Ball-Chain Pulley for Polargraph

by JohnA Oct 10, 2011
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Thank you so much for this parametric design. This helped me a ton motorizing my window blinds!

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It does not compile with the current version of Open SCAD it stops around 2/3 into the process. Am I the only one?

I had the same experience (it stopped at step 730 out of 1000), but it turned out it was just thinking really hard. I came back 10-20 minutes later and it had finished generating and rendering the final product. Does anyone know if there's an easy way to reduce the "resolution" OpenSCAD compiles to for faster prototyping?

the link to the ball chain you posted was 4mm and not 3.5mm. Is the number in your description a mistake or does the link go to a different chain than you used?

Is making the sprocket smaller and messing with the programming possible for higher resolution, or just getting .9 resolution with a 1.8 degree motor?

Even like this, it'll do impossibly small resolution. You need to start getting .02mm pens, etc....

is the ball chain better or worse than monofilament spool for this application?

Better. -- I would avoid using a "spool", of anything for this -- instead use a counter weighted chain or belt of some kind -- with a matching gear -- because with a spool the diameter is variable instead of constant, and your steps per mm will also likewise be variable instead of constant.

I'm not sure? I was trying to keep it like the original, so I went this route. You could probably use anything and be fine.

Hi there! Question : which motors are you using? I coudn
´t find any motor matching the specs (0.9 degree resolution, 0.6A ) Please help!

I'm using this one: https://www.adafruit.com/products/324https://www.adafruit.com/produ... - just took some small modifications to the code. The ones that Sandy used don't seem to be widely available in the US.

Would you mind sharing the code modifications?