Put The 3D Printer To Sleep So You Can Rest Easy

At this point you’ve probably already heard the news: cheap Chinese 3D printers sometimes catch fire. Now we can’t say we’re shocked to find out that absolute bottom of the barrel gear wasn’t designed to the highest standards (gotta cut those corners someplace), but that doesn’t change the fact that there are thousands of hackers and makers out there who are in possession of one of these suspect machines. Just tossing them to the curb is hardly the hacker way, so we’ve got to find ways to make the best of the hand dealt to us.

After sleeping with one eye (and maybe one nostril) open during some overnight prints, Hackaday.io user [TheGrim] wanted a way to make sure his Alunar Anet A6 didn’t stay powered on any longer than necessary. So he came up with a way of using the printer’s own endstop switch to detect if the print has completed, and cut the power.

The idea is simple, but of course the real trick is in the implementation. By adding a “Home” command to his ending G-Code in Cura, [TheGrim] reasoned he could use the Y endstop switch to determine if the print had completed. It was just a matter of reading the state of the switch and acting on it.

In the most basic implementation, the switch could be used to control a relay on the AC side of the power supply. But [TheGrim] doesn’t trust relays, and he wanted to pack in a couple “smart” features so he ended up using a PIC microcontroller and two 12 amp TRIACs. There’s also a couple of LEDs and toggle switches to serve as the user interface, allowing you to enable and disable the automatic shutdown and get status information about the system.

Will cutting the juice to the PSU prevent another terrible fire? It’s debatable. But it certainly can’t hurt, and if it makes [TheGrim] feel more confident about running his machine, then so be it. We’d still advise anyone with a 3D printer at home to brush up on their fire safety knowledge.

Push Button, Receive Beverage!

Here’s a rec-room ready hack: an automatic drink dispenser.

[truebassB]’s dispenser operates around a 555 timer, adjusted by a potentiometer. Push a button and a cup pours in a few seconds, or hold the other button to dispense as much as you want.

The dispenser is made from MDF and particle board glued together, with some LEDs and paper prints to spruce it up. Just don’t forget a small spill sink for any miscalculated pours. You needn’t fret over the internals either, as the parts are easily acquired: a pair of momentary switches, a 12V micro air pump, a brass nozzle, food-safe pvc tube,  a custom 555 timing circuit — otherwise readily available online — a toggle switch, a power supply plug plus adapter and a 12V battery.

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Full-Auto Crossbow Rocks and Rolls on Rubber Bands and Electric Drill

You’ve got to enjoy any project where the hacker clearly loves what he or she is doing. And when the project is as cool as a motor-driven, rubber band powered, fully automatic crossbow, it’s hard not to laugh along.

A full-auto crossbow is no mean feat, and it took a man with a love for rubber-powered firearms to get it right. [JoergSprave]’s design is based on a rack-and-pinion system and executed mainly in plywood. The main pinion gear is a composite of aluminum and wood, in a bid to increase the life of the mechanism and to properly deal with the forces involved. The pinion, turned by a powerful electric drill, drives the rack back and locks the carrier under the 30-bolt magazine. A rubber-powered follower forces a bolt down and a cam on the pinion trips the sear, the bolt is fired and the cycle continues.

We slowed the video down a bit and it looked to us like the cyclical rate of fire was about 7 rounds per second, or a respectable 420 rounds per minute. Pretty powerful, too, and the accuracy isn’t bad either.

We’ve seen [Joerg]’s inventions before, like this soda bottle Gatling arrow launcher, or his ridiculous machete launcher. We hope he keeps having fun and letting us watch.

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Hyperloops and Robot Cars, A Glimpse into The Future

His mobile blooped at him with one of those noises a company spent money to get. A timer started on the screen as he rushed to put his shoes on. He finished and pushed open his door, running down the stairs two to a bound. By the time he reached the bottom of the stairs he had his backpack slung over both shoulders, which he mentally cursed himself for since he’d just have to take the dang thing off again.

It was morning on January first, and he was due at his parent’s house for a new year’s dinner fifteen hundred miles away. He should have booked a plane weeks ago, but now the Loop was his only option. The Loop didn’t really have peak rates, and while the plane would be a little faster, more direct, and cheaper IF he had remembered to book it in time, the Loop would take him the same distance today. Plus, the seats were comfier. They reclined nicely, and he intended to nap on the way. Hopefully, by the time he got there, the bleariness from last night’s celebration would be undetectable by parental senses.

