# Sourcing R1 — engineering implications

## Interactive 3D inspection

The main `simulator.html` now opens a Three.js assembly explorer. Listed exterior dimensions inform the 40 mm rail sections, stainless pans, NEMA17 and geared NEMA23 motors, guides, electronics and cooling equipment. Slotted profiles, pan walls/rims, motor gearheads/shafts, PCB headers, driver terminals, cabinet doors and tubing are modeled for identification. These are reconstructed models, not imported vendor CAD. The inspector distinguishes listed dimensions, representative appearance, provisional mounting and unselected requirements, and links each selection to the sourced BOM.

The visual assembly supports orbit/pan/zoom, direct mesh picking, an 82-entry searchable BOM index, individual part previews, focus/isolation, exploded separation, shell visibility, selectable trays, and accelerated tray / soak previews. One-tray mode moves its inspection fixture to a temporary ground reference without changing its local dimensions. The common plate is positioned below the chute outlet; the front shell includes a nominal 740 × 100 mm lower hatch aperture and a hinged insulated flap. That aperture and flap are visual design concepts, not released cutting or actuator-linkage geometry.

The original parametric studio is preserved in `engineering-studio.html`. Its simplified checks still use their documented generic actuator/load assumptions. The 3D view uses the sourced R1 baseline and does not convert its added detail into a certified full-assembly collision check, structural analysis, fluid model or food-release model.

The sourced BOM covers the current fourteen-tray concept and a separate one-tray fixture. The parts page and Excel workbook contain direct Amazon/McMaster product links where selected, and explicit family/search links where exact size remains open. No cart or purchase was made.

## Motors

Fourteen STEPPERONLINE 17HS19-2004S1 NEMA17 motors drive fourteen GT2 slide loops. Each tray uses two 800 mm MGN12 guides. The listing motor has a 5 mm shaft and 0.59 N·m holding torque; the simulator's 0.20 N·m working allowance is still a test assumption. At 20-tooth GT2 pitch circumference 40 mm, 15 mm/s carriage speed requires 22.5 rpm at the motor. With 80% assumed belt efficiency, 0.20 N·m gives approximately 25.1 N of linear drive allowance.

Fifteen STEPPERONLINE 23HS22-2804S-PG15 geared NEMA23 motors are candidates for fourteen fresh-pan pivots and one soaking pan. Manufacturer dimensions are 57 × 57 × 116 mm, output shaft 12 mm, ratio 15.3:1, rated current 2.8 A/phase, motor holding torque 1.25 N·m. The published gearbox permissible torque is 30 N·m. Neither that limit nor motor holding torque establishes usable output torque at speed. Require a demonstrated output of at least 8 N·m at about 4.17 rpm (25 degrees/s) with the actual 24 V supply, current setting and driver, plus no skipped steps over repeated cold loaded cycles. [Manufacturer](https://www.omc-stepperonline.com/nema-23-stepper-motor-bipolar-l-56mm-w-gear-ratio-15-1-planetary-gearbox-23hs22-2804s-pg15), [published curve](https://www.omc-stepperonline.com/download/23HS22-2804S-PG15_Torque_Curve.pdf).

The smaller 17HS19-1684S-PG27 was rejected because its published maximum permissible gearbox torque is only 3 N·m. Even the old model needs about 3.14 N·m. The larger motor is a prototype selection pending running-torque and fit tests.

The 116 mm axial motor body cannot simply occupy the current 55 mm side-service bay. A purchased reduction belt or a revised under-pan/inboard motor mount may be needed. There is no released mount or collision model for this motor. It weighs about 1.5 kg, which also increases moving carriage mass and cable-chain loads. The coupler supplier does not state an adequate torque rating; this remains an open shaft interface.

Two Hiwonder HTD45H serial servos are candidates for the pellet gates. They use a UART bus, not hobby PWM. The purchase list includes a BusLinker interface, with protocol/logic/power validation required. Two PCA9685 boards from the initial concept are therefore removed from the sourced architecture.

## Pans and load correction

The purchased fresh-food pan is [Winco SPJP-204](https://www.wincous.com/products/spjp-204), exterior 327.2 × 265.2 × 101.6 mm. It fits within the original 340 × 400 × 110 mm tray bounding envelope, but its true cradle and lid clearances remain to model. Manufacturer case weight is not a measured pan tare. A **provisional 1.25 kg pan-plus-cradle tare** replaces the unrealistic 0.30 kg assumption for motor procurement; weigh the received prototype.

For a conservative 400 mm deep envelope with its centre of mass at 200 mm from the rear pivot, 0.45 kg food plus 1.25 kg tare requires:

`2 × ((1.25 + 0.45) × 9.80665 × 0.200 + 0.1) = 6.87 N·m`

The 8 N·m motor target is a provisional acceptance criterion above that simplified design load. The pan can potentially be oriented to shorten the moment arm. Actual pan/cradle centre of mass, hinges, motor brackets and deposited food must determine the final load. The old simulator's apparent torque pass does not validate this motor/pan combination.

