Merge branch 'martinbudden-pulley_children'

Note previous belt lengths were incorrect with negative turns.
Fixed spelling typos.
_belt_length() no longer needs belt type.
Uptated images and readme.

CHANGELOG.md

@@ -3,9 +3,98 @@
 This changelog is generated by `changelog.py` using manually added semantic version tags to classify commits as breaking changes, additions or fixes.
 
 
-*   2021-03-03 [`a7eae4f`](https://github.com/nophead/NopSCADlib/commit/a7eae4f549b51dbe4624a8b67012919cef6cb24a "show commit") [C.P.](# "Chris Palmer") Neater changlog format.
+### [v15.4.0](https://github.com/nophead/NopSCADlib/releases/tag/v15.4.0 "show release") Additions [...](https://github.com/nophead/NopSCADlib/compare/v15.3.1...v15.4.0 "diff with v15.3.1")
+*   2021-04-02 [`b2d712b`](https://github.com/nophead/NopSCADlib/commit/b2d712bca94165a338e5f904880d12f9c4c5ecd0 "show commit") [C.P.](# "Chris Palmer") Added `quadratic_real_roots()` and `cubic_real_roots()`.
 
-*   2021-03-03 [`7b770ab`](https://github.com/nophead/NopSCADlib/commit/7b770abe12b71fa4b4f7415aa9f46d0f2c9d54f1 "show commit") [C.P.](# "Chris Palmer") Udpated changelog
+#### [v15.3.1](https://github.com/nophead/NopSCADlib/releases/tag/v15.3.1 "show release") Fixes [...](https://github.com/nophead/NopSCADlib/compare/v15.3.0...v15.3.1 "diff with v15.3.0")
+*   2021-04-02 [`f3376ed`](https://github.com/nophead/NopSCADlib/commit/f3376edaf186b32f442b94d6d0b42f1ba0c7612c "show commit") [C.P.](# "Chris Palmer") Documented `xor()` function.
+
+### [v15.3.0](https://github.com/nophead/NopSCADlib/releases/tag/v15.3.0 "show release") Additions [...](https://github.com/nophead/NopSCADlib/compare/v15.2.0...v15.3.0 "diff with v15.2.0")
+*   2021-04-02 [`c073419`](https://github.com/nophead/NopSCADlib/commit/c073419c0b4eddcda4cda5bd0f8d48268b6e58ec "show commit") [C.P.](# "Chris Palmer") Added `opengrab_screw_depth()` function.
+
+### [v15.2.0](https://github.com/nophead/NopSCADlib/releases/tag/v15.2.0 "show release") Additions [...](https://github.com/nophead/NopSCADlib/compare/v15.1.1...v15.2.0 "diff with v15.1.1")
+*   2021-03-22 [`ca1b34e`](https://github.com/nophead/NopSCADlib/commit/ca1b34e9cad5d82bd878fa4ebf439c0fbdad7f77 "show commit") [C.P.](# "Chris Palmer") Added `sink` parameter to `screw_polysink()` to recess the head.
+
+#### [v15.1.1](https://github.com/nophead/NopSCADlib/releases/tag/v15.1.1 "show release") Fixes [...](https://github.com/nophead/NopSCADlib/compare/v15.1.0...v15.1.1 "diff with v15.1.0")
+*   2021-03-22 [`cbab9ce`](https://github.com/nophead/NopSCADlib/commit/cbab9cea028a204032a91729597572a39ed893a2 "show commit") [C.P.](# "Chris Palmer") Fixed `M6_cs_cap_screw`.
+
+### [v15.1.0](https://github.com/nophead/NopSCADlib/releases/tag/v15.1.0 "show release") Additions [...](https://github.com/nophead/NopSCADlib/compare/v15.0.1...v15.1.0 "diff with v15.0.1")
+*   2021-03-21 [`4aa7dbb`](https://github.com/nophead/NopSCADlib/commit/4aa7dbb416773e42b2b5f77b345f18fcd4d2ae2c "show commit") [C.P.](# "Chris Palmer") Added `M6_cs_cap_screw`.
+
+#### [v15.0.1](https://github.com/nophead/NopSCADlib/releases/tag/v15.0.1 "show release") Fixes [...](https://github.com/nophead/NopSCADlib/compare/v15.0.0...v15.0.1 "diff with v15.0.0")
+*   2021-03-21 [`7c7c2e5`](https://github.com/nophead/NopSCADlib/commit/7c7c2e5d3f76e84ae86892f9d90f21619fa61a47 "show commit") [C.P.](# "Chris Palmer") Pixel changes due to switch to summer computer.
+
+*   2021-03-15 [`f6f6664`](https://github.com/nophead/NopSCADlib/commit/f6f6664c0d06a7cc3d49f805a2fd4f4978a3a35a "show commit") [C.P.](# "Chris Palmer") Updated OpenSCAD version required.
+
+## [v15.0.0](https://github.com/nophead/NopSCADlib/releases/tag/v15.0.0 "show release") Breaking Changes [...](https://github.com/nophead/NopSCADlib/compare/v14.1.1...v15.0.0 "diff with v14.1.1")
+*   2021-03-14 [`9ded315`](https://github.com/nophead/NopSCADlib/commit/9ded3158010b577088fdaca8a25e478f48a27376 "show commit") [C.P.](# "Chris Palmer") Removed the belt gap options and changed the tests to use open loops instead.
+Note previous belt lengths were incorrect with negative turns.
+Fixed spelling typos.
+`_belt_length()` no longer needs belt type.
+Uptated images and readme.
+
+*   2021-03-14 [`d2c795f`](https://github.com/nophead/NopSCADlib/commit/d2c795f5f5c564ec4686a7857bd894738a93a6a0 "show commit") [S.](# "SmoothieAq") fix nan angle (hopefully)
+
+*   2021-03-14 [`573c507`](https://github.com/nophead/NopSCADlib/commit/573c50774bfb2edae25a415ca864abb39c4c1bcf "show commit") [S.](# "SmoothieAq") changes after review
+
+*   2021-03-11 [`2403347`](https://github.com/nophead/NopSCADlib/commit/240334784db8002468fe0f51c1f6404a64fe44a4 "show commit") [S.](# "SmoothieAq") Extension to `belt.scad`
+
+ * Can now:
+- render open loops
+- twist the belt
+- use pulleys instead of radius in the points list
+
+ * Fixes some precision a few places
+Breaking change in `belt_length();` now requires a type argument
+
+#### [v14.1.1](https://github.com/nophead/NopSCADlib/releases/tag/v14.1.1 "show release") Fixes [...](https://github.com/nophead/NopSCADlib/compare/v14.1.0...v14.1.1 "diff with v14.1.0")
+*   2021-03-13 [`4b93623`](https://github.com/nophead/NopSCADlib/commit/4b93623492a2b8a073ab9dccc91fb2b21c475f21 "show commit") [C.P.](# "Chris Palmer") `changelog.py` now omits "Updated changelog" commits.
+
+### [v14.1.0](https://github.com/nophead/NopSCADlib/releases/tag/v14.1.0 "show release") Additions [...](https://github.com/nophead/NopSCADlib/compare/v14.0.1...v14.1.0 "diff with v14.0.1")
+*   2021-03-13 [`544e69c`](https://github.com/nophead/NopSCADlib/commit/544e69c71b404636df320be278b3fa7442f10429 "show commit") [C.P.](# "Chris Palmer") `pulley_pr()` now has an optional belt type for non-standard belt over smooth pulleys.
+
+#### [v14.0.1](https://github.com/nophead/NopSCADlib/releases/tag/v14.0.1 "show release") Fixes [...](https://github.com/nophead/NopSCADlib/compare/v14.0.0...v14.0.1 "diff with v14.0.0")
+*   2021-03-08 [`e46e6b6`](https://github.com/nophead/NopSCADlib/commit/e46e6b6e5b95792b5b2b4d7a7e4360beed22df0b "show commit") [C.P.](# "Chris Palmer") Fixed markdown numbered points in `core_xy`.
+
+## [v14.0.0](https://github.com/nophead/NopSCADlib/releases/tag/v14.0.0 "show release") Breaking Changes [...](https://github.com/nophead/NopSCADlib/compare/v13.5.0...v14.0.0 "diff with v13.5.0")
+*   2021-03-06 [`298d1f9`](https://github.com/nophead/NopSCADlib/commit/298d1f92841f30e13b437c6770fc113954b94108 "show commit") [C.P.](# "Chris Palmer") Interface is the same but filenames to be included or used changed.
+Changlog upated.
+
+*   2021-03-06 [`491c3b4`](https://github.com/nophead/NopSCADlib/commit/491c3b4ea8d2ef51e55fd389f0dc0b9a6b9bd9a4 "show commit") [C.P.](# "Chris Palmer") Updated readme, `lib.scad` and image.
+
+*   2021-03-06 [`3023604`](https://github.com/nophead/NopSCADlib/commit/30236046a81a6251bf2e869f826c881830569c06 "show commit") [M.B.](# "Martin Budden") Renamed `rounded_right_triangle` files to `rounded_triangle`.
+
+*   2021-03-06 [`3c605d6`](https://github.com/nophead/NopSCADlib/commit/3c605d608b3d0b501d1612970ce7976c9540a9a2 "show commit") [C.P.](# "Chris Palmer") Updated path, readme and image
+
+*   2021-03-06 [`93aeb4c`](https://github.com/nophead/NopSCADlib/commit/93aeb4cf2c7edd011019203ac398a911561e7c04 "show commit") [M.B.](# "Martin Budden") Renamed `scs_bearing_blocks` files to `bearing_blocks`.
+
+*   2021-03-06 [`e9554cc`](https://github.com/nophead/NopSCADlib/commit/e9554ccffe5f2a5567859937478ae9c061e30a8f "show commit") [C.P.](# "Chris Palmer") Fixed paths and image.
+
+*   2021-03-06 [`2320cbd`](https://github.com/nophead/NopSCADlib/commit/2320cbdbb866f1e38724919772ac63bc7b887674 "show commit") [M.B.](# "Martin Budden") Renamed `kp_pillow_blocks` files to `pillow_blocks`.
+
+### [v13.5.0](https://github.com/nophead/NopSCADlib/releases/tag/v13.5.0 "show release") Additions [...](https://github.com/nophead/NopSCADlib/compare/v13.4.1...v13.5.0 "diff with v13.4.1")
+*   2021-03-06 [`7ce991e`](https://github.com/nophead/NopSCADlib/commit/7ce991e625d857213b2c485f4e16fcf7e573fd11 "show commit") [C.P.](# "Chris Palmer") Updated readme for pulleys on BOM.
+
+*   2021-03-06 [`7c1c8e9`](https://github.com/nophead/NopSCADlib/commit/7c1c8e92f2bb6687e17772ca61c9ee50639bd877 "show commit") [M.B.](# "Martin Budden") Removed green code.
+
+*   2021-03-06 [`d80fc57`](https://github.com/nophead/NopSCADlib/commit/d80fc5709e4dd448353e0770f1ed28b9cf338dfe "show commit") [M.B.](# "Martin Budden") Left pulleys on BOM when `show_pulleys` `true`.
+
+*   2021-03-06 [`54c3b4f`](https://github.com/nophead/NopSCADlib/commit/54c3b4f6007d317b0dae4b45ea254c2d7571113f "show commit") [C.P.](# "Chris Palmer") Fixed path, updated readme and picture.
+
+*   2021-03-06 [`769cb44`](https://github.com/nophead/NopSCADlib/commit/769cb442070a7dcd780593c78e9354c594460454 "show commit") [M.B.](# "Martin Budden") Renamed `core_xy` files.
+
+*   2021-03-06 [`4c12d5f`](https://github.com/nophead/NopSCADlib/commit/4c12d5fca4f00f68adeb183757d1b445808a192a "show commit") [M.B.](# "Martin Budden") Added parameterised CoreXY.
+
+#### [v13.4.1](https://github.com/nophead/NopSCADlib/releases/tag/v13.4.1 "show release") Fixes [...](https://github.com/nophead/NopSCADlib/compare/v13.4.0...v13.4.1 "diff with v13.4.0")
+*   2021-03-06 [`09956b6`](https://github.com/nophead/NopSCADlib/commit/09956b62190f701fbea0826977ef7de27c39c19f "show commit") [M.B.](# "Martin Budden") Improved resilience of `compare_images`.
+
+*   2021-03-06 [`b83e567`](https://github.com/nophead/NopSCADlib/commit/b83e56713fbde2ac25e9750c369ae9cec4d67913 "show commit") [M.B.](# "Martin Budden") Reordered openscad command line parameters.
+
+*   2021-03-04 [`da4f9fb`](https://github.com/nophead/NopSCADlib/commit/da4f9fbdc31d2ceaa853c2fa0270e6961fde28b9 "show commit") [C.P.](# "Chris Palmer") Typo in `changlog.py` doc string.
+
+*   2021-03-03 [`614e5f3`](https://github.com/nophead/NopSCADlib/commit/614e5f3a72db309a3dee996d7241317556883e8d "show commit") [C.P.](# "Chris Palmer") Issues in the changelog now link to to the issue.
+
+*   2021-03-03 [`a7eae4f`](https://github.com/nophead/NopSCADlib/commit/a7eae4f549b51dbe4624a8b67012919cef6cb24a "show commit") [C.P.](# "Chris Palmer") Neater changlog format.
 
