Refine platform geometry calculations in OpenSCAD files

Updated platform width and pivot X position calculations to align with inner plate faces and ensure correct gaps. Adjusted transverse angle iron length and side angle Z offset logic for more accurate mechanical fit. Improved parameter derivations and assertions for platform assembly.

Author: dorkmo

LifeTrac-v25/mechanical_design/openscad/lifetrac_v25.scad

@@ -2517,7 +2517,11 @@ module folding_platform_assembly(fold_angle=90) {
         // Transverse angles now run full width (approx)
         // Side angles fit between them with gap
         // Shorten transverse angles by gap on each side
-        transverse_len = 2 * angle_iron_x_from_center - 2 * PLATFORM_TRANSVERSE_GAP;
+        // Transverse Angle Length:
+        // "parametrically lengthen the transverse angle irons so that they are 1/4 of an inch from the L plates on either side."
+        // L Plate Inner Face is at `angle_iron_x_from_center`.
+        // 1/4 inch = 6.35mm.
+        transverse_len = 2 * (angle_iron_x_from_center - 6.35);
 
         // Calculate positions of transverse angles (Inner faces)
         // The outside edge of the transverse angle irons should be 1/2 inch (PLATFORM_EDGE_MARGIN)
@@ -2556,9 +2560,10 @@ module folding_platform_assembly(fold_angle=90) {
         // Side angle Z offset (in local frame before fold rotation)
         // Maps to World -Y.
         // We want World Y = side_angle_start_y at Extrusion 0.
-        // World Y = -Local Z.
-        // side_angle_start_y = -side_angle_z_trans.
-        side_angle_z_trans = -side_angle_start_y;
+        // World Y = -(z_trans - PLATFORM_LOCK_OFFSET).
+        // side_angle_start_y = -z_trans + PLATFORM_LOCK_OFFSET.
+        // z_trans = PLATFORM_LOCK_OFFSET - side_angle_start_y.
+        side_angle_z_trans = PLATFORM_LOCK_OFFSET - side_angle_start_y;
 
         // =================================================================
         // ANGLE IRON ARMS (2x - Left and Right)

LifeTrac-v25/mechanical_design/openscad/lifetrac_v25_params.scad

@@ -173,11 +173,6 @@ DECK_HEIGHT = 250;  // Height above ground
 
 // --- Derived dimensions (calculated from frame geometry) ---
 PLATFORM_CLEARANCE = 50;  // Clearance from inner walls (mm)
-PLATFORM_WIDTH = TRACK_WIDTH - SANDWICH_SPACING - PANEL_THICKNESS*2 - PLATFORM_CLEARANCE;  // ~850mm
-
-// Pivot X position - near deck edges, inside the inner panel faces
-PLATFORM_PIVOT_X_INSET = 35;  // Distance from deck edge to pivot centerline (mm)
-PLATFORM_PIVOT_X = PLATFORM_WIDTH/2 - PLATFORM_PIVOT_X_INSET;  // X position from center
 
 // --- Configurable dimensions ---
 PLATFORM_DEPTH = 400;           // Front-to-back depth of deck (mm)
@@ -187,6 +182,17 @@ PLATFORM_ARM_LENGTH = 425;      // Length of angle iron arms (mm)
 PLATFORM_PIVOT_HEIGHT = 330;    // Height of pivot / deck surface when deployed (mm)
 PLATFORM_THICKNESS = PLATE_1_4_INCH;  // Deck plate thickness
 
+// Pivot X position - Aligned with inner plate of machine walls
+// Inner Wall X = TRACK_WIDTH/2 - SANDWICH_SPACING/2 - PANEL_THICKNESS
+// Pivot Bracket Center = Inner Wall X - Bracket Thickness/2
+_inner_wall_x = TRACK_WIDTH/2 - SANDWICH_SPACING/2 - PANEL_THICKNESS;
+PLATFORM_PIVOT_X = _inner_wall_x - PLATE_1_4_INCH/2;
+
+// PLATFORM_WIDTH calculated to fill distance between L plates (Pivot Brackets) with 1/8" gap
+// Pivot Bracket Inner Face = PLATFORM_PIVOT_X - PLATFORM_THICKNESS/2
+// Gap = 1/8 inch = 3.175mm
+PLATFORM_WIDTH = 2 * (PLATFORM_PIVOT_X - PLATFORM_THICKNESS/2 - 3.175);
+
 // --- Pivot bracket dimensions ---
 PLATFORM_BRACKET_WIDTH = 100;   // Width of pivot bracket plate (mm)
 PLATFORM_BRACKET_LENGTH = PLATFORM_DEPTH - PLATFORM_BRACKET_WIDTH/2;  // Length of pivot bracket plate (mm)
@@ -242,8 +248,8 @@ assert(PLATFORM_ARM_LENGTH >= PLATFORM_DEPTH/2,
     "PLATFORM_ARM_LENGTH must be at least half of PLATFORM_DEPTH");
 
 // Pivot X must be inside the inner frame walls
-_inner_wall_x = TRACK_WIDTH/2 - SANDWICH_SPACING/2;
-assert(PLATFORM_PIVOT_X < _inner_wall_x, 
+_inner_wall_limit_x = TRACK_WIDTH/2 - SANDWICH_SPACING/2;
+assert(PLATFORM_PIVOT_X < _inner_wall_limit_x, 
     "PLATFORM_PIVOT_X must be inside inner frame walls");
 
 // Pivot must be above frame bottom