Reimplemented teardrop_plus() again.

readme.md

@@ -5292,7 +5292,7 @@ Method to print holes in mid air. See <https://hydraraptor.blogspot.com/2014/03/
 ---
 <a name="Horiholes"></a>
 ## Horiholes
-Utilities for depicting the staircase slicing of horizontal holes made with [`teardrop_plus()`](#teardrops), see <https://hydraraptor.blogspot.com/2020/07/horiholes_36.html>
+Utilities for depicting the staircase slicing of horizontal holes made with [`teardrop_plus()`](#teardrops), see <https://hydraraptor.blogspot.com/2020/07/horiholes-2.html>
 
 
 [utils/horiholes.scad](utils/horiholes.scad) Implementation.
@@ -5302,8 +5302,7 @@ Utilities for depicting the staircase slicing of horizontal holes made with [`te
 ### Functions
 | Function | Description |
 |:--- |:--- |
-| ```teardrop_plus_x(r, y, h)``` | Calculate the ordinate of a compensated teardrop given y. |
+| ```teardrop_plus_x(r, y, h)``` | Calculate the ordinate of a compensated teardrop given y and layer height. |
-| ```teardrop_x(r, y)``` | Calculate the ordinate of a teardrop given y. Sweeping y from -r to + r yields the positive X half of the shape. |
 
 ### Modules
 | Module | Description |
@@ -5886,7 +5885,7 @@ For making horizontal holes that don't need support material.
 Small holes can get away without it, but they print better with truncated teardrops.
 
 Using teardrop_plus() or setting the plus option on other modules will elongate the teardrop vertically by the layer height, so when sliced the staircase tips
-do not intrude into the circle. See <https://hydraraptor.blogspot.com/2020/07/horiholes_36.html>
+do not intrude into the circle. See <https://hydraraptor.blogspot.com/2020/07/horiholes-2.html>
 
 
 [utils/core/teardrops.scad](utils/core/teardrops.scad) Implementation.

tests/horiholes.scad

@@ -21,19 +21,21 @@ include <../utils/core/core.scad>
 use <../utils/horiholes.scad>
 
 show_disc = true;
-thickness = 3;
+use_horihole = true;
-length = 50;
+thickness = 6;
+length = 60;
 height = 20;
 overlap_x = 15;
-overlap_y = 5;
+overlap_y = 10;
 
 module hole_positions() {
+    x0 = (length - 40) / 2;
     for($i = [0 : 4], $z = 5 + $i * layer_height / 5, $r = 3)
-        translate([5 + $i * 10, $z])
+        translate([x0 + $i * 10, $z])
             children();
 
     for($i = [0 : 4], $z = 15 + $i * layer_height / 5, $r = 0.5 + $i / 2)
-        translate([5 + $i * 10, $z])
+        translate([x0 + $i * 10, $z])
             children();
 }
 
@@ -45,7 +47,10 @@ module horiholes_stl(t = thickness) {
                     square([length, height]);
 
                     hole_positions()
-                        horihole($r, $z);
+                        if(use_horihole)
+                            horihole($r, $z);
+                        else
+                            teardrop_plus(h = 0, r = $r);
                 }
             }
         }
@@ -67,16 +72,15 @@ module horiholes() {
     hole_positions()
         color("red")
             linear_extrude(2 * eps, center = true)
-                //offset(0.01, $fn = 360)
+                intersection() {
-                    intersection() {
+                    difference() {
-                        difference() {
+                        square(8, center = true);
-                            square(8, center = true);
 
-                            horihole($r, $z);
+                        horihole($r, $z);
-                        }
-
-                        circle($r, $fn = 360);
                     }
+
+                    circle($r, $fn = 360);
+                }
 }
 
 if($preview)

tests/teardrops.scad

@@ -41,7 +41,10 @@ module teardrops() {
 
                         translate([20, 10])
                             semi_teardrop(h = 0, r = 3);
-                    }
+
+                        translate([20, 20])
+                            teardrop(h = 0, r = 3, truncate = false, plus = true);
+                   }
                 }
                 translate([40, 0, 1.5]) {
                     h = 3 + eps;
@@ -61,6 +64,9 @@ module teardrops() {
 
                     translate([20, 10])
                         semi_teardrop(h = h, r = 3, chamfer = chamfer);
+
+                    translate([20, 20])
+                        teardrop(h = h, r = 3, truncate = false, plus = false, chamfer = chamfer);
                 }
             }
 }

