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# Parameter input for n-sided polygon in sketches

imants_smidchens
Member Posts:

**63**EDU
I found myself designing a configurable 3-sprocket chain for a robotics project, and as I read up on how chain pitch works, I found the simplest way to generate a variable n-toothed sprocket was to define a polygon with n sides and a side length of the chain pitch (seen below)

Currently the polygon tool does not allow for parameter-driven polygons, as variables are not considered valid expressions.

I realize this is likely because the input for such a polygon must be a natural number, but being able to configure this would be nice.

I also realize I could just define the diameter of the circle to be (# of sides)*(pitch length)/(pi) and call it good enough, but my brain prefers the geometric visual solution ¯\_(ツ)_/¯

Thanks for your time!

Currently the polygon tool does not allow for parameter-driven polygons, as variables are not considered valid expressions.

I realize this is likely because the input for such a polygon must be a natural number, but being able to configure this would be nice.

I also realize I could just define the diameter of the circle to be (# of sides)*(pitch length)/(pi) and call it good enough, but my brain prefers the geometric visual solution ¯\_(ツ)_/¯

Thanks for your time!

0

## Comments

63EDUPerhaps a more robust solution (in my case, at least) is to define the circle with an isosceles triangle.

definitely works well enough, at some point i'll get around to writing a featurescript that doesn't have this bothersome intersection issue between chain links