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[Will] wanted to build some animatronic eyes that didn’t require high-precision 3D printing. He wound up with a forgiving design that uses an Arduino and six servo motors. You can see the video of the eyes moving around in the video below.

The bill of materials is pretty simple and features an Arduino, a driver board, and a joystick. The 3D printing parts are easy to print with no supports, and will work with PLA. Other than opening up holes there wasn’t much post-processing required, though he did sand the actual eyeballs which sounds painful.

The result is a nice tight package to hold six motors, and the response time of the eye motion is very impressive. This would be great as part of a prop or even a robot in place of the conventional googly eyes.

While the joystick is nice, we’d like to see an ultrasonic sensor connected so the eyes track you as you walk across the room. Maybe they could be mounted behind an old portrait for next Halloween. Then again, perhaps a skull would be even better. If you want a refresher about servos, start with a laser turret tutorial.

This servo/gear reduction was assembled with almost all 3D-printed parts. Apart from a brushed 36 V DC-motor, a stainless steel shaft, and screws for holding the servo together, the only other non-printed part is the BTS7960B motor driver.

Some interesting stats about the plastic servo – its stall torque is about 55 kg/cm, reaching a peak current draw of 18 A when using a 6s LiPo battery outputting 22-24 V. The shaft rotates using two 20 mm holes and lubrication. (Ball bearings were originally in the design, but they didn’t arrive on time for the assembly.)

The holes of the gears are 6.2 mm in diameter in order to fit around the shaft, although some care is taken to sand or fill the opening depending on the quality of the 3D print.

This isn’t [Brian Brocken]’s only attempt at 3D-printing gears. He’s also built several crawling robots, a turntable, and a wind up car made entirely from acrylic. The .stl files for the project are all available online for anyone looking to make their own 3D-printed servo gears.

How do you know if your 3D printer bed is levelled? Oh, don’t worry – you’ll know. Without a level bed, filament won’t stick properly to the build surface and you’ll run into all sorts of other problems. Knowing how tricky it can be to get the bed just right, [Antzy] built a tool to help.

The device, which he calls the FS-Touch, is based around an Arduino Pro Micro fitted with a force sensitive resistor. This allows the distance between the bed and nozzle to be measured based on the force read by the resistor when placed in between the two.

Using the tool is simple. First, the bed is brought roughly into alignment using the typical paper method. Then, a reading is taken from one corner of the bed, and the measurement saved for reference. The other corners can then be set to the same level, with the aid of LEDs to guide the user in which direction to turn the adjustment knobs.

Measuring force in this way has the potential of being more repeatable than the somewhat difficult paper method. It promises to ease the task for users that may be struggling to get their bed in proper shape. Of course, automated bed levelling makes things even easier again. Video after the break.

There’s nothing quite like building something to your own personal specifications. It’s why desktop 3D printers are such a powerful tool, and why this scalable plotter from the [Lost Projects Office] is so appealing. You just print out the end pieces and then pair it with rods of your desired length. If you’ve got some unusually large computer-controlled scribbling in mind, this is the project for you.

The design, which the team calls the Deep Ink Diver (d.i.d) is inspired by another plotter that [JuanGg] created. While the fundamentals are the same, d.i.d admittedly looks quite a bit more polished. In fact, if your 3D printed parts look good enough, this could probably pass for a commercial product.

For the electronics, the plotter uses an Arduino Uno and a matching CNC Shield. Two NEMA 17 stepper motors are used for motion: one to spin the rod that advances the paper, and the other connected to a standard GT2 belt and pulley to move the pen back and forth.

We particularly like the way [Lost Projects Office] handled lifting the pen off the paper. In the original design a solenoid was used, which took a bit of extra circuitry to drive from the CNC Shield. But for the d.i.d, a standard SG90 servo is used to lift up the arm that the pen is attached to. A small piece of elastic puts tension on the assembly so it will drop back down when the servo releases.

If this plotter isn’t quite what you’re after, don’t worry. There’s more where that came from. We’ve seen a number of very interesting 3D printed plotters that are just begging for a spot in your OctoPrint queue.

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.

If you are a Harry Potter fan, you might remember that one of the movies showed an Isle of Lewis chess set whose pieces moved in response to a player’s voice commands. This feat has been oft replicated by hackers and [amoyag00] has a version that brings together a Raspberry Pi, Arduino, Android, and the Stockfish chess engine in case you want to play by yourself. You can see a video of the game, below.

Interestingly, the system uses Marlin — the 3D printing software — to handle motion using the Arduino. We suppose moving chess pieces over a path isn’t much different than moving a print head. It is certainly a novel use of GCode.

There are a lot of pieces integrated to make this work. There is a Bluetooth connection between the Android and Pi. We saw code in Java, Python, C++, at least. We were sad to read that the team that built it can’t modify it anymore as it was a school project and the parts have been recycled for a new class of students. On the other hand, maybe someone else will make a copy and extend it further.

We are always surprised we haven’t seen more Harry Potter paraphernalia. There was the magic wand at this year’s Superconference. We also liked the Mad Eye Moody. There have been others, of course, but not as many as you’d think given the franchise’s popularity.

