Giant pencil used as an Etch a Sketch stylus

The gang over at Waterloo Labs decided to add a team-building aspect to a plain old Etch a Sketch. Instead of just twisting the two knobs with your own mitts, they’re converting this giant pencil’s movements into Etch a Sketch art.

The challenge here is figuring out a reliable way to track the tip of the pencil as it moves through the air. You may have already guess that they are using a Microsoft Kinect depth camera for this task. The Windows SDK for the device actually has a wrapper that helps it to play nicely with LabView, where the data is converted to position commands for the display.

On the Etch a Sketch side of things they’ve chosen the time-tested technique of adding gears and stepper motors to each of the toy’s knobs. As you can see from the video after the break, the results are mixed. We’d say from the CNC ‘W’ demo that is shown there’s room for improvement when it comes to the motor driver. We can’t really tell if the Kinect data translation is working as intended or not. But we say load it up and bring to a conference. We’re sure it’ll attract a lot of attention just like this giant version did.

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[Pythagoras], a Delta Robot for Drawing

[Pythagoras] is a delta robot built originally using RC servos. Humbly, [Aaron] “concedes” that the first version of his delta robot using hobby servos was easy to build. As anyone who has built any kind of robot knows though, there is definitely a lot of work involved in even the simplest robot. Coordinating three axes and programming it to draw a picture is a really great accomplishment.

The second version, however is currently in development and uses stepper motors instead of servos. These upgraded motors should make the robot faster, more controllable, and more accurate. This version is at least somewhat working as evidenced by the time-lapse video after the break.

Although the title page listed above is a little sparse on build details, if you dig deeper into the page, there are actually 15 articles about the ‘bot, so be sure to poke around. Continue reading “[Pythagoras], a Delta Robot for Drawing”

Reduced-cost Braille display for use with computers

Apparently a Braille computer display can cost several thousand dollars. That’s why [David Pankhurst] is working on a low-cost alternative. His offering is an open source version he calls the Audrey Braille Display.

The concept is quite good. This prototype has one line of six Braille characters. Each character is made of two sliding strips containing eight arrangements of bumps. These can make up any character when positioned correctly. Two motors do all the work, one engages a single strip to reposition it, the other moves the first motor to select which strip should move. This is explained quite well in [David’s] most recent post. Or you can get a preview of the physical build here.

The concept is sound, but the refresh rate must be very slow. We wonder if there’s a way to keep one motor stationary and use solenoids to engage a drive shaft on the individual slide rods? This way, every row could be changed at the same time, disengaging when the appropriate slot is reached.

This hardware is much needed until developing Braille technologies actually come to market.

[via Dangerous Prototypes]

Full featured security lock demonstration

[Arshad Pathan] let us know about his latest project, a modular code lock that can be adapted to many different situations.

The user interface is made up of a character LCD screen and a 3×4 keypad. For this example [Arshad] is using a stepper motor as the locking mechanism. When the board is first powered up it runs the stepper in one direction until receiving input from a limiting switch. In this way, the microcontroller calibrates itself to ensure the lock is in a known position. From there it waits for user input. An unlocked door can be locked at any time by pressing the * key. Unlocking requires entry of the correct password. And a password can be changed by entering 9999 (followed by the old password when prompted).

In the video after the break [Arshad] does a great job of demonstrating the various modes which he has programmed. This stands on its own, but we always love to have more details so we’ve asked if [Arshad] is willing to share a schematic and the source code. We’ll update this post if we hear back from him.

Update: [Arshad] sent in a couple of schematics which can be found after the break.

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Half-tone CNC with man-powered Z axis

We think this is an intriguing take on half-tone art. It’s a CNC machine that uses an Arduino and two stepper motors to draw on a paper-covered drum. But you’re not just going to set it and forget it. To simplify the device, the Z-axis is not mechanized, but requires the dexterous opposing digit of a person to actuate.

The first prototype used a frame cut from plywood, but the developers moved to some attractive laser-cut Lexan for the final version. The rotating drum was inspired by observing the off-set printing process. It greatly simplifies the build when compared to a flat CNC bed. But including a Z-axis solution that could account for differently sized dots really opens a can of worms. Because of this, the choice was made not to automate that task, but to leave it up to the user. A clickable Sharpie does the marking. When the pen is in place, you click the plunger to hold the felt tip against the paper until a dot of the appropriate size has leeched onto the paper.

It’s not a bad solution to the problem. Especially if you don’t have the high-end milling equipment necessary to do this on a piece of plywood.

[Thanks Dron]

A Simple Dolly for Time-Lapse Photography

[Henrique] wrote in to tell us about his time-lapse photography hack. Triggering of the camera is done via CHDK, or Canon Hack Development kit. This experimental kit allows Canon Powershot cameras to run scripts as well as other neat features without permanently changing anything. User scripts for this hack and others can be found here.

Once the Camera was set up to take pictures in a predetermined amount of time, a LDR (light dependent resistor) is used to detect when a picture is actually taken. A LED on the camera flashes every time an image is stored in the camera, so this provided an easy way to sense when this happens.

Once this signal is received, a PIC 16f84 processor and the associated circuitry then causes the stepper to step once per shot. The results of this experiment are very impressive, so be sure to check out the results after the break.

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Photo hardware that automatically produces rotating GIFs

[Fergus Kendall’s] company is making development and breakout boards targeting electronic hobbyists. As with any endeavor that involves selling something, they need marketing. It sounds like [Fergus] was put in charge of getting some nice animated 360 degree images of each component. Instead of going through the drudgery of snapping frames by hand in a stop-motion-style, he whipped up a rotating platform that does the work for him.

The brain of the operation is a Boobie Board, a microcontroller breakout board that is one of their products. It controls a stepper motor attached to the cardboard platform via a quartet of power transistors. [Fergus] mentions in passing that their digital camera didn’t have a connection for a shutter trigger attachment. But they modded it to make things work. There’s no detail on that part of the hack but we’d wager that they soldered a transistor to the contacts for the shutter button.

The stepper motor has 48 steps, so the hardware is programmed to take 48 pictures which become the frames of an animated GIF – embedded after the break – to show off the product.

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