pressfit_horns.scad

@@ -0,0 +1,67 @@
+include <globals.scad>;
+
+use <pressfit_headband.scad>;
+
+$fn=360;
+A=30;
+N=4;
+R=45;
+LENGTH=100;
+TWIST=720;
+STEPS=360;
+SLICES=max(TWIST, STEPS, LENGTH);
+SHEIGHT=LENGTH/STEPS;
+BEND_X_FACTOR=0.5;
+BEND_Y_FACTOR=1;
+
+COLORS=[
+"#f00",
+"#f70",
+"#7f0",
+"#0f0",
+"#0f7",
+"#07f",
+"#00f",
+"#70f",
+"#f07"
+];
+
+difference() {
+  union() for (step=[1:STEPS]) {
+    a = A*(1-(step-1)/STEPS);
+    b = A*(1-step/STEPS);
+    r = TWIST/STEPS*(step-1);
+    sh_xy = 0;
+    sh_yx = 0;
+    sh_xz = 1/STEPS*step*BEND_X_FACTOR;
+    sh_yz = 1/STEPS*step*BEND_Y_FACTOR;
+    sh_zx = 0;
+    sh_zy = 0;
+    t_x = sh_xz*SHEIGHT*(step-1)*0.5;
+    t_y = sh_yz*SHEIGHT*(step-1)*0.5;
+    t_z = LENGTH/STEPS*(step-1);
+    sc_x = 1;
+    sc_y = 1;
+    sc_z = 1;
+    mm = [
+      [sc_x,  sh_xy, sh_xz, t_x],
+      [sh_yx, sc_y,  sh_yz, t_y],
+      [sh_zx, sh_zy, sc_z,  t_z],
+    ];
+    echo(a, b, b/a, r, mm);
+    multmatrix(mm)
+      color(COLORS[(step-1)%9])
+      linear_extrude(
+        SHEIGHT,
+        center=false,
+        twist=TWIST/STEPS,
+        scale=b/a,
+        slices=SLICES/STEPS
+      ) rotate(R-r)
+        circle(d=a, $fn=N);
+  }
+  translate([0, 0, INSERTICLE_Z/2])
+    inserticle();
+}
+
+echo("twist angle: ", TWIST/STEPS);