From 561427774a3178cc00936ea86a74fd239739a866 Mon Sep 17 00:00:00 2001
From: Nettika <git@nettika.cat>
Date: Sun, 5 Oct 2025 03:17:17 +0000
Subject: [PATCH] Improve modularity of cartridge

---
 cartridge.scad | 346 +++++++++++++++++++++++++++++++++++--------------
 1 file changed, 252 insertions(+), 94 deletions(-)

diff --git a/cartridge.scad b/cartridge.scad
index ba98c78..d19f507 100644
--- a/cartridge.scad
+++ b/cartridge.scad
@@ -1,123 +1,281 @@
-$fn = $preview ? 32 : 64;
+$fn = $preview ? 32 : 128;
 
-*rotate([0, -90, -90]) import("/home/nettika/Downloads/8_Track.STL");
-*translate([0, 98.6, 21.8]) rotate([-90, 0, -90]) import("/home/nettika/Downloads/Track_Lid.STL");
-
-cartridge_length = 133;
+// Cartridge base dimensions
 cartridge_width = 102;
+cartridge_length = 133;
 cartridge_height = 21;
-wedge_width = 6;
-wedge_depth = 16;
-track_inset = 6;
-foot_inset = 8;
+
+// Tape guide dimensions
+tape_guide_width = 6;
+tape_guide_depth = 16;
+tape_guide_slope = tape_guide_width / tape_guide_depth;
+
+// Track dimensions
+track_front_inset = 8;
+track_back_inset = 4;
+track_side_inset = 6;
+track_radius = 1;
+track_taper_length = 12;
+
+// Foot dimensions
+foot_width = 2.5;
+foot_height = 1;
+foot_front_inset = 8;
+foot_back_inset = 4;
+foot_side_inset = 6;
+
+// Fillets
+back_vertical_fillet_radius = 4;
+side_vertical_fillet_radius = 16;
+front_vertical_fillet_radius = 5;
+horizontal_fillets_radius = 1;
+
+// Windows on front wall
+window_vertical_inset = 2;
+window_side_inset = 14;
+window_depth = 6; // 13
+left_window_width = 20;
+right_window_width = 20;
+window_gap = 5;
+roller_window_depth = 8;
+roller_window_offset = 3.5;
+
+// Emulated gap between top and bottom half
 gap_height = 1;
 gap_depth = 0.3;
-gap_elevation = 9;
+gap_elevation = 14;
 
-module base_body() {
-  minkowski() {
-    translate([0, 0, 1]) linear_extrude(cartridge_height - 2) offset(-1) footprint();
-    sphere(1);
+// Grips
+grip_wedge_width = 2.5;
+grip_count = 5;
+
+// Tape
+roller_inset = 0;
+roller_radius = 0;
+roller_position = [12, 79.5];
+tape_line_position = [2, 14];
+tape_height = 6.4;
+
+// NFC Coin
+nfc_coin_depth = 1;
+nfc_coin_diameter = 25;
+nfc_coin_tolerance = 0.1;
+
+cartridge();
+
+module cartridge() {
+  difference() {
+    base();
+    windows();
+    grips();
+    gap();
+    undercut();
+    nfc_coin();
   }
-  translate([wedge_depth-8, 0, cartridge_height]) {
-    translate([0, track_inset]) track(cartridge_length-wedge_depth+4);
-    translate([0, cartridge_width-track_inset]) track(cartridge_length-wedge_depth+4);
+  tape();
+}
+
+module base() {
+  translate([0, 0, horizontal_fillets_radius]) minkowski() {
+    linear_extrude(cartridge_height - 2 * horizontal_fillets_radius)
+      offset(-horizontal_fillets_radius)
+      footprint();
+    sphere(horizontal_fillets_radius);
   }
-  translate([wedge_depth, foot_inset, -0.5]) foot();
-  translate([wedge_depth, cartridge_width-foot_inset, -0.5]) foot();
+  tracks();
+  feet();
 }
 
-module track(l, r=1, taper=12) rotate([0, 90, 0]) {
-  cylinder(r1=0, r2=r, h=taper);
-  translate([0, 0, taper]) cylinder(r=r, h=l-2*taper);
-  translate([0, 0, l-taper]) cylinder(r1=r, r2=0, h=taper);
+module windows() {
+  rectangular_windows();
+  roller_window();
 }
 
