We have a pretty good guess where [Krizbleen] hides away any seasonal presents for his family: behind his shiny new secret library door. An experienced woodworker, [Krizbleen] was in the process of finishing the attic in his home when he decided to take advantage of the chimney’s otherwise annoying placement in front of his soon-to-be office. He built a false wall in front of the central chimney obstacle and placed a TV in the middle of the wall (directly in front of the chimney) flanked on either side by a bookcase.
If you touch the secret book or knock out the secret sequence, however, the right-side bookcase slides gently out of the way to reveal [Krizbleen’s] home office. Behind the scenes, a heavy duty linear actuator pushes or pulls the door as necessary, onto which [Krizbleen] expertly mounted the bookcase with some 2″ caster wheels. The actuator expects +24V or -24V to send it moving in one of its two directions, so the Arduino Uno needed a couple of relays to handle the voltage difference.
The effort spent here was immense, but the result is seamless. After borrowing a knock-detection script and hooking up a secondary access button concealed in a book, [Krizbleen] had the secret door he’d always wanted: albeit maybe a bit slow to open and close. You can see a video of its operation below.
Continue reading “Secret Attic Library Door”
[Roland] has already built a few very cool and extremely realistic flight sims, but his latest project will put his current rig to shame. He’s building a six degree of freedom simulator based on homebuilt linear actuators of his own design.
The actuator is powered by a large DC motor moving timing belts along the length of the enclosure. These timing belts are connected to a shaft that’s coupled to the frame with a few bungee cords. The bungee cords are important; without them, the timing belts would be carrying all the load of the sim – not a good thing if these actuators are moving an entire cockpit around a living room.
Also on [Roland]’s list of awesome stuff he’s building for his flight sims is a vibration system based on the BFF Shaker. This board takes data in from sim software and turns it into vibrations produced by either unbalanced DC motors or one of those ‘bass kicker’ transducers.
It’s all very cool stuff, and with all the crazy upgrades [Roland] is doing to his sim rig, he’s doing much better than paying $300/hour to rent a Beechcraft Baron.
Continue reading “DIY Linear Actuators For A Flight Sim”
This physical pixel display reminds us of a couple of different hacks that we’ve seen over the years. It looks impressive, but [Matt] couldn’t quite get it to work. It wasn’t the Kinect sensor and image interpretation that was the problem. It was a failure to get the hardware components seen above to perform reliably.
If you can’t figure out what this is supposed to do, take at look at the inFORM morphing table or the pixel wall installed at the Hyundai expo last year. [Matt’s] attempt is much more modest with a grid of just 10×6. The pixels themselves are ballpoint pens (he gets bonus points for cheap and easy materials). The pens move in and out thanks to some Bowden cables connected to hobby servos. The mechanical engineers have probably already figured out the fail… the pixels seem to get hung up and despite several revisions in the materials used , it couldn’t be fixed.
The hobby servos were chosen because they are much less expensive than proper linear actuators. We thought maybe [Matt] should build his own solenoids but that’s not a great idea because you can’t have variable depth that way (can you?). Perhaps the pens should be vertical and the servos could pull on a string attached to the pen via a pulley with gravity to return them to the starting position? There’s got to be an inexpensive and relatively simple way get this thing working. Let us know how you’d get the project back on track by leaving a comment below.
Fail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.
This role reversal is quite entertaining. While the game Angry Birds is a virtual realization of knocking over stuff with a sling-shot, Super Angry Birds adds a physical control element back to the virtual game. It’s silly, but well-executed. The main controller takes advantage a part which we don’t see used very often. It’s a motorized linear actuator which would most often be seen on a high-end audio console.
Check out the video after the break to see the controller in action. The linear encoder is used to simulate pulling the rubber sling shot back. It uses the motorized feature to spring back in place, but we’re not sure whether or not the motor also provides resistance during the pull. The laser cut case also includes a companion in the form of a TNT trigger box al-a Wile E Coyote.
If this isn’t real enough for you perhaps this slingshot controller will suffice.
Continue reading “Super Angry Birds is a physical controller for the game”
[Will Finucane] of Revolt Labs/Mad Science Blog was looking for a way to keep his cats happily fed while away on a short vacation, so he put together a cheap and easy automatic feeder to ensure that his pets didn’t go hungry while he was away.
We’ve seen different iterations of automatic pet feeders here before, some relying on rotating false bottoms, while others use crank-style feeders to get the job done. [Will’s] solution is a bit different, employing a cheap linear actuator to deliver feedings.
He emptied out a glue stick, replacing the glue with a brass tube. This gives him the rigidity that the glue lacked, allowing him to easily move a platform full of cat food up and down. He mounted the glue stick on a continuous rotation servo, installing the actuator and a feeding platform inside a cardboard box.
Using an Arduino, he lowers the movable platform every 12 hours, allowing a bit of cat food to fall from the hole he cut in the side of the box. While his creation might not stand up to years of use, it’s a quick solution that can cost very little, depending on what you have sitting around.
Check out the video below to see [Will’s] cat feeder in action.
Continue reading “An easy to build cat feeder driven by a DIY linear actuator”
What do you get when you cross a glue stick with a hobby servo motor? A linear actuator, of course! Although this could be done with other household implements, the form factor of this glue stick seems perfectly suited to sit on top of a servo horn.
The servo, as you might have guessed, has to be converted to rotate fully instead of the 180 degrees or so that is typical of these types of motors. The trick to this, and what really makes it shine in our eyes, is that instead of attaching two resistors in a normal continuous rotation mod, the potentiometer is used on the glue stick allowing for position feedback.
The resulting force from this gear-reduced actuator is quite impressive, giving an “err” (over 3 Kilograms) on the scale used for testing. [Gareth] or [Chiprobot] gives a great tutorial of how to make one of these after the break, but if you’d rather just see it in action, skip to around 8:20! Continue reading “Glue Stick + Servo = Linear Actuator”
[Raul] built a cheap linear actuator out of a drawer slide and a surplus flatbed scanner.
A few builds we’ve seen, like the PCB drill press or the horribly inefficient thermostat, used linear actuators as key components of their builds. These linear actuators are fairly expensive compared to other parts we usually have lying around so going the homebrew route to reduce costs is always a welcome idea.
The first step of [Raul]’s build is to mount a drawer slide to a piece of wood. A stepper motor is attached to one end of the actuator and a timing belt is strung along the length of the assemblage. After a bracket is connected the drawer slide and the belt, you’ve got a very inexpensive linear motor.
In our days of dumpster diving, we can’t count the number of times we’ve passed up on drawer slides in unwanted furniture. Stepper motors, gear trains and timing belts from old ScanJets can be found for pocket change any day of the week. For cheap and accurate linear motion, we couldn’t come up with a build that does better than [Raul]’s.