Module 3 — 3D Moulding, Tooling & Parametric Enclosure Code

3.1 Scope

This module defines the mechanical enclosure of the Money Roll micro-ATM: the injection-moulded front fascia, the internal SPCC sheet-metal chassis, the cassette and dispenser interfaces, moulding/tooling parameters for the fascia tool, tolerance stack-ups for critical apertures, sheet-metal fabrication notes, and thermal management. It accompanies two parametric CadQuery scripts (cad/fascia.py, cad/brackets.py) that generate manufacturable solid models and STEP/STL exports for procurement and CAM.

3.2 Overall Envelope

Overall unit envelope: 420 mm (W) x 560 mm (H) x 260 mm (D), wall/pedestal mountable. The fascia is a single-shot PC/ABS moulding, 3.0 mm nominal wall, fastened to the SPCC chassis via 6 x M4 heat-set inserts plus a continuous EPDM gasket for IP54 sealing at the fascia-to-chassis parting line.

3.2.1 Front elevation (component stack-up)

                        420 mm overall width
   +----------------------------------------------------------------+
   |  o  status LED light-pipe (top strip, Ø3 mm x 40 mm run)       |
   |                                                                  |
   |     +--------------------------------------------------+        |
   |     |                                                    |       |
   |     |         10.1" CAPACITIVE TOUCHSCREEN                |      | 560 mm
   |     |         active area 216.96 x 135.6 mm               |     | overall
   |     |         outline (bezel cut) 229 x 149 mm            |     | height
   |     |                                                    |       |
   |     +--------------------------------------------------+        |
   |                                                                  |
   |   [ CAM KEYWAY Ø19 ]     [ QR CAMERA WINDOW Ø12 ]                |
   |                                                                  |
   |   +--------------------------+   +----------------------+       |
   |   | BILL VALIDATOR BEZEL     |   | HYBRID CARD READER    |       |
   |   | (Pyramid Apex 7000)      |   | SLOT (insert/swipe)   |       |
   |   | 66 x 30 mm nominal       |   | 86 x 3 mm slot         |      |
   |   +--------------------------+   +----------------------+       |
   |                                                                  |
   |   [ NFC READER ZONE - flush mark, no cut, 45 x 45 mm ]           |
   |                                                                  |
   |   +--------------------------------------+                      |
   |   | MOTORIZED CARD SLOT (Creator CRT-591) |                      |
   |   | bezel opening approx 90 x 14 mm       |                      |
   |   +--------------------------------------+                      |
   |                                                                  |
   |   [ RECEIPT PRINTER SLOT 76 x 6 mm ]   ((( SPEAKER GRILLE )))    |
   |                                                                  |
   +----------------------------------------------------------------+

Note: bill validator bezel dimensions are nominal per Pyramid Technologies Apex 7000 generic bezel cut; verify against the vendor mechanical drawing (Pyramid dwg APX7-BZL-xxx) before cutting steel — bezel position tolerance and validator throat alignment are safety/fraud-critical.

3.2.2 Side section (depth stack-up)

   Front face (outside)                                   Rear (chassis)
   |                                                                |
   |<-- 3 mm PC/ABS fascia wall
   |    1.0 mm glass rebate + 3 mm chemically strengthened glass, optically bonded
   |    -> touchscreen module (LCD + digitizer), 14.5 mm stack depth
   |
   |    Bill validator: Apex 7000 body extends 175 mm into chassis depth,
   |        bezel flush with fascia outer face, 4 x M4 cage nuts to bracket
   |
   |    Card dispenser CRT-591: bezel flush, body 195 mm into chassis
   |
   |    2.5 mm SPCC internal frame, powder coated RAL7016, forms structural
   |        backbone; cassette rail channel at bottom, cassette 100 mm deep
   |
   |    260 mm overall depth (W x H x D = 420 x 560 x 260)

3.3 Material Specifications

3.4 Moulding & Tooling Criteria

3.4.1 Tonnage calculation (worked example, bill-validator bezel local pressure zone)

Projected area of full fascia part (420 x 560 mm envelope, but effective moulded projected area excluding open apertures) approx = 1750 cm^2. Using standard PC/ABS specific pressure factor 3.5 tonf/cm^2 (t/cm^2) as directed by spec:

