Polar Giraffe Update

First off, hopefully after the end of this month, activity on the site will pick up a bit. We’ve got some neat projects we’re working on that would definitely be worth sharing. So yeah, look for more soon!

In the mean time, here’s a quick look at some updates I’ve made to the Polar Giraffe. Those who were able to see it at Maker Faire NC commented on how the the gondola was floating in mid-air. There were even a few claims of magnets.

PolarGRaph

This was because of the spool/fishing line method used to suspend the gondola from each motor. I like this effect for exactly the reaction it got: the gondola seems to float around the paper. But there are a few issues with this. First, the line doesn’t wind evenly around the spool. If there’s even a slight angle to the shaft of the motor down or up, the line tends to gather at the front or back of the spool. As the line winds up all bunched together, the diameter of the spool effectively changes, resulting in distortion of the printed image. Also, sometime the line will “skip” as it shifts position as it winds or unwinds. This causes hiccups in the drawing as any slight movement of the line is magnified at the pen location.

To solve this, I went with a method others have used for these kinds of devices: beaded cord.

NewSpools

The beaded cord (like what you would find in window blinds) fits nicely into the 3D-Printed sprockets. This method solves both the ‘skipping while winding’ and ‘changing diameter’ problems.

In addition, Adam decided to play around with 123D Design a bit and whacked together these nifty mounts. No more warped pieces of wood!

NewMountSide

NewMountTop

Before, the fishing line wound and unwound from the bottom of the spool. Because of how the cord now wraps around the top of the spool, the code needs to be tweaked a bit. Everything else should be fine, but the shafts need to spin in the opposite direction. Just a minor tweak, and then I’ll be back to printing (slightly more accurate) drawings.

BeadedCordSetup

And I’ll have to fashion better counterweights at some point. Maybe :P.

Beaded Cord Sprocket: http://www.thingiverse.com/thing:373859

NEMA 17 Stepper Bracket: http://www.thingiverse.com/thing:5166

Adjustable Mount: http://www.thingiverse.com/thing:373876

 

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