X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=reprap-play.git;a=blobdiff_plain;f=threads.scad;h=b2eee23309a8de23d208d0473ad6620bb1a8be04;hp=c958cb5558873ddf4f8e5746b82349a3ef2e42b7;hb=HEAD;hpb=80b593680027557af87b9e727dcde7a799e8e2e2
diff --git a/threads.scad b/threads.scad
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+++ /dev/null
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-/*
- * ISO-standard metric threads, following this specification:
- * http://en.wikipedia.org/wiki/ISO_metric_screw_thread
- *
- * Copyright 2020 Dan Kirshner - dan_kirshner@yahoo.com
- * This program 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.
- *
- * This program 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.
- *
- * See .
- *
- * Version 2.4. 2019-07-14 Add test option - do not render threads.
- * Version 2.3. 2017-08-31 Default for leadin: 0 (best for internal threads).
- * Version 2.2. 2017-01-01 Correction for angle; leadfac option. (Thanks to
- * Andrew Allen .)
- * Version 2.1. 2016-12-04 Chamfer bottom end (low-z); leadin option.
- * Version 2.0. 2016-11-05 Backwards compatibility (earlier OpenSCAD) fixes.
- * Version 1.9. 2016-07-03 Option: tapered.
- * Version 1.8. 2016-01-08 Option: (non-standard) angle.
- * Version 1.7. 2015-11-28 Larger x-increment - for small-diameters.
- * Version 1.6. 2015-09-01 Options: square threads, rectangular threads.
- * Version 1.5. 2015-06-12 Options: thread_size, groove.
- * Version 1.4. 2014-10-17 Use "faces" instead of "triangles" for polyhedron
- * Version 1.3. 2013-12-01 Correct loop over turns -- don't have early cut-off
- * Version 1.2. 2012-09-09 Use discrete polyhedra rather than linear_extrude ()
- * Version 1.1. 2012-09-07 Corrected to right-hand threads!
- */
-
-// Examples.
-//
-// Standard M8 x 1.
-// metric_thread (diameter=8, pitch=1, length=4);
-
-// Square thread.
-// metric_thread (diameter=8, pitch=1, length=4, square=true);
-
-// Non-standard: long pitch, same thread size.
-//metric_thread (diameter=8, pitch=4, length=4, thread_size=1, groove=true);
-
-// Non-standard: 20 mm diameter, long pitch, square "trough" width 3 mm,
-// depth 1 mm.
-//metric_thread (diameter=20, pitch=8, length=16, square=true, thread_size=6,
-// groove=true, rectangle=0.333);
-
-// English: 1/4 x 20.
-//english_thread (diameter=1/4, threads_per_inch=20, length=1);
-
-// Tapered. Example -- pipe size 3/4" -- per:
-// http://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html
-// english_thread (diameter=1.05, threads_per_inch=14, length=3/4, taper=1/16);
-
-// Thread for mounting on Rohloff hub.
-//difference () {
-// cylinder (r=20, h=10, $fn=100);
-//
-// metric_thread (diameter=34, pitch=1, length=10, internal=true, n_starts=6);
-//}
-
-
-// ----------------------------------------------------------------------------
-function segments (diameter) = min (50, max (ceil (diameter*6), 25));
-
-
-// ----------------------------------------------------------------------------
-// diameter - outside diameter of threads in mm. Default: 8.
-// pitch - thread axial "travel" per turn in mm. Default: 1.
-// length - overall axial length of thread in mm. Default: 1.
-// internal - true = clearances for internal thread (e.g., a nut).
-// false = clearances for external thread (e.g., a bolt).
-// (Internal threads should be "cut out" from a solid using
-// difference ()). Default: false.
-// n_starts - Number of thread starts (e.g., DNA, a "double helix," has
-// n_starts=2). See wikipedia Screw_thread. Default: 1.
-// thread_size - (non-standard) axial width of a single thread "V" - independent
-// of pitch. Default: same as pitch.
-// groove - (non-standard) true = subtract inverted "V" from cylinder
-// (rather thanadd protruding "V" to cylinder). Default: false.
