Polargraph Drawing Machine

Step 3: Sprocket up!

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.

Comments

[SnyperBob]

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]

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]

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