 *   2021-03-03 [`31ab856`](https://github.com/nophead/NopSCADlib/commit/31ab8562a783464f93812b8c7c45d403587efd0a "show commit") [C.P.](# "Chris Palmer") Updated images
 

docs/usage.md

@@ -1,7 +1,7 @@
 # NopSCADlib usage
 
 ## Requirements
-1. OpenSCAD 2019.05 or later, download it from here: https://www.openscad.org/downloads.html
+1. OpenSCAD 2021.01 or later, download it from here: https://www.openscad.org/downloads.html
 1. Python 2.7+ or 3.6+ from https://www.python.org/downloads/
 1. ImageMagick 7 www.imagemagick.org
 

lib.scad

@@ -26,6 +26,7 @@ include <vitamins/psus.scad>
 include <vitamins/pcbs.scad>
 
 include <vitamins/batteries.scad>
+include <vitamins/bearing_blocks.scad>
 include <vitamins/blowers.scad>
 include <vitamins/bulldogs.scad>
 include <vitamins/buttons.scad>
@@ -37,7 +38,6 @@ include <vitamins/extrusion_brackets.scad>
 include <vitamins/geared_steppers.scad>
 include <vitamins/hot_ends.scad>
 include <vitamins/inserts.scad>
-include <vitamins/kp_pillow_blocks.scad>
 include <vitamins/ldrs.scad>
 include <vitamins/leadnuts.scad>
 include <vitamins/led_meter.scad>
@@ -47,12 +47,12 @@ include <vitamins/mains_sockets.scad>
 include <vitamins/modules.scad>
 include <vitamins/panel_meters.scad>
 include <vitamins/pillars.scad>
+include <vitamins/pillow_blocks.scad>
 include <vitamins/pin_headers.scad>
 include <vitamins/pulleys.scad>
 include <vitamins/ring_terminals.scad>
 include <vitamins/rails.scad>
 include <vitamins/rod.scad>
-include <vitamins/scs_bearing_blocks.scad>
 include <vitamins/shaft_couplings.scad>
 include <vitamins/sheets.scad>
 include <vitamins/sk_brackets.scad>
@@ -89,7 +89,7 @@ use <utils/gears.scad>
 use <utils/hanging_hole.scad>
 use <utils/fillet.scad>
 use <utils/rounded_polygon.scad>
-use <utils/rounded_right_triangle.scad>
+use <utils/rounded_triangle.scad>
 use <utils/layout.scad>
 use <utils/round.scad>
 use <utils/offset.scad>

libtest.scad

@@ -43,6 +43,7 @@ include <lib.scad>
 
 use <tests/ball_bearings.scad>
 use <tests/batteries.scad>
+use <tests/bearing_blocks.scad>
 use <tests/belts.scad>
 use <tests/blowers.scad>
 use <tests/bulldogs.scad>
@@ -64,7 +65,6 @@ use <tests/hot_ends.scad>
 use <tests/IECs.scad>
 use <tests/inserts.scad>
 use <tests/jack.scad>
-use <tests/KP_pillow_blocks.scad>
 use <tests/leadnuts.scad>
 use <tests/LDRs.scad>
 use <tests/LEDs.scad>
@@ -80,6 +80,7 @@ use <tests/opengrab.scad>
 use <tests/panel_meters.scad>
 use <tests/PCBs.scad>
 use <tests/pillars.scad>
+use <tests/pillow_blocks.scad>
 use <tests/press_fit.scad>
 use <tests/PSUs.scad>
 use <tests/pulleys.scad>
@@ -88,7 +89,6 @@ use <tests/ring_terminals.scad>
 use <tests/rockers.scad>
 use <tests/rod.scad>
 use <tests/screws.scad>
-use <tests/SCS_bearing_blocks.scad>
 use <tests/sealing_strip.scad>
 use <tests/shaft_couplings.scad>
 use <tests/sheets.scad>

