Rework band as path sweep

band.scad

@@ -2,99 +2,120 @@ include <BOSL2/std.scad>;
 
 $fn = $preview ? 32 : 128;
 
-band_arc_radius = 65;
-thickness = 3;
-height = 10;
-band_arc = 240;
+band_arc_radius = 75;
+band_thickness = 3;
+band_height = 10;
 leg_length = 27;
 edge_radius = 0.5;
-punch_angles = [-95, -70, -45, 0, 45, 70, 95];
-tooth_width=2;
-tooth_height=2.5;
-teeth_max_angle = 110;
-teeth_spacing = 2.5;
-punch_clearance = 5;
 
-module tooth() {
+band_arc = turtle([
+  "move", leg_length,
+  "arcright", band_arc_radius, 80,
+  "arcright", band_arc_radius * 0.8, 20,
+  "arcright", band_arc_radius * 1.2, 40,
+  "arcright", band_arc_radius * 0.8, 20,
+  "arcright", band_arc_radius, 80,
+  "move", leg_length
+]);
+band_profile = rect(
+  size=[band_thickness, band_height],
+  rounding=edge_radius
+);
+band_length = path_length(band_arc);
+band_curve_length = band_length-leg_length*2;
+leg_frac = leg_length/band_length;
+band_curve_frac = 1-leg_frac*2;
+
+tooth_width = 2;
+tooth_height = 2.5;
+tooth_offset = band_height/2-2;
+dense_teeth_count = 70;
+teeth_step = band_curve_frac/dense_teeth_count;
+
+punch_fracs = [
+  for(frac=[0.07, 0.18, 0.29, 0.5, 0.71, 0.82, 0.93])
+  frac * band_curve_frac + leg_frac
+];
+
+function hole(anchor) = rect(
+  size=[band_height/2+1, band_height/2],
+  rounding=band_height/4,
+  anchor=anchor
+);
+
+module punch() linear_sweep(
+  region=[
+    right(1, p=hole(LEFT)),
+    left(1, p=hole(RIGHT))
+  ],
+  length=band_thickness+2
+);
+
+function punch_clearance(tooth_frac, punch_frac) = abs(punch_frac - tooth_frac) > 0.025;
+
+module punches()
+  for(punch_frac=punch_fracs)
+  sweep_attach(
+    parent=LEFT,
+    child=BOT,
+    frac=punch_frac,
+    spin=90,
+    overlap=band_thickness+1
+  )
+  tag("remove")
+  punch();
+
+module tooth()
   cyl(
     d1=tooth_width,
     d2=edge_radius*2,
     h=tooth_height,
-    rounding2=edge_radius,
-    anchor=BOT,
-    orient=FWD
+    rounding2=edge_radius
   );
-}
 
-module punch() {
-  region = right(
-    1,
-    p=rect(
-      [height/2+1, height/2],
-      rounding=height/4,
-      anchor=LEFT
-    )
-  );
-  linear_sweep(
-    [region, xflip(region)],
-    length=thickness+2,
-    center=true,
-    orient=BACK
-  );
-}
-
-
-module band() {
-  region = right(
-    band_arc_radius,
-    p=rect(
-      [thickness, height],
-      rounding=edge_radius
-    )
-  );
-  rotate_sweep(
-    region,
-    angle=band_arc,
-    spin=-band_arc/2+90
-  );
-}
-
-module leg() {
-  rotate(-band_arc/2+90)
-  right(band_arc_radius)
-  cuboid(
-    [thickness, leg_length, height],
-    rounding=edge_radius,
-    edges="Y",
-    anchor=BACK
+module teeth()
+  for(tooth_frac=[leg_frac:teeth_step:1-leg_frac])
+  if(
+    all([
+      for (punch_frac=punch_fracs)
+      punch_clearance(tooth_frac, punch_frac)
+    ])
   )
-  attach(FWD)
-  xcyl(
-    thickness,
-    d=height,
-    rounding=edge_radius
-  );
-}
+  sweep_attach(LEFT, BOT, tooth_frac) {  
+    left(tooth_offset) tooth();
+    right(tooth_offset) tooth();
+  }
 
-difference() {
-  union() {
-    band();
-    leg();
-    xflip() leg();
-  }
-  for(a=punch_angles) {
-    zrot(a) back(band_arc_radius) punch();
-  }
-}
+pip_count = 4;
+pip_size = 1.2;
+pip_frac_step = 0.0045;
 
-for(a=[-teeth_max_angle:teeth_spacing:teeth_max_angle]) {
-  if(all([
-    for (b=punch_angles)
-    abs(b - a) > punch_clearance
-  ])) {
-    zrot(a) back(band_arc_radius-thickness/2+0.1) {
-      up(height/4) tooth();
-      down(height/4) tooth();
-    };
+module pips()
+  for(pip_idx=[0:1:pip_count-1])
+  sweep_attach(
+    parent=LEFT,
+    child=BOT,
+    frac=leg_frac+pip_idx*pip_frac_step,
+    overlap=pip_size/2
+  )
+  tag("remove")
+  sphere(d=pip_size);
+
+module ends()
+  attach(["end", "start"])
+    xcyl(
+      h=band_thickness,
+      d=band_height,
+      rounding=edge_radius
+    );
+
+module band()
+  diff()
+  path_sweep(band_profile, band_arc) {
+    punches();
+    teeth();
+    pips();
+    ends();
   }
-}
+
+band();