Budget Dehydrator Gives Your Damp Filament A Second Chance

June 2, 2018 by 24 Comments

If you’ve had the misfortune of leaving your 3D printer filament out on a muggy day or, heaven forbid: showering with it, it’s probably soaked up quite a bit of moisture. Moisture will do more than just make your printer sound like Rice Crispies, it’ll ruin surface finishes and cause the filament to string into thin wisps between separate geometries on the same layer. Luckily for us, though, both [SafetyGlassesRequired] and [Joe Mike Terranella] give us the breakdown on taking a pair of snippers and about $40 in cash to start drying out our filament far away from the possibility of ruining any nearby kitchen ovens.

If you’ve been circling the 3D printer community for a while, you might have already heard about this trick. But with the arrival of a curiously-culinary-looking contraption called PrintDry, we can’t let the elephant in the room keep silent for much longer. Rather than risk our own pennies and leave ourselves stranded with a device that only makes the jerky on the box cover, [SafetlyGlassesRequired] and [Joe Mike Terranella] kindly prove our suspicions for us once and for all: a food dehydrator works perfectly for drying all that filament that we left out in the rain!

Clumsiness aside, a dehydrator isn’t a bad investment in the long run. Not only can we keep our supply dry, we might just be able to give all that freebie filament (that we dug out of the trash) a second life by resetting it to a clean, dry state.

These dehyrdators will toast all that moisture out of your filament, but it wont keep them dry whilst printing. For that problem, you’ll need to summon a heated drybox like this one.

[Joe Mike’s] solution will run us about $40. If you can do better, let us know in the comments.

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Servo Becomes Mini Linear Actuator

June 2, 2018 by 11 Comments

RC servos are a common component in many robotics projects, but [Giovanni Leal] needed linear motion instead of the rotary actuation that servos normally offer. The 3D Printed Mini Linear Actuator was developed as a way to turn a mini servo into a linear actuator, giving it more power in the process.

A servo uses a potentiometer attached to the output shaft in order to sense position, and the internal electronics take care of driving the motor to move the shaft to the desired angle. [Giovanni] took apart an economical mini servo and after replacing the motor with a 100:1 gear motor and using it to power a compact 3D printed linear actuator, he used the servo’s potentiometer to read the linear actuator’s position. As a result, the linear actuator can exert considerably more force than the original servo while retaining exactly the same servo interface. You can see one being assembled and tested in the video embedded below, which is part of [Giovanni]’s entry for The 2018 Hackaday Prize.

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Buck Converter Efficiency

June 2, 2018 by 9 Comments

We always appreciate when someone takes the time to build something and then demonstrates what different design choices impact using the real hardware. Sure, you can work out the math and do simulations, but there’s something about having real hardware that makes it tangible. [Julian Ilett] recently posted two videos that fit this description. He built a buck converter and made measurements about its efficiency using different configurations.

The test setup is simple. He monitors the drive PWM with a scope and has power meters on the input and output. That makes it easy to measure the efficiency since it is just the ratio of the power output to input. You can see the two videos, below.

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Print Your Own Filament

June 2, 2018 by 25 Comments

Ask anyone with a 3D printer what they make the most. They’ll probably say “trash.” There are extra pieces, stuff that oozes out of the extruder, support material, parts that didn’t stick to the bed, or just parts that needed a little tweaking to get right. No matter what you do, you are going to wind up with a lot of scraps. It would be great if you could recycle all this, and [3D Printing Nerd] looks at the FelFil Evo Filament extruder that promises it can do just that. You can see the video below.

As you’d expect, the device is a motorized auger that extrudes filament through a hot end not dissimilar to your printer’s hot end. You have to run a bag of special material through it first to clean out the plastic path. After that, you can create filament from standard pellets or pieces of old plastic.

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Bike Helmet Plays Music Via Tiny Motors For Bone Conduction

June 2, 2018 by 20 Comments

[Matlek] had an interesting problem. On one hand, a 40 minute bike commute without music is a dull event but in France it is illegal for any driver to wear headphones. What to do? Wanting neither to break the law nor accept the risk of blocking out surrounding sounds by wearing headphones anyway, and unwilling to create noise pollution for others with a speaker system, [Matlek] decided to improvise a custom attachment for a bike helmet that plays audio via bone conduction. We’ll admit that our first thought was a worrisome idea of sandwiching metal surface transducers between a helmet and one’s skull (and being one crash away from the helmet embedding said transducers…) but happily [Matlek]’s creation is nothing of the sort.

A 3D printed rack and pinon provides adjustability and stable contact with the “sweet spot” behind each ear.

The bone conduction is cleverly achieved by driving small DC motors with an audio signal through a TPA2012 based audio amplifier, which is powered by a single 18650 cell. By using motors in place of speakers, and using a 3D printed enclosure to hold the motors up to a sweet spot just behind the ears, it’s possible to play music that only the wearer can hear and does not block environmental sounds.

[Matlek] didn’t just throw this together, either. This design was the result of researching bone conduction audio, gathering a variety of different components to use as transducers, testing which performed best, and testing different locations on the body. Just behind the ear was the sweet spot, with the bony area having good accessibility to a helmet-mounted solution. Amusingly, due to the contact between the motors and the rest of the hardware, the helmet itself acts as a large (but weak) speaker and faint music is audible from close range. [Matlek] plans to isolate the motors from the rest of the assembly to prevent this.

Another good way to get audio to transmit via bone conduction? Send it through the teeth. While maybe not the best option for a bike rider, biting down on this metal rod sends audio straight to your inner ear.

3D Printed Tank Has Slick Tread Design

June 2, 2018 by 4 Comments

Tank projects are great because while every tank design is the same in a fundamental way, there’s nevertheless endless variety in the execution and results. [Hoo Jian Li]’s 3D Printed Tank is smartly laid out and has an unusual tank tread that shows off some slick curves.

The tank itself is remotely controlled over Bluetooth with a custom controller that uses the common HC-05 Bluetooth radio units. The treads are driven by four hobby gearmotors with custom designed wheels, and run over an idler wheel in the center of the body. There isn’t any method of taking up slack in the track and a ripple in the top surface of the track is visible as it drives, but the tank is small enough that it doesn’t seem to mind much. STL files and source code is available on GitHub; unfortunately the repository lacks a wiring diagram but between the low component count, photos, and source code that’s not a show-stopper.

Tank treads see a lot of variation, from 3D printed designs for tracks that use a piece of filament as hinges to an attempt to use a conveyor belt as a tank tread for a go-kart. Some tank projects even eschew treads altogether and go for a screw drive.

A HID For Robots

June 1, 2018 by 5 Comments

Whether with projects featured here or out in the real world, we have a tendency to focus most upon the end product. The car, solar panel, or even robot. But there’s a lot more going on behind the scenes that needs to be taken care of as well, whether it’s fuel infrastructure to keep the car running, a semiconductor manufacturer to create silicon wafers, or a control system for the robot. This project is one of the latter: a human interface device for a robot arm that is completely DIY.

While robots are often automated, some still need human input. The human input can be required all the time, or can be used to teach the robot initially how to perform a task which will then be automated. This “keyboard” of sorts built by [Ahmed] comes with a joystick, potentiometer, and four switch inputs that are all fully programmable via an Arduino Due. With that, you can perform virtually any action with whatever type of robot you need, and since it’s based on an Arduino it would also be easy to expand.

The video below and project page have all the instructions and bill of materials if you want to roll out your own. It’s a pretty straightforward project but one that might be worth checking out since we don’t often feature controllers for other things, although we do see them sometimes for controlling telescopes rather than robots.

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