-// square - true = square threads (per
-// https://en.wikipedia.org/wiki/Square_thread_form). Default:
-// false.
-// rectangle - (non-standard) "Rectangular" thread - ratio depth/(axial) width
-// Default: 0 (standard "v" thread).
-// angle - (non-standard) angle (deg) of thread side from perpendicular to
-// axis (default = standard = 30 degrees).
-// taper - diameter change per length (National Pipe Thread/ANSI B1.20.1
-// is 1" diameter per 16" length). Taper decreases from 'diameter'
-// as z increases. Default: 0 (no taper).
-// leadin - 0 (default): no chamfer; 1: chamfer (45 degree) at max-z end;
-// 2: chamfer at both ends, 3: chamfer at z=0 end.
-// leadfac - scale of leadin chamfer (default: 1.0 = 1/2 thread).
-// test - true = do not render threads (just draw "blank" cylinder).
-// Default: false (draw threads).
-module metric_thread (diameter=8, pitch=1, length=1, internal=false, n_starts=1,
- thread_size=-1, groove=false, square=false, rectangle=0,
- angle=30, taper=0, leadin=0, leadfac=1.0, test=false)
-{
- // thread_size: size of thread "V" different than travel per turn (pitch).
- // Default: same as pitch.
- local_thread_size = thread_size == -1 ? pitch : thread_size;
- local_rectangle = rectangle ? rectangle : 1;
-
- n_segments = segments (diameter);
- h = (test && ! internal) ? 0 : (square || rectangle) ? local_thread_size*local_rectangle/2 : local_thread_size / (2 * tan(angle));
-
- h_fac1 = (square || rectangle) ? 0.90 : 0.625;
-
- // External thread includes additional relief.
- h_fac2 = (square || rectangle) ? 0.95 : 5.3/8;
-
- tapered_diameter = diameter - length*taper;
-
- difference () {
- union () {
- if (! groove) {
- if (! test) {
- metric_thread_turns (diameter, pitch, length, internal, n_starts,
- local_thread_size, groove, square, rectangle, angle,
- taper);
- }
- }
-
- difference () {
-
- // Solid center, including Dmin truncation.
- if (groove) {
- cylinder (r1=diameter/2, r2=tapered_diameter/2,
- h=length, $fn=n_segments);
- } else if (internal) {
- cylinder (r1=diameter/2 - h*h_fac1, r2=tapered_diameter/2 - h*h_fac1,
- h=length, $fn=n_segments);
- } else {
-
- // External thread.
- cylinder (r1=diameter/2 - h*h_fac2, r2=tapered_diameter/2 - h*h_fac2,
- h=length, $fn=n_segments);
- }
-
- if (groove) {
- if (! test) {
- metric_thread_turns (diameter, pitch, length, internal, n_starts,
- local_thread_size, groove, square, rectangle,
- angle, taper);
- }
- }
- }
- }
-
- // chamfer z=0 end if leadin is 2 or 3
- if (leadin == 2 || leadin == 3) {
- difference () {
- cylinder (r=diameter/2 + 1, h=h*h_fac1*leadfac, $fn=n_segments);
-
- cylinder (r2=diameter/2, r1=diameter/2 - h*h_fac1*leadfac, h=h*h_fac1*leadfac,
- $fn=n_segments);
- }
- }
-
- // chamfer z-max end if leadin is 1 or 2.
- if (leadin == 1 || leadin == 2) {
- translate ([0, 0, length + 0.05 - h*h_fac1*leadfac]) {
- difference () {
- cylinder (r=diameter/2 + 1, h=h*h_fac1*leadfac, $fn=n_segments);
- cylinder (r1=tapered_diameter/2, r2=tapered_diameter/2 - h*h_fac1*leadfac, h=h*h_fac1*leadfac,
- $fn=n_segments);
- }
- }
- }
- }
-}
-
-
-// ----------------------------------------------------------------------------
-// Input units in inches.
-// Note: units of measure in drawing are mm!
