ARK VAULT: PARTS TO PRINT AND ETCH (version 9, for a Raspberry Pi 4 or 5)
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The full step-by-step build, with pictures and a 3D model, is the "ARK Vault" guide
(AMMO-CAN-COMPUTER-GUIDE.html in the library, or on the website). This sheet is the
quick reference: sizes, where things go, and the wiring.

These parts are a first fit. Print the Pi's base first, then the riser, and check them
against your own can and parts. The mesh radio's base is new in version 9 and has not been
printed or tried yet: check it against your own board before you stick it down. The whole build to scale is in ARK-Vault-assembly.3dm
(Rhino, mm).

WHAT TO PRINT  (ABS, no supports, 3 walls with a 0.4 mm nozzle, layers 0.2-0.28 mm)
  printed/ARK-printer-riser.stl   96 x 91 x 153 mm   The stand with one leg. Holds the printer on top,
                                                     the meter, power switch and meter button in front,
                                                     and the converter and fuse on the inside of the leg.
  printed/ARK-riser-cleat.stl     27 x 77 x 3 mm     A small strip taped to the can's hinge-end wall.
                                                     The riser hooks onto it.
  printed/ARK-pi-base-on-lid.stl  57 x 66 x 5 mm     A thin plate the Pi screws to. Sticks under the lid
                                                     with double-sided foam tape (VHB).
  printed/ARK-mesh-radio-base-on-lid.stl             OPTIONAL: only if you add the mesh radio.
                                  45 x 58 x 17 mm    A thin plate with two rails the mesh radio's board
                                                     slides into, and a tab that holds the antenna's
                                                     screw-on socket. Sticks under the lid beside the Pi
                                                     (VHB). Prints flat, rails up.
  The files open in the slicer the way they print.

WHAT TO ETCH  (laser/, see laser/READ-ME.md)
  The ARK Vault logo on both long sides, and bare-metal strips all round the lid seam for the
  foil tape. No laser? Scrape the paint off the same strips by hand.

WHERE EVERYTHING GOES
  Hinge end:   the printer riser, against the back wall. Its leg stands on the floor beside the
               battery; its other end hooks onto the wall cleat.
               Wall cleat: thick edge up, top corners about 29 mm (1 1/8 in) below the rim,
               about 6 mm from the back wall.
               Converter: on the raised frame inside the leg, terminals toward the front, with
               SHORT screws (M3 x 6 mm or #4 x 1/4 in - longer ones poke through).
               Fuse holder: across the leg, about 1 cm above the bottom (foam tape).
  Lid:         the Pi on its base, over the printer, USB ports toward the front, about 13 mm
               in from the hinge wall and 9 mm in from the back wall. Small thumb drive only
               (about 19 mm of room).
               Mesh radio (optional): on its base beside the Pi, on the latch side, screen facing
               away from the lid. The base's long edge about 5 mm from the Pi's base; its antenna
               end about 10 mm in from the front wall; the board's USB end toward the back wall.
               It hangs over the hinge end of the wall charger, so keep the charger's coiled cord
               and plug toward the latch end, clear of it.
  Latch end:   the battery against the back wall, terminals toward the back, rubber boots on
               both terminals. In front of it: the solar controller on its edge (stored, not
               wired) with the wall charger lying on top.
               Packed with them (optional): a second phone with the pocket mesh radio (a card)
               taped to its back, on its long edge in the slot between the solar controller and
               the battery, screen toward the controller (lift the charger to reach it); the
               mesh radio's antenna, folded at its joint, standing in the corner between the
               battery and the latch end. These are packed for storage and come out after an
               event; they don't need to be quick to reach.
  Front wall:  the crank radio on the floor in front of the riser; the phone standing on its end
               beside it.
  Keep every bare wire end and bolt covered so nothing metal touches the can.

