Added screw threads to most things that are threaded.

Added a mechanism for tests.py and views.py to have command line options.
2024-11-23 07:13:51 -05:00 · 2020-02-22 19:44:01 +00:00 · 2020-02-22 19:44:01 +00:00 · e068918e21
commit e068918e21
parent 1614f50b73
76 changed files with 650 additions and 242 deletions
--- a/.gitignore
+++ b/.gitignore
@ -7,6 +7,7 @@ tests/bom/
 *.log
 *.html
 bounds.json
+options.json
 times.txt
 *_diff.png
 *.echo
--- a/docs/metric_threads.png
+++ b/docs/metric_threads.png
--- a/libtest.png
+++ b/libtest.png
--- a/readme.md
+++ b/readme.md
@ -32,8 +32,8 @@ See [usage](docs/usage.md) for requirements, installation instructions and a usa
 <tr><td> <a href = "#Fans">Fans</a> </td><td> <a href = "#Rod">Rod</a> </td><td> <a href = "#Handle">Handle</a> </td><td> <a href = "#Rounded_polygon">Rounded_polygon</a> </td><td></td></tr>
 <tr><td> <a href = "#Fuseholder">Fuseholder</a> </td><td> <a href = "#Screws">Screws</a> </td><td> <a href = "#Pcb_mount">Pcb_mount</a> </td><td> <a href = "#Sector">Sector</a> </td><td></td></tr>
 <tr><td> <a href = "#Geared_steppers">Geared_steppers</a> </td><td> <a href = "#Sealing_strip">Sealing_strip</a> </td><td> <a href = "#Psu_shroud">Psu_shroud</a> </td><td> <a href = "#Sweep">Sweep</a> </td><td></td></tr>
-<tr><td> <a href = "#Green_terminals">Green_terminals</a> </td><td> <a href = "#Sheets">Sheets</a> </td><td> <a href = "#Ribbon_clamp">Ribbon_clamp</a> </td><td> <a href = "#Tube">Tube</a> </td><td></td></tr>
-<tr><td> <a href = "#Hot_ends">Hot_ends</a> </td><td> <a href = "#Spades">Spades</a> </td><td> <a href = "#Screw_knob">Screw_knob</a> </td><td></td><td></td></tr>
+<tr><td> <a href = "#Green_terminals">Green_terminals</a> </td><td> <a href = "#Sheets">Sheets</a> </td><td> <a href = "#Ribbon_clamp">Ribbon_clamp</a> </td><td> <a href = "#Thread">Thread</a> </td><td></td></tr>
+<tr><td> <a href = "#Hot_ends">Hot_ends</a> </td><td> <a href = "#Spades">Spades</a> </td><td> <a href = "#Screw_knob">Screw_knob</a> </td><td> <a href = "#Tube">Tube</a> </td><td></td></tr>
 <tr><td> <a href = "#Hygrometer">Hygrometer</a> </td><td> <a href = "#Spools">Spools</a> </td><td> <a href = "#Socket_box">Socket_box</a> </td><td></td><td></td></tr>
 <tr><td> <a href = "#Iecs">Iecs</a> </td><td> <a href = "#Springs">Springs</a> </td><td> <a href = "#Ssr_shroud">Ssr_shroud</a> </td><td></td><td></td></tr>
 <tr><td> <a href = "#Inserts">Inserts</a> </td><td> <a href = "#Ssrs">Ssrs</a> </td><td> <a href = "#Strap_handle">Strap_handle</a> </td><td></td><td></td></tr>
@ -1152,7 +1152,9 @@ Nuts for leadscrews.
 | ```leadnut_hole_dia(type)``` | The diameter of the screw holes |
 | ```leadnut_hole_pitch(type)``` | The radia pitch of the screw holes |
 | ```leadnut_holes(type)``` | The number of screw holes |
+| ```leadnut_lead(type)``` | Screw lead |
 | ```leadnut_od(type)``` | Outer diameter of the shank |
+| ```leadnut_pitch(type)``` | Screw pitch |
 | ```leadnut_screw(type)``` | The type of the fixing screws |

 ### Functions
@ -2281,14 +2283,20 @@ Steel rods and studding with chamfered ends.
 ### Modules
 | Module | Description |
 |:--- |:--- |
-| ```rod(d , l)``` | Draw a smooth rod with specified length and diameter |
-| ```studding(d , l)``` | Draw a threaded rod with specified length and diameter |
+| ```leadscrew(d , l, lead, starts, center = true)``` | Draw a leadscrew with specified diameter, length, lead and number of starts |
+| ```rod(d , l, center = true)``` | Draw a smooth rod with specified diameter and length |
+| ```studding(d , l, center = true)``` | Draw a threaded rod with specified diameter and length |

 ![rod](tests/png/rod.png)

 ### Vitamins
 | Qty | Module call | BOM entry |
 | ---:|:--- |:---|
+|   1 | ```leadscrew(10, 80, 8, 4)``` |  Leadscrew 10 x 80mm, 8mm lead, 4 starts |
+|   1 | ```leadscrew(12, 80, 12, 4)``` |  Leadscrew 12 x 80mm, 12mm lead, 4 starts |
+|   1 | ```leadscrew(16, 80, 16, 4)``` |  Leadscrew 16 x 80mm, 16mm lead, 4 starts |
+|   1 | ```leadscrew(6, 80, 2, 1)``` |  Leadscrew 6 x 80mm, 2mm lead, 1 starts |
+|   1 | ```leadscrew(8, 80, 8, 4)``` |  Leadscrew 8 x 80mm, 8mm lead, 4 starts |
 |   1 | ```rod(10, 80)``` |  Smooth rod 10mm x 80mm |
 |   1 | ```rod(12, 80)``` |  Smooth rod 12mm x 80mm |
 |   1 | ```rod(16, 80)``` |  Smooth rod 16mm x 80mm |
@ -2358,17 +2366,17 @@ Machine screws and wood screws with various head styles.
 | Qty | Module call | BOM entry |
 | ---:|:--- |:---|
 |   1 | ```screw(No632_pan_screw, 30)``` |  Screw 6-32 pan x 30mm |
-|   1 | ```screw(M2_cap_screw, 25)``` |  Screw M2 cap x 25mm |
-|   1 | ```screw(M2_cs_cap_screw, 25)``` |  Screw M2 cs cap x 25mm |
-|   1 | ```screw(M2p5_cap_screw, 25)``` |  Screw M2.5 cap x 25mm |
-|   1 | ```screw(M2p5_pan_screw, 30)``` |  Screw M2.5 pan x 30mm |
-|   1 | ```screw(M3_cap_screw, 25)``` |  Screw M3 cap x 25mm |
-|   1 | ```screw(M3_cs_cap_screw, 25)``` |  Screw M3 cs cap x 25mm |
-|   1 | ```screw(M3_dome_screw, 25)``` |  Screw M3 dome x 25mm |
+|   1 | ```screw(M2_cap_screw, 10)``` |  Screw M2 cap x 10mm |
+|   1 | ```screw(M2_cs_cap_screw, 10)``` |  Screw M2 cs cap x 10mm |
+|   1 | ```screw(M2p5_cap_screw, 10)``` |  Screw M2.5 cap x 10mm |
+|   1 | ```screw(M2p5_pan_screw, 10)``` |  Screw M2.5 pan x 10mm |
+|   1 | ```screw(M3_cap_screw, 10)``` |  Screw M3 cap x 10mm |
+|   1 | ```screw(M3_cs_cap_screw, 10)``` |  Screw M3 cs cap x 10mm |
+|   1 | ```screw(M3_dome_screw, 10)``` |  Screw M3 dome x 10mm |
 |   1 | ```screw(M3_grub_screw, 6)``` |  Screw M3 grub x 6mm |
-|   1 | ```screw(M3_hex_screw, 30)``` |  Screw M3 hex x 30mm |
-|   1 | ```screw(M3_low_cap_screw, 25)``` |  Screw M3 low cap x 25mm |
-|   1 | ```screw(M3_pan_screw, 30)``` |  Screw M3 pan x 30mm |
+|   1 | ```screw(M3_hex_screw, 10)``` |  Screw M3 hex x 10mm |
+|   1 | ```screw(M3_low_cap_screw, 10)``` |  Screw M3 low cap x 10mm |
+|   1 | ```screw(M3_pan_screw, 10)``` |  Screw M3 pan x 10mm |
 |   1 | ```screw(M4_cap_screw, 25)``` |  Screw M4 cap x 25mm |
 |   1 | ```screw(M4_cs_cap_screw, 25)``` |  Screw M4 cs cap x 25mm |
 |   1 | ```screw(M4_dome_screw, 25)``` |  Screw M4 dome x 25mm |
@ -2383,8 +2391,8 @@ Machine screws and wood screws with various head styles.
 |   1 | ```screw(M6_pan_screw, 30)``` |  Screw M6 pan x 30mm |
 |   1 | ```screw(M8_cap_screw, 35)``` |  Screw M8 cap x 35mm |
 |   1 | ```screw(M8_hex_screw, 30)``` |  Screw M8 hex x 30mm |
-|   1 | ```screw(No2_screw, 30)``` |  Screw No2 pan wood x 30mm |
-|   1 | ```screw(No4_screw, 30)``` |  Screw No4 pan wood x 30mm |
+|   1 | ```screw(No2_screw, 10)``` |  Screw No2 pan wood x 10mm |
+|   1 | ```screw(No4_screw, 10)``` |  Screw No4 pan wood x 10mm |
 |   1 | ```screw(No6_cs_screw, 30)``` |  Screw No6 cs wood x 30mm |
 |   1 | ```screw(No6_screw, 30)``` |  Screw No6 pan wood x 30mm |