Clamp tonnage = projected area (cm^2) x 3.5 t/cm^2 = 1750 cm^2 x 3.5 t/cm^2 = 6125 tonf (theoretical, full-shot single-cavity worst case)

This exceeds realistic single-cavity clamp tonnage for a part this size using generic 3.5 t/cm^2 (a conservative factor normally used for engineering resins with high viscosity / thick sections, e.g. glass-filled nylon); for PC/ABS thin-wall (3 mm) mouldings the practical industry factor is 2.0-3.0 t/cm^2. The specification factor is retained for conservative machine sizing:

Local bezel cut-out projected area (bill validator bezel 66 x 30 mm = 19.8 cm^2): Tonnage(bezel zone) = 19.8 cm^2 x 3.5 t/cm^2 = 69.3 tonf

For the whole-part conservative case, select a 650-800 tonne press using the 2.0-2.5 t/cm^2 industry-typical factor (1750 x 2.25 avg = ~3940 kN = ~394 tonf, rounded to 450-500 tonf press with process margin); document both calculations in the tool-transfer package and confirm with the moulder's process engineer prior to tool design freeze.

3.4.2 Ejector pin map

Ejector pins Ø 6 mm placed at every boss base and rib intersection on the B-side (rear face), referenced to fascia origin (0,0) at bottom-left corner of the outer envelope, Z at parting line.

3.5 Tolerance Stack-Up

3.5.1 Touchscreen aperture to bezel cut-out

Design intent: aperture nominal 1.0 mm larger per side than module outline, giving 0.5 mm nominal gap per edge, comfortably absorbing the 0.40 mm RSS stack with margin for the visible reveal line.

3.5.2 Card slot to dispenser throat alignment

Design intent: card slot bezel opening height (14.0 mm) provides +/- 1.5 mm clearance beyond the CRT-591 throat height (nominal 11 mm card thickness path plus mechanical envelope), which exceeds both RSS (0.32 mm) and worst-case (0.75 mm) stacks with wide margin; slotted (not round) mounting holes on the dispenser cradle (see brackets.py) provide +/-3 mm field adjustment to absorb any residual mis-registration at install.

3.6 Sheet-Metal Frame

3.7 Thermal Management

3.8 Running the CadQuery Files

1. python3 -m venv .venv && source .venv/bin/activate
2. pip install cadquery cadquery-ocp
3. python docs/engineering/cad/fascia.py
4. python docs/engineering/cad/brackets.py

Outputs (written next to each script):

• fascia.step, fascia.stl — front fascia, production (nominal) geometry
• fascia_cavity.step — cavity-scaled geometry when TOOLING=True is set in Params (0.5% uniform scale-up for mould cavity machining)
• bracket_pcb.step, bracket_validator_cradle.step, bracket_card_tray.step

3.9 DFM Checklist

• All wall sections within 3.0 +/- 0.15 mm; no section exceeds 2x nominal without core-out
• All bosses have >= 1.5 deg draft, ribs >= 1.5 deg draft, textured faces >= 2.0 deg
• Rib-to-wall thickness ratio <= 0.6 to avoid sink marks on Class-A face
• No unsupported bosses/ribs directly opposite show-surface without a sink study
• Sharp internal corners eliminated; minimum internal radius 0.5 x wall (1.5 mm)
• Insert bosses checked for hoop-stress crack risk at hole edge (min 1.5 mm wall around insert hole)
• Gate location avoids weld lines crossing touchscreen or card-slot aperture edges
• Ejector pins avoid Class-A show surfaces; placed on bosses/ribs only
• Gasket channel depth (1.5 mm) less than gasket free height by design compression 25-35%
• Cavity dimensions include 0.5% shrink compensation verified against first-shot CMM report
• Sheet-metal minimum flange 10 mm maintained at all formed edges; bend relief present at all flange intersections
• PEM nut squareness and pull-out force verified per PEM install spec at press setup
• IP54 gasket compression validated at all four fascia corners and cassette door under worst-case tolerance stack