readme.md

@@ -22,30 +22,30 @@ A list of changes classified as breaking, additions or fixes is maintained in [C
 <table><tr>
 <th align="left"> Vitamins A-I </th><th align="left"> Vitamins J-Q </th><th align="left"> Vitamins R-Z </th><th align="left"> Printed </th><th align="left"> Utilities </th><th align="left"> Core Utilities </th></tr>
 <tr><td> <a href = "#Axials">Axials</a> </td><td> <a href = "#Jack">Jack</a> </td><td> <a href = "#Rails">Rails</a> </td><td> <a href = "#Box">Box</a> </td><td> <a href = "#Annotation">Annotation</a> </td><td> <a href = "#BOM">BOM</a> </td></tr>
-<tr><td> <a href = "#Ball_bearings">Ball_bearings</a> </td><td> <a href = "#KP_pillow_blocks">KP_pillow_blocks</a> </td><td> <a href = "#Ring_terminals">Ring_terminals</a> </td><td> <a href = "#Butt_box">Butt_box</a> </td><td> <a href = "#Bezier">Bezier</a> </td><td> <a href = "#Clip">Clip</a> </td></tr>
-<tr><td> <a href = "#Batteries">Batteries</a> </td><td> <a href = "#LDRs">LDRs</a> </td><td> <a href = "#Rockers">Rockers</a> </td><td> <a href = "#Cable_grommets">Cable_grommets</a> </td><td> <a href = "#Catenary">Catenary</a> </td><td> <a href = "#Global">Global</a> </td></tr>
-<tr><td> <a href = "#Belts">Belts</a> </td><td> <a href = "#LED_meters">LED_meters</a> </td><td> <a href = "#Rod">Rod</a> </td><td> <a href = "#Camera_housing">Camera_housing</a> </td><td> <a href = "#Core_xy">Core_xy</a> </td><td> <a href = "#Polyholes">Polyholes</a> </td></tr>
-<tr><td> <a href = "#Blowers">Blowers</a> </td><td> <a href = "#LEDs">LEDs</a> </td><td> <a href = "#SCS_bearing_blocks">SCS_bearing_blocks</a> </td><td> <a href = "#Carriers">Carriers</a> </td><td> <a href = "#Dogbones">Dogbones</a> </td><td> <a href = "#Rounded_rectangle">Rounded_rectangle</a> </td></tr>
-<tr><td> <a href = "#Bulldogs">Bulldogs</a> </td><td> <a href = "#Leadnuts">Leadnuts</a> </td><td> <a href = "#SK_brackets">SK_brackets</a> </td><td> <a href = "#Corner_block">Corner_block</a> </td><td> <a href = "#Fillet">Fillet</a> </td><td> <a href = "#Sphere">Sphere</a> </td></tr>
-<tr><td> <a href = "#Buttons">Buttons</a> </td><td> <a href = "#Light_strips">Light_strips</a> </td><td> <a href = "#SMDs">SMDs</a> </td><td> <a href = "#Door_hinge">Door_hinge</a> </td><td> <a href = "#Gears">Gears</a> </td><td> <a href = "#Teardrops">Teardrops</a> </td></tr>
-<tr><td> <a href = "#Cable_strips">Cable_strips</a> </td><td> <a href = "#Linear_bearings">Linear_bearings</a> </td><td> <a href = "#SSRs">SSRs</a> </td><td> <a href = "#Door_latch">Door_latch</a> </td><td> <a href = "#Hanging_hole">Hanging_hole</a> </td><td></td></tr>
-<tr><td> <a href = "#Cameras">Cameras</a> </td><td> <a href = "#Magnets">Magnets</a> </td><td> <a href = "#Screws">Screws</a> </td><td> <a href = "#Drag_chain">Drag_chain</a> </td><td> <a href = "#Horiholes">Horiholes</a> </td><td></td></tr>
-<tr><td> <a href = "#Circlips">Circlips</a> </td><td> <a href = "#Mains_sockets">Mains_sockets</a> </td><td> <a href = "#Sealing_strip">Sealing_strip</a> </td><td> <a href = "#Fan_guard">Fan_guard</a> </td><td> <a href = "#Layout">Layout</a> </td><td></td></tr>
-<tr><td> <a href = "#Components">Components</a> </td><td> <a href = "#Microswitches">Microswitches</a> </td><td> <a href = "#Shaft_couplings">Shaft_couplings</a> </td><td> <a href = "#Fixing_block">Fixing_block</a> </td><td> <a href = "#Maths">Maths</a> </td><td></td></tr>
-<tr><td> <a href = "#DIP">DIP</a> </td><td> <a href = "#Microview">Microview</a> </td><td> <a href = "#Sheets">Sheets</a> </td><td> <a href = "#Flat_hinge">Flat_hinge</a> </td><td> <a href = "#Offset">Offset</a> </td><td></td></tr>
-<tr><td> <a href = "#D_connectors">D_connectors</a> </td><td> <a href = "#Modules">Modules</a> </td><td> <a href = "#Spades">Spades</a> </td><td> <a href = "#Foot">Foot</a> </td><td> <a href = "#Quadrant">Quadrant</a> </td><td></td></tr>
-<tr><td> <a href = "#Displays">Displays</a> </td><td> <a href = "#Nuts">Nuts</a> </td><td> <a href = "#Spools">Spools</a> </td><td> <a href = "#Handle">Handle</a> </td><td> <a href = "#Round">Round</a> </td><td></td></tr>
-<tr><td> <a href = "#Extrusion_brackets">Extrusion_brackets</a> </td><td> <a href = "#O_ring">O_ring</a> </td><td> <a href = "#Springs">Springs</a> </td><td> <a href = "#PCB_mount">PCB_mount</a> </td><td> <a href = "#Rounded_cylinder">Rounded_cylinder</a> </td><td></td></tr>
-<tr><td> <a href = "#Extrusions">Extrusions</a> </td><td> <a href = "#Opengrab">Opengrab</a> </td><td> <a href = "#Stepper_motors">Stepper_motors</a> </td><td> <a href = "#PSU_shroud">PSU_shroud</a> </td><td> <a href = "#Rounded_polygon">Rounded_polygon</a> </td><td></td></tr>
-<tr><td> <a href = "#Fans">Fans</a> </td><td> <a href = "#PCB">PCB</a> </td><td> <a href = "#Swiss_clips">Swiss_clips</a> </td><td> <a href = "#Pocket_handle">Pocket_handle</a> </td><td> <a href = "#Rounded_right_triangle">Rounded_right_triangle</a> </td><td></td></tr>
-<tr><td> <a href = "#Fuseholder">Fuseholder</a> </td><td> <a href = "#PCBs">PCBs</a> </td><td> <a href = "#Toggles">Toggles</a> </td><td> <a href = "#Press_fit">Press_fit</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 = "#PSUs">PSUs</a> </td><td> <a href = "#Transformers">Transformers</a> </td><td> <a href = "#Printed_box">Printed_box</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 = "#Panel_meters">Panel_meters</a> </td><td> <a href = "#Tubings">Tubings</a> </td><td> <a href = "#Printed_pulleys">Printed_pulleys</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 = "#Pillars">Pillars</a> </td><td> <a href = "#Variacs">Variacs</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 = "#Hygrometer">Hygrometer</a> </td><td> <a href = "#Pin_headers">Pin_headers</a> </td><td> <a href = "#Veroboard">Veroboard</a> </td><td> <a href = "#SSR_shroud">SSR_shroud</a> </td><td></td><td></td></tr>
-<tr><td> <a href = "#IECs">IECs</a> </td><td> <a href = "#Pulleys">Pulleys</a> </td><td> <a href = "#Washers">Washers</a> </td><td> <a href = "#Screw_knob">Screw_knob</a> </td><td></td><td></td></tr>
-<tr><td> <a href = "#Inserts">Inserts</a> </td><td></td><td> <a href = "#Wire">Wire</a> </td><td> <a href = "#Socket_box">Socket_box</a> </td><td></td><td></td></tr>
-<tr><td></td><td></td><td> <a href = "#Zipties">Zipties</a> </td><td> <a href = "#Strap_handle">Strap_handle</a> </td><td></td><td></td></tr>
+<tr><td> <a href = "#Ball_bearings">Ball_bearings</a> </td><td> <a href = "#LDRs">LDRs</a> </td><td> <a href = "#Ring_terminals">Ring_terminals</a> </td><td> <a href = "#Butt_box">Butt_box</a> </td><td> <a href = "#Bezier">Bezier</a> </td><td> <a href = "#Clip">Clip</a> </td></tr>
+<tr><td> <a href = "#Batteries">Batteries</a> </td><td> <a href = "#LED_meters">LED_meters</a> </td><td> <a href = "#Rockers">Rockers</a> </td><td> <a href = "#Cable_grommets">Cable_grommets</a> </td><td> <a href = "#Catenary">Catenary</a> </td><td> <a href = "#Global">Global</a> </td></tr>
+<tr><td> <a href = "#Bearing_blocks">Bearing_blocks</a> </td><td> <a href = "#LEDs">LEDs</a> </td><td> <a href = "#Rod">Rod</a> </td><td> <a href = "#Camera_housing">Camera_housing</a> </td><td> <a href = "#Core_xy">Core_xy</a> </td><td> <a href = "#Polyholes">Polyholes</a> </td></tr>
+<tr><td> <a href = "#Belts">Belts</a> </td><td> <a href = "#Leadnuts">Leadnuts</a> </td><td> <a href = "#SK_brackets">SK_brackets</a> </td><td> <a href = "#Carriers">Carriers</a> </td><td> <a href = "#Dogbones">Dogbones</a> </td><td> <a href = "#Rounded_rectangle">Rounded_rectangle</a> </td></tr>
+<tr><td> <a href = "#Blowers">Blowers</a> </td><td> <a href = "#Light_strips">Light_strips</a> </td><td> <a href = "#SMDs">SMDs</a> </td><td> <a href = "#Corner_block">Corner_block</a> </td><td> <a href = "#Fillet">Fillet</a> </td><td> <a href = "#Sphere">Sphere</a> </td></tr>
+<tr><td> <a href = "#Bulldogs">Bulldogs</a> </td><td> <a href = "#Linear_bearings">Linear_bearings</a> </td><td> <a href = "#SSRs">SSRs</a> </td><td> <a href = "#Door_hinge">Door_hinge</a> </td><td> <a href = "#Gears">Gears</a> </td><td> <a href = "#Teardrops">Teardrops</a> </td></tr>
+<tr><td> <a href = "#Buttons">Buttons</a> </td><td> <a href = "#Magnets">Magnets</a> </td><td> <a href = "#Screws">Screws</a> </td><td> <a href = "#Door_latch">Door_latch</a> </td><td> <a href = "#Hanging_hole">Hanging_hole</a> </td><td></td></tr>
+<tr><td> <a href = "#Cable_strips">Cable_strips</a> </td><td> <a href = "#Mains_sockets">Mains_sockets</a> </td><td> <a href = "#Sealing_strip">Sealing_strip</a> </td><td> <a href = "#Drag_chain">Drag_chain</a> </td><td> <a href = "#Horiholes">Horiholes</a> </td><td></td></tr>
+<tr><td> <a href = "#Cameras">Cameras</a> </td><td> <a href = "#Microswitches">Microswitches</a> </td><td> <a href = "#Shaft_couplings">Shaft_couplings</a> </td><td> <a href = "#Fan_guard">Fan_guard</a> </td><td> <a href = "#Layout">Layout</a> </td><td></td></tr>
+<tr><td> <a href = "#Circlips">Circlips</a> </td><td> <a href = "#Microview">Microview</a> </td><td> <a href = "#Sheets">Sheets</a> </td><td> <a href = "#Fixing_block">Fixing_block</a> </td><td> <a href = "#Maths">Maths</a> </td><td></td></tr>
+<tr><td> <a href = "#Components">Components</a> </td><td> <a href = "#Modules">Modules</a> </td><td> <a href = "#Spades">Spades</a> </td><td> <a href = "#Flat_hinge">Flat_hinge</a> </td><td> <a href = "#Offset">Offset</a> </td><td></td></tr>
+<tr><td> <a href = "#DIP">DIP</a> </td><td> <a href = "#Nuts">Nuts</a> </td><td> <a href = "#Spools">Spools</a> </td><td> <a href = "#Foot">Foot</a> </td><td> <a href = "#Quadrant">Quadrant</a> </td><td></td></tr>
+<tr><td> <a href = "#D_connectors">D_connectors</a> </td><td> <a href = "#O_ring">O_ring</a> </td><td> <a href = "#Springs">Springs</a> </td><td> <a href = "#Handle">Handle</a> </td><td> <a href = "#Round">Round</a> </td><td></td></tr>
+<tr><td> <a href = "#Displays">Displays</a> </td><td> <a href = "#Opengrab">Opengrab</a> </td><td> <a href = "#Stepper_motors">Stepper_motors</a> </td><td> <a href = "#PCB_mount">PCB_mount</a> </td><td> <a href = "#Rounded_cylinder">Rounded_cylinder</a> </td><td></td></tr>
+<tr><td> <a href = "#Extrusion_brackets">Extrusion_brackets</a> </td><td> <a href = "#PCB">PCB</a> </td><td> <a href = "#Swiss_clips">Swiss_clips</a> </td><td> <a href = "#PSU_shroud">PSU_shroud</a> </td><td> <a href = "#Rounded_polygon">Rounded_polygon</a> </td><td></td></tr>
+<tr><td> <a href = "#Extrusions">Extrusions</a> </td><td> <a href = "#PCBs">PCBs</a> </td><td> <a href = "#Toggles">Toggles</a> </td><td> <a href = "#Pocket_handle">Pocket_handle</a> </td><td> <a href = "#Rounded_triangle">Rounded_triangle</a> </td><td></td></tr>
+<tr><td> <a href = "#Fans">Fans</a> </td><td> <a href = "#PSUs">PSUs</a> </td><td> <a href = "#Transformers">Transformers</a> </td><td> <a href = "#Press_fit">Press_fit</a> </td><td> <a href = "#Sector">Sector</a> </td><td></td></tr>
+<tr><td> <a href = "#Fuseholder">Fuseholder</a> </td><td> <a href = "#Panel_meters">Panel_meters</a> </td><td> <a href = "#Tubings">Tubings</a> </td><td> <a href = "#Printed_box">Printed_box</a> </td><td> <a href = "#Sweep">Sweep</a> </td><td></td></tr>
+<tr><td> <a href = "#Geared_steppers">Geared_steppers</a> </td><td> <a href = "#Pillars">Pillars</a> </td><td> <a href = "#Variacs">Variacs</a> </td><td> <a href = "#Printed_pulleys">Printed_pulleys</a> </td><td> <a href = "#Thread">Thread</a> </td><td></td></tr>
+<tr><td> <a href = "#Green_terminals">Green_terminals</a> </td><td> <a href = "#Pillow_blocks">Pillow_blocks</a> </td><td> <a href = "#Veroboard">Veroboard</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 = "#Pin_headers">Pin_headers</a> </td><td> <a href = "#Washers">Washers</a> </td><td> <a href = "#SSR_shroud">SSR_shroud</a> </td><td></td><td></td></tr>
+<tr><td> <a href = "#Hygrometer">Hygrometer</a> </td><td> <a href = "#Pulleys">Pulleys</a> </td><td> <a href = "#Wire">Wire</a> </td><td> <a href = "#Screw_knob">Screw_knob</a> </td><td></td><td></td></tr>
+<tr><td> <a href = "#IECs">IECs</a> </td><td></td><td> <a href = "#Zipties">Zipties</a> </td><td> <a href = "#Socket_box">Socket_box</a> </td><td></td><td></td></tr>
+<tr><td> <a href = "#Inserts">Inserts</a> </td><td></td><td></td><td> <a href = "#Strap_handle">Strap_handle</a> </td><td></td><td></td></tr>
 </table>
 
 ---
@@ -200,18 +200,89 @@ exposing enough information to make a battery box.
 |   1 | `battery(S25R18650)` |  Cell Samsung 25R 18650 LION |
 
 
+<a href="#top">Top</a>
+
+---
+<a name="Bearing_blocks"></a>
+## Bearing_blocks
+SCSnUU and SCSnLUU bearing blocks
+
+[vitamins/bearing_blocks.scad](vitamins/bearing_blocks.scad) Object definitions.
+
+[vitamins/bearing_block.scad](vitamins/bearing_block.scad) Implementation.
+
+[tests/bearing_blocks.scad](tests/bearing_blocks.scad) Code for this example.
+
+### Properties
+| Function | Description |
+|:--- |:--- |
+| `scs_bearing(type)` | Linear bearing used |
+| `scs_block_center_height(type)` | Height of the center of the block |
+| `scs_block_side_height(type)` | Height of the side of the block, this determines the minimum screw length |
+| `scs_circlip(type)` | Circlip used |
+| `scs_hole_offset(type)` | Offset of bearing hole from base of block |
+| `scs_screw(type)` | Screw type |
+| `scs_screw_separation_x(type)` | Screw separation in X direction |
+| `scs_screw_separation_z(type)` | Screw separation in Z direction |
+| `scs_spacer(type)` | Spacer used in long bearings |
+
+### Functions
+| Function | Description |
+|:--- |:--- |
+| `scs_size(type)` | Size of scs bracket bounding block |
+
+### Modules
+| Module | Description |
+|:--- |:--- |
+| `scs_bearing_block(type)` | Draw the specified SCS bearing block |
+| `scs_bearing_block_assembly(type, part_thickness, screw_type, nut_type)` | Assembly with screws and nuts in place |
+| `scs_bearing_block_hole_positions(type)` | Place children at hole positions |
+
+![bearing_blocks](tests/png/bearing_blocks.png)
+
+### Vitamins
+| Qty | Module call | BOM entry |
+| ---:|:--- |:---|
+|  12 | `nut(M4_nut)` |  Nut M4 x 3.2mm  |
+|  24 | `nut(M5_nut)` |  Nut M5 x 4mm  |
+|   1 | `scs_bearing_block(SCS10LUU)` |  SCS10LUU bearing block |
+|   1 | `scs_bearing_block(SCS10UU)` |  SCS10UU bearing block |
+|   1 | `scs_bearing_block(SCS12LUU)` |  SCS12LUU bearing block |
+|   1 | `scs_bearing_block(SCS12UU)` |  SCS12UU bearing block |
+|   1 | `scs_bearing_block(SCS16LUU)` |  SCS16LUU bearing block |
+|   1 | `scs_bearing_block(SCS16UU)` |  SCS16UU bearing block |
+|   1 | `scs_bearing_block(SCS6UU)` |  SCS6UU bearing block |
+|   1 | `scs_bearing_block(SCS8LUU)` |  SCS8LUU bearing block |
+|   1 | `scs_bearing_block(SCS8UU)` |  SCS8UU bearing block |
+|   4 | `screw(M4_cap_screw, 25)` |  Screw M4 cap x 25mm |
+|   8 | `screw(M4_cap_screw, 30)` |  Screw M4 cap x 30mm |
+|  16 | `screw(M5_cap_screw, 35)` |  Screw M5 cap x 35mm |
+|   8 | `screw(M5_cap_screw, 45)` |  Screw M5 cap x 45mm |
+|  12 | `washer(M4_washer)` |  Washer  M4 x 9mm x 0.8mm |
+|  24 | `washer(M5_washer)` |  Washer  M5 x 10mm x 1mm |
+
+
 <a href="#top">Top</a>
 
 ---
 <a name="Belts"></a>
 ## Belts
-Models timing belt running over toothed or smooth pulleys and calculates an accurate length.
-Only models 2D paths, so not crossed belt core XY!
+Models timing belt running in a path over toothed or smooth pulleys and calculates an accurate length.
+Only models 2D paths, belt may twist to support crossed belt core XY and other designes where the belt twists!
+
+By default the path is a closed loop. An open loop can be specified by specifying `open=true`, and in that case the start and end points are not connected, leaving the loop open.
+
+To get a 180 degree twist of the loop, you can use the `twist` argument. `Twist` can be a single number, and in that case the belt will twist after
+the position with that number. Alternatively `twist` can be a list of boolean values with a boolean for each position; the belt will then twist after
+the position that have a `true` value in the `twist` list. If the path is specified with pulley/idler types, then you can use `auto_twist=true`; in
+that case the belt will automatically twist so the back of the belt always runs against idlers and the tooth side runs against pullies. If you use
+`open=true` then you might also use `start_twist=true` to let the belt start the part with the back side out.
+
+The path must be specified as a list of positions. Each position should be either a vector with `[x, y, pulley]` or `[x, y, r]`. A pully is a type from
+`pulleys.scad`, and correct radius and angle will automatically be calculated. Alternatively a radius can be specified directly.
 