@ -2672,7 +2680,7 @@ NEMA stepper motor model.
 | ```NEMA_length(type)``` | Body length |
 | ```NEMA_radius(type)``` | End cap radius |
 | ```NEMA_shaft_dia(type)``` | Shaft diameter |
-| ```NEMA_shaft_length(type)``` | Shaft length above the face |
+| ```NEMA_shaft_length(type)``` | Shaft length above the face, if a list then a leadscrew: length, lead, starts |
 | ```NEMA_width(type)``` | Width of the square face |

 ### Functions
@ -2684,7 +2692,7 @@ NEMA stepper motor model.
 ### Modules
 | Module | Description |
 |:--- |:--- |
-| ```NEMA(type)``` | Draw specified NEMA stepper motor |
+| ```NEMA(type, shaft_angle = 0)``` | Draw specified NEMA stepper motor |
 | ```NEMA_outline(type)``` | 2D outline |
 | ```NEMA_screw_positions(type, n = 4)``` | Positions children at the screw holes |
 | ```NEMA_screws(type, screw, n = 4, screw_length = 8, earth = undef)``` | Place screws and optional earth tag |
@ -4431,6 +4439,8 @@ Maths utilities for manipulating vectors and matrices.
 ### Functions
 | Function | Description |
 |:--- |:--- |
+| ```angle_between(v1, v2)``` | Return the angle between two vectors |
+| ```euler(R)``` | Convert a rotation matrix to a Euler rotation vector. |
 | ```identity(n, x = 1)``` | Construct an arbitrary size identity matrix |
 | ```reverse(v)``` | Reverse a vector |
 | ```rotate(a, v)``` | Generate a 4x4 rotation matrix, ```a``` can be a vector of three angles or a single angle around ```z```, or around axis ```v``` |
@ -4441,6 +4451,7 @@ Maths utilities for manipulating vectors and matrices.
 | ```transpose(m)``` | Transpose an arbitrary size matrix |
 | ```unit(v)``` | Convert ```v``` to a unit vector |
 | ```vec3(v)``` | Return a 3 vector with the first three elements of ```v``` |
+| ```vec4(v)``` | Return a 4 vector with the first three elements of ```v``` |

 ![maths](tests/png/maths.png)

@ -4607,9 +4618,12 @@ An additional twist around the path can be specified. If the path is closed this
 | ```after(path1, path2)``` | Translate ```path2``` so its start meets the end of ```path1``` and then concatenate |
 | ```arc_points(r, a = [90, 0, 180], al = 90)``` | Generate the points of a circular arc |
 | ```before(path1, path2)``` | Translate ```path1``` so its end meets the start of ```path2``` and then concatenate |
-| ```circle_points(r = 1, z = 0)``` | Generate the points of a circle, setting z makes a single turn spiral |
+| ```cap(facets, segment = 0, end)``` | Create the mesh for an end cap |
+| ```circle_points(r = 1, z = 0, dir = -1)``` | Generate the points of a circle, setting z makes a single turn spiral |
+| ```helical_twist_per_segment(r, pitch, sides)``` | Calculate the twist around Z that rotate_from_to() introduces |
 | ```path_length(path, i = 0, length = 0)``` | Calculated the length along a path |
 | ```rectangle_points(w, h)``` | Generate the points of a rectangle |
+| ```skin_faces(points, npoints, facets, loop, offset = 0)``` | Create the mesh for the swept volume without end caps |
 | ```sweep(path, profile, loop = false, twist = 0)``` | Generate the point list and face list of the swept volume |

 ### Modules
@ -4620,6 +4634,50 @@ An additional twist around the path can be specified. If the path is closed this
 ![sweep](tests/png/sweep.png)


+<a href="#top">Top</a>
+
+---
+<a name="Thread"></a>
+## Thread
+Utilities for making threads with sweep. They can be used to model screws, nuts, studding, leadscrews, etc, and also to make printed threads.
+
+The ends can be tapered, flat or chamfered by setting the ```top``` and ```bot``` parameters to -1 for tapered, 0 for a flat cut and positive to
+specify a chamfer angle.
+
+Threads are by default solid, so the male version is wrapped around a cylinder and the female inside a tube. This can be suppressed to just get the helix, for
+example to make a printed pot with a screw top lid.
+
+Threads with a typical 60 degree angle appear too bright with OpenSCAD's primitive lighting model as they face towards the lights more than the top and sides of
+a cylinder. To get around this a colour can be passed to thread that is used to colour the cylinder and then toned down to colour the helix.
+
+Making the ends requires a CGAL intersection, which make threads relatively slow. For this reason they are generally disabled when using the GUI but can
+be enabled by setting ```$show_threads``` to ```true```. When the tests are run, by default, threads are enabled only for things that feature them like screws.
+This behaviour can be changed by setting a ```SHOW_THREADS``` environment variable to ```false``` to disable all threads and ```true``` to enable all threads.
+The same variable also affects the generation of assembly diagrams.
+
+Threads obey the $fn, $fa, $fs variables.
+
+
+[utils/thread.scad](utils/thread.scad) Implementation.
+
+[tests/thread.scad](tests/thread.scad) Code for this example.
+
+### Functions
+| Function | Description |
+|:--- |:--- |
+| ```metric_coarse_pitch(d)``` | Convert metric diameter to pitch |
+| ```thread_profile(h, crest, angle, overlap = 0.1)``` | Create thread profile path |
+
+### Modules
+| Module | Description |
+|:--- |:--- |
+| ```female_metric_thread(d, pitch, length, center = true, top = -1, bot = -1, colour = undef)``` | Create female thread with metric profile |
+| ```male_metric_thread(d, pitch, length, center = true, top = -1, bot = -1, solid = true, colour = undef)``` | Create male thread with metric profile |
+| ```thread(dia, pitch, length, profile, center = true, top = -1, bot = -1, starts = 1, solid = true, female = false, colour = undef)``` | Create male or femail thread, ends can be tapered, chamfered or square |
+
+![thread](tests/png/thread.png)
+
+
 <a href="#top">Top</a>

 ---
--- a/scripts/openscad.py
+++ b/scripts/openscad.py
@ -24,7 +24,7 @@ from __future__ import print_function

 import subprocess, sys

-def _run(args, silent):
+def run_list(args, silent = False):
    cmd = ["openscad"] + args
    if not silent:
        for arg in cmd:
@ -39,7 +39,7 @@ def _run(args, silent):
        sys.exit(rc)

 def run(*args):
-    _run(list(args), False)
+    run_list(list(args), False)

 def run_silent(*args):
-    _run(list(args), True);
+    run_list(list(args), True);
--- a/scripts/options.py
+++ b/scripts/options.py
@ -0,0 +1,49 @@
+#
+# NopSCADlib Copyright Chris Palmer 2020
+# 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/>.
+#
+
+# Set command line options from enviroment variables and check if they have changed
+
+import json, os, deps
+
+def check_options(dir = '.'):
+    global options, options_mtime
+    options = { "show_threads": str(os.getenv("SHOW_THREADS")) }
+    options_fname = dir + '/options.json'
+    try:
+        with open(options_fname) as json_file:
+            last_options = json.load(json_file)
+    except:
+        last_options = {}
+    if last_options != options:
+        with open(options_fname, 'w') as outfile:
+            json.dump(options, outfile, indent = 4)
+    options_mtime = deps.mtime(options_fname)
+
+def have_changed(changed, target):
+    if not changed and deps.mtime(target) < options_mtime:
+        return "command line options changed"
+    return changed
+
+def list():
+    result = []
+    for name in options.keys():
+        value = options[name]
+        if value != 'None':
+            result.append('-D$' + name + '=' + value)
+    return result
--- a/scripts/tests.py
+++ b/scripts/tests.py
@ -27,6 +27,7 @@ import openscad
 import subprocess
 import bom
 import times
+import options
 import time
 import json
 import shutil
@ -96,6 +97,7 @@ def tests(tests):
    index = {}
    bodies = {}
    times.read_times()
+    options.check_options(deps_dir)
    #
    # Make cover pic if does not exist as very slow. Delete it to force an update.
    #
@ -190,11 +192,12 @@ def tests(tests):
            oldest = png_name if mtime(png_name) < mtime(bom_name) else bom_name
            changed = check_deps(oldest, dname)
            changed = times.check_have_time(changed, scad_name)
+            changed = options.have_changed(changed, oldest)
            if changed:
                print(changed)
                t = time.time()
                tmp_name = 'tmp.png'
-                openscad.run("-D", "$bom=2", colour_scheme, "--projection=p", "--imgsize=%d,%d" % (w, h), "--camera=0,0,0,70,0,315,500", "--autocenter", "--viewall", "-d", dname, "-o", tmp_name, scad_name);
+                openscad.run_list(options.list() + ["-D$bom=2", colour_scheme, "--projection=p", "--imgsize=%d,%d" % (w, h), "--camera=0,0,0,70,0,315,500", "--autocenter", "--viewall", "-d", dname, "-o", tmp_name, scad_name]);
                times.add_time(scad_name, t)
                do_cmd(["magick", tmp_name, "-trim", "-resize", "1000x600", "-bordercolor", background, "-border", "10", tmp_name])
                update_image(tmp_name, png_name)
--- a/scripts/views.py
+++ b/scripts/views.py
@ -28,6 +28,7 @@ import openscad
 from tests import do_cmd, update_image, colour_scheme, background
 import time
 import times
+import options
 from deps import *
 import os
 import json
@ -102,6 +103,7 @@ def views(target, do_assemblies = None):
        os.makedirs(deps_dir)

