb as a whole. Power is transferred by a cable acting as a tendon and is offset by spring tension in the joints. The result is light, slim legs that lift and move in a remarkable gait.

[Bijuo] credits the Cheetah_Cub project as their original inspiration, and names their own variation Mini Serval, on account of the ears and in keeping with the feline nomenclature. Embedded below are two videos, the first showing leg and gait detail, and the second demonstrating the robot in motion.

There’s more than one way to make a robot cat, of course, and here’s another design that doesn’t completely evict motors from the limbs, but still manages to keep them looking sleek and nimble.

[via Let’s Make Robots]