NopSCADlib/vitamins/screw.scad

340 lines
13 KiB
OpenSCAD

//
// 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/>.
//
//
//! Machine screws and wood screws with various head styles.
//!
//! For an explanation of `screw_polysink()` see <https://hydraraptor.blogspot.com/2020/12/sinkholes.html>.
//
include <../utils/core/core.scad>
use <washer.scad>
use <nut.scad>
use <../utils/rounded_cylinder.scad>
use <../utils/thread.scad>
include <inserts.scad>
function screw_head_type(type) = type[2]; //! Head style hs_cap, hs_pan, hs_cs, hs_hex, hs_grub, hs_cs_cap, hs_dome
function screw_radius(type) = type[3] / 2; //! Nominal radius
function screw_head_radius(type) = type[4] / 2; //! Head radius
function screw_head_height(type) = type[5]; //! Head height
function screw_socket_depth(type) = type[6]; //! Socket or slot depth
function screw_socket_af(type) = type[7]; //! Socket across flats
function screw_max_thread(type) = type[8]; //! Maximum thread length
function screw_washer(type) = type[9]; //! Default washer
function screw_nut(type) = type[10]; //! Default nut
function screw_pilot_hole(type) = type[11]; //! Pilot hole radius for wood screws, tap radius for machine screws
function screw_clearance_radius(type) = type[12]; //! Clearance hole radius
function screw_nut_radius(type) = screw_nut(type) ? nut_radius(screw_nut(type)) : 0; //! Radius of matching nut
function screw_boss_diameter(type) = max(washer_diameter(screw_washer(type)) + 1, 2 * (screw_nut_radius(type) + 3 * extrusion_width)); //! Boss big enough for nut trap and washer
function screw_head_depth(type, d = 0) = //! How far a counter sink head will go into a straight hole diameter d
screw_head_height(type)
? 0
: let(r = screw_radius(type)) screw_head_radius(type) - max(r, d / 2) + r / 5;
function screw_longer_than(x) = x <= 5 ? 5 : //! Returns the length of the shortest screw length longer or equal to x
x <= 6 ? 6 :
x <= 8 ? 8 :
x <= 10 ? 10 :
x <= 12 ? 12 :
x <= 16 ? 16 :
ceil(x / 5) * 5;
function screw_shorter_than(x) = x >= 20 ? floor(x / 5) * 5 : //! Returns the length of the longest screw shorter than or equal to x
x >= 16 ? 16 :
x >= 12 ? 12 :
x >= 10 ? 10 :
x >= 8 ? 8 :
x >= 6 ? 6 :
5;
function screw_length(screw, thickness, washers, insert = false, nyloc = false, nut = false, longer = false) = //! Returns the length of the longest or shortest screw that will got through `thickness` and `washers` and possibly an `insert`, `nut` or `nyloc`
let(washer = washers ? washers * washer_thickness(screw_washer(screw)) : 0,
insert = insert ? insert_length(screw_insert(screw)) : 0,
nut = nut || nyloc ? nut_thickness(screw_nut(screw), nyloc) : 0,
total = thickness + washer + insert + nut
)
longer || nut || nyloc ? screw_longer_than(total) : screw_shorter_than(total);
function screw_smaller_than(d) = d >= 2.5 && d < 3 ? 2.5 : floor(d); // Largest diameter screw less than or equal to specified diameter
function screw_insert(screw, i = 0) = let(d = screw_radius(screw) * 2)
i >= len(inserts) ? undef
: insert_screw_diameter(inserts[i]) == d ? inserts[i]
: screw_insert(screw, i + 1);
module screw(type, length, hob_point = 0, nylon = false) { //! Draw specified screw, optionally hobbed or nylon
description = str("Screw ", nylon ? "Nylon " : "", type[1], length < 10 ? " x " : " x ", length, "mm", hob_point ? str(", hobbed at ", hob_point) : "");
vitamin(str("screw(", type[0], "_screw, ", length, arg(hob_point, 0, "hob_point"), arg(nylon, false, "nylon"), "): ", description));
head_type = screw_head_type(type);
rad = screw_radius(type) - eps;
head_rad = screw_head_radius(type);
head_height = screw_head_height(type);
socket_af = screw_socket_af(type);
socket_depth= screw_socket_depth(type);
socket_rad = socket_af / cos(30) / 2;
max_thread = screw_max_thread(type);
thread = max_thread ? length >= max_thread + 5 ? max_thread
: length
: length;
d = 2 * screw_radius(type);
pitch = metric_coarse_pitch(d);
colour = nylon || head_type == hs_grub ? grey(40) : grey(80);
module shaft(socket = 0, headless = false) {
point = screw_nut(type) ? 0 : 3 * rad;
shank = length - thread - socket;
if(show_threads && !point && pitch)
translate_z(-length)
male_metric_thread(d, pitch, thread - (shank > 0 || headless ? 0 : socket), false, top = headless ? -1 : 0, solid = !headless, colour = colour);
else
color(colour * 0.9)
rotate_extrude() {
translate([0, -length + point])
square([rad, length - socket - point]);
if(point)
polygon([
[0.4, -length], [0, point - length], [rad, point - length]
]);
}
if(shank > 0)
color(colour)
translate_z(-shank - socket)
cylinder(r = rad + eps, h = shank);
}
module cs_head(socket_rad, socket_depth) {
head_t = rad / 5;