    times.read_times(target_dir)
+    options.check_options(deps_dir)
    bounds_fname = top_dir + 'stls/bounds.json'
    with open(bounds_fname) as json_file:
        bounds_map = json.load(json_file)
@ -163,11 +165,12 @@ def views(target, do_assemblies = None):
                                            png_name = png_name.replace('_assembly', '_assembled')
                                        changed = check_deps(png_name, dname)
                                        changed = times.check_have_time(changed, png_name)
+                                        changed = options.have_changed(changed, png_name)
                                        tmp_name = 'tmp.png'
                                        if changed:
                                            print(changed)
                                            t = time.time()
-                                            openscad.run("-D$show_threads=1", "-D$pose=1", "-D$explode=%d" % explode, colour_scheme, "--projection=p", "--imgsize=4096,4096", "--autocenter", "--viewall", "-d", dname, "-o", tmp_name, png_maker_name);
+                                            openscad.run_list(options.list() + ["-D$pose=1", "-D$explode=%d" % explode, colour_scheme, "--projection=p", "--imgsize=4096,4096", "--autocenter", "--viewall", "-d", dname, "-o", tmp_name, png_maker_name]);
                                            times.add_time(png_name, t)
                                            do_cmd(["magick", tmp_name, "-trim", "-resize", "1004x1004", "-bordercolor", background, "-border", "10", tmp_name])
                                            update_image(tmp_name, png_name)
--- a/tests/inserts.scad
+++ b/tests/inserts.scad
@ -37,4 +37,5 @@ module inserts() {
 }

 if($preview)
+    let($show_threads = true)
        inserts();
--- a/tests/leadnuts.scad
+++ b/tests/leadnuts.scad
@ -27,4 +27,5 @@ module leadnuts()
        leadnut(leadnuts[$i]);

 if($preview)
+    let($show_threads = true)
        leadnuts();
--- a/tests/maths.scad
+++ b/tests/maths.scad
@ -56,7 +56,7 @@ module maths() {
    //
    z = [0, 0, 1];
    v = cross(u, z);
-    a = acos(u * z);
+    a = angle_between(u, z);


    l = 20;
@ -64,6 +64,11 @@ module maths() {
        translate_z(l)
            vflip()
                arrow(l);
+
+    //
+    // Test Euler
+    //
+    assert(euler(rotate(r)) == r, "euler() failed");
 }

 rotate(45)
--- a/tests/nuts.scad
+++ b/tests/nuts.scad
@ -48,4 +48,5 @@ module nuts() {
 }

 if($preview)
+    let($show_threads = true)
        nuts();
--- a/tests/opengrab.scad
+++ b/tests/opengrab.scad
@ -29,4 +29,5 @@ module opengrab_test() {
 }

 if($preview)
+    let($show_threads = true)
        opengrab_test();
--- a/tests/png/belts.png
+++ b/tests/png/belts.png
--- a/tests/png/blowers.png
+++ b/tests/png/blowers.png
--- a/tests/png/bom.png
+++ b/tests/png/bom.png
--- a/tests/png/box.png
+++ b/tests/png/box.png
--- a/tests/png/butt_box.png
+++ b/tests/png/butt_box.png
--- a/tests/png/components.png
+++ b/tests/png/components.png
--- a/tests/png/corner_block.png
+++ b/tests/png/corner_block.png
--- a/tests/png/d_connectors.png
+++ b/tests/png/d_connectors.png
--- a/tests/png/displays.png
+++ b/tests/png/displays.png
--- a/tests/png/door_hinge.png
+++ b/tests/png/door_hinge.png
--- a/tests/png/fan_guard.png
+++ b/tests/png/fan_guard.png
--- a/tests/png/fans.png
+++ b/tests/png/fans.png
--- a/tests/png/fixing_block.png
+++ b/tests/png/fixing_block.png
--- a/tests/png/flat_hinge.png
+++ b/tests/png/flat_hinge.png
--- a/tests/png/foot.png
+++ b/tests/png/foot.png
--- a/tests/png/handle.png
+++ b/tests/png/handle.png
--- a/tests/png/iecs.png
+++ b/tests/png/iecs.png
--- a/tests/png/inserts.png
+++ b/tests/png/inserts.png
--- a/tests/png/leadnuts.png
+++ b/tests/png/leadnuts.png
--- a/tests/png/modules.png
+++ b/tests/png/modules.png
--- a/tests/png/nuts.png
+++ b/tests/png/nuts.png
--- a/tests/png/opengrab.png
+++ b/tests/png/opengrab.png
--- a/tests/png/pcb_mount.png
+++ b/tests/png/pcb_mount.png
--- a/tests/png/pcbs.png
+++ b/tests/png/pcbs.png
--- a/tests/png/pillars.png
+++ b/tests/png/pillars.png
--- a/tests/png/psu_shroud.png
+++ b/tests/png/psu_shroud.png
--- a/tests/png/pulleys.png
+++ b/tests/png/pulleys.png
--- a/tests/png/rails.png
+++ b/tests/png/rails.png
--- a/tests/png/ribbon_clamp.png
+++ b/tests/png/ribbon_clamp.png
--- a/tests/png/ring_terminals.png
+++ b/tests/png/ring_terminals.png
--- a/tests/png/rod.png
+++ b/tests/png/rod.png
--- a/tests/png/screw_knob.png
+++ b/tests/png/screw_knob.png
--- a/tests/png/screws.png
+++ b/tests/png/screws.png
--- a/tests/png/socket_box.png
+++ b/tests/png/socket_box.png
--- a/tests/png/spools.png
+++ b/tests/png/spools.png
--- a/tests/png/ssr_shroud.png
+++ b/tests/png/ssr_shroud.png
--- a/tests/png/ssrs.png
+++ b/tests/png/ssrs.png
--- a/tests/png/stepper_motors.png
+++ b/tests/png/stepper_motors.png
--- a/tests/png/thread.png
+++ b/tests/png/thread.png
--- a/tests/png/toggles.png
+++ b/tests/png/toggles.png
--- a/tests/png/veroboard.png
+++ b/tests/png/veroboard.png
--- a/tests/png/washers.png
+++ b/tests/png/washers.png
--- a/tests/rod.scad
+++ b/tests/rod.scad
@ -24,12 +24,21 @@ include <../vitamins/linear_bearings.scad>
 use <../vitamins/rod.scad>

 module rods()
-    layout([for(b = linear_bearings) 2 * bearing_radius(b)]) {
+    layout([for(b = linear_bearings) 2 * bearing_radius(b)]) let(d = bearing_rod_dia(linear_bearings[$i])){

-        rod(bearing_rod_dia(linear_bearings[$i]), 80);
+        rod(d, 80);

        translate([0, 30])
-            studding(bearing_rod_dia(linear_bearings[$i]), 80);
+            studding(d, 80);
+
+        if(d >= 6)
+            translate([0, 60]) {
+                starts = d > 6 ? 4 : 1;
+                pitch = d > 14 ? 4
+                               : d > 10 ? 3 : 2;
+                let($show_threads = true)
+                    leadscrew(d, 80, starts * pitch, starts);
+            }
    }

 if($preview)
--- a/tests/screws.scad
+++ b/tests/screws.scad
@ -25,9 +25,10 @@ for(y = [0 : len(screw_lists) -1])
    for(x = [0 : len(screw_lists[y]) -1]) {
        screw = screw_lists[y][x];
        if(screw) {
-             length = screw_max_thread(screw)
-                    ? screw_longer_than(screw_max_thread(screw) + 5)
-                    : screw_head_type(screw) == hs_grub ? 6 : 30;
+             length = screw_head_type(screw) == hs_grub ? 6
+                    : screw_radius(screw) <= 1.5 ? 10
+                    : screw_max_thread(screw) ? screw_longer_than(screw_max_thread(screw) + 5)
+                    : 30;
            translate([x * 20, y * 20])
                screw(screw, length);
        }
--- a/tests/sweep.scad
+++ b/tests/sweep.scad
@ -44,7 +44,7 @@ knot = [ for(i=[0:.2:359])
           (19*cos(3*i) + 40)*sin(2*i),
            19*sin(3*i) ] ];

