NopSCADlib/vitamins/pulley.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/>.
//
//
//! Timing belt pulleys, both toothed and plain with internal bearings for idlers.
//
include <../core.scad>
use <screw.scad>
use <belt.scad>
use <../utils/round.scad>
function pulley_type(type) = type[1]; //! Part description
function pulley_teeth(type) = type[2]; //! Number of teeth
function pulley_od(type) = type[3]; //! Outer diameter
function pulley_belt(type) = type[4]; //! Belt type
function pulley_width(type) = type[5]; //! Width of teeth / belt channel
function pulley_hub_dia(type) = type[6]; //! Hub diameter
function pulley_hub_length(type) = type[7]; //! Hub length
function pulley_bore(type) = type[8]; //! Bore diameter for shaft
function pulley_flange_dia(type) = type[9]; //! Flange diameter
function pulley_flange_thickness(type) = type[10]; //! Flange thickness
function pulley_screw_length(type) = type[11]; //! Grup screw length
function pulley_screw_z(type) = type[12]; //! Grub screw position
function pulley_screw(type) = type[13]; //! Grub screw type
function pulley_screws(type) = type[14]; //! Number of grub screws
function pulley_ir(type) = pulley_od(type) / 2 - (pulley_teeth(type) ? belt_tooth_height(pulley_belt(type)) : 0); //! Inside radius of the teeth
function pulley_pr(type) = let(belt = pulley_belt(type)) //! Pitch radius
pulley_teeth(type) ? pulley_teeth(type) * belt_pitch(belt) / 2 / PI
: pulley_ir(type) + belt_thickness(belt) - belt_pitch_height(belt);
function pulley_offset(type) = -pulley_hub_length(type) - pulley_flange_thickness(type) - pulley_width(type) / 2; //! Offset of the belt path centre
function pulley_height(type) = pulley_hub_length(type) + 2 * pulley_flange_thickness(type) + pulley_width(type); //! Total height of pulley
function pulley_extent(type) = max(pulley_flange_dia(type), pulley_hub_dia(type)) / 2; //! Largest diameter
T_angle = 40;
GT_r = 0.555;
module pulley(type) { //! Draw a pulley
teeth = pulley_teeth(type);
od = pulley_od(type);
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vitamin(str("pulley(", type[0], "): Pulley ", pulley_type(type), pulley_screws(type) ? " " : " idler ", teeth ? str(teeth, " teeth") : str("smooth ", od, "mm")));
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ft = pulley_flange_thickness(type);
tw = pulley_od(type) * PI / (teeth * 2);
hl = pulley_hub_length(type);
w = pulley_width(type);
r1 = pulley_bore(type) / 2;
or = od / 2;
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ir = pulley_ir(type);
module core() {
translate_z(pulley_hub_length(type) + ft)
linear_extrude(height = w) let($fa = 1, $fs = 0.1)
difference() {
circle(or);
circle(r1);
for(i = [0 : 1 : teeth - 1])
rotate(i * 360 / teeth)
if(pulley_type(type)[0] == "G")
translate([0, ir + GT_r])
hull() {
circle(GT_r);
translate([0, GT_r])
square(2 * GT_r, center = true);
}
else
translate([0, (ir + or) / 2])
hull() {
for(side = [-1, 1])
translate([side * tw / 2, 0])
rotate(-side * T_angle / 2)
square([eps, (or - ir)], center = true);
translate([0, 1])
square([tw, eps], center = true);
}
}
}
module screw_holes() {
if(pulley_screws(type))
translate_z(pulley_screw_z(type))
for(i = [0 : pulley_screws(type) - 1])
rotate([-90, 0, i * -90])
cylinder(r = screw_radius(pulley_screw(type)), h = 100);
}
color("silver") {
render() difference() {
rotate_extrude() translate([r1, 0]) {
if(hl)
square([pulley_hub_dia(type) / 2 - r1, hl]);
for(z = [pulley_hub_length(type), hl + ft + w])
translate([0, z])
square([pulley_flange_dia(type) / 2 - r1, ft]);
}
if(pulley_screw_z(type) < hl)
screw_holes();
}
render() difference() { // T5 pulleys have screw through the teeth
core();
if(pulley_screw_z(type) > hl)
screw_holes();
}
}
}
module pulley_assembly(type) { //! Draw a pulley with its grub screws in place
translate_z(pulley_offset(type)) {
pulley(type);
if(pulley_screws(type))
translate_z(pulley_screw_z(type))
for(i = [0 : pulley_screws(type) - 1])
rotate([-90, 0, i * -90])
translate_z(pulley_bore(type) / 2 + pulley_screw_length(type))
screw(pulley_screw(type), pulley_screw_length(type));
}
}