head_height = head_rad + head_t;
rotate_extrude()
difference() {
polygon([[0, 0], [head_rad, 0], [head_rad, -head_t], [0, -head_height]]);
translate([0, -socket_depth + eps])
square([socket_rad, 10]);
}
translate_z(-socket_depth)
linear_extrude(socket_depth)
difference() {
circle(socket_rad + 0.1);
children();
}
}
explode(length + 10) {
if(head_type == hs_cap) {
color(colour) {
cylinder(r = head_rad, h = head_height - socket_depth);
translate_z(head_height - socket_depth)
linear_extrude(socket_depth)
difference() {
circle(head_rad);
circle(socket_rad, $fn = 6);
}
}
shaft();
}
if(head_type == hs_grub) {
color(colour) {
r = show_threads ? rad - pitch / 2 : rad;
translate_z(-socket_depth)
linear_extrude(socket_depth)
difference() {
circle(r);
circle(socket_rad, $fn = 6);
}
shaft(socket_depth, true);
if(show_threads)
translate_z(-length)
cylinder(r = r, h = length - socket_depth);
}
}
if(head_type == hs_hex) {
color(colour)
cylinder(r = head_rad, h = head_height, $fn = 6);
shaft();
}
if(head_type == hs_pan) {
socket_rad = 0.6 * head_rad;
socket_depth = 0.5 * head_height;
socket_width = 1;
color(colour) {
rotate_extrude()
difference() {
rounded_corner(r = head_rad, h = head_height, r2 = head_height / 2);
translate([0, head_height - socket_depth])
square([socket_rad, 10]);
}
linear_extrude(head_height)
difference() {
circle(socket_rad + eps);
square([2 * socket_rad, socket_width], center = true);
square([socket_width, 2 * socket_rad], center = true);
}
}
shaft();
}
if(head_type == hs_dome) {
lift = 0.38;
h = head_height - lift;
r = min(2 * head_height, (sqr(head_rad) + sqr(h)) / 2 * h); // Special case for M2
y = sqrt(sqr(r) - sqr(head_rad));
color(colour) {
rotate_extrude() {
difference() {
intersection() {
translate([0, -y + lift])
circle(r);
square([head_rad, head_height]);
}
translate([0, head_height - socket_depth])
square([socket_rad, 10]);
}
}
linear_extrude(head_height)
difference() {
circle(socket_rad + eps);
circle(socket_rad, $fn = 6);
}
}
shaft();
}
if(head_type == hs_cs) {
socket_rad = 0.6 * head_rad;
socket_depth = 0.3 * head_rad;
socket_width = 1;
color(colour)
cs_head(socket_rad, socket_depth) {
square([2 * socket_rad, socket_width], center = true);
square([socket_width, 2 * socket_rad], center = true);
}
shaft(socket_depth);
}
if(head_type == hs_cs_cap) {
color(colour)
cs_head(socket_rad, socket_depth)
circle(socket_rad, $fn = 6);
shaft(socket_depth);
}
}
}
module screw_countersink(type, drilled = true) { //! Countersink shape
head_type = screw_head_type(type);
head_rad = screw_head_radius(type);
rad = screw_radius(type);
head_t = rad / 5;
head_height = head_rad + head_t;
if(head_type == hs_cs || head_type == hs_cs_cap)
translate_z(-head_height)
if(drilled)
cylinder(h = head_height + eps, r1 = 0, r2 = head_rad + head_t);
else
render() intersection() {
cylinder(h = head_height + eps, r1 = 0, r2 = head_rad + head_t);
cylinder(h = head_height + eps, r = head_rad + eps);
}
}
function screw_polysink_r(type, z) = //! Countersink hole profile corrected for rounded staircase extrusions.
let(rad = screw_radius(type),
head_t = rad / 5,
head_rad = screw_head_radius(type)
)
limit(head_rad + head_t - z + (sqrt(2) - 1) * layer_height / 2, screw_clearance_radius(type), head_rad);
module screw_polysink(type, h = 100, alt = false) { //! A countersink hole made from stacked polyholes for printed parts
head_depth = screw_head_depth(type);
assert(head_depth, "Not a countersunk screw");
layers = ceil(head_depth / layer_height);
rmin = screw_clearance_radius(type);
sides = sides(rmin);
lh = layer_height + eps;
render(convexity = 5)
for(side = [0, 1]) mirror([0, 0, side]) {
for(i = [0 : layers - 1])
translate_z(i * layer_height) {
r = screw_polysink_r(type, i * layer_height + layer_height / 2);
if(alt)
rotate(i % 2 == layers % 2 ? 180 / sides : 0)
poly_cylinder(r = r, h = lh, center = false, sides = sides);
else
poly_cylinder(r = r, h = lh, center = false);
}
remainder = h / 2 - layers * layer_height;
if(remainder > 0)
translate_z(layers * layer_height)
poly_cylinder(r = rmin, h = remainder, center = false);
}
}
module screw_and_washer(type, length, star = false, penny = false) { //! Screw with a washer which can be standard or penny and an optional star washer on top
washer = screw_washer(type);
head_type = screw_head_type(type);
if(head_type != hs_cs && head_type != hs_cs_cap) {
translate_z(exploded() * 6)
if(penny)
penny_washer(washer);
else
washer(washer);
translate_z(washer_thickness(washer)) {
if(star) {
translate_z(exploded() * 8)
star_washer(washer);
translate_z(washer_thickness(washer))
screw(type, length);
}
else
screw(type, length);
}
}
else
translate_z(eps)
screw(type, length);
}