Updated readme

readme.md

@@ -626,10 +626,10 @@ Brackets for joining extrusions at a corner.
 ### Vitamins
 | Qty | Module call | BOM entry |
 | ---:|:--- |:---|
-|   1 | ```extrusion(E2020, 20)``` |  Extrusion E2020 x 20mm |
-|   1 | ```extrusion(E2020, 30)``` |  Extrusion E2020 x 30mm |
-|   1 | ```extrusion(E2020, 40)``` |  Extrusion E2020 x 40mm |
-|   1 | ```extrusion(E2020, 50)``` |  Extrusion E2020 x 50mm |
+|   1 | ```extrusion(E2020, 20, false)``` |  Extrusion E2020 x 20mm |
+|   1 | ```extrusion(E2020, 30, false)``` |  Extrusion E2020 x 30mm |
+|   1 | ```extrusion(E2020, 40, false)``` |  Extrusion E2020 x 40mm |
+|   1 | ```extrusion(E2020, 50, false)``` |  Extrusion E2020 x 50mm |
 |   2 | ```extrusion_corner_bracket(E20_corner_bracket)``` |  Extrusion corner bracket 20 |
 |   2 | ```extrusion_inner_corner_bracket(E20_inner_corner_bracket, true)``` |  Extrusion inner corner bracket 4.5 |
 |   1 | ```extrusion_inner_corner_bracket(E20_inner_corner_bracket, false)``` |  Extrusion inner corner bracket 4.5 |
@@ -669,21 +669,21 @@ Aluminium  extrusion.
 ### Modules
 | Module | Description |
 |:--- |:--- |
-| ```extrusion(type, length, cornerHole = false)``` | Draw the specified extrusion |
+| ```extrusion(type, length, center = false, cornerHole = false)``` | Draw the specified extrusion |
 
 ![extrusions](tests/png/extrusions.png)
 
 ### Vitamins
 | Qty | Module call | BOM entry |
 | ---:|:--- |:---|
-|   1 | ```extrusion(E2020, 80)``` |  Extrusion E2020 x 80mm |
-|   1 | ```extrusion(E2040, 80)``` |  Extrusion E2040 x 80mm |
-|   1 | ```extrusion(E2060, 80)``` |  Extrusion E2060 x 80mm |
-|   1 | ```extrusion(E2080, 80)``` |  Extrusion E2080 x 80mm |
-|   1 | ```extrusion(E3030, 80)``` |  Extrusion E3030 x 80mm |
-|   1 | ```extrusion(E3060, 80)``` |  Extrusion E3060 x 80mm |
-|   1 | ```extrusion(E4040, 80)``` |  Extrusion E4040 x 80mm |
-|   1 | ```extrusion(E4080, 80)``` |  Extrusion E4080 x 80mm |
+|   1 | ```extrusion(E2020, 80, false)``` |  Extrusion E2020 x 80mm |
+|   1 | ```extrusion(E2040, 80, false)``` |  Extrusion E2040 x 80mm |
+|   1 | ```extrusion(E2060, 80, false)``` |  Extrusion E2060 x 80mm |
+|   1 | ```extrusion(E2080, 80, false)``` |  Extrusion E2080 x 80mm |
+|   1 | ```extrusion(E3030, 80, false)``` |  Extrusion E3030 x 80mm |
+|   1 | ```extrusion(E3060, 80, false)``` |  Extrusion E3060 x 80mm |
+|   1 | ```extrusion(E4040, 80, false)``` |  Extrusion E4040 x 80mm |
+|   1 | ```extrusion(E4080, 80, false)``` |  Extrusion E4080 x 80mm |
 
 
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@@ -2474,6 +2474,8 @@ Rocker switch. Also used for neon indicator in the same form factor.
 ## Rod
 Steel rods and studding with chamfered ends.
 
+These items are sysmtrical, so by default the origin is in the centre but it can be changed to the bottom.
+
 
 [vitamins/rod.scad](vitamins/rod.scad) Implementation.
 
@@ -2782,8 +2784,8 @@ SK shaft support brackets
 ### Vitamins
 | Qty | Module call | BOM entry |
 | ---:|:--- |:---|
-|   2 | ```extrusion(E2020, 20)``` |  Extrusion E2020 x 20mm |
-|   2 | ```extrusion(E3030, 20)``` |  Extrusion E3030 x 20mm |
+|   2 | ```extrusion(E2020, 20, false)``` |  Extrusion E2020 x 20mm |
+|   2 | ```extrusion(E3030, 20, false)``` |  Extrusion E3030 x 20mm |
 |   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 |
@@ -2885,6 +2887,8 @@ Filament spool models
 ## Springs
 Compression springs. Can be tapered, have open, closed or ground ends. Ground ends will render a lot slower.
 
+By default springs have their origin at the bottom but can be centered.
+
 
 [vitamins/springs.scad](vitamins/springs.scad) Object definitions.
 
