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Polargraph Drawing Machine

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Step 3: Sprocket up!

Picture of Sprocket up!
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I couldn't find a source for these beaded cord sprockets.  Roller blind mechanisms have them in, but not in an easily usable form.  I made my own and had them printed through Shapeways.  John Abella has made a parametric sprocket suitable for other bead spacings that can be 3d printed at home if you have access to something like a makerbot or a reprap.

Push-fit a sprocket onto the 5mm shaft of the motor.
 
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SnyperBob2 years ago
I want to get your stuff made up via Ponoko (gondola, sprockets), but I need to figure out what setting to input on their site for the sprockets.

When I upload this file to their site, it then wants me to select units. Options are mm, cm, or inches. Do you know which I need to select?

I don't know anything about 3D modeling, so I don't know what the units even mean, or what it applies to.
Euphy (author)  SnyperBob2 years ago
The STLs (the sprocket files) use mm. Note that the gondola and the brackets are made to be cut from 3mm material because that's what I have locally here in the UK - I think the US materials are very slightly different. It might be so small that it makes no difference, but just be aware.
SnyperBob Euphy2 years ago
Thanks for clarifying this. I ordered the sprockets and gondola thru Ponoko now. I have everything ordered, I'll let you know how it turns out once I receive everything. Probably will be 2-3 weeks, since the Steppers are coming from your side of the pond

Have a great weekend