WIRING
  Battery +  -> 7.5 A fuse -> power switch -> converter Input + and printer +
  Battery -  -> meter's thick BLACK wire.  Meter's thick RED wire -> converter Input - and printer -
  Meter's thin wires:
               black  -> battery -
               yellow -> battery + (after the fuse)
               red    -> microswitch COM, microswitch NO -> battery + (after the fuse)
               (the meter only lights while you hold the button)
               Check your meter's own wiring sheet: some have the thick wires the other way round.
  Converter Output + -> Pi pin 2 (5 V).   Converter Output - -> Pi pin 14 (ground).
               !! BEFORE plugging onto the Pi: switch on and check with a multimeter -
               5.0 to 5.25 V, and + and - the right way round. A mistake here can kill the Pi.
  Cooler fan -> Pi pins 4 (red), 6 (black), 8 (blue).
               All on the outer row of pins. Pin 2 is the corner pin farthest from the USB ports.
               (A Pi 5's cooler plugs into its own fan socket instead.)
  Printer USB -> a Pi USB port.  Library drive -> a BLUE Pi USB port.
  Mesh radio  -> the other BLUE Pi USB port (the one above the library drive), with a short
               USB-A to USB-C cable (30 cm / 1 ft). Run it along the lid between the Pi and the
               radio's base, round to the board's USB end, and tape the slack flat to the lid.
               The antenna's thin lead clips onto the board's antenna end; its screw-on socket
               goes through the tab's hole, nut on the outside. Tuck the spare loop flat.
  Route:       the Pi's power wires and the printer cable run together along the front wall to
               the hinge corner and up into the lid. Leave a loop of about 6 cm so the lid opens.
               Tie the short wire from battery + to the fuse down, away from sharp edges.

PARTS
  Rocker switch (21 x 15 mm), DC volt/amp meter (48 x 29 mm, 100 V 10 A), microswitch with its
  lever removed (20 x 10 x 6.4 mm, 2 x M2 screws), inline blade fuse holder with a 7.5 A fuse,
  TOBSUN EA25-5V converter (12 V to 5 V, 5 A), about 1.5 m each of 16 AWG red and black wire,
  about 80 cm of 18 AWG red/black pair with two female jumper plugs for the Pi, 4 x M2.5 x 8 mm
  screws (Pi), 2-4 M3 x 6 mm self-tapping screws (converter), zip ties, VHB foam tape.
  Mesh radio (optional): Heltec WiFi LoRa 32 V4, 915 MHz, WITH its screen and WITHOUT the pin
  strips soldered on; a 915 MHz antenna with a thin lead (U.FL / IPEX to SMA socket); a short
  USB-A to USB-C cable; one more M2.5 x 8 mm screw. Pocket mesh radio: SenseCAP T1000-E.

USING IT
  Mesh radio fitted? Screw its antenna onto the socket BEFORE you flip the switch, every time.
  The switch powers the radio too, and sending with no antenna can burn it out.
  Open the lid, flip the red switch on, wait 2-3 minutes, join the Pi's Wi-Fi on the phone.
  Flip it off when done: always safe, because the Pi is set to read-only.
  Hold the meter button to check the battery: about 13.3 V full, 13.0 V half, 12.0 V empty.

CHARGING
  Wall:   MOTOPOWER MP00207A on its LITHIUM setting, lid open. About 10 hours from empty.
          Unplug when the Full light comes on.
  Solar:  Victron BlueSolar MPPT 75/15, stored in the can, not wired. After an event: set it
          once in the VictronConnect app (battery LiFePO4, about 10 A), wire the battery first
          (20 A fuse near the battery), then the panel. Unplug the panel first.
  Never charge with the lid shut, and never run a cable through the can.

CHECK FIRST
  Measured from one .50 cal can: 11 x 5.5 in inside, 7.06 in deep to the top of the lip, a
  1/4 in bump in the floor. Measure yours.
  The microswitch (KW12-3) slot assumes its screw holes are 9.5 mm apart: measure yours.
  The printer's hole in the riser is 78.2 x 54.2 mm (1 mm over the printer, for ABS shrinking).
  The mesh radio's base is drawn from Heltec's own drawing of the V4 board (51.7 x 25.4 mm,
  1.6 mm thick), with 0.35 mm of play each side. The board slides in from its USB end, pins
  left off, until it stops; one M2.5 x 8 mm screw in either post at the USB end then shuts it
  in. A board with its pins soldered on will not slide in. The socket's hole is 6.6 mm.
  Under the closed lid the radio reaches 15 mm down, and the socket's tab 18 mm: check nothing
  in your can stands that high under them.
