# Parametric Column, Cylinder with varying radius

## by TakeItAndRun, published May 31, 2012

Parametric Column, Cylinder with varying radius May 31, 2012
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# Summary

This is an openSCAD file that shows how to make cylinders with varying radius. This is a responce to http://www.thingiverse.com/thing:21868. Parametric Doric Temple Building Set
by elindow

# Instructions

The radius of the column can now vary as a function of the hight:

The program draws a series of cones of height dh+e on top of each other.
They overlap by e=0.02 so that we will get a continious object without internal, paralell faces. The lower radius of the cone is taken at a height of: i(h/nh) and its upper radius at a height of (i+1/nh)(h/nh), where h is the total height, nh is the number of slices(=cones) in h, and i runs from 0 to 1.

rn(i) are the radi of the sample colums,
with
a, the strength of the modulation funktion in r

Replace the r-function to make your own shapes.

// define the radius of the column for every height i (i runs from 0 to 1)
// the 'trivial case of a straight column
function r0(i)=r0;
// a quadratic or parabel column: concave
// (the zero point of the modulation function is at i=0.5
function r1(i)=r0(1+2a(i-.5)(i-.5));
// a quadratic or parabel column: convex
function r2(i)=r0(1-2a(i-.5)(i-.5));
// a sinus function with half a period
function r3(i)=r0(1-asin(1i180));
// a sinus function with a frequency of 5'Hz', resulting in 5/2=2.5 bloobs
function r4(i)=r0(1-asin(5i180));
// this 1/x function has is divergend at i=0.5 (meaning the value would be infinity and
// the divergence is shifted to 0.55 (0.45, respectatly) and then drawn only for
// the values i=0 to 0.5 (i=0.5 to 1, respectatly)
function r5(i)=(i<.5)?r0(1-a/(i-.55)):r0(1+a/(i-.45));

If someone could give me the formular for greek/roman colums I will make .stl files for them

Have fun!

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I do like this design.
I would like to hire you to design something similar,

This is a really clever solution. Thanks for figuring that one out!

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