 To make the back of the belt run against a smooth pulley on the outside of the loop specify a negative pitch radius.
-
-By default the path is a closed loop but a gap length and position can be specified to make open loops.
-To draw the gap its XY position is specified by `gap_pos`. `gap_pos.z` can be used to specify a rotation if the gap is not at the bottom of the loop.
+Alternativley you can just specify smooth pulleys in the path, and it will then happen automatically.
 
 Individual teeth are not drawn, instead they are represented by a lighter colour.
 
@@ -233,13 +304,15 @@ Individual teeth are not drawn, instead they are represented by a lighter colour
 ### Functions
 | Function | Description |
 |:--- |:--- |
-| `belt_length(points, gap = 0)` | Compute belt length given path and optional gap |
+| `_belt_points_info(type, points, open, twist, auto_twist, start_twist)` | Helper function that calculates [twist, istwisted, points, tangents, arcs] |
+| `belt_length(type, points, open = false)` | Compute belt length given path |
 | `belt_pitch_to_back(type)` | Offset of the back from the pitch radius |
+| `belt_pulley_pr(type, pulley, twisted=false)` | Pitch radius. Default it expects the belt tooth to be against a toothed pulley an the backside to be against a smooth pulley (an idler). If `twisted` is true, the the belt is the other way around. |
 
 ### Modules
 | Module | Description |
 |:--- |:--- |
-| `belt(type, points, gap = 0, gap_pos = undef, belt_colour = grey(20)` | Draw a belt path given a set of points and pitch radii where the pulleys are. Closed loop unless a gap is specified |
+| `belt(type, points, belt_colour = grey(20)` | Draw a belt path given a set of points and pitch radii where the pulleys are. Closed loop unless open is specified |
 
 ![belts](tests/png/belts.png)
 
@@ -247,17 +320,18 @@ Individual teeth are not drawn, instead they are represented by a lighter colour
 | Qty | Module call | BOM entry |
 | ---:|:--- |:---|
 |   1 | `belt(GT2x6, [ ... ])` |  Belt GT2 x 6mm x 128mm |
-|   2 | `belt(GT2x6, [ ... ], 80, [0, 0])` |  Belt GT2 x 6mm x 572mm |
+|   1 | `belt(GT2x6, [ ... ])` |  Belt GT2 x 6mm x 552mm |
+|   2 | `belt(GT2x6, [ ... ])` |  Belt GT2 x 6mm x 556mm |
 |   1 | `belt(T2p5x6, [ ... ])` |  Belt T2.5 x 6mm x 130mm |
 |   1 | `belt(T5x10, [ ... ])` |  Belt T5 x 10mm x 130mm |
 |   1 | `belt(T5x6, [ ... ])` |  Belt T5 x 6mm x 130mm |
 |   2 | `insert(F1BM3)` |  Heatfit insert M3 |
 |   2 | `pulley(GT2x16_toothed_idler)` |  Pulley GT2 idler 16 teeth |
 |   4 | `pulley(GT2x20_toothed_idler)` |  Pulley GT2 idler 20 teeth |
-|   2 | `pulley(GT2x16_plain_idler)` |  Pulley GT2 idler smooth 9.63mm |
-|   2 | `pulley(GT2x20ob_pulley)` |  Pulley GT2OB 20 teeth |
+|   6 | `pulley(GT2x16_plain_idler)` |  Pulley GT2 idler smooth 9.63mm |
+|   3 | `pulley(GT2x20ob_pulley)` |  Pulley GT2OB 20 teeth |
 |   2 | `screw(M3_cs_cap_screw, 20)` |  Screw M3 cs cap x 20mm |
-|   4 | `screw(M3_grub_screw, 6)` |  Screw M3 grub x  6mm |
+|   6 | `screw(M3_grub_screw, 6)` |  Screw M3 grub x  6mm |
 
 
 <a href="#top">Top</a>
@@ -1309,58 +1383,6 @@ E.g. a "brown" socket for mains live needs to be displayed as "sienna" to look r
 |   1 | `jack_4mm_shielded("brown", 3, "sienna")` |  4mm shielded jack socket brown |
 
 
-<a href="#top">Top</a>
-
----
-<a name="KP_pillow_blocks"></a>
-## KP_pillow_blocks
-KP pillow block bearings
-
-[vitamins/kp_pillow_blocks.scad](vitamins/kp_pillow_blocks.scad) Object definitions.
-
-[vitamins/kp_pillow_block.scad](vitamins/kp_pillow_block.scad) Implementation.
-
-[tests/KP_pillow_blocks.scad](tests/KP_pillow_blocks.scad) Code for this example.
-
-### Properties
-| Function | Description |
-|:--- |:--- |
-| `kp_base_height(type)` | Height of base containing the bolts |
-| `kp_diameter(type)` | Rod hole diameter |
-| `kp_hole_offset(type)` | Rod hole offset |
-| `kp_screw_separation(type)` | Separation of bolts in the base |
-
-### Functions
-| Function | Description |
-|:--- |:--- |
-| `kp_size(type)` | Size of bracket |
-
-### Modules
-| Module | Description |
-|:--- |:--- |
-| `kp_pillow_block(type)` | Draw the KP pillow block |
-| `kp_pillow_block_assembly(type, part_thickness = 2, screw_type = M5_cap_screw, nut_type = undef)` | Assembly with fasteners in place |
-| `kp_pillow_block_hole_positions(type)` | Place children at hole positions |
-
-![kp_pillow_blocks](tests/png/kp_pillow_blocks.png)
-
-### Vitamins
-| Qty | Module call | BOM entry |
-| ---:|:--- |:---|
-|   1 | `kp_pillow_block(KP000)` |  KP000 pillow block |
-|   1 | `kp_pillow_block(KP001)` |  KP001 pillow block |
-|   1 | `kp_pillow_block(KP08_15)` |  KP08_15 pillow block |
-|   1 | `kp_pillow_block(KP08_18)` |  KP08_18 pillow block |
-|   2 | `sliding_t_nut(M4_hammer_nut)` |  Nut M4 hammer |
-|   2 | `sliding_t_nut(M4_sliding_t_nut)` |  Nut M4 sliding T |
-|   2 | `sliding_t_nut(M5_sliding_t_nut)` |  Nut M5 sliding T |
-|   2 | `nut(M5_nut, nyloc = undef)` |  Nut M5 x 4mm  |
-|   4 | `screw(M4_cap_screw, 10)` |  Screw M4 cap x 10mm |
-|   4 | `screw(M5_cap_screw, 12)` |  Screw M5 cap x 12mm |
-|   4 | `washer(M4_washer)` |  Washer  M4 x 9mm x 0.8mm |
-|   6 | `washer(M5_washer)` |  Washer  M5 x 10mm x 1mm |
-
-
 <a href="#top">Top</a>
 
 ---
@@ -2008,6 +2030,7 @@ A permanent magnet that can be magnatized and de-magnatized electronically.
 | `opengrab_depth()` | Module height |
 | `opengrab_pcb()` | The PCB |
 | `opengrab_pcb_z()` | PCB offset from the front |
+| `opengrab_screw_depth()` | Max screw depth in pillars |
 | `opengrab_target_thickness()` | Target sheet thickness |
 | `opengrab_width()` | Module width |
 
@@ -2444,6 +2467,58 @@ Threaded pillars. Each end can be male or female.
 |   1 | `pillar(M4x17_nylon_pillar)` |  Pillar nylon M/F M4x20 |
 
 
+<a href="#top">Top</a>
+
+---
+<a name="Pillow_blocks"></a>
+## Pillow_blocks
+KP pillow block bearings
+
+[vitamins/pillow_blocks.scad](vitamins/pillow_blocks.scad) Object definitions.
+
+[vitamins/pillow_block.scad](vitamins/pillow_block.scad) Implementation.
+
+[tests/pillow_blocks.scad](tests/pillow_blocks.scad) Code for this example.
+
+### Properties
+| Function | Description |
+|:--- |:--- |
+| `kp_base_height(type)` | Height of base containing the bolts |
+| `kp_diameter(type)` | Rod hole diameter |
+| `kp_hole_offset(type)` | Rod hole offset |
+| `kp_screw_separation(type)` | Separation of bolts in the base |
+
+### Functions
+| Function | Description |
+|:--- |:--- |
+| `kp_size(type)` | Size of bracket |
+
+### Modules
+| Module | Description |
+|:--- |:--- |
+| `kp_pillow_block(type)` | Draw the KP pillow block |
+| `kp_pillow_block_assembly(type, part_thickness = 2, screw_type = M5_cap_screw, nut_type = undef)` | Assembly with fasteners in place |
+| `kp_pillow_block_hole_positions(type)` | Place children at hole positions |
+
+![pillow_blocks](tests/png/pillow_blocks.png)
+
+### Vitamins
+| Qty | Module call | BOM entry |
+| ---:|:--- |:---|
+|   1 | `kp_pillow_block(KP000)` |  KP000 pillow block |
+|   1 | `kp_pillow_block(KP001)` |  KP001 pillow block |
+|   1 | `kp_pillow_block(KP08_15)` |  KP08_15 pillow block |
+|   1 | `kp_pillow_block(KP08_18)` |  KP08_18 pillow block |
+|   2 | `sliding_t_nut(M4_hammer_nut)` |  Nut M4 hammer |
+|   2 | `sliding_t_nut(M4_sliding_t_nut)` |  Nut M4 sliding T |
+|   2 | `sliding_t_nut(M5_sliding_t_nut)` |  Nut M5 sliding T |
+|   2 | `nut(M5_nut, nyloc = undef)` |  Nut M5 x 4mm  |
+|   4 | `screw(M4_cap_screw, 10)` |  Screw M4 cap x 10mm |
+|   4 | `screw(M5_cap_screw, 12)` |  Screw M5 cap x 12mm |
+|   4 | `washer(M4_washer)` |  Washer  M4 x 9mm x 0.8mm |
+|   6 | `washer(M5_washer)` |  Washer  M5 x 10mm x 1mm |
+
+
 <a href="#top">Top</a>
 
 ---
@@ -2619,12 +2694,12 @@ Timing belt pulleys, both toothed and plain with internal bearings for idlers.
 | `pulley_height(type)` | Total height of pulley |
 | `pulley_ir(type)` | Inside radius of the teeth |
 | `pulley_offset(type)` | Offset of the belt path centre |
-| `pulley_pr(type)` | Pitch radius |
+| `pulley_pr(type, belt = undef)` | Pitch radius, `belt` only needed for non-standard belt over smooth pulleys |
 
 ### Modules
 | Module | Description |
 |:--- |:--- |
-| `pulley(type, colour = silver)` | Draw a pulley |
+| `pulley(type, colour = silver)` | Draw a pulley, any children are placed above. |
 | `pulley_assembly(type, colour = silver)` | Draw a pulley with its grub screws in place |
 
 ![pulleys](tests/png/pulleys.png)
@@ -2931,7 +3006,7 @@ For an explanation of `screw_polysink()` see <https://hydraraptor.blogspot.com/2
 | `screw(type, length, hob_point = 0, nylon = false)` | Draw specified screw, optionally hobbed or nylon |
 | `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 |
 | `screw_countersink(type, drilled = true)` | Countersink shape |
-| `screw_polysink(type, h = 100, alt = false)` | A countersink hole made from stacked polyholes for printed parts |
+| `screw_polysink(type, h = 100, alt = false, sink = 0)` | A countersink hole made from stacked polyholes for printed parts, default is flush, `sink` can be used to recess the head |
 