He locked the door to his apartment complex, a reassuringly square assembly from the seventies, and walked to the sidewalk where a friendly light blue car waited for him. When he got close, his mobile vibrated and made another distressingly cheery noise. The doors of the car swung open opposite of each other to expose the space inside. The car displayed two rows of inward facing bench seats, a panoramic row of windows around the entire perimeter of the vehicle, and… yes, his nose was telling him before his eyes fixed on it, a very unsettling amount of vomit in the center of the floor.

He turned around, a bit squeamish, and took out his mobile. He navigated through the controls. Where is the menu option? What year is it now? Why is this still hard? Three awkward menus deep and he finally found and selected the option to let the dispatch know the car had an issue which made it uninhabitable. The car immediately began to chirp warnings and the doors soon started to close. In a moment, a human somewhere in the city would be looking at a video of the inside of the car, determining him a liar or not. As expected, a few seconds later, the little car began to drive off. The lights on the rear of the car turned from bright red to the yellow amber of headlights as it decided its front would be its back. It drove off to the dispatch center for cleaning and repair. Someone would be eating a 100 dollar cleaning bill today. He didn’t feel sorry for them.

His phone began to vibrate. He picked it up to answer a call from a bored customer service representative who was trying hard to sound earnest. “Sorry for the trouble sir, the ride today will be free. We have another car on its way”

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There Is No Spoon; Automatic Self Stirring Mug

Sometimes it’s helpful to realize the truth that there is no spoon. At least, not with [Ronaldo]’s automatic self-stirring mug. At first it was just a small propeller in the bottom of the mug that turned on by pushing a button in the handle, but this wasn’t as feature-rich as [Ronaldo] hoped it could be, so he decided to see just how deep the automatic beverage-mixing rabbit hole goes.

The first thing to do was to get a microcontroller installed to handle the operation of the motor. The ATtiny13a was perfect for the job since it’s only using one output pin to control the motor, and can be configured to only draw 0.5 microamps in power-saving mode. This ensures a long life for the two AAA batteries that power the microcontroller and the motor.

As far as operation goes, the motor operates in different modes depending on how many times the button in the handle is pushed. It can be on continuously or it can operate at pre-determined intervals for a certain amount of time, making sure to keep the beverage thoroughly mixed for as long as the power lasts. Be sure to check out the video below for a detailed explanation of all of the operating modes. We could certainly see some other possible uses for more interesting beverages as well.

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Custom driver board for paintball gun

custom-driver-circuit-for-paintball

[Gabe’s] been wanting to do some embedded development for years, and his other hobby of playing paintball recently provided him with a test project. He’s been working on a custom driver board for his paintball gun.  Don’t be confused by the name, GCode is a mash-up of his name and the fact that he wrote the code for the project. It has nothing to do with the G Code CNC language.

At first this might seem like a trivial hack, but this Viking paintball gun has some serious velocity and throughput so he needs a reliable control that won’t just start shooting randomly. Another thing that [Gabe] took into consideration was monitoring the loading process to make sure the paintball is full seated before firing. All of this is handled by that tiny little Femtoduino board. it interfaces with the guns hardware using the connector board mounted above it.

There are several videos sprinkled throughout the build log. But we found the officially sanctioned 12.5 balls per second mode and the ridiculously fast auto-fire clips the most interesting. It should come in handy when on the run from paintball shotgun wielding opponents.

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Automating a mechanical typewriter

typewriter-driven-by-automotive-door-lock-motors

Check out all the work going on in the cabinet below this typewriter. The hack which automates a mechanical typewriter  is for an art installation, but wouldn’t it be fun to build one of these to use as a résumé printer? It really makes us wish we had an old typewriter sitting around.

It would have been much easier to patch into an electric typewriter, but we have seen the string trick used on those as well. In this case a loop of string attaches to the the bar under each key, allowing a pull from below to type the character. An automotive door lock actuator ([Harvey Moon] tells us they’re not solenoids) connects to the other end of the string for every key. But then you’ve got to have a way to drive the actuators and that’s where the protoboard full of forty relays seen to the right comes into play. That image, which was taken from the demo video after the break, shows the board being testing. We’d guess more wires are added later to multiplex the array as we can’t figure out how the Arduino manages to drive all forty of them as shown. One thing we are sure about, the completed project looks and sounds amazing!

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