chamfer.scad

@@ -0,0 +1,78 @@
+/// Chamfering OpenSCAD Example
+/// Written by Robert Quattlebaum, 2022-12-14
+///
+/// This example shows a method for adding a chamfer to a certain
+/// class of 3D objects where the profile in the Z dimension doesn't
+/// change significantly.
+///
+/// You must specify the size of the chamfer, the height of the child
+/// and the Z-offset for the bottom of the object. You can also specify
+/// the shape of the chamfer, which can be either "cone", "curve", "curve-in",
+/// or "pyramid".
+///
+/// This process is ultimately slow, but should be faster than using minkowski.
+
+module chamfer(size=2, child_h=5, child_bot=0, shape="curve") {
+    chamfer_size=size;
+    
+    module chamfer_shape() {
+		if (shape == "cone") {
+            $fn=16;
+            cylinder(chamfer_size/2,chamfer_size/2,0);
+        } else if (shape == "curve") {
+            $fn=4;
+            for( y = [0:1/$fn:1]) {
+                cylinder(chamfer_size/2*(1-y),chamfer_size/2/cos(180/$fn)*y,0);
+            }
+        } else if (shape == "curve-in") {
+            $fn=16;
+            intersection() {
+                sphere(chamfer_size/2/cos(180/$fn));
+                translate([0,0,chamfer_size/2])
+                    cube(chamfer_size, center=true);
+            }
+        } else if (shape == "pyramid") {
+            $fn=4;
+            cylinder(chamfer_size/2/cos(180/$fn),chamfer_size/2,0);
+        }
+    }
+    
+    module lower_chamfer() {
+        minkowski()
+        {
+            linear_extrude(0.0001) difference() {
+                square([1000,1000],center=true);
+                projection()children(0);
+            }
+            chamfer_shape();
+        }
+    }
+
+    module upper_chamfer() {
+		scale([1,1,-1])lower_chamfer()children();
+    }
+    
+    render()difference() {
+        children();
+        translate([0,0,child_bot])lower_chamfer()children();
+        translate([0,0,child_bot+child_h])upper_chamfer()children();
+    }
+}
+
+/////////////////////////////////////////////////////////////////////////
+
+module my_shape(h=5) {
+    translate([0,0,h/2]) {
+        difference() {
+            cube([50,50,h],center=true);
+            cube([20,20,h+1],center=true);
+        }
+        translate([20,21,0])cylinder(h=h,r=20,center=true);
+    }
+}
+
+
+h=5;
+
+chamfer(3, child_h=h, shape="cone")
+    my_shape(h);

headband.scad

@@ -10,7 +10,11 @@ TIP_BEND=20;
 RAKE_DEPTH=1;
 RAKE_WIDTH=1;
 RAKE_STRETCH=1;
-RAKE_CHAMPFER=0.5;
+RAKE_CHAMFER=0.5;
+CHAMFER=1;
+CHAMFER_SHAPE="cone";
+
+use <chamfer.scad>
 
 module partial_ring(part, radius, thickness, height) {
   rotate(180-180*part, [0, 0, 1])
@@ -19,10 +23,13 @@ module partial_ring(part, radius, thickness, height) {
         square([thickness, height], center=true);
 }
 
-module headband(debug=DEBUG, size=SIZE, height=HEIGHT, thickness=THICKNESS, part=PART, stretch_len=STRETCH_LEN, tip_len=TIP_LEN, tip_bend=TIP_BEND, rake_depth=RAKE_DEPTH, rake_width=RAKE_WIDTH, rake_stretch=RAKE_STRETCH, rake_champfer=RAKE_CHAMPFER) {
+module headband(debug=DEBUG, size=SIZE, height=HEIGHT, thickness=THICKNESS, part=PART, stretch_len=STRETCH_LEN, tip_len=TIP_LEN, tip_bend=TIP_BEND, rake_depth=RAKE_DEPTH, rake_width=RAKE_WIDTH, rake_stretch=RAKE_STRETCH, rake_chamfer=RAKE_CHAMFER, chamfer=CHAMFER, chamfer_shape=CHAMFER_SHAPE) {
   union() {
-        color("purple") partial_ring(part, radius=size, thickness=thickness, height=height);
+    chamfer(size=chamfer, child_h=height, child_bot=-height/2, shape=chamfer_shape) union() {
-        rotate( 90-180*part, [0, 0, 1]) translate([stretch_len/2,  size, 0]) {
+      color("purple")
+        partial_ring(part, radius=size, thickness=thickness, height=height);
+      rotate( 90-180*part, [0, 0, 1])
+        translate([stretch_len/2,  size, 0]) {
           color("orange") cube([stretch_len, thickness, height], center=true);
             color("purple") translate([stretch_len/2, tip_bend, 0])
               rotate(90+180*tip_len, [0, 0, 1])
@@ -33,9 +40,13 @@ module headband(debug=DEBUG, size=SIZE, height=HEIGHT, thickness=THICKNESS, part
                   height=height
                 );
         }
-        rotate(-90+180*part, [0, 0, 1]) translate([stretch_len/2, -size, 0]) {
+      rotate(-90+180*part, [0, 0, 1])
-            color("orange") cube([stretch_len, thickness, height], center=true);
+        translate([stretch_len/2, -size, 0]) {
-            color("purple") scale([1, -1, 1]) translate([stretch_len/2, tip_bend, 0])
+          color("orange")
+            cube([stretch_len, thickness, height], center=true);
+          color("purple")
+            scale([1, -1, 1])
+              translate([stretch_len/2, tip_bend, 0])
                 rotate(90+180*tip_len, [0, 0, 1])
                   partial_ring(
                     part=tip_len,
@@ -44,14 +55,17 @@ module headband(debug=DEBUG, size=SIZE, height=HEIGHT, thickness=THICKNESS, part
                     height=height
                   );
         }
+    }
     for (i=[-size/2:size/2]) {
-            rotate(i*2-rake_width/2, [0, 0, 1]) intersection() {
+      rotate(i*2-rake_width/2, [0, 0, 1])
+        intersection() {
           scale([1, 1, rake_stretch/(rake_depth/height)])
-                    translate([0, rake_width/2, 0]) rotate_extrude(angle=rake_width)
+            translate([0, rake_width/2, 0])
+              rotate_extrude(angle=rake_width)
                 translate([rake_depth/2-size+thickness/2, 0, 0])
                   scale([1, 0.5, 1])
                     circle(r=rake_depth, $fn=3);
-                translate([rake_depth/2-size+thickness/2-rake_champfer, 0, 0])
+          translate([rake_depth/2-size+thickness/2-rake_chamfer, 0, 0])
             color("red")
               cube([2*rake_depth, rake_width, height], center=true);
         }