NopSCADlib/utils/core/polyholes.scad

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//
// NopSCADlib Copyright Chris Palmer 2018
// nop.head@gmail.com
// hydraraptor.blogspot.com
//
// This file is part of NopSCADlib.
//
// NopSCADlib is free software: you can redistribute it and/or modify it under the terms of the
// GNU General Public License as published by the Free Software Foundation, either version 3 of
// the License, or (at your option) any later version.
//
// NopSCADlib is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
// without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along with NopSCADlib.
// If not, see <https://www.gnu.org/licenses/>.
//
//
//! A method of making 3D printed holes come out the right size regardless of the printer, providing
//! it gets the linear dimensions right. See <https://hydraraptor.blogspot.com/2011/02/polyholes.html>
//!
//! The module provides `poly_circle()`, `poly_cylinder()` and `poly_ring()` that is useful for making printed washers and pillars.
//
function sides(r) = max(round(4 * r), 3); //! Optimium number of sides for specified radius
function corrected_radius(r, n = 0) = r / cos(180 / (n ? n : sides(r))); //! Adjusted radius to make flats lie on the circle
function corrected_diameter(d, n = 0) = d / cos(180 / (n ? n : sides(d / 2))); //! Adjusted diameter to make flats lie on the circle
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module poly_circle(r, sides = 0) { //! Make a circle adjusted to print the correct size
n = sides ? sides : sides(r);
circle(r = corrected_radius(r,n), $fn = n);
}
module poly_cylinder(r, h, center = false, sides = 0, chamfer = false) {//! Make a cylinder adjusted to print the correct size
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extrude_if(h, center)
poly_circle(r, sides);
if(h && chamfer)
poly_cylinder(r + layer_height, center ? layer_height * 2 : layer_height, center, sides = sides ? sides : sides(r));
}
module poly_ring(or, ir, sides = 0) { //! Make a 2D ring adjusted to have the correct internal radius
cir = corrected_radius(ir, sides);
filaments = (or - cir) / extrusion_width;
if(filaments > 3 + eps)
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difference() {
circle(or);
poly_circle(ir, sides);
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}
else
if(filaments >= 2)
difference() {
offset(or - cir)
poly_circle(ir, sides);
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poly_circle(ir, sides);
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}
else
difference() {
poly_circle(or, sides);
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offset(-squeezed_wall)
poly_circle(or, sides);
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}
}
module poly_tube(or, ir, h, center = false) //! Make a tube adjusted to have the correct internal radius
extrude_if(h, center)
poly_ring(or, ir);
module drill(r, h = 100, center = true) //! Make a cylinder for drilling holes suitable for CNC routing, set h = 0 for circle
extrude_if(h, center)
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circle(r = corrected_radius(r, r2sides(r)));
module poly_drill(r, h = 100, center = true) //! Make a cylinder for drilling holes suitable for CNC routing if cnc_bit_r is non zero, otherwise a poly_cylinder.
if(cnc_bit_r)
drill(r, h, center = true);
else
poly_cylinder(r, h, center);
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//
// Horizontal slot
//
module slot(r, l, h = 100) //! Make a horizontal slot suitable for CNC routing, set h = 0 for 2D version
extrude_if(h)
hull() {
translate([l / 2,0])
drill(r, 0);
translate([-l / 2,0])
drill(r, 0);
}