-module english_thread (diameter=0.25, threads_per_inch=20, length=1,
- internal=false, n_starts=1, thread_size=-1, groove=false,
- square=false, rectangle=0, angle=30, taper=0, leadin=0,
- leadfac=1.0, test=false)
-{
- // Convert to mm.
- mm_diameter = diameter*25.4;
- mm_pitch = (1.0/threads_per_inch)*25.4;
- mm_length = length*25.4;
-
- echo (str ("mm_diameter: ", mm_diameter));
- echo (str ("mm_pitch: ", mm_pitch));
- echo (str ("mm_length: ", mm_length));
- metric_thread (mm_diameter, mm_pitch, mm_length, internal, n_starts,
- thread_size, groove, square, rectangle, angle, taper, leadin,
- leadfac, test);
-}
-
-// ----------------------------------------------------------------------------
-module metric_thread_turns (diameter, pitch, length, internal, n_starts,
- thread_size, groove, square, rectangle, angle,
- taper)
-{
- // Number of turns needed.
- n_turns = floor (length/pitch);
-
- intersection () {
-
- // Start one below z = 0. Gives an extra turn at each end.
- for (i=[-1*n_starts : n_turns+1]) {
- translate ([0, 0, i*pitch]) {
- metric_thread_turn (diameter, pitch, internal, n_starts,
- thread_size, groove, square, rectangle, angle,
- taper, i*pitch);
- }
- }
-
- // Cut to length.
- translate ([0, 0, length/2]) {
- cube ([diameter*3, diameter*3, length], center=true);
- }
- }
-}
-
-
-// ----------------------------------------------------------------------------
-module metric_thread_turn (diameter, pitch, internal, n_starts, thread_size,
- groove, square, rectangle, angle, taper, z)
-{
- n_segments = segments (diameter);
- fraction_circle = 1.0/n_segments;
- for (i=[0 : n_segments-1]) {
- rotate ([0, 0, i*360*fraction_circle]) {
- translate ([0, 0, i*n_starts*pitch*fraction_circle]) {
- //current_diameter = diameter - taper*(z + i*n_starts*pitch*fraction_circle);
- thread_polyhedron ((diameter - taper*(z + i*n_starts*pitch*fraction_circle))/2,
- pitch, internal, n_starts, thread_size, groove,
- square, rectangle, angle);
- }
- }
- }
-}
-
-
-// ----------------------------------------------------------------------------
-module thread_polyhedron (radius, pitch, internal, n_starts, thread_size,
- groove, square, rectangle, angle)
-{
- n_segments = segments (radius*2);
- fraction_circle = 1.0/n_segments;
-
- local_rectangle = rectangle ? rectangle : 1;
-
- h = (square || rectangle) ? thread_size*local_rectangle/2 : thread_size / (2 * tan(angle));
- outer_r = radius + (internal ? h/20 : 0); // Adds internal relief.
- //echo (str ("outer_r: ", outer_r));
-
- // A little extra on square thread -- make sure overlaps cylinder.
- h_fac1 = (square || rectangle) ? 1.1 : 0.875;
- inner_r = radius - h*h_fac1; // Does NOT do Dmin_truncation - do later with
- // cylinder.
-
- translate_y = groove ? outer_r + inner_r : 0;
- reflect_x = groove ? 1 : 0;
-
- // Make these just slightly bigger (keep in proportion) so polyhedra will
- // overlap.