-module foot(w=2.5) {
-  cube([cartridge_length-wedge_depth-2, w, 2]);
-  translate([cartridge_length-wedge_depth-2, w, 1]) rotate([90, 90]) cylinder(r=1, h=w);
-  translate([0, w, 1]) rotate([90, 90]) cylinder(r=1, h=w);
+module rectangular_windows() {
+  translate([
+    0,
+    window_side_inset,
+    window_vertical_inset
+  ]) {
+    window_height = cartridge_height - 2 * window_vertical_inset;
+    cube([window_depth, left_window_width, window_height]);
+    translate([
+      0,
+      left_window_width + window_gap,
+    ])
+    cube([window_depth, right_window_width, window_height]);
+  }
 }
 
-color("salmon")
-difference() {
-  base_body();
-  let(inset=2, d=6/*13*/) {
-    translate([0, 0, inset]) {
-      translate([0, 14]) cube([d, 20, cartridge_height-inset*2]);
-      translate([0, 40]) cube([d, 22, cartridge_height-inset*2]);
+module roller_window() {
+  translate([
+    -roller_window_depth,
+    roller_position.y - roller_window_offset,
+  ])
+    cylinder(h=cartridge_height, r=12);
+}
+
+module grips() {
+  for(i=[0:grip_count-1]) {
+    translate([cartridge_length - i * grip_wedge_width - back_vertical_fillet_radius, 0]) {
+      grip_wedge();
+      translate([0, cartridge_width]) mirror([0, 1]) grip_wedge();
     }
   }
-  translate([0, 0, gap_elevation-(gap_height/2)])
-  linear_extrude(cartridge_height-gap_elevation+gap_height) {
-    for(i=[0:2.5:12.5]) {
-        polygon([
-          [cartridge_length-5-i, 0],
-          [cartridge_length-5-i, 1+gap_depth],
-          [cartridge_length-7.5-i, gap_depth],
-          [cartridge_length-7.5-i, 0]
-        ]);
-        polygon([
-          [cartridge_length-5-i, cartridge_width],
-          [cartridge_length-5-i, cartridge_width-1-gap_depth],
-          [cartridge_length-7.5-i, cartridge_width-gap_depth],
-          [cartridge_length-7.5-i, cartridge_width]
-        ]);
-    }
-  }
-  translate([0, 0, gap_elevation-(gap_height/2)]) linear_extrude(gap_height) {
+}
+
+module grip_wedge() {
+  linear_extrude(gap_elevation)
+    polygon([
+      [0, 0],
+      [0, 1 + gap_depth],
+      [-grip_wedge_width, gap_depth],
+      [-grip_wedge_width, 0]
+    ]);
+}
+
+module gap() {
+  translate([0, 0, gap_elevation])
+    linear_extrude(gap_height)
     difference() {
-      offset(10) footprint();
+      footprint();
       offset(-gap_depth) footprint();
     }
-  }
-  translate([0, 0, -gap_height/2 - 2]) linear_extrude(gap_elevation+2) translate([53, cartridge_width-7]) rotate(45) offset(3) square([16, 16]);
 }
 
-color("teal")
-let(h=6.4) {
-  translate([12, 79.5, (cartridge_height-h)/2]) cylinder(r=10, h);
-  translate([2, 14, (cartridge_height-h)/2]) cube([10, 65.5, h]);
+module undercut() {
+  translate([53, cartridge_width - 7, -foot_height])
+    linear_extrude(gap_elevation + foot_height)
+    rotate(45)
+    offset(3)
+    square([16, 16]);
 }
 