 ![screws](tests/png/screws.png)
 
@@ -2963,6 +3038,7 @@ For an explanation of `screw_polysink()` see <https://hydraraptor.blogspot.com/2
 |   1 | `screw(M5_hex_screw, 30)` |  Screw M5 hex x 30mm |
 |   1 | `screw(M5_pan_screw, 30)` |  Screw M5 pan x 30mm |
 |   1 | `screw(M6_cap_screw, 30)` |  Screw M6 cap x 30mm |
+|   1 | `screw(M6_cs_cap_screw, 30)` |  Screw M6 cs cap x 30mm |
 |   1 | `screw(M6_hex_screw, 30)` |  Screw M6 hex x 30mm |
 |   1 | `screw(M6_pan_screw, 30)` |  Screw M6 pan x 30mm |
 |   1 | `screw(M8_cap_screw, 35)` |  Screw M8 cap x 35mm |
@@ -2978,68 +3054,6 @@ For an explanation of `screw_polysink()` see <https://hydraraptor.blogspot.com/2
 |   1 | polysink.stl |
 
 
-<a href="#top">Top</a>
-
----
-<a name="SCS_bearing_blocks"></a>
-## SCS_bearing_blocks
-SCSnUU and SCSnLUU bearing blocks
-
-[vitamins/scs_bearing_blocks.scad](vitamins/scs_bearing_blocks.scad) Object definitions.
-
-[vitamins/scs_bearing_block.scad](vitamins/scs_bearing_block.scad) Implementation.
-
-[tests/SCS_bearing_blocks.scad](tests/SCS_bearing_blocks.scad) Code for this example.
-
-### Properties
-| Function | Description |
-|:--- |:--- |
-| `scs_bearing(type)` | Linear bearing used |
-| `scs_block_center_height(type)` | Height of the center of the block |
-| `scs_block_side_height(type)` | Height of the side of the block, this determines the minimum screw length |
-| `scs_circlip(type)` | Circlip used |
-| `scs_hole_offset(type)` | Offset of bearing hole from base of block |
-| `scs_screw(type)` | Screw type |
-| `scs_screw_separation_x(type)` | Screw separation in X direction |
-| `scs_screw_separation_z(type)` | Screw separation in Z direction |
-| `scs_spacer(type)` | Spacer used in long bearings |
-
-### Functions
-| Function | Description |
-|:--- |:--- |
-| `scs_size(type)` | Size of scs bracket bounding block |
-
-### Modules
-| Module | Description |
-|:--- |:--- |
-| `scs_bearing_block(type)` | Draw the specified SCS bearing block |
-| `scs_bearing_block_assembly(type, part_thickness, screw_type, nut_type)` | Assembly with screws and nuts in place |
-| `scs_bearing_block_hole_positions(type)` | Place children at hole positions |
-
-![scs_bearing_blocks](tests/png/scs_bearing_blocks.png)
-
-### Vitamins
-| Qty | Module call | BOM entry |
-| ---:|:--- |:---|
-|  12 | `nut(M4_nut)` |  Nut M4 x 3.2mm  |
-|  24 | `nut(M5_nut)` |  Nut M5 x 4mm  |
-|   1 | `scs_bearing_block(SCS10LUU)` |  SCS10LUU bearing block |
-|   1 | `scs_bearing_block(SCS10UU)` |  SCS10UU bearing block |
-|   1 | `scs_bearing_block(SCS12LUU)` |  SCS12LUU bearing block |
-|   1 | `scs_bearing_block(SCS12UU)` |  SCS12UU bearing block |
-|   1 | `scs_bearing_block(SCS16LUU)` |  SCS16LUU bearing block |
-|   1 | `scs_bearing_block(SCS16UU)` |  SCS16UU bearing block |
-|   1 | `scs_bearing_block(SCS6UU)` |  SCS6UU bearing block |
-|   1 | `scs_bearing_block(SCS8LUU)` |  SCS8LUU bearing block |
-|   1 | `scs_bearing_block(SCS8UU)` |  SCS8UU bearing block |
-|   4 | `screw(M4_cap_screw, 25)` |  Screw M4 cap x 25mm |
-|   8 | `screw(M4_cap_screw, 30)` |  Screw M4 cap x 30mm |
-|  16 | `screw(M5_cap_screw, 35)` |  Screw M5 cap x 35mm |
-|   8 | `screw(M5_cap_screw, 45)` |  Screw M5 cap x 45mm |
-|  12 | `washer(M4_washer)` |  Washer  M4 x 9mm x 0.8mm |
-|  24 | `washer(M5_washer)` |  Washer  M5 x 10mm x 1mm |
-
-
 <a href="#top">Top</a>
 
 ---
@@ -5583,6 +5597,7 @@ Parameterised Core XY implementation. Draws the belts and provides utilities for
 
 The belts are positioned according the bottom left "anchor" pulley and the top right drive pulley.
 Implementation has the following features:
+
 1. The drive and idler pulleys may be different sizes.
 2. The belt separation is parameterised.
 3. The separation of the plain and toothed pulleys on the Y carriages is parameterised, in both the X and the Y direction.
@@ -5627,8 +5642,8 @@ allows flexible positioning of the motors.
 ### Vitamins
 | Qty | Module call | BOM entry |
 | ---:|:--- |:---|
-|   1 | `belt(GT2x6, [ ... ], [10.0078, 11.69], [0, -24.686])` |  Belt GT2 x 6mm x 742mm |
-|   1 | `belt(GT2x6, [ ... ], [10.0078, 11.69], [0, -24.686])` |  Belt GT2 x 6mm x 852mm |
+|   1 | `belt(GT2x6, [ ... ])` |  Belt GT2 x 6mm x 728mm |
+|   1 | `belt(GT2x6, [ ... ])` |  Belt GT2 x 6mm x 824mm |
 |   7 | `pulley(GT2x16_toothed_idler)` |  Pulley GT2 idler 16 teeth |
 |   3 | `pulley(GT2x16_plain_idler)` |  Pulley GT2 idler smooth 9.63mm |
 |   2 | `pulley(GT2x20ob_pulley)` |  Pulley GT2OB 20 teeth |
@@ -5819,12 +5834,17 @@ Maths utilities for manipulating vectors and matrices.
 | `circle_intersect(c1, r1, c2, r2)` | Calculate one point where two circles in the X-Z plane intersect, clockwise around c1 |
 | `cosh(x)` | hyperbolic cosine |
 | `coth(x)` | hyperbolic cotangent |
+| `cubic_real_roots(a, b, c, d)` | Returns real roots of cubic equation |
 | `degrees(radians)` | Convert degrees to radians |
 | `euler(R)` | Convert a rotation matrix to a Euler rotation vector. |
 | `identity(n, x = 1)` | Construct an arbitrary size identity matrix |
 | `invert(m)` | Invert a matrix |
+| `map(v, func)` | make a new vector where the func function argument is applied to each element of the vector v |
+| `mapi(v, func)` | make a new vector where the func function argument is applied to each element of the vector v. The func will get the index number as first argument, and the element as second argument. |
 | `nearly_zero(x)` | True if x is close to zero |
+| `quadratic_real_roots(a, b, c)` | Returns real roots of a quadratic equation, biggest first. Returns empty list if no real roots |
 | `radians(degrees)` | Convert radians to degrees |
+| `reduce(v, func, unity)` | reduce a vector v to a single entity by applying the func function recursively to the reduced value so far and the next element, starting with unity as the initial reduced value |
 | `reverse(v)` | Reverse a vector |
 | `rot2_z(a)` | Generate a 2x2 matrix to rotate around z |
 | `rot3_z(a)` | Generate a 3x3 matrix to rotate around z |
@@ -5835,14 +5855,17 @@ Maths utilities for manipulating vectors and matrices.
 | `solve(m, i = 0, j = 0)` | Solve each row ensuring diagonal is not zero |
 | `solve_row(m, i)` | Make diagonal one by dividing the row by it and subtract from other rows to make column zero |
 | `sqr(x)` | Square x |
+| `sumv(v)` | sum a vector of values that can be added with "+" |
 | `tanh(x)` | hyperbolic tangent |
 | `transform(v, m)` | Apply 4x4 transform to a 3 vector by extending it and cropping it again |
 | `transform_points(path, m)` | Apply transform to a path |
 | `translate(v)` | Generate a 4x4 translation matrix, `v` can be `[x, y]`, `[x, y, z]` or `z` |
 | `transpose(m)` | Transpose an arbitrary size matrix |
 | `unit(v)` | Convert `v` to a unit vector |
+| `vec2(v)` | Return a 2 vector with the first two elements of `v` |
 | `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` |
+| `xor(a,b)` | Logical exclusive OR |
 
 ### Modules
 | Module | Description |
@@ -5956,8 +5979,9 @@ Because the tangents need to be calculated to find the length these can be calcu
 | Function | Description |
 |:--- |:--- |
 | `circle_tangent(p1, p2)` | Compute the clockwise tangent between two circles represented as [x,y,r] |
+| `rounded_polygon_arcs(points, tangents)` | Compute the arcs at the points, for each point [angle, rotate_angle, length] |
 | `rounded_polygon_length(points, tangents)` | Calculate the length given the point list and the list of tangents computed by ` rounded_polygon_tangents` |
-| `rounded_polygon_tangents(points)` | Compute the straight sections needed to draw and to compute the lengths |
+| `rounded_polygon_tangents(points)` | Compute the straight sections between a point and the next point, for each section [start_point, end_point, length] |
 
 ### Modules
 | Module | Description |
@@ -5970,20 +5994,20 @@ Because the tangents need to be calculated to find the length these can be calcu
 <a href="#top">Top</a>
 
 ---
-<a name="Rounded_right_triangle"></a>
-## Rounded_right_triangle
+<a name="Rounded_triangle"></a>
+## Rounded_triangle
 Draw a 3D right triangle with rounded edges. Intended to be embedded in other parts. Can be optionally offset by the filleted amount.
 
-[utils/rounded_right_triangle.scad](utils/rounded_right_triangle.scad) Implementation.
+[utils/rounded_triangle.scad](utils/rounded_triangle.scad) Implementation.
 
-[tests/rounded_right_triangle.scad](tests/rounded_right_triangle.scad) Code for this example.
+[tests/rounded_triangle.scad](tests/rounded_triangle.scad) Code for this example.
 