-sweep(knot, L_points, loop = true, twist = 0);
+sweep(knot, L_points, loop = true);

 p = transform_points([[0,0,0], [20,0,5], [10,30,4], [0,0,0], [0,0,20]], scale(10));
 n = 100;
--- a/tests/thread.scad
+++ b/tests/thread.scad
@ -0,0 +1,52 @@
+//
+// NopSCADlib Copyright Chris Palmer 2020
+// 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/>.
+//
+include <../core.scad>
+use <../utils/thread.scad>
+
+pitch = 2;
+starts = 4;
+
+profile = thread_profile(pitch / 2, pitch * 0.366, 30);
+
+module threads()
+    for(female = [false, true]) translate([0, female ? -20 : 0]) {
+    length = female ? 8  : 40;
+    dia = female ? 8 : 8 - pitch;
+    colour = female ? brass : silver;
+
+    thread(dia, starts * pitch, length, profile, starts = starts, top = 45, bot = 45, female = female, colour = colour);
+
+    color(colour)
+        translate([20, 0])
+            thread(dia, starts * pitch, length, profile, starts = starts, top = 0, bot = 0, female = female);
+
+    translate([40, 0])
+        thread(dia, starts * pitch, length, profile, starts = starts, top = -1, bot = -1, female = female, colour = colour);
+
+    color(colour)
+        translate([60, 0])
+            thread(dia, 2 * pitch, length, profile, starts = 2, top = -1, bot = -1, female = female);
+
+    color(colour)
+        translate([80, 0])
+            thread(dia, pitch, length, profile, starts = 1, top = -1, bot = -1, female = female);
+}
+
+let($show_threads = true)
+    threads();
--- a/tests/toggles.scad
+++ b/tests/toggles.scad
@ -27,4 +27,5 @@ module toggles()
         toggle(toggles[$i], 3);

 if($preview)
+    let($show_threads = true)
        toggles();
--- a/utils/maths.scad
+++ b/utils/maths.scad
@ -39,9 +39,9 @@ function rotate(a, v) = //! Generate a 4x4 rotation matrix, ```a``` can be a vec
                      sy = sin(av[1]),
                      sz = sin(av[2]))
                          [
-                              [ cy * cz, cz * sx * sy - cx * sz, cx * cz * sy + sx * sz, 0],
-                              [ cy * sz, cx * cz + sx * sy * sz,-cz * sx + cx * sy * sz, 0],
-                              [-sy,      cy * sx,                cx * cy,                0],
+                              [ cy * cz, sx * sy * cz - cx * sz, cx * sy * cz + sx * sz, 0],
+                              [ cy * sz, sx * sy * sz + cx * cz, cx * sy * sz - sx * cz, 0],
+                              [-sy,      sx * cy,                cx * cy,                0],
                              [ 0,       0,                      0,                      1]
                          ]
                : let(s = sin(a),
@ -65,6 +65,7 @@ function scale(v) = let(s = is_list(v) ? v : [v, v, v]) //!  Generate a 4x4 matr
                        ];

 function vec3(v) = [v.x, v.y, v.z]; //! Return a 3 vector with the first three elements of ```v```
+function vec4(v) = [v.x, v.y, v.z, 1]; //! Return a 4 vector with the first three elements of ```v```
 function transform(v, m) = vec3(m * [v.x, v.y, v.z, 1]); //! Apply 4x4 transform to a 3 vector by extending it and cropping it again
 function transform_points(path, m) = [for(p = path) transform(p, m)]; //! Apply transform to a path
 function unit(v) = let(n = norm(v)) n ? v / n : v; //! Convert ```v``` to a unit vector
@ -74,3 +75,11 @@ function transpose(m) = [ for(j = [0 : len(m[0]) - 1]) [ for(i = [0 : len(m) - 1
 function identity(n, x = 1) = [for(i = [0 : n - 1]) [for(j = [0 : n - 1]) i == j ? x : 0] ]; //! Construct an arbitrary size identity matrix

 function reverse(v) = let(n = len(v) - 1) n < 0 ? [] : [for(i = [0 : n]) v[n - i]]; //! Reverse a vector
+
+function angle_between(v1, v2) = acos(v1 * v2 / (norm(v1) * norm(v2))); //! Return the angle between two vectors
+
+// https://www.gregslabaugh.net/publications/euler.pdf
+function euler(R) = let(ay = asin(-R[2][0]), cy = cos(ay)) //! Convert a rotation matrix to a Euler rotation vector.
+    cy ? [ atan2(R[2][1] / cy, R[2][2] / cy), ay, atan2(R[1][0] / cy, R[0][0] / cy) ]
+       : R[2][0] < 0 ? [atan2( R[0][1],  R[0][2]),  180, 0]
+                     : [atan2(-R[0][1], -R[0][2]), -180, 0];
--- a/utils/sweep.scad
+++ b/utils/sweep.scad
@ -62,6 +62,7 @@ function rotate_from_to(a, b) =
 function calculate_twist(A, B) = let(D = transpose3(B) * A) atan2(D[1][0], D[0][0]);
 //
 // Compute a 4x3 matrix to orientate a frame of the sweep given the position and a 3x3 rotation matrix.
+// Note that the rotation matrix is transposed to allow post multiplication.
 //
 function orientate(p, r) =
    let(x = r[0], y = r[1], z = r[2])
@ -79,12 +80,21 @@ function rot3_z(a) =
        [ [ c, -s,  0],
          [ s,  c,  0],
          [ 0,  0,  1] ];
-
 //
 // Calculate the unit tangent at a vertex given the indices before and after. One of these can be the same as i in the case
-// of the start and end of a non closed path.
+// of the start and end of a non closed path. Note that the edges are converted to unit vectors so that their relative lengths
+// don't affect the direction of the tangent.
 //
-function tangent(path, before, i, after) = unit(unit(path[after] - path[i]) - unit(path[before] - path[i]));
+function tangent(path, before, i, after) = unit(unit(path[i] - path[before]) + unit(path[after] - path[i]));
+//
+// Calculate the twist per segment caused by rotate_from_to() instead of a simple Euler rotation around Z.
+//
+function helical_twist_per_segment(r, pitch, sides) = //! Calculate the twist around Z that rotate_from_to() introduces
+    let(step_angle = 360 / sides,
+        lt = 2 * r * sin(step_angle),               // length of tangent between two facets
+        slope = atan(2 * pitch / sides / lt)        // slope of tangents
+       ) step_angle * sin(slope);                   // angle tangent should rotate around z projected onto axis rotate_from_to() uses
+
 //
 // Generate all the surface points of the swept volume.
 //
@ -111,24 +121,28 @@ function skin_points(profile, path, loop, twist = 0) =
            each profile4 * orientate(path[i], rotations[i] * rot3_z(za))
    ];

-function cap(facets, segment = 0) = [for(i = [0 : facets - 1]) segment ? facets * segment + i : facets - 1 - i];
+function cap(facets, segment = 0, end) = //! Create the mesh for an end cap
+    let(reverse = is_undef(end) ? segment : end)
+        [for(i = [0 : facets - 1]) facets * segment + (reverse ? i : facets - 1 - i)];

 function quad(p, a, b, c, d) = norm(p[a] - p[c]) > norm(p[b] - p[d]) ? [[b, c, d], [b, d, a]] : [[a, b, c], [a, c, d]];

-function skin_faces(points, segs, facets, loop) = [for(i = [0 : facets - 1], s = [0 : segs - (loop ? 1 : 2)])
+function skin_faces(points, npoints, facets, loop, offset = 0) = //! Create the mesh for the swept volume without end caps
+    [for(i = [0 : facets - 1], s = [0 : npoints - (loop ? 1 : 2)])
+       let(j = s + offset, k = loop ? (j + 1) % npoints : j + 1)
       each quad(points,
-        s * facets + i,
-        s * facets + (i + 1) % facets,
-       ((s + 1) % segs) * facets + (i + 1) % facets,
-       ((s + 1) % segs) * facets + i)];
+            j * facets + i,
+            j * facets + (i + 1) % facets,
+            k * facets + (i + 1) % facets,
+            k * facets + i)];

 function sweep(path, profile, loop = false, twist = 0) = //! Generate the point list and face list of the swept volume
    let(
-        segments = len(path),
+        npoints = len(path),
        facets = len(profile),
        points = skin_points(profile, path, loop, twist),
-        skin_faces = skin_faces(points, segments, facets, loop),
-        faces = loop ? skin_faces : concat([cap(facets)], skin_faces, [cap(facets, segments - 1)])
+        skin_faces = skin_faces(points, npoints, facets, loop),
+        faces = loop ? skin_faces : concat([cap(facets)], skin_faces, [cap(facets, npoints - 1)])
        ) [points, faces];

 module sweep(path, profile, loop = false, twist = 0) { //! Draw a polyhedron that is the swept volume
@ -141,9 +155,9 @@ function path_length(path, i = 0, length = 0) = //! Calculated the length along
    i >= len(path) - 1 ? length
                       : path_length(path, i + 1, length + norm(path[i + 1] - path[i]));

-function circle_points(r = 1, z = 0) = //! Generate the points of a circle, setting z makes a single turn spiral
+function circle_points(r = 1, z = 0, dir = -1) = //! Generate the points of a circle, setting z makes a single turn spiral
    let(sides = r2sides(r))
-        [for(i = [0 : sides - 1]) let(a = i * 360 / sides) [r * sin(a), r * cos(a), z * a / 360]];
+        [for(i = [0 : sides - 1]) let(a = dir * i * 360 / sides) [r * cos(a), r * sin(a), z * i / sides]];

 function rectangle_points(w, h) = [[-w/2, -h/2, 0], [-w/2, h/2, 0], [w/2, h/2, 0], [w/2, -h/2, 0]]; //! Generate the points of a rectangle

