Linear Extrude with Twist as an interpolated function

thingiverse

OpenScad Linear_Extrude extended use example. Module and function example to make the linear_extrude twisting functionality follow a function. It is a piecewise union of linear_extrudes. The example uses a sine function as a twisting function. Scaling by a Scalar is incorporated and can also be passed to the module. How I Designed This Motivation In a attempt to emulate a propeller blade with an aerofoil profile I wanted to define a progressive increment and the decrement of the blade width, maintaining the profile as moving from root to tip of the blade. The twist part was a follow up once I managed to get the scaling section done. Main Code module linear_extrude_ft(height=1,isteps=20,scale=1,slices=0){ union(){ for(i = [ 0: 1: isteps-1]){ translate([0,0,iheight/isteps]) linear_extrude( height=height/isteps, twist=f_left((i+1)/isteps)-f_left((i)/isteps), scale=(1-(1-scale)(i+1)/isteps)/(1-(1-scale)i/isteps), slices=slices ) rotate([0,0,-f_left(i/isteps)]) scale(1-(1-scale)(i/isteps)) obj2D_left(); } } } User must implement a function with the name function f_left(x) =...; which returns the value of the twist with an expected input ranging from 0 to 1 along the extruded height. User must also implement a module named module obj2D_left(){...} to define the 2 dimensional object to extrude.