+module tape() {
+  translate([0, 0, (cartridge_height - tape_height) / 2]) {
+    roller();
+    tape_line();
+  }
+}
+
+module roller() {
+  translate(roller_position)
+    cylinder(
+      h=tape_height,
+      r=10,
+    );
+}
+
+module tape_line() {
+  translate(tape_line_position)
+    cube([
+      window_depth - tape_line_position.x,
+      roller_position.y - tape_line_position.y,
+      tape_height
+    ]);
+}
+
+module nfc_coin() {
+  translate([
+    cartridge_length / 2,
+    cartridge_width / 2,
+    cartridge_height - nfc_coin_depth
+  ])
+    cylinder(
+      h=nfc_coin_depth + nfc_coin_tolerance,
+      d=nfc_coin_diameter + 2 * nfc_coin_tolerance,
+    );
+};
+
 module footprint() {
-  difference() {
-    polygon([
-      [0, wedge_width],
-      [0, cartridge_width - wedge_width],
-      [wedge_depth, cartridge_width],
-      [cartridge_length, cartridge_width],
-      [cartridge_length, 0],
-      [wedge_depth, 0],
-    ]);
-    let(r=4) {
-      translate([cartridge_length - r, 0]) {
-        translate([0, r]) fillet(r, a1=90, a2=180);
-        translate([0, cartridge_width - r]) fillet(r, a1=0, a2=90);
-      }
+  hull() {
+    translate([
+      cartridge_length - back_vertical_fillet_radius,
+      back_vertical_fillet_radius,
+    ]) {
+      circle(back_vertical_fillet_radius);
+      // translate([0, cartridge_width - back_vertical_fillet_radius])
+      //   circle(back_vertical_fillet_radius);
     }
-    let(m=wedge_width/wedge_depth, r=20) {
-      translate([wedge_depth + r * tan(atan(m)/2), 0]) {
-        translate([0, r]) fillet(r, a1=180, a2=180+atan(m));
-        translate([0, cartridge_width - r]) fillet(r, a1=0, a2=-atan(m));
-      }
-    }
-    let(m=wedge_depth/wedge_width, r=5) {
-      translate([r, 0]) {
-        translate([0, wedge_width + r * tan(atan(m)/2)]) fillet(r, a1=180+atan(1/m), a2=270);
-        translate([0, cartridge_width - wedge_width - r * tan(atan(m)/2)]) fillet(r, a1=270, a2=360-atan(1/m));
-      }
-    }
-    translate([-8, 76]) circle(r=12);
+    translate([
+      cartridge_length - back_vertical_fillet_radius,
+      cartridge_width - back_vertical_fillet_radius,
+    ]) circle(back_vertical_fillet_radius);
+    translate([
+      tape_guide_depth + side_vertical_fillet_radius * tan(0.5 * atan(tape_guide_slope)),
+      side_vertical_fillet_radius,
+    ]) circle(side_vertical_fillet_radius);
+    translate([
+      tape_guide_depth + side_vertical_fillet_radius * tan(0.5 * atan(tape_guide_slope)),
+      cartridge_width - side_vertical_fillet_radius,
+    ]) circle(side_vertical_fillet_radius);
+    translate([
+      front_vertical_fillet_radius,
+      tape_guide_width + front_vertical_fillet_radius * tan(0.5 * atan(1 / tape_guide_slope)),
+    ]) circle(front_vertical_fillet_radius);
+    translate([
+      front_vertical_fillet_radius,
+      cartridge_width - tape_guide_width - front_vertical_fillet_radius * tan(0.5 * atan(1 / tape_guide_slope)),
+    ]) circle(front_vertical_fillet_radius);
   }
 }
 
-module fillet(r, d, a1=0, a2=360, p=10) {
-  difference() {
-    polygon([
-        [0, 0],
-        each [for (a=[a1:a2]) [p * sin(a) * r, p * cos(a) * r]],
-    ]);
-    circle(r, d);
+module tracks() {
+  track_interval = cartridge_width - 2 * track_side_inset;
+  translate([track_front_inset, track_side_inset, cartridge_height])
+    rotate([0, 90, 0]) {
+      track();
+      translate([0, track_interval]) track();
+    }
+}
+
+module track() {
+  track_length = cartridge_length - track_front_inset - track_back_inset;
+  cylinder(
+    h=track_taper_length,
+    r1=0,
+    r2=track_radius,
+  );
+  translate([0, 0, track_taper_length]) cylinder(
+    h=track_length - 2 * track_taper_length,
+    r=track_radius,
+  );
+  translate([0, 0, track_length - track_taper_length]) cylinder(
+    h=track_taper_length,
+    r1=track_radius,
+    r2=0,
+  );
+}
+
+module feet() {
+  foot_interval = cartridge_width - 2 * foot_side_inset - foot_width;
+  translate([foot_front_inset, foot_side_inset, -foot_height]) {
+    foot();
+    translate([0, foot_interval, 0]) foot();
   }
-}
\ No newline at end of file
+}
+
+module foot() {
+  foot_length = cartridge_length - foot_front_inset - foot_back_inset;
+  translate([foot_height, 0])
+    cube([
+      foot_length - foot_height * 2,
+      foot_width,
+      foot_height,
+    ]);
+  intersection() {
+    cube([
+      cartridge_length,
+      foot_width,
+      foot_height,
+    ]);
+    union() {
+      translate([foot_height, foot_width, foot_height])
+        rotate([90, 90, 0])
+        cylinder(h=foot_width, r=foot_height);
+      translate([foot_length - foot_height, foot_width, foot_height])
+        rotate([90, 90, 0])
+        cylinder(h=foot_width, r=foot_height);
+    }
+  }
+}