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How to Build a $20 3-Axis CNC Robot (plotterbot.com)
3 points by danshapiro 1413 days ago | hide | past | web | 3 comments | favorite

I'm working right now to improve the design to make it compatible with the more common micro servo motors out there.

I'm also working on some improvements to reduce the amount of plastic used, decrease the footprint, and increase the drawing area. :)

What resolution/level of precision can this design achieve?

@na85: TLDR: The resolution, I'll admit, isn't great. :)

The robot is theoretically capable of very fine control. A 1/2 degree rotation of the X or Y servo theoretically equates to about a 0.2mm movement in the corresponding direction. Since my pen tips are about a 0.5mm in diameter, this is pretty good.

However, the play/backlash from the existing plastic rack/pinion design is a major factor. This is mostly a function of a plastic rack/pinion rather than ground precision metal rods and expensive bearings. With improvements in the design including the exact way in which the rack/pinions mesh, I think I could improve this a great deal. I could further reduce the backlash by using herringbone rack/pinions, but I'm trying to refine the rest of the design before I come back to this.

The top post on the site, http://shor.tw/11d, has a couple examples of my recent drawings.

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