 ### Modules
 | Module | Description |
 |:--- |:--- |
 | `rounded_right_triangle(x, y, z, fillet, center = true, offset = false)` | Draw a 3D right triangle with rounded edges. |
 
-![rounded_right_triangle](tests/png/rounded_right_triangle.png)
+![rounded_triangle](tests/png/rounded_triangle.png)
 
 
 <a href="#top">Top</a>

scripts/changelog.py

@@ -159,5 +159,6 @@ if __name__ == '__main__':
                 print('%s [%s](%s "show release") %s %s' % ('#' * (level + 1), ver, url + '/releases/tag/' + ver, type, diff), file = file)
 
             # Print commits excluding merges
-            if not c.comment.startswith('Merge branch') and not c.comment.startswith('Merge pull'):
+
+            if not c.comment.startswith('Merge branch') and not c.comment.startswith('Merge pull') and not re.match(r'U..ated changelog.*', c.comment):
                 print('* %s [`%s`](%s "show commit") %s %s\n' % (c.date, c.hash[:7], url + '/commit/' + c.hash, initials(c.author), fixup_comment(c.comment, url)), file = file)

tests/bearing_blocks.scad

@@ -17,7 +17,7 @@
 // If not, see <https://www.gnu.org/licenses/>.
 //
 include <../core.scad>
-include <../vitamins/scs_bearing_blocks.scad>
+include <../vitamins/bearing_blocks.scad>
 
 use <../utils/layout.scad>
 

tests/belts.scad

@@ -25,9 +25,9 @@ use <../utils/layout.scad>
 module belt_test() {
     p2 = [-75, -50];
     p3 = [-75, 100];
-    p4 = [75,  100];
+    p4 = [ 75, 100];
 
-    p5 = [75  + pulley_pr(GT2x20ob_pulley) - pulley_pr(GT2x16_plain_idler), +pulley_pr(GT2x16_plain_idler)];
+    p5 = [ 75 + pulley_pr(GT2x20ob_pulley) - pulley_pr(GT2x16_plain_idler), +pulley_pr(GT2x16_plain_idler)];
     p6 = [-75 + pulley_pr(GT2x20ob_pulley) + pulley_pr(GT2x16_plain_idler), -pulley_pr(GT2x16_plain_idler)];
 
     module pulleys(flip = false) {
@@ -52,19 +52,21 @@ module belt_test() {
         translate(p6) pulley_assembly(GT2x16_plain_idler);
     }
 
-    path = [ [p5.x, p5.y, pulley_pr(GT2x16_plain_idler)],
+    path = [ [-40,  0, 0],
              [p6.x, p6.y, -pulley_pr(GT2x16_plain_idler)],
              [p2.x, p2.y, pulley_pr(GT2x20ob_pulley)],
              [p3.x, p3.y, pulley_pr(GT2x20ob_pulley)],
-             [p4.x, p4.y, pulley_pr(GT2x20ob_pulley)]
+             [p4.x, p4.y, pulley_pr(GT2x20ob_pulley)],
+             [p5.x, p5.y, pulley_pr(GT2x16_plain_idler)],
+             [40,   0, 0],
            ];
 
     belt = GT2x6;
-    belt(belt, path, 80, [0,  0]);
+    belt(belt, path, open = true);
     pulleys();
     translate_z(20)
         hflip() {
-            belt(belt, path, 80, [0,  0], belt_colour = grey(90), tooth_colour = grey(50));
+            belt(belt, path, open = true, belt_colour = grey(90), tooth_colour = grey(50));
             pulleys(flip=true);
         }
 
@@ -72,6 +74,31 @@ module belt_test() {
         layout([for(b = belts) belt_width(b)], 10)
             rotate([0, 90, 0])
                 belt(belts[$i], [[0, 0, 20], [0, 1, 20]], belt_colour = $i%2==0 ? grey(90) : grey(20), tooth_colour = $i%2==0 ? grey(70) : grey(50));
+
+    // new example with open loop - this is a simplified example of the style used for example for the BLV 3D printer
+    pulley = GT2x20ob_pulley;
+    idler = GT2x16_plain_idler;
+    corners = [[-75,-50],[75,100]];
+    carriagepos = [0,0];
+    carriagew = 80;
+
+    points = [
+        [carriagepos.x - carriagew / 2, carriagepos.y, 0],
+        [corners[0].x + belt_pulley_pr(belt, pulley) + belt_pulley_pr(belt, idler), carriagepos.y - belt_pulley_pr(belt, idler), idler],
+        [corners[0].x, corners[0].y, pulley],
+        [corners[0].x, corners[1].y, idler],
+        [corners[1].x, corners[1].y, idler],
+        [corners[1].x, carriagepos.y + belt_pulley_pr(belt, idler), idler],
+        [carriagepos.x + carriagew / 2, carriagepos.y, 0]
+    ];
+    translate_z(-30) {
+        belt(belt, points, open=true, auto_twist=true);
+        for (p = points)
+            if (is_list(p.z))
+                translate([p.x, p.y, 0])
+                    pulley_assembly(p.z);
+    }
+
 }
 
 if($preview)

tests/pillow_blocks.scad

@@ -17,7 +17,7 @@
 // If not, see <https://www.gnu.org/licenses/>.
 //
 include <../core.scad>
-include <../vitamins/kp_pillow_blocks.scad>
+include <../vitamins/pillow_blocks.scad>
 
 use <../utils/layout.scad>
 

tests/rounded_triangle.scad

@@ -18,7 +18,7 @@
 //
 
 include <../global_defs.scad>
-use <../utils/rounded_right_triangle.scad>
+use <../utils/rounded_triangle.scad>
 
 
 module rounded_right_triangles() {

tests/screws.scad

@@ -16,6 +16,10 @@
 // You should have received a copy of the GNU General Public License along with NopSCADlib.
 // If not, see <https://www.gnu.org/licenses/>.
 //
+
+// Extra countersink depth
+sink = 0; // [0 : 0.05: 1.0]
+
 include <../core.scad>
 
 module polysink_stl() {
@@ -32,9 +36,9 @@ module polysink_stl() {
             let(s = cs_screws[i])
                 translate([i * 20, 0]) {
                     translate_z(size.z)
-                        screw_polysink(s, 2 * size.z + 1);
+                        screw_polysink(s, 2 * size.z + 1, sink = sink);
 
-                    screw_polysink(s, 2 * size.z + 1, alt = true);
+                    screw_polysink(s, 2 * size.z + 1, alt = true, sink = sink);
                 }
     }
 }

utils/core_xy.scad

@@ -22,6 +22,7 @@
 //!
 //! The belts are positioned according the bottom left "anchor" pulley and the top right drive pulley.
 //! Implementation has the following features:
+//!
 //! 1. The drive and idler pulleys may be different sizes.
 //! 2. The belt separation is parameterised.
 //! 3. The separation of the plain and toothed pulleys on the Y carriages is parameterised, in both the X and the Y direction.
@@ -50,15 +51,20 @@ function coreXY_lower_tooth_colour(type)    = type[8]; //! Colour of the lower b
 // relative to the anchor pulley so that the belts align properly
 function coreXY_drive_pulley_x_alignment(type) = //! Belt alignment offset of the drive pulley relative to the anchor pulley
     (pulley_od(coreXY_drive_pulley(type)) - pulley_od(coreXY_toothed_idler(type))) / 2;
+
 function coreXY_coincident_separation(type) = //! Value of x, y separation to make y-carriage pulleys coincident
     [ -coreXY_plain_idler_offset(type).x, -(pulley_od(coreXY_plain_idler(type)) + pulley_od(coreXY_toothed_idler(type)))/2, 0 ];
+
 function coreXY_plain_idler_offset(type)    = //! Offset of y-carriage plain idler
     [ (pulley_od(coreXY_plain_idler(type)) + pulley_od(coreXY_drive_pulley(type))) / 2 + coreXY_drive_pulley_x_alignment(type), pulley_od(coreXY_plain_idler(type))/2, 0 ];
+
 function coreXY_toothed_idler_offset(type)  = //! offset of y-carriage toothed idler
     [ 0, -pulley_pr(coreXY_toothed_idler(type)), 0 ];
+
 // helper functions for positioning idlers when the stepper motor drive pulley is offset
 function coreXY_drive_toothed_idler_offset(type) = //! Offset of toothed drive idler pulley
     [ 0, coreXY_drive_pulley_x_alignment(type), 0 ];
+
 function coreXY_drive_plain_idler_offset(type) = //! Offset of plain drive idler pulley
     [ coreXY_plain_idler_offset(type).x, -(pulley_od(coreXY_plain_idler(type)) + pulley_od(coreXY_drive_pulley(type))) / 2, 0 ];
 
@@ -85,7 +91,7 @@ module coreXY_half(type, size, pos, separation_y = 0, x_gap = 0, plain_idler_off
 
     // toothed idler for offset stepper motor drive pulley
     p3t_type = coreXY_toothed_idler(type);
-    p3t = [ -size.x / 2 + (drive_pulley_offset.x > 0 ? 0 : 2*coreXY_drive_pulley_x_alignment(type)),
+    p3t = [ -size.x / 2 + (drive_pulley_offset.x > 0 ? 0 : 2 * coreXY_drive_pulley_x_alignment(type)),
             size.y / 2 + coreXY_drive_pulley_x_alignment(type) + drive_pulley_offset.y
     ];
 
@@ -101,11 +107,11 @@ module coreXY_half(type, size, pos, separation_y = 0, x_gap = 0, plain_idler_off
             size.y / 2 - pulley_od(p3p_type) / 2 - pulley_od(p3d_type) / 2 + drive_pulley_offset.y
     ];
 
-    // dummy pulleys for y separation
-    p5_type = p4_type;
-    p5 = [ pos.x - size.x / 2, -size.y / 2 + pos.y + separation_y / 2 ];
-    p6_type = p0_type;
-    p6 = [ pos.x - size.x / 2, -size.y / 2 + pos.y - separation_y / 2 ];
+    // Start and end points
+    start_p = [ pos.x - size.x / 2 + x_gap / 2, -size.y / 2 + pos.y - separation_y / 2, 0 ];
+    end_p   = [ pos.x - size.x / 2 - x_gap / 2, -size.y / 2 + pos.y + separation_y / 2, 0 ];
+
+    //p6_type = p0_type;
 
     module show_pulleys(show_pulleys) {// Allows the pulley colour to be set for debugging
         if (is_list(show_pulleys))
@@ -118,16 +124,21 @@ module coreXY_half(type, size, pos, separation_y = 0, x_gap = 0, plain_idler_off
     show_pulleys(show_pulleys) {
         translate(p0)
             pulley_assembly(p0_type); // y-carriage toothed pulley
+
         translate(p1)
             pulley_assembly(p1_type); // bottom right toothed idler pulley
+
         translate(p2)
             pulley_assembly(p2_type); // bottom left anchor toothed idler pulley
+
         translate(p3d)
             hflip(hflip)
                 pulley_assembly(p3d_type); // top left stepper motor drive pulley
+
         if (drive_pulley_offset.x) { // idler pulleys for offset stepper motor drive pulley
             translate(p3t)
                 pulley_assembly(p3t_type); // toothed idler
+
             translate(p3p)
                 pulley_assembly(p3p_type); // plain idler
         }
@@ -156,20 +167,15 @@ module coreXY_half(type, size, pos, separation_y = 0, x_gap = 0, plain_idler_off
         [ p3t.x, p3t.y, pulley_od(p3t_type) / 2 ],
         [ p4.x, p4.y, -pulley_od(p4_type) / 2 ]
     ];
-    path1 = [ // use eps for corner radius to get sharp corners so this part of the belt is deleted by the gap
-        [ p5.x, p5.y, eps ],
-        [ p6.x, p6.y, eps ]
-    ];
 
     belt = coreXY_belt(type);
 
     path0 = drive_pulley_offset.x == 0 ? concat(path0a, path0b) : drive_pulley_offset.x > 0 ? concat(path0a, path0c) : concat(path0a, path0d);
-    path = separation_y == 0 ? path0 : concat(path0, path1);
+    path = concat([start_p], path0, [end_p]);
 
     belt(type = belt,
         points = path,
-        gap = [ x_gap + eps, abs(separation_y) + 2 ],
-        gap_pos = [ pos.x - size.x / 2, pos.y - size.y / 2 + belt_pitch_height(belt) - belt_thickness(belt) / 2 ],
+        open = true,
         belt_colour  = lower_belt ? coreXY_lower_belt_colour(type) : coreXY_upper_belt_colour(type),
         tooth_colour = lower_belt ? coreXY_lower_tooth_colour(type) : coreXY_upper_tooth_colour(type));
 }
@@ -180,6 +186,7 @@ module coreXY(type, size, pos, separation, x_gap, plain_idler_offset = 0, upper_
         hflip()
             explode(25)
                 coreXY_half(type, size, [size.x - pos.x - separation.x, pos.y], separation.y, x_gap, plain_idler_offset, [-lower_drive_pulley_offset.x, lower_drive_pulley_offset.y], show_pulleys, lower_belt = true, hflip = true);
+
         // upper belt
         translate([separation.x, 0, separation.z])
             explode(25)

utils/maths.scad

@@ -88,6 +88,7 @@ function scale(v) = let(s = is_list(v) ? v : [v, v, v]) //!  Generate a 4x4 matr
                           [0,   0,   0,   1]
                         ];
 
