fix: base plate dimensions 270x240mm per spec (issue #18)
Both chassis files corrected. Previous dimensions were wrong:
prototype_baseplate.scad: was 680x130mm → now 270x240mm
chassis_frame.scad: was 640x220mm → now 270x240mm
Geometry recalculated for 270x240mm envelope:
PLATE_W = 270mm (axle direction)
PLATE_D = 240mm (front-to-rear)
PLATE_X_HALF = 135mm (plate edge / axle entry)
FORK_SLOT_D = 50mm → AXLE_X = 85mm from plate centre
Axle-to-axle = 170mm (2 × 85mm)
Wheels extend beyond plate edges as expected:
Tire at X = ±(85 ± 27) = ±58–112mm, plate edge at ±135mm ✓
Mount positions recalculated for smaller plate:
Dropout clamp bolt holes: X = ±(85±22) = ±63 and ±107mm ✓ (all within ±135mm)
Stem flange bolts: r=33mm BC, at (±33,0) and (0,±33) ✓
FC mount: X = -40mm offset, holes at ±15mm ✓
Wiring slots: Y = ±55mm (clear of stem flange bolts at ±33mm)
Lightening ovals: Y = ±80mm in open front/rear corridors
Bumper length: 300mm (was 660mm, now PLATE_D + 60)
Longitudinal ribs: 270mm long (was 600mm)
chassis_frame.scad also updated:
AXLE_HEIGHT corrected: 310mm → 127mm (TIRE_OD/2)
Axle dimensions: 14mm → 16.11mm, flat 10mm → 13.00mm
AXLE_X for fork bracket positioning
Motor fork bracket logic cleaned up (no more negative cube dimensions)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
sl-mechanical
6ea4b56471