

How to Build a $20 3-Axis CNC Robot - danshapiro
http://plotterbot.com/2013/12/how-to-build-a-tiny-3-axis-cnc-drawing-robot/

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MakerBlock
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. :)

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na85
What resolution/level of precision can this design achieve?

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MakerBlock
@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](http://shor.tw/11d), has a
couple examples of my recent drawings.