--- a/utils/thread.scad
+++ b/utils/thread.scad
@ -18,69 +18,169 @@
 //

 //
-//! A utilities for making threads with sweep.
+//! Utilities for making threads with sweep. They can be used to model screws, nuts, studding, leadscrews, etc, and also to make printed threads.
+//!
+//! The ends can be tapered, flat or chamfered by setting the ```top``` and ```bot``` parameters to -1 for tapered, 0 for a flat cut and positive to
+//! specify a chamfer angle.
+//!
+//! Threads are by default solid, so the male version is wrapped around a cylinder and the female inside a tube. This can be suppressed to just get the helix, for
+//! example to make a printed pot with a screw top lid.
+//!
+//! Threads with a typical 60 degree angle appear too bright with OpenSCAD's primitive lighting model as they face towards the lights more than the top and sides of
+//! a cylinder. To get around this a colour can be passed to thread that is used to colour the cylinder and then toned down to colour the helix.
+//!
+//! Making the ends requires a CGAL intersection, which make threads relatively slow. For this reason they are generally disabled when using the GUI but can
+//! be enabled by setting ```$show_threads``` to ```true```. When the tests are run, by default, threads are enabled only for things that feature them like screws.
+//! This behaviour can be changed by setting a ```SHOW_THREADS``` environment variable to ```false``` to disable all threads and ```true``` to enable all threads.
+//! The same variable also affects the generation of assembly diagrams.
+//!
+//! Threads obey the $fn, $fa, $fs variables.
 //
 include <../core.scad>
 use <sweep.scad>
 use <maths.scad>
+use <tube.scad>

-function thread_profile(h, crest, angle) = //! Create thread profile path
-    let(base = crest + 2 * h * tan(angle / 2))
-        [[-base / 2, 0, 0], [-crest / 2, h, 0], [crest / 2, h, 0], [base / 2, 0, 0]];
+thread_colour_factor = 0.8; // 60 degree threads appear too bright due to the angle facing the light sources

-module male_thread(pitch, minor_d, length, profile, taper_top = true, center = true, solid = true) { //! Create male thread
-    turns = length / pitch + (taper_top ? 0 : 1);
-    r = minor_d / 2;
-    sides = r2sides(r);
-    h = max([for(p = profile) p.y]);
-    final = (turns - 1) * sides;
-    path = [for(i = [0 : sides * turns],
-                R = i < sides ? r - h + h * i / sides
-                    : i > final && taper_top ? r - h * (i - final) / sides : r,
-                a = i * 360 / sides)
-                    [R * sin(-a), R * cos(-a), pitch * a / 360]];
-    t = atan(pitch / sides / (r * cos(225 / sides)));
-    translate_z(center ? -length / 2 : 0) {
+function thread_profile(h, crest, angle, overlap = 0.1) = //! Create thread profile path
+    let(base = crest + 2 * (h + overlap) * tan(angle / 2))
+        [[-base / 2, -overlap, 0], [-crest / 2, h, 0], [crest / 2, h, 0], [base / 2, -overlap, 0]];
+
+module thread(dia, pitch, length, profile, center = true, top = -1, bot = -1, starts = 1, solid = true, female = false, colour = undef) { //! Create male or femail thread, ends can be tapered, chamfered or square
+    //
+    // Apply colour if defined
+    //
+    module colour(factor) if(is_undef(colour)) children(); else color(colour * factor) children();
+    //
+    // Compress the profile to compensate for it being tilted by the helix angle
+    //
+    scale = cos(atan(pitch / (PI * dia)));
+    sprofile = [for(p = profile) [p.x * scale, p.y, p.z]];
+    //
+    // Extract some properties from the profile, perhaps they should be stored in it.
+    //
+    h = max([for(p = sprofile) p.y]);
+    maxx = max([for(p = sprofile) p.x]);
+    minx = min([for(p = sprofile) p.x]);
+    crest_xmax = max([for(p = sprofile) if(p.x != maxx) p.x]);
+    crest_xmin = min([for(p = sprofile) if(p.x != minx) p.x]);
+    //
+    // If the ends don't taper we need an extra half turn past the ends to be cropped horizontally.
+    //
+    extra_top = top < 0 ? 0 : -minx / pitch;
+    extra_bot = bot < 0 ? 0 :  maxx / pitch;
+    turns = length / pitch + extra_top + extra_bot;
+    //
+    // Generate the helix path, possibly with tapered ends
+    //
+    dir = female ? 1 : -1;
+    r = dia / 2;
+    sides = r2sides4n(r);
+    step_angle = 360 / sides;
+    segs = ceil(turns * sides);
+    leadin = ceil(sides / starts);
+    final = floor(turns * sides) - leadin;
+    path = [for(i = [0 : segs],
+                R = i < leadin && bot < 0 ? r + dir * (h - h * i / leadin)
+                  : i > final  && top < 0 ? r + dir * h * (i - final) / leadin : r,
+                a = i * step_angle - 360 * extra_bot)
+                    [R * cos(a), R * sin(a), a * pitch / 360]];
+    //
+    // Generate the skin vertices
+    //
+    facets = len(profile);
+    twist  = helical_twist_per_segment(r, pitch, sides);
+    //
+    // For female threads we need to invert the profile
+    //
+    iprofile = female ? reverse([for(p = sprofile) [p.x, -p.y, 0]]) : sprofile;
+    //
+    // If the bottom is tapered then the twist will be greater, so pre-twist the profile to get the straight bit at the correct angle
+    //
+    rprofile = bot < 0 ? transform_points(iprofile, rotate(-dir * (helical_twist_per_segment(r - h, pitch, sides) - twist) * sides / PI))
+                       : iprofile;
+    points = skin_points(rprofile, path, false, twist * segs);
+    //
+    // To form the ends correctly we need to use intersection but it is very slow with the full thread so we just
+    // intersect the start and the end and sweep the rest outside of the intersection.
+    //
+    top_chamfer_h = (top > 0 ? h * tan(top) : 0);
+    bot_chamfer_h = (bot > 0 ? h * tan(bot) : 0);
+    top_overlap = max( maxx, top_chamfer_h - crest_xmin) / pitch;
+    bot_overlap = max(-minx, bot_chamfer_h + crest_xmax) / pitch;
+    start =      ceil(sides * (bot_overlap + extra_bot));
+    end = segs - ceil(sides * (top_overlap + extra_top));
+
+    start_skin_faces  = skin_faces(points, start + 1,            facets, false);
+    middle_skin_faces = skin_faces(points, end - start + 1,      facets, false, start);
+    end_skin_faces    = skin_faces(points, segs - end + 1,       facets, false, end);
+
+    start_faces  = concat([cap(facets)              ], start_skin_faces,  [cap(facets, start)]);
+    middle_faces = concat([cap(facets, start, false)], middle_skin_faces, [cap(facets, end)]);
+    end_faces    = concat([cap(facets, end,   false)], end_skin_faces,    [cap(facets, segs)]);
+
+    overlap = - profile[0].y;
+    translate_z((center ? -length / 2 : 0)) {
+        ends_faces = concat(start_faces, end_faces);
+        for(i = [0 : starts - 1])
+            colour(thread_colour_factor)
+                rotate(360 * i / starts + (female ? 180 / starts : 0)) {
                    render() intersection() {
-            sweep(path, profile, twist = t * sides * turns);
-            cylinder(d = minor_d + 5, h = length);
+                        polyhedron(points, ends_faces);
+
+                        len = length - 2 * eps;
+                        rotate_extrude()
+                            if(female) {
+                                difference() {
+                                    translate([0, eps])
+                                        square([r + h + overlap, len]);
+
+                                    if(top_chamfer_h)
+                                        polygon([[0, length], [r, length], [r - h, length - top_chamfer_h], [0, length - top_chamfer_h]]);
+
+                                    if(bot_chamfer_h)
+                                        polygon([[0, 0], [r, 0], [r - h, bot_chamfer_h], [0, bot_chamfer_h]]);
                               }
+                            }
+                            else
+                                difference() {
+                                    hull() {
+                                        translate([0, eps])
+                                            square([r, len]);
+
+                                        translate([0, bot_chamfer_h])
+                                            square([r + h + overlap, len - top_chamfer_h - bot_chamfer_h]);
+                                    }
+                                    if(!solid)
+                                        square([r - overlap, length]);
+                                }
+                    }
+
+                    polyhedron(points, middle_faces);
+                }
+
        if(solid)
+            colour(1)
                rotate(90)
-                cylinder(d = minor_d + eps, h = length);
+                    if(female)
+                        tube(or = r + (top < 0 || bot < 0 ? h : 0) + 2 * overlap, ir = r, h = length, center = false);
+                    else
+                        cylinder(d = dia, h = length);
    }
 }