+function vec2(v) = [v.x, v.y]; //! Return a 2 vector with the first two elements of `v`
 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
@@ -153,3 +154,36 @@ function circle_intersect(c1, r1, c2, r2) =     //! Calculate one point where tw
         d = norm(v),                            // Distance between centres
         a = atan2(v.z, v.x) - acos((sqr(d) + sqr(r2) - sqr(r1)) / (2 * d * r2)) // Cosine rule to find angle from c2
      ) c2 + r2 * [cos(a), 0, sin(a)];           // Point on second circle
+
+function map(v, func) = [ for (e = v) func(e) ]; //! make a new vector where the func function argument is applied to each element of the vector v
+function mapi(v, func) = [ for (i = [0:len(v)-1]) func(i,v[i]) ]; //! make a new vector where the func function argument is applied to each element of the vector v. The func will get the index number as first argument, and the element as second argument.
+function reduce(v, func, unity) = let ( r = function(i,val) i == len(v) ? val : r(i + 1, func(val, v[i])) ) r(0, unity); //! reduce a vector v to a single entity by applying the func function recursively to the reduced value so far and the next element, starting with unity as the initial reduced value
+function sumv(v) = reduce(v, function(a, b) a + b, 0); //! sum a vector of values that can be added with "+"
+
+function xor(a,b) = (a && !b) || (!a && b);     //! Logical exclusive OR
+function cuberoot(x)= sign(x)*abs(x)^(1/3);
+
+function quadratic_real_roots(a, b, c) =        //! Returns real roots of a quadratic equation, biggest first. Returns empty list if no real roots
+    let(2a = 2 * a,
+        2c = 2 * c,
+        det = b^2 - 2a * 2c
+    ) det < 0 ? [] :
+        let(r = sqrt(det),
+            x1 = b < 0 ? 2c / (-b + r) : (-b - r) / 2a,
+            x2 = b < 0 ? (-b + r) / 2a : 2c / (-b - r)
+        ) [x2, x1];
+
+function cubic_real_roots(a, b, c, d) = //! Returns real roots of cubic equation
+    let(b = b / a,
+        c = c / a,
+        d = d / a,
+        inflection = -b / 3,
+        p = c - b^2 / 3,
+        q = 2 * b^3 / 27 - b * c / 3 + d,
+        det = q^2 / 4 + p^3 / 27,
+        roots = !p && !q ? 1 : nearly_zero(det) ? 2 :  det < 0 ? 3 : 1,
+        r = sqrt(det),
+        x = cuberoot(-q / 2 - r) + cuberoot(-q / 2 + r)
+    ) roots == 1 ? [x] :
+      roots == 2 ? [3 * q /p + inflection, -3 * q / p / 2 + inflection] :
+      [for(i = [0 : roots - 1]) 2 * sqrt(-p / 3) * cos(acos(3 * q * sqrt(-3 / p) / p / 2) - i * 120) + inflection];

utils/rounded_polygon.scad

@@ -24,6 +24,7 @@
 //! Because the tangents need to be calculated to find the length these can be calculated separately and re-used when drawing to save calculating them twice.
 //
 include <../utils/core/core.scad>
+use <../utils/maths.scad>
 
 function circle_tangent(p1, p2) = //! Compute the clockwise tangent between two circles represented as [x,y,r]
     let(
@@ -36,36 +37,45 @@ function circle_tangent(p1, p2) = //! Compute the clockwise tangent between two
         v = [cos(theta), sin(theta)]
     )[ p1 + r1 * v, p2 + r2 * v ];
 
-function rounded_polygon_tangents(points) = //! Compute the straight sections needed to draw and to compute the lengths
-    let(len = len(points))
-        [for(i = [0 : len - 1])
-            let(ends = circle_tangent(points[i], points[(i + 1) % len]))
-                for(end = [0, 1])
-                    ends[end]];
+function rounded_polygon_arcs(points, tangents) = //! Compute the arcs at the points, for each point [angle, rotate_angle, length]
+    let(
+        len = len(points)
+    ) [ for (i = [0: len-1])
+        let(
+            p1 = vec2(tangents[(i - 1 + len) % len][1]),
+            p2 = vec2(tangents[i][0]),
+            p = vec2(points[i]),
+            v1 = p1 - p,
+            v2 = p2 - p,
+            sr = points[i][2],
+            r = abs(sr),
+            a = r < 0.001 ? 0 : let( aa = acos((v1 * v2) / sqr(r)) ) cross(v1, v2) * sign(sr) <= 0 ? aa : 360 - aa,
+            l = PI * a * r / 180,
+            v0 = [r, 0],
+            v = let (
+                vv = norm(v0 - v2) < 0.001 ? 0 : abs(v2.y) < 0.001 ? 180 :
+                        let( aa = acos((v0 * v2) / sqr(r)) ) cross(v0, v2) * sign(sr) <= 0 ? aa : 360 - aa
+            ) sr > 0 ? 360 - vv : vv - a
+        ) [a, v, l]
+    ];
 
-function sumv(v, i = 0, sum = 0) = i == len(v) ? sum : sumv(v, i + 1, sum + v[i]);
+function rounded_polygon_tangents(points) = //! Compute the straight sections between a point and the next point, for each section [start_point, end_point, length]
+    let(len = len(points))
+    [ for(i = [0 : len - 1])
+        let(ends = circle_tangent(points[i], points[(i + 1) % len]))
+            [ends[0], ends[1], norm(ends[0] - ends[1])]
+    ];
 
 // the cross product of 2D vectors is the area of the parallelogram between them. We use the sign of this to decide if the angle is bigger than 180.
 function rounded_polygon_length(points, tangents) = //! Calculate the length given the point list and the list of tangents computed by ` rounded_polygon_tangents`
     let(
-      len = len(points),
-      indices = [0 : len - 1],
-      straights = [for(i = indices) norm(tangents[2 * i] - tangents[2 * i + 1])],
-      arcs = [for(i = indices) let(p1 = tangents[2 * i + 1],
-                                   p2 = tangents[(2 * i + 2) % (2 * len)],
-                                   corner = points[(i + 1) % len],
-                                   c = [corner.x, corner.y],
-                                   v1 = p1 - c,
-                                   v2 = p2 - c,
-                                   r = abs(corner.z),
-                                   a = acos((v1 * v2) / sqr(r))) r ? PI * (cross(v1, v2) <= 0 ? a : 360 - a) * r / 180 : 0]
-     )
-    sumv(concat(straights, arcs));
+        arcs = rounded_polygon_arcs(points, tangents)
+    ) sumv( map( concat(tangents, arcs), function(e) e[2] ) );
 
 module rounded_polygon(points, _tangents = undef) { //! Draw the rounded polygon from the point list, can pass the tangent list to save it being calculated
     len = len(points);
     indices = [0 : len - 1];
-    tangents = _tangents ? _tangents : rounded_polygon_tangents(points);
+    tangents = [ for (t = _tangents ? _tangents : rounded_polygon_tangents(points)) each [t.x, t.y] ];
 
     difference(convexity = points) {
         union() {
@@ -74,6 +84,7 @@ module rounded_polygon(points, _tangents = undef) { //! Draw the rounded polygon
                     hull() {
                         translate([points[i].x, points[i].y])
                             circle(points[i][2]);
+
                         polygon([tangents[(2 * i - 1 + 2 * len) % (2 * len)], tangents[2 * i], [points[i].x, points[i].y]]);
                     }
 
@@ -85,7 +96,7 @@ module rounded_polygon(points, _tangents = undef) { //! Draw the rounded polygon
                     translate([points[i].x, points[i].y])
                         circle(-points[i][2]);
 
-                    polygon([tangents[(2 * i - 1 + 2 * len) % (2 *len)], tangents[2 * i], [points[i].x, points[i].y]]);
+                    polygon([tangents[(2 * i - 1 + 2 * len) % (2 * len)], tangents[2 * i], [points[i].x, points[i].y]]);
                 }
      }
 }

utils/rounded_triangle.scad

@@ -21,7 +21,6 @@
 //! Draw a 3D right triangle with rounded edges. Intended to be embedded in other parts. Can be optionally offset by the filleted amount.
 //
 include <../utils/core/core.scad>
-include <..//utils/core/rounded_rectangle.scad>
 
 module rounded_right_triangle(x, y, z, fillet, center = true, offset = false) { //! Draw a 3D right triangle with rounded edges.
     fillet = max(fillet, eps);

vitamins/bearing_blocks.scad

@@ -40,4 +40,4 @@ SCS16LUU  = ["SCS16LUU",  9, 19, 25, 50, 85, 38.5, 32.5, 36, 60, 7,    M5_cap_sc
 scs_bearing_blocks = [SCS6UU, SCS8UU,  SCS10UU, SCS12UU, SCS16UU];
 scs_bearing_blocks_long = [SCS8LUU,  SCS10LUU, SCS12LUU, SCS16LUU];
 
-use <scs_bearing_block.scad>
+use <bearing_block.scad>

vitamins/belt.scad

@@ -18,19 +18,29 @@
 //
 
 //
-//! Models timing belt running over toothed or smooth pulleys and calculates an accurate length.
-//! Only models 2D paths, so not crossed belt core XY!
+//! Models timing belt running in a path over toothed or smooth pulleys and calculates an accurate length.
+//! Only models 2D paths, belt may twist to support crossed belt core XY and other designes where the belt twists!
+//!
+//! By default the path is a closed loop. An open loop can be specified by specifying `open=true`, and in that case the start and end points are not connected, leaving the loop open.
+//!
+//! To get a 180 degree twist of the loop, you can use the `twist` argument. `Twist` can be a single number, and in that case the belt will twist after
+//! the position with that number. Alternatively `twist` can be a list of boolean values with a boolean for each position; the belt will then twist after
+//! the position that have a `true` value in the `twist` list. If the path is specified with pulley/idler types, then you can use `auto_twist=true`; in
+//! that case the belt will automatically twist so the back of the belt always runs against idlers and the tooth side runs against pullies. If you use
+//! `open=true` then you might also use `start_twist=true` to let the belt start the part with the back side out.
+//!
+//! The path must be specified as a list of positions. Each position should be either a vector with `[x, y, pulley]` or `[x, y, r]`. A pully is a type from
+//! `pulleys.scad`, and correct radius and angle will automatically be calculated. Alternatively a radius can be specified directly.
 //!
 //! To make the back of the belt run against a smooth pulley on the outside of the loop specify a negative pitch radius.
-//!
-//! By default the path is a closed loop but a gap length and position can be specified to make open loops.
-//! To draw the gap its XY position is specified by `gap_pos`. `gap_pos.z` can be used to specify a rotation if the gap is not at the bottom of the loop.
+//! Alternativley you can just specify smooth pulleys in the path, and it will then happen automatically.
 //!
 //! Individual teeth are not drawn, instead they are represented by a lighter colour.
 //
 include <../utils/core/core.scad>
 use <../utils/rounded_polygon.scad>
 use <../utils/maths.scad>
+use <pulley.scad>
 
 function belt_pitch(type)        = type[1]; //! Pitch in mm
 function belt_width(type)        = type[2]; //! Width in mm
@@ -41,47 +51,102 @@ function belt_pitch_height(type) = type[5] + belt_tooth_height(type); //! Offset
 function belt_pitch_to_back(type) = belt_thickness(type) - belt_pitch_height(type); //! Offset of the back from the pitch radius
 //
 // We model the belt path at the pitch radius of the pulleys and the pitch line of the belt to get an accurate length.
-// The belt is then drawn by offseting each side from the pitch line.
 //
-module belt(type, points, gap = 0, gap_pos = undef, belt_colour = grey(20), tooth_colour = grey(50)) { //! Draw a belt path given a set of points and pitch radii where the pulleys are. Closed loop unless a gap is specified
+module belt(type, points, belt_colour = grey(20), tooth_colour = grey(50), open = false, twist = undef, auto_twist = false, start_twist = false) { //! Draw a belt path given a set of points and pitch radii where the pulleys are. Closed loop unless open is specified
     width = belt_width(type);
     pitch = belt_pitch(type);
     thickness = belt_thickness(type);
+
+    info = _belt_points_info(type, points, open, twist, auto_twist, start_twist);
+    dotwist = info[0]; // array of booleans, true if a twist happen after the position
+    twisted = info[1]; // array of booleans, true if the belt is twisted at the position
+    pointsx = info[2]; // array of [x,y,r], r is negative if left-angle (points may have pulleys as third element, but pointsx have radi)
+    tangents = info[3];
+    arcs = info[4];
+    length = ceil(_belt_length(info, open) / pitch) * pitch;
+
     part = str(type[0],pitch);
-    vitamin(str("belt(", no_point(part), "x", width, ", ", points, arg(gap, 0), arg(gap_pos, undef), "): Belt ", part," x ", width, "mm x ", length, "mm"));
+    vitamin(str("belt(", no_point(part), "x", width, ", ", pointsx, "): Belt ", part," x ", width, "mm x ", length, "mm"));
 
     len = len(points);
 