The selected soaking pan is [SPJL-604](https://www.wincous.com/products/spjl-604), 177.8 × 163.5 × 101.6 mm exterior. It is a different, thinner-gauge model than the old SPJP-604 reference. Its true interior working volume and wet-pellet release must be measured. The conservative original 781 mL wet-volume allowance versus 932 mL estimated working volume is not a manufacturer capacity claim. The pan retains standing water without a drain, then tips into the shared plate. Pump calibration and an independent hardware maximum run time are required.

## Frame hardware correction

The actual rail is [McMaster 6575N406](https://www.mcmaster.com/6575N406/), 40 × 40 mm, four 8 mm T-slots. Full-build finished member lengths are 55 pieces totalling 56.62 m. The observed rate for every member in this full-build schedule is $0.40/cm, giving $2,264.80 before freight/tax. The supplier allows 2.5 mm cut increments. This is a direct supplier-cut estimate; it does not charge kerf as finished length.

[5537T937](https://www.mcmaster.com/5537T937/) brackets cost $7.06 each, include two M8 × 16 screw/nut sets each, and require no rail machining. 84 brackets cost $593.04. Accessory mounting and anchoring are additional allowances.

**6266N15 was wrong.** It belongs to the locking-slotted rail system, explicitly incompatible with T-slot components. Replace it with [6000N207](https://www.mcmaster.com/6000N207/), an M6 self-aligning T-slot drop-in nut, four per $5.49 package. The 200-nut quantity is a mount/panel allowance, separate from hardware included with the corner brackets. Final nut/screw quantities follow a hole schedule.

## Controls and power

The full candidate architecture is 29 stepper drivers, two gate servos, one 12 V hatch actuator and one 24 V pump. Use one moving stepper axis at a time. A 280 W, 24 V supply is selected only for this sequential architecture, with mechanically supported parked trays and disabled idle axes. It is not sized to energize all 29 motors simultaneously. Gearboxes are not assumed self-locking.

Seven MCP23017 expanders provide 112 slow I/O positions. Preliminary allocation is 29 enables and 67 feedback inputs (96 total). ESP32 hardware provides pulse timing. Do not connect a bank of optocoupler inputs directly to one GPIO; design separate current-drive buffers and bounded fanout. The six ULN2803A modules are a preliminary channel allowance, not a completed wiring schematic. Enable polarity, power-up inhibit, current settings, noise filtering, NC feedback, latch behavior and stop/restart interlocks need a proper schematic and fault tests.

Two large control boxes are preliminary packaging candidates. Driver spacing, conductor routing, heat rejection, bonding and Wi-Fi antenna path are not validated. The frame envelope does not include these boxes, the AC projection or battery shelter. A stainless cabinet can attenuate Wi-Fi; a purchased external-antenna ESP32 variant or suitable nonmetallic logic enclosure may be needed after range testing.

The selected Mean Well supply has a C6P six-pin output. It needs a matching rated harness and IEC cord. It is not a barrel-jack adapter. The stop button should operate a correctly rated DC relay/control circuit; an AC switch rating is insufficient evidence for interrupting the full DC motor bus.

## Refrigeration

The original model's 850 × 1210 × 2205 mm clear envelope is about 2,268 L. A small portable refrigerator cannot enclose it. The research route is an intact [LG LW8024R window AC](https://www.amazon.com/dp/B0D9HRZ91W) with a [genuine CoolBot](https://www.amazon.com/dp/B07T32HF9H). Amazon shows the exact AC at $295.47; the genuine controller listing has no displayed offer price. The manufacturer's $399 controller price is reference context only and is excluded from the priced Amazon/McMaster subtotal.

[CoolBot compatibility instructions](https://www.storeitcold.com/choose-a-compatible-a-c-unit/) must confirm the exact model and installation. Digital controls and auto-restart alone do not prove compatibility. [CoolBot insulation guidance](https://www.storeitcold.com/wp-content/uploads/2025/12/Insulation-Guide.pdf) recommends R25 on walls, floor and ceiling. The current 50 mm enclosure cannot be assumed to meet that. A preliminary 100 mm or greater insulation stack will change clearances or the frame, and its R value depends on the material. No insulation or skin cut schedule is released.

AC support, outdoor condenser clearance, condensate management, coil freeze behavior, pull-down time and independent temperature logging must be demonstrated with the loaded cabinet. The earlier 188 W average/4.4 hour backup estimate uses assumed U/COP and cannot be applied directly to the chosen AC/CoolBot package. Validate compressor surge and transfer on the specific Anker unit. Refrigerator temperatures do not by themselves validate seven days of prepared-food shelf life.

## Order sequence

The workbook includes installed quantities, rounded purchase packs and one-tray prototype quantities. The prototype subtotal is only its priced portion. The fixture uses 4 × 800 mm, 4 × 500 mm and 4 × 400 mm rails; short McMaster cuts are $0.48/cm, so its 6.8 m rail estimate is $300.80 rather than simply multiplying all lengths by the long-member rate.

First obtain a single representative pan, slide pair, slide motor, tip motor and the necessary control/fixture parts. Resolve loaded torque, food release, moving clearances and lid/latch mechanics before multiplying by fourteen. The full BOM deliberately leaves exact fastener lengths, food-grade tubing, passive latches and cooling installation hardware open where the physical interface is not determined. Those are explicit remaining design tasks, not hidden purchases or zero-dollar components.