Arduino Etch A Sketcher

Lots of folks have done these, including me -- this is my second or third try. When I first started doing Arduino projects this year I expected to learn about electronics. I didn't realize how much I'd end up learning about mechanical design issues, which was the biggest hurdle to getting this working well.

Full set of build pictures at http://www.atomsandelectrons.com/blog/post/Make-It-Work.aspx

In mechanical devices, just like software, simplicity rules over all. So this newer version tries to optimize for fewer parts and maximum rigidity.

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Well done!

That's outstanding. You should have it draw the descartes image.

I wonder if you could reduce the backlash by systematically drawing in one direction for as long as possible.

Could you find a line drawing of Descartes nfor your demo?

I considered your suggestion on trying to minimize direction changes, but it doesn’t work for a lot of images. Since you can’t “pick up” the pen to make it not draw, you can end up with lots of unwanted lines connecting things. I’ve done some work to reorder the points in the SVG documents to start and end polygons/paths on points in common with other polygons/paths and it improves things somewhat.

The other strategy is do create images that require minimal direction changes like you suggest, and also create them in a way where it’s a single contiguous path to avoid the “pen up” problem. I’m trying this out for something to sketch photographs:

It will travel all the way from top to bottom doing one column and then bottom to top for the next column. With each step vertically it draws a width proportional to the brightness of the pixel at that spot.

Surprisingly, it seems a good strategy to change directions frequently as it does for the line widths. Since what it’s doing is moving half the width left, then right, then back to center the errors appear to cancel out. Still a work in progress, but looking hopeful.

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