THP Entry: Etch-A-CNC

etchacncCNC machines have been around for decades, but only recently have small desktop routers, 3D printers, and laser cutters brought G code to the tabletop. Obviously, this is a teaching opportunity, and if you’re trying to get kids interested in the inner workings of machines that build things, you can’t begin with obtuse codes understood only by machines and CNC operators.

[johnyang] is building his own CNC controller based on something just about every kid is already familiar with: the Etch A Sketch. He’s retrofitted a small, travel size Etch A Sketch with an LCD, buttons, rotary encoders, and a Raspberry Pi to turn this primitive drawing toy into a machine that generates G code for a Shapeoko 2 CNC mill.

The user interface for this CNC controller is as similar to the Etch A Sketch as [johnyang] can make it – two rotary encoders draw a shape on the LCD, and G code is generated from the drawn shape. Adding a third dimension is a bit of a challenge – it looks like two buttons take care of the up and down movement of the spindle. Still, [johnyang] plans to add the definitive Etch A Sketch feature – holding it upside down and shaking it will reset the CNC to its original state.

There are a few videos of [johnyang]‘s progress. You can check those out below.


SpaceWrencherThe project featured in this post is an entry in The Hackaday Prize. Build something awesome and win a trip to space or hundreds of other prizes.

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An Etch-A-Sketch to Fetch the Time

For someone who has never used stepper motors, real-time clocks, or built anything from scratch, [Dodgey99] has done a great job of bending them to his will while building his Etch-A-Sketch clock.

He used two 5V stepper motors with ULN2003 drivers. These motors are mounted on the back and rotate the knobs via pulleys. They are kind of slow; it takes about 2 1/2 minutes to draw the time, but the point of the hack is to watch the Etch-A-Sketch. [Dodgey99] is working to replace these steppers with Nema 17 motors which are much faster. [Dodgey99] used an EasyDriver for Arduino to drive them. He’s got an Arduino chip kit in this clock to save on the BOM, but you could use a regular Arduino. He left out the 5V regulator because the EasyDriver has one.

[Dodgey99] has published three sketches for the clock: one to set up the RTC so that the correct time is displayed once the Etch-A-Sketch is finished, some code to test the hardware and sample the look of the digits, and the main code to replace the test code.

The icing on this timekeeping cake is the acrylic base and mounting he’s fashioned. During his mounting trials, he learned a valuable lesson about drilling holes into an Etch-A-Sketch. You can’t shake an Etch-A-Sketch programmatically, so he rotates it with a Nema 17. Check it out after the jump.

If you’re paying attention, you’ll realize we just saw the exact opposite of this project a few hours ago: a CNC tool (laser cutter) controlled by turning Etch-A-Sketch knobs.

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Laser Cutter Becomes An Etch A Sketch

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The mirror in a laser cutter moves along an X Y axis. An Etch A Sketch moves its stylus along an X Y axis. Honestly, this laser cutter with Etch A Sketch controls is so obvious, we’re shocked we haven’t seen it before.

The Etch A Sketch interface is extremely simple – just two rotary encoders attached to laser cut knobs set inside a small, laser cut frame. The lines from the encoders are connected to an Arduino Pro Mini that interfaces with the controller unit on the laser cutter, moving the steppers and turning on the laser only when the head is moving. There’s an additional safety that only turns on the laser when the lid is closed and the water pump is running.

The circuit is extremely simple, and with just a few connections, it’s possible to retrofit the Etch A Sketch controller to the laser cutter in just a few minutes.  Just the thing for a weekend hackerspace project.

 

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LED Etch-a-Sketch built without a microcontroller

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This project is a wonderful example of what can be accomplished with a rather complicated logic circuit. It’s an Etch-a-Sketch made from a 16×16 LED grid. That in itself is only somewhat interesting. But when hearing about the features and that it is driven by logic chips we were unable to dream up how it was designed. There’s no schematic but the video commentary explains all.

The thing that confused us the most is that the cursor is shining brighter than the rest of the pixels. This is done with two different 555 times and a duty cycle trick. When you turn the trimpots the cursor position is tracked by some decade counters. Pixels in your path are written to a RAM chip which acts as the frame buffer. And there’s even a level conversion hack that let’s the display run at 15v to achieve the desired brightness. Top notch!
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Logging temperatures with an Etch-a-Sketch

What do you do if you’re given a gigantic ancient printer? If you’re [IronJungle], you throw that printer on your workbench and salvage all the parts you can. After coming across a few stepper motors in an old Oki printer, [IronJungle] decided to automate an Etch-a-Sketch with the help of a PIC microcontroller and H-bridge chip to log the ambient temperature on an Etch-a-Sketch display.

After [IronJungle] was finished figuring out his stepper motor circuit, the only thing left to do was to add a thermometer. For this task, he chose a very cool one-wire digital thermometer that carries power and data over the same wire.

In the video after the break, you can check out [IronJungle] playing with his new Etch-a-Sketch temperature logger with a shot glass of hot water and a cold can of holy water. There’s no scale or graph lines drawn on this Etch-a-Sketch temperature logger, but [IronJungle] has a few more things planned for this rig. We can’t wait to see those plans come to fruition.

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Your mug on an Etch a Sketch — automatically

[Jim's] pretty serious about his Etch a Sketch. He’s gone to the trouble of building a rig that will automatically render a photograph as Etch a Sketch art. Do you recognize the US political figure being plotted in this image? He actually cracks these open and removes all of the internals to preserve the artwork when the reassembled body is ready to be hung on a wall. But we like it for the hacker-friendly interface techniques he used.

He moves the knobs using a pair of stepper motors. They attach thanks to a pair of 3D printed gears he modeled which go over the stock knobs and secure with four set screws. He says he can be up and printing in five minutes using these along with the MDF jig that holds the body and the motors.

He converts photos to 1-bit images, then runs them through ImageMagick to convert them into a text file. A Python script parses that text, sending appropriate commands to an Arduino which drives the motors. The image is drawn much like a scanning CRT monitor. The stylus tracks one horizontal line at a time, drawing a squiggle if the pixel should be black, or skipping it if it should be white.

We wish there was a video of the printing process. Since we didn’t find one, there’s a bonus project unrelated to this one after the break. It’s an Etch a Sketch clock.

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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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