custom-nas/mechanical/02_SendCutSend_Sheet_Metal_Package.md

SendCutSend Sheet Metal Manufacturing Package & DFM Specification

System: 6U 19-Inch Open-Source Tri-Mode Storage Array
Document ID: MECH-SPEC-02
Supplier Compatibility: SendCutSend / Xometry / Protocase
Material Specification: 5052-H32 Aluminum (1.27mm / 0.050" or 1.60mm / 0.063") / 3.0mm for Rack Ears
Manufacturing Process: CNC Fiber Laser Cut (Tolerance \pm 0.1\,\text{mm} / \pm 0.005"), Deburred, Flat (Zero Bends)

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1. Design-for-Manufacturing (DFM) Strategy

To achieve the sub-$65 chassis budget target and eliminate costly multi-axis sheet metal press brake tooling:

1. 100% Bend-Free Flat Pattern Topology: Every panel is a 2D flat laser-cut plate. All structural stiffness, corner joints, and 3D volume are provided by the 2020 extrusion skeleton.
2. Standardized Hole Sizing:
   • Panel mounting screw clearance holes are standardized to Ø4.5mm (for M4 button head screws into drop-in T-nuts).
   • Component standoff holes are Ø3.5mm (for M3 motherboard/PCB standoffs).
3. Minimum Feature Spacing Rules (SendCutSend DFM Checked):
   • Hole diameter \ge \text{Material Thickness} (4.5\,\text{mm} > 1.27\,\text{mm} \checkmark).
   • Hole-to-edge distance \ge 2\times \text{Thickness} (10.0\,\text{mm} > 2.54\,\text{mm} \checkmark).
   • Hole-to-hole web thickness \ge 2\times \text{Thickness} (20.0\,\text{mm} > 2.54\,\text{mm} \checkmark).

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2. Complete Sheet Metal Panel Schedule

Panel ID	Panel Description	Dimensions (W x H / L)	Qty	Material & Thickness	Est. Cost / Unit (SendCutSend 100+ Vol)
SMP-01	Top Enclosure Cover Plate	436.0\,\text{mm} \times 500.0\,\text{mm}	1	5052-H32 Aluminum 1.27mm	$5.20
SMP-02	Bottom Base Plate	436.0\,\text{mm} \times 500.0\,\text{mm}	1	5052-H32 Aluminum 1.27mm	$5.40
SMP-03	Left Side Exterior Skin	500.0\,\text{mm} \times 260.0\,\text{mm}	1	5052-H32 Aluminum 1.27mm	$3.10
SMP-04	Right Side Exterior Skin	500.0\,\text{mm} \times 260.0\,\text{mm}	1	5052-H32 Aluminum 1.27mm	$3.10
SMP-05	Rear I/O & Exhaust Vent Plate	396.0\,\text{mm} \times 220.0\,\text{mm}	1	5052-H32 Aluminum 1.27mm	$4.80
SMP-06L	6U Structural Rack Mount Ear (Left)	40.0\,\text{mm} \times 260.0\,\text{mm}	1	5052-H32 Aluminum 3.00mm	$2.60
SMP-06R	6U Structural Rack Mount Ear (Right)	40.0\,\text{mm} \times 260.0\,\text{mm}	1	5052-H32 Aluminum 3.00mm	$2.60
TOTAL	Complete Sheet Metal Package	—	7 pcs	—	~$26.80

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3. Detailed CAD Dimensioning & Hole Coordinate Maps

3.1 SMP-01: Top Cover Plate (436.0\,\text{mm} \times 500.0\,\text{mm})

• Outer Bounds: X \in [0, 436.0], Y \in [0, 500.0].
• Mounting Hole Centers (Ø4.5mm Clearance for M4):
  • Left Edge (X = 10.0\,\text{mm}): Y = 25.0, 150.0, 275.0, 400.0, 475.0\,\text{mm} (5 holes).
  • Right Edge (X = 426.0\,\text{mm}): Y = 25.0, 150.0, 275.0, 400.0, 475.0\,\text{mm} (5 holes).
  • Front Edge (Y = 10.0\,\text{mm}): X = 109.0, 218.0, 327.0\,\text{mm} (3 holes).
  • Rear Edge (Y = 490.0\,\text{mm}): X = 109.0, 218.0, 327.0\,\text{mm} (3 holes).
• Total Holes: 16x Ø4.5mm holes.