-module female_thread(pitch, outer_d, length, profile, taper_top = true, center = true) { //! Create female thread
-    turns = length / pitch + (taper_top ? 0 : 1);
-    r = outer_d / 2;
-    sides = r2sides(r);
-    h = max([for(p = profile) p.y]);
-    final = (turns - 1) * sides;
-    path = [for(i = [0 : sides * turns],
-                R = i < sides ? r + h - h * i / sides
-                    : i > final && taper_top ? r + h * (i - final) / sides : r,
-                a = i * 360 / sides)
-                    [R * sin(-a), R * cos(-a), pitch * a / 360]];
-    t = atan(pitch / sides / (r * cos(225 / sides)));
-    translate_z(center ? -length / 2 : 0) {
-        render() intersection() {
-            sweep(path, reverse([for(p = profile) [p.x, -p.y, 0]]), twist = t * sides * turns);
-            cylinder(d = outer_d + 5, h = length);
-        }
-    }
+module male_metric_thread(d, pitch, length, center = true, top = -1, bot = -1, solid = true, colour = undef) { //! Create male thread with metric profile
+    H = pitch * sqrt(3) / 2;
+    h = 5 * H / 8;
+    minor_d = d - 2 * h;
+    thread(minor_d, pitch, length, thread_profile(h, pitch / 8, 60), center, top, bot, solid = solid, colour = colour);
 }

-module male_metric_thread(d, pitch, length, taper_top = true, center = true) { //! Create male thread with metric profile
-    h = sqrt(3) / 2 * pitch;
-    minor_d = d - 5 * h / 4;
-    male_thread(pitch, minor_d, length, thread_profile((d - minor_d) / 2, pitch / 8, 60), taper_top, center);
-}
-
-module female_metric_thread(d, pitch, length, taper_top = true, center = true) { //! Create male thread with metric profile
-    h = sqrt(3) / 2 * pitch;
-    outer_d = d + 5 * h / 4;
-    male_thread(pitch, outer_d, length, thread_profile((outer_d - d) / 2, pitch / 8, 60), taper_top, center);
+module female_metric_thread(d, pitch, length, center = true, top = -1, bot = -1, colour = undef) { //! Create female thread with metric profile
+    H = pitch * sqrt(3) / 2;
+    h = 5 * H / 8;
+    thread(d, pitch, length, thread_profile(h, pitch / 4, 60), center, top, bot, solid = false, female = true, colour = colour);
 }

 function metric_coarse_pitch(d) //! Convert metric diameter to pitch
@ -106,9 +206,12 @@ function metric_coarse_pitch(d) //! Convert metric diameter to pitch
                  0,
                  0,
                  1.75, // M12
+                  0,
+                  0,
+                  0,
+                  0,    // M14
+                  0,
+                  0,
+                  0,
+                  2.0,  // M16
                 ][d * 2 - 4];
-
-male_metric_thread(3, 0.5, 25);
-
-translate([10, 0])
-male_metric_thread(8, 1.25, 30);
--- a/vitamins/d_connector.scad
+++ b/vitamins/d_connector.scad
@ -52,22 +52,25 @@ module d_pillar() { //! Draw a pillar for a D-connector
    height = 4.5;
    screw = 2.5;
    screw_length = 8;
+    pitch = metric_coarse_pitch(screw);

    translate_z(-screw_length)
        if(show_threads)
-            color(d_pillar_color * 0.7)
-                male_metric_thread(screw, metric_coarse_pitch(screw), screw_length, false, false);
+            male_metric_thread(screw, pitch, screw_length, false, top = 0, colour = d_pillar_color);
        else
            color(d_pillar_color)
                cylinder(d = screw, h = screw_length + 1);

-    color(d_pillar_color)
+    color(d_pillar_color) {
        linear_extrude(height = height)
            difference() {
                circle(r = rad, $fn = 6);
                circle(d = screw);
            }
        }
+    if(show_threads)
+        female_metric_thread(screw, pitch, height, false, colour = d_pillar_color);
+}

 module d_plug(type, socket = false, pcb = false, idc = false) { //! Draw specified D plug, which can be IDC, PCB or plain solder bucket
    hole_r = 3.05 / 2;
--- a/vitamins/insert.scad
+++ b/vitamins/insert.scad
@ -22,6 +22,7 @@
 //
 include <../core.scad>
 use <../utils/quadrant.scad>
+use <../utils/thread.scad>

 function insert_length(type)         = type[1]; //! Length
 function insert_outer_d(type)        = type[2]; //! Outer diameter at the top
@ -45,9 +46,9 @@ module insert(type) { //! Draw specified insert

    vitamin(str("insert(", type[0], "): Heatfit insert M", insert_screw_diameter(type)));
    $fn = 64;
-    explode(20, offset =[0, 0, -5]) color(brass) translate_z(eps) {
-        vflip(){
-            r1 = insert_screw_diameter(type) / 2;
+    thread_d = insert_screw_diameter(type);
+    explode(20, offset =[0, 0, -5]) translate_z(eps) vflip() {
+        r1 = thread_d / 2;
        r2 = insert_barrel_d(type) / 2;
        r3 = insert_ring3_d(type) / 2;
        r4 = insert_ring2_d(type) / 2;
@ -56,6 +57,7 @@ module insert(type) { //! Draw specified insert
        h2 = ring1_h + gap;
        h3 = ring1_h + gap + ring2_h;
        h4 = ring1_h + gap + ring2_h + gap;
+        color(brass)
            rotate_extrude()
                polygon([
                    [r1, 0],
@ -72,7 +74,9 @@ module insert(type) { //! Draw specified insert
                    [r5, h1],
                    [r5, 0],
                ]);
-        }
+
+        if(show_threads)
+            female_metric_thread(thread_d, metric_coarse_pitch(thread_d), length, center = false, colour = brass);
    }
 }

--- a/vitamins/leadnut.scad
+++ b/vitamins/leadnut.scad
@ -21,7 +21,8 @@
 //! Nuts for leadscrews.
 //
 include <../core.scad>
-include <../utils/tube.scad>
+use <../utils/tube.scad>
+use <../utils/thread.scad>

 function leadnut_bore(type)          = type[2];     //! Thread size
 function leadnut_od(type)            = type[3];     //! Outer diameter of the shank
@ -33,6 +34,8 @@ function leadnut_holes(type)         = type[8];     //! The number of screw hole
 function leadnut_hole_dia(type)      = type[9];     //! The diameter of the screw holes
 function leadnut_hole_pitch(type)    = type[10];    //! The radia pitch of the screw holes
 function leadnut_screw(type)         = type[11];    //! The type of the fixing screws
+function leadnut_pitch(type)         = type[12];    //! Screw pitch
+function leadnut_lead(type)          = type[13];    //! Screw lead

 function leadnut_shank(type)         = leadnut_height(type) - leadnut_flange_t(type) - leadnut_flange_offset(type); //! The length of the shank below the flange

@ -47,11 +50,18 @@ module leadnut_screw_positions(type) { //! Position children at the screw holes

 module leadnut(type) { //! Draw specified leadnut
    vitamin(str("leadnut(", type[0], "): ", type[1]));
-    bore_r = (leadnut_bore(type) + 0.5) / 2;
+    bore_d = leadnut_bore(type);
+    bore_r = bore_d / 2;
+    h = leadnut_height(type);
+    pitch = leadnut_pitch(type);
+    lead = leadnut_lead(type);

    color("dimgrey") vflip()
        translate_z(-leadnut_flange_offset(type) - leadnut_flange_t(type)) {
-            tube(or = leadnut_od(type) / 2, ir = bore_r, h = leadnut_height(type), center = false);
+            tube(or = leadnut_od(type) / 2, ir = bore_r, h = h, center = false);
+
+            if(show_threads)
+                thread(bore_d, lead, h, thread_profile(pitch / 2, pitch * 0.366, 30), false, starts = lead / pitch, female = true, solid = false);

            translate_z(leadnut_flange_offset(type))
                linear_extrude(height = leadnut_flange_t(type))
--- a/vitamins/leadnuts.scad
+++ b/vitamins/leadnuts.scad
@ -17,8 +17,8 @@
 // If not, see <https://www.gnu.org/licenses/>.
 //

-LSN8x2 = ["LSN8x2", "Leadscrew nut 8 x 2",          8, 10.2, 15, 22,   3.5, 1.5, 4, 3.5, 8,       M3_cap_screw];
-LSN8x8 = ["LSN8x8", "Leadscrew nut 8 x 8 RobotDigg",8, 12.75,19, 25.4, 4.1, 0,   3, 3.5, 19.05/2, M3_cap_screw];
+LSN8x2 = ["LSN8x2", "Leadscrew nut 8 x 2",          8, 10.2, 15, 22,   3.5, 1.5, 4, 3.5, 8,       M3_cap_screw, 2, 2];
+LSN8x8 = ["LSN8x8", "Leadscrew nut 8 x 8 RobotDigg",8, 12.75,19, 25.4, 4.1, 0,   3, 3.5, 19.05/2, M3_cap_screw, 2, 8];

 leadnuts = [LSN8x2, LSN8x8];