Despite the title, this isn’t a tale of conversing with Michael Jackson’s chimp. Rather, it is about [KyungYun]’s machine that transforms speech into whimsical bubbles. While the speech control is novel, we were more fascinated with how the mechanism uses a system of strings to blow bubbles, along with the workmanship to make the device portable.

The rate of fire isn’t that great, so the bubbles appear to simply get larger the longer you talk. Essentially, the device increases the size of the iris — the part that blows the bubble — until you pause speaking. Then it burps out a bubble.

The iris mechanism has borrowed ideas from a much larger bubble machine, though the actual build is much smaller and uses both laser-cut and 3D printed pieces. A Teensy provides the brain, and there’s a pump for transferring bubble solution into the iris.

As best we can tell, soapy liquid drips down the strings which are touching. When the strings separate, it forms a soap film between them. A burst of air, then, can produce a bubble. It is possible to make colored bubble solution and we were trying to think of a way to make different colors for different kinds of sounds, although, having three iris mechanism would make the device much less portable. Perhaps it would be more practical to have multiple tanks of the solution and mix them differently based on sound analysis. In any event, this would be a fun project to extend with some creative additions.

We’ve seen more than one approach to blowing bubbles. If you want lots of bubbles, you might 3D print this contraption.

We always think that crossing the Atlantic in a blimp would be very serene — at least once they put heaters on board. The Hindenburg, the R-101, and the Shenandoah put an end to the age of the airship, at least for commercial passenger travel. But you can still fly your own with a helium balloon and some electronics. One notable project — the Blimpduino — has evolved into the Blimpduino 2. The open-source software is on GitHub. We couldn’t find the PCB layout, so we aren’t sure if it is or will be open. The 3D printed parts are available, though.

The PCB is the heart of the matter, a four-layer board with an ARM M0 processor, an ESP8266 WiFi module, four motor outputs, two motor outputs, a 9-axis inertial navigation system, an altimeter, and a forward object detection system. There’s also a battery charger onboard.

The standard set up uses three props: two for thrust and one for altitude. There’s a smartphone app and apparently, you can even have a copilot with a second phone. The lifting body is a mylar balloon with helium and they say the control is suitable even for a very large balloon. The altimeter data is from a time-of-flight sensor and there’s also a pressure transducer with temperature sensor if you want to measure higher altitudes.

We couldn’t embed the video, but there’s one of people flying the things through hoops on the website. You can, however, see a promotional video, below. As you might expect, payload capability is very low and so 3D printed parts have low infill and the board is made to be light.

Of course, our own [Sophi Kravitz] has been building her drone blimp army for some time and we are waiting for her attempt at world domination any day now. If you are in the mood for something lower tech, you can always rip apart a toy car and add your own balloon.


It isn’t a unique idea, but we liked [Eric Wiemers’s] take on the classic animated skull for Halloween. In addition to showing you the code and the wiring, the video spends some time discussing what the audio looks like and what has to happen to get it into a format suitable for the Arduino. You can see the spooky video, below.

Of course, this is also a 3D printing project, although the skull is off-the-shelf. We wondered if he felt like a brain surgeon taking the Dremel to the poor skull. To fix the two parts of the device, he used brass threaded inserts that are heat set, something we’ve seen before, but are always surprised we don’t see more often.

Of course, the project uses a servo. We may have missed it but other than freezing the video, we didn’t see the Arduino source code online. It isn’t much code, though, so typing it from the video is an option. The schematic is a little easier to read when you realize the top part is the schematic and the bottom part is the “as built” layout.

We are glad this skull doesn’t taunt us with our time remaining like some we’ve seen. We’ve seen this done with fewer parts, by the way, and you can compare the videos to see how different the circuits respond.

We’ve been seeing an influx of repurposed 3D printers recently. Thrifty hackers have been leveraging cheap 3D printers as a way to bootstrap their builds, on everything from laser engravers to pick and place machines. There’s nothing wrong with that, and honestly when you can get a cheap 3D printer for less than the cost of the components separately thanks to the economies of scale, you’d be foolish not to.

But there’s still something to be said for the classic RepRap mentality of building things using printed parts and smooth rods. Case in point, the largely 3D printed plotter that [darth vader] sent in for our viewing pleasure. This isn’t somebody sicking a pen on the extruder of their open box Monoprice special, this is a purpose built plotter and it shows. In the video after the break you can see not only how well it draws, but also how large of a work area it has compared to a modified 3D printer.

If you know your way around a 3D printer, most of it should look pretty familiar to you. Using the same GT2 belts, steppers, end stop switches, and linear bearings which are ubiquitous in 3D printers, it shouldn’t be difficult to source the parts to build your own. It even uses a Mega 2560 with RAMPS 1.4 running Marlin 1.1.9 for control.

The biggest difference is the physical layout. Since there’s no heavy hotend or extruder assembly to move around, the plotter has a cantilever design which gives it far greater reach. As it only needs to sightly lift the pen off the paper, there’s no need for a complex Z axis with leadscrews either; a simple servo mounted to the end of the arm is used to raise and lift the pen. We especially like the use of a tape measure as strain relief for his wiring, a fantastic tip that we (and many of you) fell in love with last year.

While it’s hard to beat just tossing a pen onto the business end of your desktop 3D printer in terms of convenience, we think it’s pretty clear from this build that the results don’t quite compare. If you want a real plotter, build a real plotter.

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