3.2 SMP-02: Bottom Base Plate (436.0\,\text{mm} \times 500.0\,\text{mm})

• Outer Bounds: X \in [0, 436.0], Y \in [0, 500.0].
• Perimeter Extrusion Holes (Ø4.5mm): Identical 16-hole pattern to SMP-01.
• Baseboard Mounting Grid (Ø3.5mm for M3 Standoffs):
  • Radxa + Broadcom Carrier PCB footprint (180.0\,\text{mm} \times 120.0\,\text{mm} at X_{\text{offset}} = 30.0\,\text{mm}, Y_{\text{offset}} = 220.0\,\text{mm}):
    • Hole 1: (X=40.0, Y=230.0)
    • Hole 2: (X=200.0, Y=230.0)
    • Hole 3: (X=40.0, Y=330.0)
    • Hole 4: (X=200.0, Y=330.0)
• Mezzanine PCIe Anchor Grid: 4x Ø3.5mm holes at X = 280.0\,\text{mm} and 380.0\,\text{mm}, Y = 230.0\,\text{mm} and 430.0\,\text{mm}.

3.3 SMP-03 & SMP-04: Left & Right Side Panels (500.0\,\text{mm} \times 260.0\,\text{mm})

• Outer Bounds: X \in [0, 500.0], Y \in [0, 260.0].
• Top Edge (Y = 250.0\,\text{mm}): X = 25.0, 150.0, 275.0, 400.0, 475.0\,\text{mm} (5 holes).
• Bottom Edge (Y = 10.0\,\text{mm}): X = 25.0, 150.0, 275.0, 400.0, 475.0\,\text{mm} (5 holes).
• Front Upright (X = 10.0\,\text{mm}): Y = 70.0, 130.0, 190.0\,\text{mm} (3 holes).
• Rear Upright (X = 490.0\,\text{mm}): Y = 70.0, 130.0, 190.0\,\text{mm} (3 holes).
• Total Holes per Side Panel: 16x Ø4.5mm holes.

3.4 SMP-05: Rear I/O & Exhaust Vent Plate (396.0\,\text{mm} \times 220.0\,\text{mm})

• Outer Bounds: X \in [0, 396.0], Y \in [0, 220.0].
• Perimeter Frame Mounting (Ø4.5mm):
  • Top & Bottom Edges (Y=10.0, 210.0\,\text{mm}): X = 30.0, 130.0, 266.0, 366.0\,\text{mm}.
  • Left & Right Edges (X=10.0, 386.0\,\text{mm}): Y = 60.0, 110.0, 160.0\,\text{mm}.
• Exhaust Vent Honeycomb Array:
  • Hexagonal perforation zone: X \in [30.0, 220.0], Y \in [30.0, 190.0] (190mm x 160mm active area).
  • Hexagon geometry: 6.0mm across flats, 1.2mm web, >68% open area to guarantee unimpeded exhaust airflow.
• Vertical PCIe / GPU Expansion Slot Cutouts (Zone X \in [250.0, 310.0], Y \in [30.0, 190.0]):
  • Dual vertical full-height bracket openings (120.0\,\text{mm} \times 21.6\,\text{mm}) with top screw retention tabs.
• Host & Power Cutouts (Zone X \in [330.0, 380.0]):
  • Dual RJ45 Port Opening: 32.0\,\text{mm} \times 14.0\,\text{mm} at (X=335.0, Y=40.0).
  • Dual USB 3.0 Opening: 16.0\,\text{mm} \times 15.0\,\text{mm} at (X=335.0, Y=65.0).
  • 12V DC Barrel Jack Port: Ø11.5mm circular cutout at (X=355.0, Y=110.0).
  • High-Current 8-pin Molex Power Cutout: 20.0\,\text{mm} \times 10.5\,\text{mm} at (X=345.0, Y=140.0).

3.5 SMP-06L & SMP-06R: 6U Heavy-Duty Rack Ears (40.0\,\text{mm} \times 260.0\,\text{mm}, 3.0mm Thickness)

• Outer Bounds: X \in [0, 40.0], Y \in [0, 260.0].
• Chassis Extrusion Attachment Holes (Ø5.5mm for M5 Bolts into Corner Upright EXT-01):
  • Centers at X = 15.0\,\text{mm}: Y = 20.0, 70.0, 130.0, 190.0, 240.0\,\text{mm} (5 holes).
• EIA-310-D Standard 19" Rack Mounting Slots (10.0\,\text{mm} \times 6.8\,\text{mm} Oblong Slots):
  • Centers at X = 30.0\,\text{mm} (aligned with 465.1mm standard rack hole spacing):
    • 1U (Base): Y = 12.7\,\text{mm}, 28.6\,\text{mm}, 44.5\,\text{mm}
    • 2U: Y = 57.2\,\text{mm}, 73.0\,\text{mm}, 88.9\,\text{mm}
    • 3U: Y = 101.6\,\text{mm}, 117.5\,\text{mm}, 133.4\,\text{mm}
    • 4U: Y = 146.0\,\text{mm}, 161.9\,\text{mm}, 177.8\,\text{mm}
    • 5U: Y = 190.5\,\text{mm}, 206.4\,\text{mm}, 222.2\,\text{mm}
    • 6U: Y = 235.0\,\text{mm}, 250.8\,\text{mm}