Merge branch 'martinbudden-drag_chain_links'

CHANGELOG.md

@@ -3,6 +3,18 @@
 This changelog is generated by `changelog.py` using manually added semantic version tags to classify commits as breaking changes, additions or fixes.
 
 
+### [v17.8.0](https://github.com/nophead/NopSCADlib/releases/tag/v17.8.0 "show release") Additions [...](https://github.com/nophead/NopSCADlib/compare/v17.7.2...v17.8.0 "diff with v17.7.2")
+*   2021-12-11 [`c4895f8`](https://github.com/nophead/NopSCADlib/commit/c4895f84c7cff48baa14040c2759da15d2a165be "show commit") [C.P.](# "Chris Palmer") Updated image and readme.
+
+*   2021-11-20 [`b1ad206`](https://github.com/nophead/NopSCADlib/commit/b1ad206ce4d29b61f3a9be15adde7f1a51c225b5 "show commit") [M.B.](# "Martin Budden") Rotated conical horihole.
+
+*   2021-11-20 [`da55f86`](https://github.com/nophead/NopSCADlib/commit/da55f86536746657a1e105858109f177d24c362e "show commit") [M.B.](# "Martin Budden") Added variant of drag chain without supports.
+Unsupported drag chain has conical pin and corresponding horihole and is printed with cutout facing upwards.
+
+ * Also made clearance a property of the drag chain so it can be altered for printing chain assemblies
+
+*   2021-12-11 [`43c78fd`](https://github.com/nophead/NopSCADlib/commit/43c78fd1a38de87a210a64c3587bc994731b41c6 "show commit") [C.P.](# "Chris Palmer") Annual image changes due to change of computer.
+
 #### [v17.7.2](https://github.com/nophead/NopSCADlib/releases/tag/v17.7.2 "show release") Fixes [...](https://github.com/nophead/NopSCADlib/compare/v17.7.1...v17.7.2 "diff with v17.7.1")
 *   2021-11-13 [`74e5698`](https://github.com/nophead/NopSCADlib/commit/74e569896bd9b4f98bcd7c84322cd358fee8941f "show commit") [C.P.](# "Chris Palmer") Updated images.
 

printed/drag_chain.scad

@@ -62,6 +62,9 @@ function drag_chain_outer_size(type) = //! Link outer dimensions
     let(s = drag_chain_size(type), z = s.z + drag_chain_bwall(type) + drag_chain_twall(type))
         [s.x + z, s.y + 4 * drag_chain_wall(type) + 2 * drag_chain_clearance(type), z];
 
+function drag_chain_links(type) = //! Number of links in chain
+    ceil(drag_chain_travel(type) / drag_chain_size(type).x) + 4;
+
 function screw_lug_radius(screw) = //! Radius of a screw lug
     corrected_radius(screw_clearance_radius(screw)) + 3.1 * extrusion_width;
 
@@ -277,16 +280,15 @@ module _drag_chain_assembly(type, pos = 0, render = false) {
     s = drag_chain_size(type);
     x = (1 + exploded()) * s.x;
     r = drag_chain_radius(type) * x / s.x;
-    travel = drag_chain_travel(type);
-    links = ceil(travel / s.x);
-    actual_travel = links * s.x;
+    links = drag_chain_links(type);
+    actual_travel = (links - 4) * s.x;
     z = drag_chain_outer_size(type).z;
 
     zb = z / 2;                                     // z of bottom track
     c = [actual_travel / 2 + pos / 2, 0, r + zb];   // centre of bend
 
     points = [                                      // Calculate list of hinge points
-        for(i = 0, p = [0, 0, z / 2 + 2 * r]; i < links + 5;
+        for(i = 0, p = [0, 0, z / 2 + 2 * r]; i < links + 1;
             i = i + 1,
             dx = p.z > c.z ? x : -x,
             p = max(p.x + dx, p.x) <= c.x ? p + [dx, 0, 0]      // Straight sections

readme.md

@@ -4954,6 +4954,7 @@ to the assembly, for example to add inserts.
 | Function | Description |
 |:--- |:--- |
 | `drag_chain(name, size, travel, wall = 1.6, bwall = 1.5, twall = 1.5, clearance = 0.1, supports = true, screw = M2_cap_screw, screw_lists = [[1,0,0,1],[1,0,0,1]])` | Constructor |
+| `drag_chain_links(type)` | Number of links in chain |
 | `drag_chain_outer_size(type)` | Link outer dimensions |
 | `drag_chain_radius(type)` | The bend radius at the pivot centres |
 | `drag_chain_z(type)` | Outside dimension of a 180 bend |