utils/core/teardrops.scad

@@ -22,22 +22,31 @@
 //! Small holes can get away without it, but they print better with truncated teardrops.
 //!
 //! Using teardrop_plus() or setting the plus option on other modules will elongate the teardrop vertically by the layer height, so when sliced the staircase tips
-//! do not intrude into the circle. See <https://hydraraptor.blogspot.com/2020/07/horiholes_36.html>
+//! do not intrude into the circle. See <https://hydraraptor.blogspot.com/2020/07/horiholes-2.html>
 //
 module teardrop(h, r, center = true, truncate = true, chamfer = 0, plus = false) { //! For making horizontal holes that don't need support material, set ```truncate = false``` to make traditional RepRap teardrops that don't even need bridging
-    module teardrop_2d(r, truncate)
+    module teardrop_2d(r, truncate) {
+        er = layer_height / 2 - eps;    // Extrustion edge radius
+        R = plus ? r + er : r;          // Corrected radius
+        offset = plus ? -er : 0;        // Offset inwards
         hull()
-            for(y = plus ? [-1 : 1] : 0)
+            for(side = [0 : 1])
-                translate([0, y * (layer_height / 2 - eps)]) {
+                mirror([side, 0, 0])
+                    intersection() {
+                        hull()
+                        translate([offset, 0]) {
+                            circle4n(R);
 
-                circle4n(r);
+                            if(truncate)
-
+                                translate([0, R / 2])
-                if(truncate)
+                                    square([2 * R * (sqrt(2) - 1), R], center = true);
-                    translate([0, r / 2])
+                            else
-                        square([2 * r * (sqrt(2) - 1), r], center = true);
+                                polygon([[0, 0], [eps, 0], [0, R * sqrt(2)]]);
-                else
+                        }
-                    polygon([[0, 0], [eps, 0], [0, r * sqrt(2)]]);
+                        translate([0, -2 * R])
-            }
+                            square([R, 4 * R]);
+                    }
+    }
 
     render(convexity = 5)
         extrude_if(h, center)

utils/horiholes.scad

@@ -18,21 +18,20 @@
 //
 
 //
-//! Utilities for depicting the staircase slicing of horizontal holes made with [`teardrop_plus()`](#teardrops), see <https://hydraraptor.blogspot.com/2020/07/horiholes_36.html>
+//! Utilities for depicting the staircase slicing of horizontal holes made with [`teardrop_plus()`](#teardrops), see <https://hydraraptor.blogspot.com/2020/07/horiholes-2.html>
 //
 include <../utils/core/core.scad>
 
-function teardrop_x(r, y) = //! Calculate the ordinate of a teardrop given y. Sweeping y from -r to + r yields the positive X half of the shape.
+function teardrop_plus_x(r, y, h) = //! Calculate the ordinate of a compensated teardrop given y and layer height.
-    let(x2 = sqr(r) - sqr(y))
+    let(fr = h / 2,
-        y > r / sqrt(2) ? y >= r ? 0
+        hpot = r + fr,
-                                 : r * sqrt(2) - y
+        x2 = sqr(hpot) - sqr(y),
-                        : x2 > 0 ? sqrt(x2)
+        x = x2 > 0 ? sqrt(x2) : 0
-                                 : 0;
+    )
-
+    max(0,
-function teardrop_plus_x(r, y, h) = //! Calculate the ordinate of a compensated teardrop given y.
+        y < hpot / sqrt(2) ? x - fr :
-    y < -h ? teardrop_x(r, y + h)
+        y < hpot           ? hpot * sqrt(2) - y - fr :
-           : y > h ? teardrop_x(r, y - h)
+        0);
-                   : r;
 
 module horihole(r, z, h = 0, center = true) { //! For making horizontal holes that don't need support material and are correct dimensions
     bot_layer = floor((z - r) / layer_height);
@@ -41,9 +40,16 @@ module horihole(r, z, h = 0, center = true) { //! For making horizontal holes th
         extrude_if(h, center)
             for(i = [bot_layer : top_layer]) {
                 Z = i * layer_height;
-                x = teardrop_plus_x(r, Z - z + layer_height / 2, layer_height / 2);
+                y = Z - z + layer_height / 2;
+                x = teardrop_plus_x(r, y, layer_height);
                 if(x > 0)
-                    translate([-x, Z - z])
+                    translate([0, y])
-                        square([2 * x, layer_height]);
+                        difference() {
+                            square([2 * x + layer_height, layer_height], center = true);
+
+                            for(end = [-1, 1])
+                                translate([end * (x + layer_height / 2), 0])
+                                    circle(d = layer_height, $fn = 32);
+                        }
              }
 }