@@ -2913,7 +2917,7 @@ Compression springs. Can be tapered, have open, closed or ground ends. Ground en
 ### Modules
 | Module | Description |
 |:--- |:--- |
-| ```comp_spring(type, l = 0)``` | Draw specified spring, l can be set to specify the compressed length. |
+| ```comp_spring(type, l = 0, center = false)``` | Draw specified spring, l can be set to specify the compressed length. |
 
 ![springs](tests/png/springs.png)
 

vitamins/extrusion.scad

@@ -43,7 +43,7 @@ module extrusion_cross_section(type, cornerHole) {
         fillet = extrusion_fillet(type);
         cornerSize = (width-channelWidth)/2;
         cornerSquare = (width-extrusion_channel_width_internal(type))/2;
-        cornerHoleDiameter =extrusion_corner_hole(type);
+        cornerHoleDiameter = extrusion_corner_hole(type);
 
         translate([-width/2,-width/2]) {
             difference() {
@@ -57,7 +57,7 @@ module extrusion_cross_section(type, cornerHole) {
                     translate([fillet,fillet])
                         square([cornerSquare-fillet,cornerSquare-fillet]);
                 }
-                if(cornerHole)
+                if(cornerHole && cornerHoleDiameter > 0)
                     translate([cornerSquare/2,cornerSquare/2])
                         circle(d=cornerHoleDiameter);
             }
@@ -117,12 +117,12 @@ module extrusion_cross_section(type, cornerHole) {
                 extrusion_center_section(type);
 }
 
-module extrusion(type, length, cornerHole = false) { //! Draw the specified extrusion
+module extrusion(type, length, center = false, cornerHole = false) { //! Draw the specified extrusion
 
-    vitamin(str("extrusion(", type[0], ", ", length, "): Extrusion ", type[0], " x ", length, "mm"));
+    vitamin(str("extrusion(", type[0], ", ", length, ", ", center, "): Extrusion ", type[0], " x ", length, "mm"));
 
     color(grey90)
-        linear_extrude(height = length)
+        linear_extrude(length, center = center)
             extrusion_cross_section(type, cornerHole);
 }
 

vitamins/extrusions.scad

@@ -20,10 +20,10 @@
 // Extrusion
 //
 //                   W   H    d1   d2   s  cw   cwi    t  st  f
-E2020  = [ "E2020", 20, 20,  4.2,   0,  8,  6, 12.0,   2,  2, 1 ];
-E2040  = [ "E2040", 20, 40,  4.2,   0,  8,  6, 12.0,   2,  2, 1 ];
-E2060  = [ "E2060", 20, 60,  4.2,   0,  8,  6, 12.0,   2,  2, 1 ];
-E2080  = [ "E2080", 20, 80,  4.2,   0,  8,  6, 12.0,   2,  2, 1 ];
+E2020  = [ "E2020", 20, 20,  4.2,   3,  8,  6, 12.0,   2,  2, 1 ];
+E2040  = [ "E2040", 20, 40,  4.2,   3,  8,  6, 12.0,   2,  2, 1 ];
+E2060  = [ "E2060", 20, 60,  4.2,   3,  8,  6, 12.0,   2,  2, 1 ];
+E2080  = [ "E2080", 20, 80,  4.2,   3,  8,  6, 12.0,   2,  2, 1 ];
 E3030  = [ "E3030", 30, 30,  6.8, 4.2, 12,  8, 16.5,   2,  2, 1 ];
 E3060  = [ "E3060", 30, 60,  6.8, 4.2, 12,  8, 16.5,   2,  2, 1 ];
 E4040  = [ "E4040", 40, 40, 10.5, 6.0, 15, 10, 20.0, 5.5,  3, 1 ];

vitamins/rod.scad

@@ -19,6 +19,8 @@
 
 //
 //! Steel rods and studding with chamfered ends.
+//!
+//! These items are sysmtrical, so by default the origin is in the centre but it can be changed to the bottom.
 //
 include <../core.scad>
 use <../utils/thread.scad>

vitamins/spring.scad

@@ -19,6 +19,8 @@
 
 //
 //! Compression springs. Can be tapered, have open, closed or ground ends. Ground ends will render a lot slower.
+//!
+//! By default springs have their origin at the bottom but can be centered.
 //
 include <../core.scad>
 
@@ -64,7 +66,7 @@ function comp_spring(type, l = 0) = //! Calculate the mesh for spring
         profile = circle_points(wire_d / 2 - eps, $fn = 16)
        ) concat(type, [concat(sweep(path, profile), [l])]);
 
-module comp_spring(type, l = 0) { //! Draw specified spring, l can be set to specify the compressed length.
+module comp_spring(type, l = 0, center = false) { //! Draw specified spring, l can be set to specify the compressed length.
     length = spring_length(type);
     closed = spring_closed(type);
     od = spring_od(type);
@@ -79,14 +81,17 @@ module comp_spring(type, l = 0) { //! Draw specified spring, l can be set to spe
 
     mesh = len(type) > 9 ? spring_mesh(type) : spring_mesh(comp_spring(type, l));
     assert(l == mesh[2], "can't change the length of a pre-generated spring");
-    color(spring_colour(type))
-        if(ground)
-            clip(zmin = 0, zmax = h)
+    len = l ? l : length;
+    translate_z(center ? - len / 2 : 0) {
+        color(spring_colour(type))
+            if(ground)
+                clip(zmin = 0, zmax = h)
+                    polyhedron(mesh[0], mesh[1]);
+            else
                 polyhedron(mesh[0], mesh[1]);
-        else
-            polyhedron(mesh[0], mesh[1]);
 
-    if($children)
-        translate_z(l)
-            children();
+        if($children)
+            translate_z(len)
+                children();
+    }
 }