- x_incr_outer = (! groove ? outer_r : inner_r) * fraction_circle * 2 * PI * 1.02;
- x_incr_inner = (! groove ? inner_r : outer_r) * fraction_circle * 2 * PI * 1.02;
- z_incr = n_starts * pitch * fraction_circle * 1.005;
-
- /*
- (angles x0 and x3 inner are actually 60 deg)
-
- /\ (x2_inner, z2_inner) [2]
- / \
- (x3_inner, z3_inner) / \
- [3] \ \
- |\ \ (x2_outer, z2_outer) [6]
- | \ /
- | \ /|
- z |[7]\/ / (x1_outer, z1_outer) [5]
- | | | /
- | x | |/
- | / | / (x0_outer, z0_outer) [4]
- | / | / (behind: (x1_inner, z1_inner) [1]
- |/ | /
- y________| |/
- (r) / (x0_inner, z0_inner) [0]
-
- */
-
- x1_outer = outer_r * fraction_circle * 2 * PI;
-
- z0_outer = (outer_r - inner_r) * tan(angle);
- //echo (str ("z0_outer: ", z0_outer));
-
- //polygon ([[inner_r, 0], [outer_r, z0_outer],
- // [outer_r, 0.5*pitch], [inner_r, 0.5*pitch]]);
- z1_outer = z0_outer + z_incr;
-
- // Give internal square threads some clearance in the z direction, too.
- bottom = internal ? 0.235 : 0.25;
- top = internal ? 0.765 : 0.75;
-
- translate ([0, translate_y, 0]) {
- mirror ([reflect_x, 0, 0]) {
-
- if (square || rectangle) {
-
- // Rule for face ordering: look at polyhedron from outside: points must
- // be in clockwise order.
- polyhedron (
- points = [
- [-x_incr_inner/2, -inner_r, bottom*thread_size], // [0]
- [x_incr_inner/2, -inner_r, bottom*thread_size + z_incr], // [1]
- [x_incr_inner/2, -inner_r, top*thread_size + z_incr], // [2]
- [-x_incr_inner/2, -inner_r, top*thread_size], // [3]
-
- [-x_incr_outer/2, -outer_r, bottom*thread_size], // [4]
- [x_incr_outer/2, -outer_r, bottom*thread_size + z_incr], // [5]
- [x_incr_outer/2, -outer_r, top*thread_size + z_incr], // [6]
- [-x_incr_outer/2, -outer_r, top*thread_size] // [7]
- ],
-
- faces = [
- [0, 3, 7, 4], // This-side trapezoid
-
- [1, 5, 6, 2], // Back-side trapezoid
-
- [0, 1, 2, 3], // Inner rectangle
-
- [4, 7, 6, 5], // Outer rectangle
-
- // These are not planar, so do with separate triangles.
- [7, 2, 6], // Upper rectangle, bottom
- [7, 3, 2], // Upper rectangle, top
-
- [0, 5, 1], // Lower rectangle, bottom
- [0, 4, 5] // Lower rectangle, top
- ]
- );
- } else {
-
- // Rule for face ordering: look at polyhedron from outside: points must
- // be in clockwise order.
- polyhedron (
- points = [
- [-x_incr_inner/2, -inner_r, 0], // [0]
- [x_incr_inner/2, -inner_r, z_incr], // [1]
- [x_incr_inner/2, -inner_r, thread_size + z_incr], // [2]
- [-x_incr_inner/2, -inner_r, thread_size], // [3]
-
- [-x_incr_outer/2, -outer_r, z0_outer], // [4]
- [x_incr_outer/2, -outer_r, z0_outer + z_incr], // [5]
- [x_incr_outer/2, -outer_r, thread_size - z0_outer + z_incr], // [6]
- [-x_incr_outer/2, -outer_r, thread_size - z0_outer] // [7]
- ],
-
- faces = [
- [0, 3, 7, 4], // This-side trapezoid
-
- [1, 5, 6, 2], // Back-side trapezoid
-
- [0, 1, 2, 3], // Inner rectangle
-
- [4, 7, 6, 5], // Outer rectangle
-
- // These are not planar, so do with separate triangles.
- [7, 2, 6], // Upper rectangle, bottom
- [7, 3, 2], // Upper rectangle, top
-
- [0, 5, 1], // Lower rectangle, bottom
- [0, 4, 5] // Lower rectangle, top
- ]
- );
- }
- }
- }
-}
-
-
diff --git a/threads.scad b/threads.scad
new file mode 120000
index 0000000..de35975
--- /dev/null
+++ b/threads.scad
@@ -0,0 +1 @@
+diziet-utils/threads.scad
\ No newline at end of file