60 lines
2.0 KiB
OpenSCAD
60 lines
2.0 KiB
OpenSCAD
|
D=300; // start diameter
|
||
|
|
N=1; // number of spirals
|
||
|
|
FN=100;
|
||
|
|
$fn=FN;
|
||
|
|
|
||
|
|
include <../libraries/path_extrude.scad>;
|
||
|
|
|
||
|
|
|
||
|
|
bottom = 1.2;
|
||
|
|
top = .3;
|
||
|
|
top_offset = (bottom - top);
|
||
|
|
h = 2.2;
|
||
|
|
|
||
|
|
facetProfile = [[0, 0], [top_offset, -h], [bottom, -h], [bottom, 0]];
|
||
|
|
|
||
|
|
|
||
|
|
function X (start_r, spacing, fn, r, i) = (start_r + (r * spacing) + (i * calcIncrement(spacing, fn))) * cos(i * calcAngle(fn));
|
||
|
|
function Y (start_r, spacing, fn, r, i) = (start_r + (r * spacing) + (i * calcIncrement(spacing, fn))) * sin(i * calcAngle(fn));
|
||
|
|
|
||
|
|
function circ (d) = PI * d;
|
||
|
|
function calcFacetSize (end_d, fn) = circ( end_d ) / fn;
|
||
|
|
//function calcSteps(rotations, fn) = fn * rotations;
|
||
|
|
function calcAngle (fn) = 360 / fn;
|
||
|
|
function calcFn(start_d, start_fn, end_d, spacing, r) = start_fn +
|
||
|
|
( ((circ(calcR(start_d, spacing, r) * 2) - circ(start_d) )
|
||
|
|
/ (circ(end_d) - circ(start_d))) * ($fn - start_fn));
|
||
|
|
function calcR(start_d, spacing, r) = (start_d / 2) + (spacing * r);
|
||
|
|
function calcIncrement(spacing, fn) = spacing / fn;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* spiral_7 - Combination of spiral_3 and spiral_4 that doesn't sacrifice
|
||
|
|
* performance. Hits an overflow when $fn is higher than 245 which creates
|
||
|
|
* 8418 vectors at 60 rotations. This is an edge case, only appearing in OpenSCAD
|
||
|
|
* 2019.05 (and maybe earlier), but should be explored.
|
||
|
|
**/
|
||
|
|
module spiral (rotations = 40, start_d = 48, spacing = 2.075, fn) {
|
||
|
|
|
||
|
|
end_d = start_d + (spacing * 2 * rotations);
|
||
|
|
end_r = end_d / 2;
|
||
|
|
start_r = start_d / 2;
|
||
|
|
|
||
|
|
facetSize = calcFacetSize(end_d, fn);
|
||
|
|
start_fn = round(circ(start_d) / facetSize);
|
||
|
|
|
||
|
|
echo(facetSize);
|
||
|
|
|
||
|
|
spiralPath = [ for (r = [0 : rotations - 1]) for (i = [0 : round(calcFn(start_d, start_fn, end_d, spacing, r )) - 1 ])
|
||
|
|
[
|
||
|
|
X(start_r, spacing, round(calcFn(start_d, start_fn, end_d, spacing, r )), r, i),
|
||
|
|
Y(start_r, spacing, round(calcFn(start_d, start_fn, end_d, spacing, r )), r, i),
|
||
|
|
0]
|
||
|
|
];
|
||
|
|
echo(len(spiralPath));
|
||
|
|
path_extrude(exShape=facetProfile, exPath=spiralPath);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
spiral(N, D, 2.075, $fn);
|
||
|
|
|