--- a/vitamins/nut.scad
+++ b/vitamins/nut.scad
@ -26,6 +26,8 @@ include <../core.scad>
 use <washer.scad>
 use <screw.scad>
 use <../utils/rounded_cylinder.scad>
+use <../utils/thread.scad>
+use <../utils/tube.scad>
 brass_colour = brass;

 function nut_size(type)       = type[1];        //! Diameter of the corresponding screw
@ -37,7 +39,8 @@ function nut_trap_depth(type) = type[6];        //! Depth of nut trap
 function nut_flat_radius(type) = nut_radius(type) * cos(30); //! Radius across the flats

 module nut(type, nyloc = false, brass = false, nylon = false) { //! Draw specified nut
-    hole_rad  = nut_size(type) / 2;
+    thread_d = nut_size(type);
+    hole_rad  = thread_d / 2;
    outer_rad = nut_radius(type);
    thickness = nut_thickness(type);
    nyloc_thickness = nut_thickness(type, true);
@ -45,18 +48,29 @@ module nut(type, nyloc = false, brass = false, nylon = false) { //! Draw specifi
    vitamin(str("nut(", type[0], arg(nyloc, false, "nyloc"), arg(brass, false, "brass"), arg(nylon, false, "nylon"),
                   "): Nut M", nut_size(type), " x ", thickness, "mm ", desc));

-    explode(nyloc ? 10 : 0)
-        color(brass ? brass_colour : nylon ? grey30: grey70) {
+    colour = brass ? brass_colour : nylon ? grey30: grey70;
+    explode(nyloc ? 10 : 0) {
+        color(colour) {
            linear_extrude(height = thickness)
                difference() {
                    circle(outer_rad, $fn = 6);

                    circle(hole_rad);
                }
+
            if(nyloc)
                translate_z(-eps)
                    rounded_cylinder(r = outer_rad * cos(30) , h = nyloc_thickness, r2 = (nyloc_thickness - thickness) / 2, ir = hole_rad);
        }
+
+        if(show_threads)
+            female_metric_thread(thread_d, metric_coarse_pitch(thread_d), thickness, center = false, colour = colour);
+
+        if(nyloc)
+            translate_z(thickness)
+                color("royalblue")
+                    tube(or = thread_d / 2 + eps, ir = (thread_d * 0.8) / 2, h = (nyloc_thickness - thickness) * 0.8, center = false);
+    }
    if($children)
        translate_z(nut_thickness(type, nyloc))
            children();
@ -73,7 +87,8 @@ module nut_and_washer(type, nyloc) { //! Draw nut with corresponding washer
 }

 module wingnut(type) { //! Draw a wingnut
-    hole_rad  = nut_size(type) / 2;
+    thread_d = nut_size(type);
+    hole_rad  = thread_d / 2;
    bottom_rad = nut_radius(type);
    top_rad = type[4] / 2;
    thickness = nut_thickness(type);
@ -87,7 +102,9 @@ module wingnut(type) { //! Draw a wingnut

    vitamin(str("wingnut(", type[0], "): Wingnut M", nut_size(type)));

-    explode(10) color(grey70) {
+    colour = silver;
+    explode(10) {
+        color(colour) {
            rotate_extrude()
                polygon([
                    [hole_rad, 0],
@ -107,6 +124,10 @@ module wingnut(type) { //! Draw a wingnut
                        ]);
                    }
        }
+
+        if(show_threads)
+            female_metric_thread(thread_d, metric_coarse_pitch(thread_d), thickness, center = false, colour = colour);
+    }
 }
 function nut_trap_radius(nut, horizontal = false) = nut_radius(nut) + (horizontal ? layer_height / 4 : 0); //! Radius across the corners of a nut trap
 function nut_trap_flat_radius(nut, horizontal = false) = nut_trap_radius(nut, horizontal) * cos(30);       //! Radius across the flats of a nut trap
--- a/vitamins/opengrab.scad
+++ b/vitamins/opengrab.scad
@ -23,6 +23,7 @@
 //! A permanent magnet that can be magnatized and de-magnatized electronically.
 //
 include <../core.scad>
+use <../utils/thread.scad>

 pitch = 33.8;
 width = 40;
@ -64,15 +65,20 @@ module opengrab() { //! Draw OpenGrab module
        translate_z(depth - pillar - pcb / 2)
            cube([width, width, pcb], center = true);

-    color(brass)
+
    translate_z(1)
-            opengrab_hole_positions()
+        opengrab_hole_positions() {
+            color(brass)
                linear_extrude(height = depth - 1)
                    difference() {
                            circle(d = 4.7 / cos(30), $fn = 6);

                            circle(r = 3/2);
                    }
+
+            if(show_threads)
+                female_metric_thread(3, metric_coarse_pitch(3), depth - 1, center = false, colour = brass);
+        }
 }

 module opengrab_target() { //! Draw OpenGrab target
--- a/vitamins/pillar.scad
+++ b/vitamins/pillar.scad
@ -44,26 +44,26 @@ module pillar(type) { //! Draw specified pillar
    thread_d = pillar_thread(type);
    bot_thread_l = pillar_bot_thread(type);
    top_thread_l = pillar_top_thread(type);
-    thread_colour = pillar_i_colour(type) * (show_threads ? 0.7 : 1);
+    thread_colour = pillar_i_colour(type);
+    pitch = metric_coarse_pitch(thread_d);

    vitamin(str("pillar(", type[0], "): Pillar ", pillar_name(type), " ", sex, " M", thread_d, "x", height));

-    color(thread_colour) {
    if(bot_thread_l > 0)
        translate_z(-bot_thread_l + eps)
            if(show_threads)
-                    male_metric_thread(thread_d, metric_coarse_pitch(thread_d), bot_thread_l, false, false);
+                male_metric_thread(thread_d, pitch, bot_thread_l, false, top = 0, colour = thread_colour);
            else
+                color(thread_colour)
                    cylinder(h = bot_thread_l, d = thread_d);

    if(top_thread_l > 0)
-            translate_z(height + top_thread_l - eps)
+        translate_z(height - eps)
            if(show_threads)
-                    vflip()
-                        male_metric_thread(thread_d, metric_coarse_pitch(thread_d), top_thread_l, false, false);
+                male_metric_thread(thread_d, pitch, top_thread_l, false, bot = 0, colour = thread_colour);
            else
+                color(thread_colour)
                    cylinder(h = top_thread_l, d = thread_d);
-    }

    color(pillar_i_colour(type))  {
        linear_extrude(height = height)
@ -79,6 +79,16 @@ module pillar(type) { //! Draw specified pillar
            cylinder(h = top - bot,  d = thread_d + eps);
    }

+    if(show_threads) {
+        if(top_thread_l < 0)
+            translate_z(height)
+                vflip()
+                    female_metric_thread(thread_d, pitch, -top_thread_l, false, colour = thread_colour);
+
+        if(bot_thread_l < 0)
+            female_metric_thread(thread_d, pitch, -bot_thread_l, false, colour = thread_colour);
+    }
+
    if(pillar_od(type) > pillar_id(type))
        color(pillar_o_colour(type)) linear_extrude(height = height)
            difference() {
--- a/vitamins/rod.scad
+++ b/vitamins/rod.scad
@ -25,12 +25,14 @@ use <../utils/thread.scad>

 rod_colour = grey80;
 studding_colour = grey70;
+leadscrew_colour = grey70;

-module rod(d , l) { //! Draw a smooth rod with specified length and diameter
+module rod(d , l, center = true) { //! Draw a smooth rod with specified diameter and length
    vitamin(str("rod(", d, ", ", l, "): Smooth rod ", d, "mm x ", l, "mm"));

    chamfer = d / 10;
    color(rod_colour)
+        translate_z(center ? 0 : l / 2)
            hull() {
                cylinder(d = d, h = l - 2 * chamfer, center = true);

@ -38,15 +40,35 @@ module rod(d , l) { //! Draw a smooth rod with specified length and diameter
            }
 }

-module studding(d , l) { //! Draw a threaded rod with specified length and diameter
+module studding(d , l, center = true) { //! Draw a threaded rod with specified diameter and length
    vitamin(str("studding(", d, ", ", l,"): Threaded rod M", d, " x ", l, "mm"));

    chamfer = d / 20;
    pitch = metric_coarse_pitch(d);
-    color(studding_colour)
+
+    translate_z(center ? 0 : l / 2)
        if(show_threads && pitch)
-            male_metric_thread(d, pitch, l);
+            male_metric_thread(d, pitch, l, colour = rod_colour);
        else
+            color(studding_colour)
+                hull() {
+                    cylinder(d = d, h = l - 2 * chamfer, center = true);
+
+                    cylinder(d = d - 2 * chamfer, h = l, center = true);
+                }
+}
+
+module leadscrew(d , l, lead, starts, center = true) { //! Draw a leadscrew with specified diameter, length, lead and number of starts
+    vitamin(str("leadscrew(", d, ", ", l, ", ", lead, ", ", starts, "): Leadscrew ", d, " x ", l, "mm, ", lead, "mm lead, ", starts, " starts"));
+
+    pitch = lead / starts;
+    chamfer = pitch / 2;
+
+    translate_z(center ? 0 : l / 2)
+        if(show_threads && pitch)
+            thread(d - pitch, lead, l, thread_profile(pitch / 2, pitch * 0.366, 30), top = 45, bot = 45, starts = starts, center = center, colour = rod_colour);
+        else
+            color(leadscrew_colour)
                hull() {
                    cylinder(d = d, h = l - 2 * chamfer, center = true);

