Detail the sheet metal box for the STM

We have 4 springs, so the effective spring constant is 4 times higher.
Reflect this in the calculations and adjust the CAD model for the
updated spring length.

Connector-Plate.ipynb

@@ -0,0 +1,76 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": 20,
+   "id": "e70e1154-7d5d-4c92-9f62-2dd2c734f586",
+   "metadata": {
+    "editable": true,
+    "slideshow": {
+     "slide_type": ""
+    },
+    "tags": []
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "171.312323780292 kg"
+      ],
+      "text/latex": [
+       "$171.312323780292\\ \\mathrm{kg}$"
+      ],
+      "text/plain": [
+       "<Quantity(171.312324, 'kilogram')>"
+      ]
+     },
+     "execution_count": 20,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "from pint import UnitRegistry\n",
+    "unit = UnitRegistry()\n",
+    "unit.formatter.default_format = \"~\"\n",
+    "\n",
+    "preload_m4 = 3000 * unit.N\n",
+    "n_screws = 4 # 2 on each side\n",
+    "friction_coeff = 0.21 # Al on Al\n",
+    "safety_factor = 1.5\n",
+    "\n",
+    "max_load = preload_m4 * friction_coeff * n_screws / safety_factor / unit.standard_gravity\n",
+    "max_load.to(unit.kg)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "d945d6aa-a1d0-4f9b-8f0e-2742e5c75b31",
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3 (ipykernel)",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.13.3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}

Spring-Dimensioning.ipynb

@@ -2,7 +2,7 @@
  "cells": [
   {
    "cell_type": "code",
-   "execution_count": 17,
+   "execution_count": 1,
    "id": "5bef2913-4855-471d-9594-5ec45c029048",
    "metadata": {},
    "outputs": [
@@ -10,8 +10,8 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Length: 236.9 mm\n",
-      "Freq:   1.411 Hz\n"
+      "Length: 143.2 mm\n",
+      "Freq:   2.822 Hz\n"
      ]
     }
    ],
@@ -19,7 +19,7 @@
     "import math\n",
     "\n",
     "# Parameters\n",
-    "spring_constant_n_mm = 1.1\n",
+    "spring_constant_n_mm = 1.1 * 4\n",
     "spring_length_resting_mm = 112\n",
     "\n",
     "def spring_length_at(weight):\n",
@@ -39,7 +39,13 @@
    "cell_type": "code",
    "execution_count": null,
    "id": "f21d84d9-c7a1-4fd2-aa32-136f04db32e5",
-   "metadata": {},
+   "metadata": {
+    "editable": true,
+    "slideshow": {
+     "slide_type": ""
+    },
+    "tags": []
+   },
    "outputs": [],
    "source": []
   }