Add a simple OpenSCAD based tray style case

This could be extended to a full case but since the stacked height may
vary that requires some thought.
For dual cs setups both the top and bottom cs board could use their own
tray if the pico is stacked between the boards.

Signed-off-by: Janne Grunau <j@jannau.net>
Signed-off-by: Marc Zyngier <maz@kernel.org>

2 files changed, 114 insertions, 0 deletions

diff --git a/README.txt b/README.txt
index 79c1d1d..8b45653 100644
--- a/README.txt
+++ b/README.txt
@@ -102,3 +102,9 @@ For the SW that runs on the RPi Pico and how to use the damn thing,
 head to 
 
 https://git.kernel.org/pub/scm/linux/kernel/git/maz/cs-sw.git
+
+* Case:
+
+case_v3.2.scad contains an OpenSCAD design for a tray case.
+The model file is available on
+https://www.printables.com/model/585592-central-scrutinizer-case
diff --git a/case_v3.2.scad b/case_v3.2.scad
new file mode 100644
index 0000000..365f5d1
--- /dev/null
+++ b/case_v3.2.scad
@@ -0,0 +1,108 @@
+/* SPDX-License-Identifier: MIT */
+// Copyright (c) 2023 Janne Grunau
+
+// tray style case for Central Scrutinizer v3.2
+
+$fn=60;
+
+// layer resolution for bottom chamfer
+lh = 0.1;
+// height of the case base
+base_h = 1.2;
+
+// height of the case without base
+height = 6;
+// wall thickness
+wt = 1.8;
+
+// Cutouts for USB-C/micro USB connectors
+gap_c = 14 + wt;
+// make the case symmetric
+gap_m = gap_c; //12 + wt;
+
+// M2 tapping bore, assume this approximation works well enough for
+// self-"tapping" with regular M2 machine screws.
+m2_bore = 1.85; // tapping diameter would be 1.6
+
+// board size
+size = [53, 33];
+// size of the mounting hole pattern
+h_pos = [38.1, 27.9];
+
+
+module mirror_copy(v = [0, 1, 0]) {
+    union() {
+        children();
+        mirror(v) children();
+    }
+}
+
+module connector_cutout(width, off=0) {
+    mirror_copy() translate([off, off, 0]) union() {
+        difference() {
+            translate([-wt/2 - 0.1, (width - wt)/4 - off]) square([wt + 0.2, (width - wt) / 2 + 2 * off], center=true);
+            translate([-wt/2, (width) / 2 - wt]) square([wt / 2, wt / 2]);
+        }
+        translate([-wt/2, (width)/2-wt]) circle(d=wt);
+        translate([-wt/2, width/2]) difference() {
+            translate([-wt/4 - 0.1, -wt/4]) square([wt / 2 + 0.2, wt / 2], center=true);
+            circle(d=wt);
+        }
+    }
+}
+
+module standoff(st_h) {
+    difference() {
+        union() {
+            cylinder(d=5, h=st_h);
+            translate([0, (size.y - h_pos.y - wt) / 2, st_h / 2]) cube([5, (size.y - h_pos.y) - wt, st_h], center=true);
+        }
+        cylinder(d=m2_bore, h=st_h + 0.1);
+        translate([0, 0, st_h - 0.5]) cylinder(d1=m2_bore, d2=m2_bore + 0.5, h=0.51);
+    }
+}
+
+union() {
+    // main case without bottom
+    difference() {
+        hull() {
+            for (x_pos = [-size.x, size.x], y_pos = [-size.y, size.y]) {
+                translate([x_pos / 2, y_pos / 2, 0]) cylinder(r=wt, h=height);
+            }
+        
+        }
+        translate([0, 0, height / 2 + 0.049]) {
+            translate([0, 0, 0])         cube([size.x, size.y, height+0.1], center=true);
+            translate([-size.x/2, 0, 0]) cube([2 * wt + .1, gap_c, height+0.1], center=true);
+            translate([ size.x/2, 0, 0]) cube([2 * wt + .1, gap_m, height+0.1], center=true);
+        }
+    }
+    // add rounded corners to usb-c / micro usb cutouts
+    mirror_copy() translate([-(size.x + wt) / 2,  gap_c / 2, 0]) cylinder(d=wt, h=height);
+    mirror_copy() translate([ (size.x + wt) / 2,  gap_m / 2, 0]) cylinder(d=wt, h=height);
+
+    // add 4 standoffs to mount the Central Scrutinizer board to
+    for (xoff = [-h_pos.x, h_pos.x], yoff = [-h_pos.y, h_pos.y])
+    {
+        translate([xoff/2, yoff/2, 0]) 
+        rotate([0, 0, (yoff < 0.0) ? 180 : 0]) standoff(4);
+    }
+    
+    // add case bottom with chamfer and partial cutouts for the usb connectors
+    mirror([0, 0, 1])  difference() {
+        // base plate with chamfers
+        union() for (z_off = [0:lh:base_h]) {
+            translate([0, 0, z_off]) linear_extrude(height = lh) hull() {
+                lsize = [size.x - z_off, size.y - z_off];
+                for (x_pos = [-lsize.x, lsize.x], y_pos = [-lsize.y, lsize.y]) {
+                    translate([x_pos / 2, y_pos / 2]) circle(r=wt);
+                }
+            }
+        }
+        // chamfered cutouts for usb connectors
+        union() for (z_off = [0:lh:base_h]) {
+            translate([-size.x/2, 0, z_off]) linear_extrude(height = lh) connector_cutout(gap_c, z_off/2);
+            translate([ size.x/2, 0, z_off]) linear_extrude(height = lh) mirror([1,0,0]) connector_cutout(gap_m, z_off/2);
+        }
+    }
+}