J. & I have been working hard on a fabulous new project called the “Magic Screen Machine.” By using gears, stepper motors, a micro-controller and and two ULN2803′s we’ve re-created part of Jeff Epler’s Etch CNC project.
This is a multi-step process and we actually made it through the first stage successfully.
It all started off with an Etch-A-Sketch® and a plan. Jeff Epler made this project look easy and it was… up to a point.
These are the gears we used for this project. We picked them up at a local hobby shop. Initially, we were going to manufacture our own gears by learning how to do casting & molding. But saner heads prevailed and we decided to go the “already made” route. We do still plan to learn how to cast our own gears, but that will be another project for another day.
The gears fit perfectly onto the Etch-A-Sketch® knobs. The next step is gluing. I tried super glue but couldn’t get it to hold. So, I graduated to “Super Glue Super Instant Epoxy 90.” Good stuff! It is quite stinky, so ventilation is required.
Gluing is not as easy as it looks…
I got the gear glued to knob. Now, it’s time to lay out the design of the frame. One important aspect of the design was to make sure the the Etch-A-Sketch® was not permanently mounted. We wanted to be able to remove it for shaking or replacing or whatever. To allow device mobility, I planned to bolt a piece of 2X4 and use a wing nut to secure it. This piece will wedge the device into the frame and will easy to remove.
The motors needed spacers. I glued 7 tiny washers together to make a spacer. I built four of these things, without any mishaps, other than some of the washers not being the same height. I eventually found matching washers and my spacers are relatively uniform in height.
The frame has been built, a gear has been glued, and spacers created. Next, we’re mounting the motor to see if this idea is going to work. Lining up the motor with the gear was a bit tricky and involved a bit of guesswork.
In this step, we’ve attached the motor to the project bread board. It actually worked! The chip is telling the motor which way to turn. The motor is controlling the knob, which is drawing on the screen!
After this successful test, we glued the second gear to the left knob, added spacers and a motor. This was relatively simple and we were quite excited to get to the next step…
One of the vital elements that will make this a CNC Magic Screen Machine is the cable. So, we took an old cable, mapped the wires and soldered on new connectors. The first cable we mapped was not useful for this project. The cable and the map got thrown into a ziplock bag, for future use. The second cable was perfect.
In the end, we couldn’t get the computer to talk to the Etch-A-Sketch® before time ran out. Instead, J. programmed a design onto the chip and we used that for our demo. This project took about 8 hours. We had a few missteps that were not chronicled here. And we spent a bit of time trying to find the perfect gear. Hopefully, we can get the next step done in a couple of weeks and then it’s time to start programming the awesome designs. Yay!
*The source code can be found here:
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