-    tangents = rounded_polygon_tangents(points);
-
-    length = ceil((rounded_polygon_length(points, tangents) - (is_list(gap) ? gap.x + gap.y : gap)) / pitch) * pitch;
-
-    module shape() rounded_polygon(points, tangents);
-
-    ph = belt_pitch_height(type);
     th = belt_tooth_height(type);
-    module gap()
-        if(gap)
-            translate([gap_pos.x, gap_pos.y])
-                rotate(is_undef(gap_pos.z) ? 0 : gap_pos.z)
-                    translate([0, ph - thickness / 2])
-                        square(is_list(gap) ? [gap.x, gap.y + thickness + eps] : [gap, thickness + eps], center = true);
+    ph = belt_pitch_height(type);
+    module beltp() translate([ph - th, -width / 2]) square([th, width]);
+    module beltb() translate([ph - thickness, -width / 2]) square([thickness - th, width]);
 
-    color(belt_colour)
-        linear_extrude(width, center = true)
-            difference() {
-                offset(-ph + thickness ) shape();
-                offset(-ph + th) shape();
-                gap();
-            }
+    for (i = [0 : len - (open ? 2 : 1)]) {
+        p1 = tangents[i].x;
+        p2 = tangents[i].y;
+        v = p2-p1;
+        a =  atan(v.y / v.x) - (v.x < 0 ? 180 : 0); //a2(p2-p1);
+        l = norm(v);
+        translate(p1) rotate([-90, 0, a - 90]) {
+            twist = dotwist[i] ? 180 : 0;
+            mirrored = twisted[i] ? 1 : 0;
+            color(tooth_colour) linear_extrude(l, twist = twist) mirror([mirrored, 0, 0]) beltp();
+            color(belt_colour)  linear_extrude(l, twist = twist) mirror([mirrored, 0, 0]) beltb();
+        }
+    }
 
-    color(tooth_colour)
-        linear_extrude(width, center = true)
-            difference() {
-                offset(-ph + th) shape();
-                offset(-ph) shape();
-                gap();
-            }
+    for (i = [(open ? 1 : 0) : len - (open ? 2 : 1)]) {
+        p = pointsx[i];
+        arc = arcs[i];
+        translate([p.x, p.y]) rotate([0, 0, arc[1]]) {
+            mirrored = xor(twisted[i], p[2] < 0) ? 0 : 1;
+            color(tooth_colour) rotate_extrude(angle = arc[0]) translate([abs(p[2]), 0, 0]) mirror([mirrored, 0, 0]) beltp();
+            color(belt_colour)  rotate_extrude(angle = arc[0]) translate([abs(p[2]), 0, 0]) mirror([mirrored, 0, 0]) beltb();
+        }
+    }
 }
 
-function belt_length(points, gap = 0) = rounded_polygon_length(points, rounded_polygon_tangents(points)) - gap; //! Compute belt length given path and optional gap
+function _belt_points_info(type, points, open, twist, auto_twist, start_twist) = //! Helper function that calculates [twist, istwisted, points, tangents, arcs]
+let(
+    len = len(points),
+    isleft = function(i) let(
+            p = vec2(points[i]),
+            p0 = vec2(points[(i - 1 + len) % len]),
+            p1 = vec2(points[(i + 1) % len])
+        ) cross(p-p0,p1-p) > 0,
+    dotwist = function(i, istwisted) let( in = (i + 1) % len )
+        is_list(twist) ? twist[i] :
+        !is_undef(twist) ? i == twist :
+        open && is_list(points[in][2]) && auto_twist ? !pulley_teeth(points[in][2]) && !xor(isleft(in), istwisted) :
+        false,
+    twisted = [
+        for (
+            i = 0,
+            istwisted = start_twist,
+            twist = dotwist(i, istwisted),
+            nexttwisted = xor(twist, istwisted);
+            i < len;
+            i = i + 1,
+            istwisted = nexttwisted,
+            twist = dotwist(i, istwisted),
+            nexttwisted = xor(twist, istwisted)
+        ) [twist, istwisted] ],
+    pointsx = mapi(points, function(i, p) !is_list(p[2]) ? p : [p.x, p.y, let( // if p[2] is not a list it is just r, otherwise it is taken to be a pulley and we calculate r
+            isleft = isleft(i),
+            r = belt_pulley_pr(type, p[2], twisted = !xor(pulley_teeth(p[2]), xor(isleft, twisted[i][1])))
+        ) isleft ? -r : r ] ),
+    tangents = rounded_polygon_tangents(pointsx),
+    arcs = rounded_polygon_arcs(pointsx, tangents)
+) [ [ for (t = twisted) t[0] ], [ for (t = twisted) t[1] ], pointsx, tangents, arcs];
+
+function belt_pulley_pr(type, pulley, twisted=false) = //! Pitch radius. Default it expects the belt tooth to be against a toothed pulley an the backside to be against a smooth pulley (an idler). If `twisted` is true, the the belt is the other way around.
+    let(
+        thickness = belt_thickness(type),
+        ph = belt_pitch_height(type)
+    ) pulley_teeth(pulley)
+        ? pulley_pr(pulley) + (twisted ? thickness - ph : 0 )
+        : pulley_ir(pulley) + (twisted ? ph : thickness - ph );
+
+
+function belt_length(type, points, open = false) = _belt_length(_belt_points_info(type, points, open), open); //! Compute belt length given path
+
+function _belt_length(info, open) = let(
+    len = len(info[0]),
+    d = open ? 1 : 0,
+    tangents = slice(info[3], 0, len - d) ,
+    arcs = slice(info[4], d, len - d)
+) sumv( map( concat(tangents, arcs), function(e) e[2] ));

vitamins/opengrab.scad

@@ -62,6 +62,7 @@ function opengrab_depth() = depth;                               //! Module heig
 function opengrab_target_thickness() = target;                   //! Target sheet thickness
 function opengrab_pcb() = pcb;                                   //! The PCB
 function opengrab_pcb_z() = depth - pillar - pcb_thickness(pcb); //! PCB offset from the front
+function opengrab_screw_depth() = 4;                             //! Max screw depth in pillars
 
 module opengrab() { //! Draw OpenGrab module
     vitamin("opengrab(): OpenGrab V3 electro permanent magnet");

vitamins/pillow_blocks.scad

@@ -31,4 +31,4 @@ KP001 =   ["KP001",    12, 19, 71, 56, 16, 7.0,  6, 38, 14.5, 4, 32, M6_clearanc
 
 kp_pillow_blocks = [KP08_15, KP08_18, KP000, KP001];
 
-use <kp_pillow_block.scad>
+use <pillow_block.scad>

vitamins/pulley.scad

@@ -42,7 +42,7 @@ 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
+function pulley_pr(type, belt = undef) = let(belt = is_undef(belt) ? pulley_belt(type) : belt)      //! Pitch radius, `belt` only needed for non-standard belt over smooth pulleys
                                  pulley_teeth(type) ? pulley_teeth(type) * belt_pitch(belt) / 2 / PI
                                                     : pulley_ir(type) + belt_thickness(belt) - belt_pitch_height(belt);
 
@@ -53,7 +53,7 @@ function pulley_extent(type) = max(pulley_flange_dia(type), pulley_hub_dia(type)
 T_angle = 40;
 GT_r = 0.555;
 
-module pulley(type, colour = silver) { //! Draw a pulley
+module pulley(type, colour = silver) { //! Draw a pulley, any children are placed above.
     teeth = pulley_teeth(type);
     od = pulley_od(type);
 
@@ -138,6 +138,10 @@ module pulley(type, colour = silver) { //! Draw a pulley
         else
             core();
     }
+
+    if($children)
+        translate_z(pulley_height(type))
+            children();
 }
 
 module pulley_assembly(type, colour = silver) { //! Draw a pulley with its grub screws in place

vitamins/screw.scad

@@ -284,10 +284,10 @@ function screw_polysink_r(type, z) = //! Countersink hole profile corrected for
     )
     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
+module screw_polysink(type, h = 100, alt = false, sink = 0) { //! A countersink hole made from stacked polyholes for printed parts, default is flush, `sink` can be used to recess the head
     head_depth = screw_head_depth(type);
     assert(head_depth, "Not a countersunk screw");
-    layers = ceil(head_depth / layer_height);
+    layers = ceil((head_depth + sink) / layer_height);
     rmin = screw_clearance_radius(type);
     sides = sides(rmin);
     lh = layer_height + eps;
@@ -295,7 +295,7 @@ module screw_polysink(type, h = 100, alt = false) { //! A countersink hole made
         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);
+                    r = screw_polysink_r(type, i * layer_height + layer_height / 2 - sink);
                     if(alt)
                         rotate(i % 2 == layers % 2 ? 180 / sides : 0)
                             poly_cylinder(r = r, h = lh, center = false, sides = sides);

vitamins/screws.scad

@@ -79,6 +79,7 @@ M2_cs_cap_screw  = ["M2_cs_cap","M2 cs cap",    hs_cs_cap,2, 3.8, 0,    0.65,1.3
 M3_cs_cap_screw  = ["M3_cs_cap","M3 cs cap",    hs_cs_cap,3, 6.0, 0,    1.05,2.0, 18,  M3_washer, M3_nut,   M3_tap_radius,    M3_clearance_radius];
 M4_cs_cap_screw  = ["M4_cs_cap","M4 cs cap",    hs_cs_cap,4, 8.0, 0,    1.49,2.5, 20,  M4_washer, M4_nut,   M4_tap_radius,    M4_clearance_radius];
 M5_cs_cap_screw  = ["M5_cs_cap","M5 cs cap",    hs_cs_cap,5,10.0, 0,    3.00,3.0, 22,  M5_washer, M5_nut,   M5_tap_radius,    M5_clearance_radius];
+M6_cs_cap_screw  = ["M6_cs_cap","M6 cs cap",    hs_cs_cap,6,12.0, 0,    3.00,4.0, 24,  M6_washer, M6_nut,   M6_tap_radius,    M6_clearance_radius];
 
 M2_dome_screw    = ["M2_dome", "M2 dome",       hs_dome,  2, 3.5, 1.3,  0.6, 1.3, 16,  M2_washer, M2_nut,   M2_tap_radius,    M2_clearance_radius];
 M3_dome_screw    = ["M3_dome", "M3 dome",       hs_dome,  3, 5.7, 1.65, 1.04,2.0, 18,  M3_washer, M3_nut,   M3_tap_radius,    M3_clearance_radius];
@@ -109,12 +110,12 @@ No6_screw        = ["No6", "No6 pan wood",      hs_pan, 3.5, 6.7, 2.2,    0,   0
 No6_cs_screw     = ["No6_cs", "No6 cs wood",    hs_cs,  3.5, 7.0, 0,      0,   0, 0,   M4_washer, false,    No6_pilot_radius, No6_clearance_radius];
 
 screw_lists = [
-[ M2_cap_screw,    M2p5_cap_screw, M3_cap_screw,    M4_cap_screw,    M5_cap_screw, M6_cap_screw, M8_cap_screw],
+[ M2_cap_screw,    M2p5_cap_screw, M3_cap_screw,    M4_cap_screw,    M5_cap_screw,    M6_cap_screw, M8_cap_screw],
 [ 0,               0,              M3_low_cap_screw],
-[ M2_cs_cap_screw, 0,              M3_cs_cap_screw, M4_cs_cap_screw, M5_cs_cap_screw],
+[ M2_cs_cap_screw, 0,              M3_cs_cap_screw, M4_cs_cap_screw, M5_cs_cap_screw, M6_cs_cap_screw],
 [ M2_dome_screw,   0,              M3_dome_screw,   M4_dome_screw,   M5_dome_screw],
-[ 0,               0,              M3_hex_screw,    M4_hex_screw,    M5_hex_screw, M6_hex_screw, M8_hex_screw],
-[ 0,               M2p5_pan_screw, M3_pan_screw,    M4_pan_screw,    M5_pan_screw, M6_pan_screw, No632_pan_screw],
+[ 0,               0,              M3_hex_screw,    M4_hex_screw,    M5_hex_screw,    M6_hex_screw, M8_hex_screw],
+[ 0,               M2p5_pan_screw, M3_pan_screw,    M4_pan_screw,    M5_pan_screw,    M6_pan_screw, No632_pan_screw],
 [ No2_screw,       0,              No4_screw,       No6_screw,       No6_cs_screw],
 [ 0,               0,              M3_grub_screw,   M4_grub_screw]
 ];