122 lines
5.0 KiB
OpenSCAD
122 lines
5.0 KiB
OpenSCAD
//
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// NopSCADlib Copyright Chris Palmer 2018
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// nop.head@gmail.com
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// hydraraptor.blogspot.com
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//
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// This file is part of NopSCADlib.
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//
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// NopSCADlib is free software: you can redistribute it and/or modify it under the terms of the
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// GNU General Public License as published by the Free Software Foundation, either version 3 of
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// the License, or (at your option) any later version.
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//
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// NopSCADlib is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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// without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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// See the GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License along with NopSCADlib.
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// If not, see <https://www.gnu.org/licenses/>.
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//
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//
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//! A method of making 3D printed holes come out the right size regardless of the printer, providing
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//! it gets the linear dimensions right. See <https://hydraraptor.blogspot.com/2011/02/polyholes.html>
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//!
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//! The module provides `poly_circle()`, `poly_cylinder()` and `poly_ring()` that is useful for making printed washers and pillars.
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//!
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//! `poly_cylinder()` has a `twist` parameter which can be set to make the polygon rotate each layer.
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//! This can be used to mitigate the number of sides being small and make small holes stronger and more round, but is quite slow due to the
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//! large increase in the number of facets.
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//! When set to 1 the polygons alternate each layer, when set higher the rotation takes `twist + 1` layers to repeat.
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//! A small additional rotation is added to make the polygon rotate one more side over the length of the hole to make it appear round when
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//! veiwed end on.
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//!
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//! When `twist` is set the resulting cylinder is extended by `eps` at each end so that the exact length of the hole can be used without
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//! leaving a scar on either surface.
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//
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function sides(r, n = undef) = is_undef(n) ? max(round(4 * r), 3) : n ? max(n, 3) : r2sides(r); //! Optimium number of sides for specified radius
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function corrected_radius(r, n = undef) = r / cos(180 / sides(r, n)); //! Adjusted radius to make flats lie on the circle
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function corrected_diameter(d, n = undef) = 2 * corrected_radius(d / 2 , n); //! Adjusted diameter to make flats lie on the circle
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module poly_circle(r, sides = undef) { //! Make a circle adjusted to print the correct size
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n = sides(r, sides);
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circle(r = corrected_radius(r, n), $fn = n);
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}
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module poly_cylinder(r, h, center = false, sides = undef, chamfer = false, twist = 0) {//! Make a cylinder adjusted to print the correct size
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if(twist) {
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slices = ceil(h / layer_height);
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twists = min(twist + 1, slices);
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sides = sides(r, sides);
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rot = 360 / sides / twists * (twists < slices ? (1 + 1 / slices) : 1);
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if(center)
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for(side = [0, 1])
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mirror([0, 0, side])
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poly_cylinder(r = r, h = h / 2, sides = sides, twist = twist);
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else
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render(convexity = 5)
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for(i = [0 : slices - 1])
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translate_z(i * layer_height - eps)
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rotate(rot * i)
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poly_cylinder(r = r, h = layer_height + 2 * eps, sides = sides);
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}
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else
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extrude_if(h, center)
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poly_circle(r, sides);
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if(h && chamfer)
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poly_cylinder(r + layer_height, center ? layer_height * 2 : layer_height, center, sides = sides(r, sides));
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}
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module poly_ring(or, ir, sides = undef) { //! Make a 2D ring adjusted to have the correct internal radius
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cir = corrected_radius(ir, sides);
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filaments = (or - cir) / extrusion_width;
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if(filaments > 3 + eps)
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difference() {
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circle(or);
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poly_circle(ir, sides);
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}
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else
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if(filaments >= 2)
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difference() {
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offset(or - cir)
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poly_circle(ir, sides);
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poly_circle(ir, sides);
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}
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else
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difference() {
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poly_circle(or, sides);
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offset(-squeezed_wall)
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poly_circle(or, sides);
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}
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}
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module poly_tube(or, ir, h, center = false) //! Make a tube adjusted to have the correct internal radius
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extrude_if(h, center)
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poly_ring(or, ir);
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module drill(r, h = 100, center = true) //! Make a cylinder for drilling holes suitable for CNC routing, set h = 0 for circle
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extrude_if(h, center)
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circle(r = corrected_radius(r, r2sides(r)));
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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.
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if(cnc_bit_r)
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drill(r, h, center = true);
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else
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poly_cylinder(r, h, center);
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//
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// Horizontal slot
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//
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module slot(r, l, h = 100) //! Make a horizontal slot suitable for CNC routing, set h = 0 for 2D version
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extrude_if(h)
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hull() {
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translate([l / 2,0])
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drill(r, 0);
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translate([-l / 2,0])
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drill(r, 0);
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}
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