--- a/vitamins/screw.scad
+++ b/vitamins/screw.scad
@ -73,34 +73,33 @@ module screw(type, length, hob_point = 0, nylon = false) { //! Draw specified sc
    thread = max_thread ? length >= max_thread + 5 ? max_thread
                                                   : length
                        : length;
-    shank  = length - thread;
-    colour = nylon || head_type == hs_grub ? grey40 : grey80;
-
-    module shaft(headless = 0) {
-        point = screw_nut(type) ? 0 : 3 * rad;
    d = 2 * screw_radius(type);
    pitch = metric_coarse_pitch(d);
-        l = length - shank;
+    colour = nylon || head_type == hs_grub ? grey40 : grey80;
+
+    module shaft(socket = 0, headless = false) {
+        point = screw_nut(type) ? 0 : 3 * rad;
+        shank  = length - thread - socket;
+
        if(show_threads && !point && pitch)
-            translate_z(-l - shank)
-                color(colour * 0.7)
-                    male_metric_thread(d, pitch, l, !!headless, false);
+            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 - headless - point]);
+                        square([rad, length - socket - point]);

                    if(point)
                        polygon([
-                            [0, -length], [0, point - length], [rad - 0.1, point - length]
+                            [0.4, -length], [0, point - length], [rad, point - length]
                        ]);
                }
-        if(shank - headless > 0)
-            color(colour)
-                translate_z(-shank)
-                    cylinder(r = rad + eps, h = shank - headless);

+        if(shank > 0)
+            color(colour)
+                translate_z(-shank - socket)
+                    cylinder(r = rad + eps, h = shank);
    }

    explode(length + 10) {
@ -121,23 +120,20 @@ module screw(type, length, hob_point = 0, nylon = false) { //! Draw specified sc
        }
        if(head_type == hs_grub) {
            color(colour) {
-                if(!show_threads) {
+                r = show_threads ? rad - pitch / 2 : rad;
                translate_z(-socket_depth)
                    linear_extrude(height = socket_depth)
                        difference() {
-                                circle(r = rad);
+                            circle(r);

                            circle(socket_rad, $fn = 6);
                        }

-                    shaft(socket_depth);
-                }
-                else
-                    render() difference() {
-                        shaft(socket_depth);
+                shaft(socket_depth, true);

-                        cylinder(r = socket_rad, $fn = 6, h = 2 * socket_depth, center = true);
-                    }
+                if(show_threads)
+                    translate_z(-length)
+                        cylinder(r = r, h = length - socket_depth);
            }
        }
        if(head_type == hs_hex) {
--- a/vitamins/stepper_motor.scad
+++ b/vitamins/stepper_motor.scad
@ -26,6 +26,7 @@ include <screws.scad>
 use <washer.scad>
 include <ring_terminals.scad>
 use <../utils/tube.scad>
+use <rod.scad>

 function NEMA_width(type)       = type[1]; //! Width of the square face
 function NEMA_length(type)      = type[2]; //! Body length
@ -34,7 +35,7 @@ function NEMA_body_radius(type) = type[4]; //! Body radius
 function NEMA_boss_radius(type) = type[5]; //! Boss around the spindle radius
 function NEMA_boss_height(type) = type[6]; //! Boss height
 function NEMA_shaft_dia(type)   = type[7]; //! Shaft diameter
-function NEMA_shaft_length(type)= type[8]; //! Shaft length above the face
+function NEMA_shaft_length(type)= type[8]; //! Shaft length above the face, if a list then a leadscrew: length, lead, starts
 function NEMA_hole_pitch(type)  = type[9]; //! Screw hole pitch
 function NEMA_holes(type)       = [-NEMA_hole_pitch(type) / 2, NEMA_hole_pitch(type) / 2]; //! Screw positions for for loop
 function NEMA_big_hole(type)    = NEMA_boss_radius(type) + 0.2; //! Clearance hole for the big boss
@ -50,7 +51,7 @@ module NEMA_outline(type) //! 2D outline
        circle(NEMA_radius(type));
    }

-module NEMA(type) { //! Draw specified NEMA stepper motor
+module NEMA(type, shaft_angle = 0) { //! Draw specified NEMA stepper motor
    side = NEMA_width(type);
    length = NEMA_length(type);
    body_rad = NEMA_body_radius(type);
@ -88,9 +89,15 @@ module NEMA(type) { //! Draw specified NEMA stepper motor
                        }
        }

-        color(NEMA_shaft_length(type) > 50 ? "silver" : stepper_cap_colour)
+        shaft =  NEMA_shaft_length(type);
        translate_z(-5)
-                cylinder(r = shaft_rad, h = NEMA_shaft_length(type) + 5);  // shaft
+            rotate(shaft_angle)
+                if(!is_list(shaft))
+                    color(stepper_cap_colour)
+                        cylinder(r = shaft_rad, h = shaft + 5);  // shaft
+                else
+                    not_on_bom()
+                        leadscrew(shaft_rad * 2, shaft.x + 5, shaft.y, shaft.z, center = false)

        translate([0, side / 2, -length + cap / 2])
            rotate([90, 0, 0])
--- a/vitamins/stepper_motors.scad
+++ b/vitamins/stepper_motors.scad
@ -25,7 +25,7 @@
 //                     side, length, radius, radius, radius, depth, shaft, length,      holes
 NEMA17  = ["NEMA17",   42.3, 47,     53.6/2, 25,     11,     2,     5,     24,          31 ];
 NEMA17M = ["NEMA17M",  42.3, 40,     53.6/2, 25,     11,     2,     5,     20,          31 ];
-NEMA17M8= ["NEMA17M8", 42.3, 40,     53.6/2, 25,     11,     2,     8,     280,    31 ];
+NEMA17M8= ["NEMA17M8", 42.3, 40,     53.6/2, 25,     11,     2,     8,     [280, 8, 4], 31 ];
 NEMA17S = ["NEMA17S",  42.3, 34,     53.6/2, 25,     11,     2,     5,     24,          31 ];
 NEMA16  = ["NEMA16",   39.5, 19.2,   50.6/2, 50.6/2, 11,     2,     5,     12,          31 ];
 NEMA14  = ["NEMA14",   35.2, 36,     46.4/2, 21,     11,     2,     5,     21,          26 ];
--- a/vitamins/toggle.scad
+++ b/vitamins/toggle.scad
@ -23,6 +23,8 @@
 include <../core.scad>
 use <nut.scad>
 use <washer.scad>
+use <../utils/thread.scad>
+use <../utils/tube.scad>

 function toggle_part(type)     = type[1];       //! Part description
 function toggle_width(type)    = type[2];       //! Body width
@ -80,16 +82,18 @@ module toggle(type, thickness) { //! Draw specified toggle switch with the nuts
            translate_z(-h1 / 2 - t)
                cube([toggle_width(type), toggle_height(type), h1], center = true);

-        color("silver") {
-            if(toggle_collar_t(type))
-                cylinder(d = toggle_collar_d(type), h = toggle_collar_t(type));
+        if(show_threads) {
+            d = toggle_od(type);
+            pitch = inch(1/40);
+            h = 5 * pitch * sqrt(3) / 16;

-            translate_z(-t / 2)
-                cube([toggle_width(type), toggle_height(type), t], center = true);
-
-            translate_z(-h2 / 2)
-                cube([toggle_width(type) + 2 * eps, toggle_height(type) - 2 * inset, h2], center = true);
+            male_metric_thread(d, pitch, thread, center = false, solid = false, colour = silver);

+            color(silver)
+                tube(or = d / 2 - h, ir = toggle_id(type) / 2, h = thread, center = false);
+        }
+        else
+            color(silver)
                rotate_extrude()
                    difference() {
                        hull() {
@ -100,6 +104,17 @@ module toggle(type, thickness) { //! Draw specified toggle switch with the nuts
                        square([toggle_id(type) / 2, thread + 1]);
                    }

+        color(silver) {
+            if(toggle_collar_t(type))
+                cylinder(d = toggle_collar_d(type), h = toggle_collar_t(type));
+
+            translate_z(-t / 2)
+                cube([toggle_width(type), toggle_height(type), t], center = true);
+
+            translate_z(-h2 / 2)
+                cube([toggle_width(type) + 2 * eps, toggle_height(type) - 2 * inset, h2], center = true);
+
+
            translate_z(toggle_pivot(type)) {
                angle = toggle_angle(type);
                l1 = toggle_paddle_l(type);
--- a/vitamins/washer.scad
+++ b/vitamins/washer.scad
@ -103,12 +103,14 @@ module spring_washer(type) { //! Draw spring version of washer
    vitamin(str("spring_washer(", type[0], "_washer): Washer spring M", hole, " x ", thickness, "mm"));
    ir =  washer_id(type) / 2;
    or = diameter / 2;
-    path = circle_points((ir + or) / 2, exploded() ? thickness / 2 : 0);
+    pitch = exploded() ? thickness / 2 : 0;
+    path = circle_points((ir + or) / 2, pitch);
    profile = rectangle_points(thickness, or - ir);
+    len = len(path);
    color(hard_washer_colour)
        translate_z(thickness / 2)
-            rotate(180)
-                sweep(path, profile);
+            rotate(-90)
+                sweep(path, profile, twist = -helical_twist_per_segment(ir, pitch, len) * (len - 1));

    if($children)
        translate_z(thickness)