ARK VAULT: PARTS TO PRINT AND ETCH (version 10, 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. Version 10 adds brass heat-set inserts (below), and shapes the
riser for the converter as measured. The mesh radio's base has not been printed or tried yet:
check it against your own board before you stick it down.
Rhino file (mm): ARK-Vault-assembly.3dm is the whole build to scale.

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). Four posts: two
                                                     take M2.5 inserts, two have a hole right through
                                                     for long screws put in from underneath.
  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, and two round posts with M3
                                                     inserts. Sticks under the lid beside the Pi
                                                     (VHB). Prints flat, rails up.
  The files open in the slicer the way they print.

HEAT-SET INSERTS  (brass, melted in with a soldering iron at about 230 C, small end down,
                   flush with the surface; every hole has a 0.4 mm bevel at its mouth)
  Printer riser   2 x M2.5 (3.5 mm across, 4 mm long)   in the leg's raised frame, under the
                                                        converter's two ears (3.2 mm holes)
  Pi's base       2 x M2.5                              in the two posts with a blind hole
  Mesh radio base 2 x M3 (4.6 mm across, 5.6 mm long,   in the two round posts at the USB end
                  "M3 x 5.7 x 4.6")                     (4.0 mm holes). The fatter M3 inserts in
                                                        most mixed kits do not fit these holes.

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 (TOBSUN EA25-5V): on the raised frame inside the leg, terminals toward
               the front, an M2.5 x 6 mm screw with a washer through each ear into the inserts.
               The ears' 3.33 mm holes give the screws about 0.4 mm of play to line up.
               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.
               Handheld radio (optional): a UV-5R-size two-way radio, ANTENNA SCREWED OFF,
               standing on the floor against the front wall under the overhanging half of the
               wall charger, between the phone at the hinge end and the solar controller. It
               needs 113 mm of clear height and that is the only place in the can with it, so
               nothing taller goes there. Its antenna stands loose in the front corner of the
               latch end, beside the mesh aerial. Lift the charger to get it out.
               Its battery is stored OUT of the radio, about half charged, beside it.
  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  (every run, its wire, and about how long, with some spare)
  12 V power - 16 AWG (all of it draws at most about 4.5 A; the 7.5 A fuse protects the wire)
   1  Battery +                 -> fuse holder (either end)             16 AWG red     30 cm
   2  Fuse holder (other end)   -> power switch INPUT terminal          16 AWG red     30 cm
   3  Power switch OUTPUT       -> a splice                             16 AWG red     10 cm
   4  that splice               -> converter IN +                       16 AWG red     12 cm
   5  that splice               -> printer + (its power lead)           16 AWG red      8 cm
   6  Battery -                 -> meter's thick BLACK wire             16 AWG black   40 cm
   7  Meter's thick RED wire    -> a splice                             (its own wire)
   8  that splice               -> converter IN -                       16 AWG black   10 cm
   9  that splice               -> printer -                            16 AWG black   10 cm
  The meter's thin wires - 22 AWG (they carry almost nothing)
  10  Meter thin BLACK          -> the battery - side of the meter (join it where run 6 meets the
                                   thick black)                         its own / 22 AWG
  11  Meter thin YELLOW         -> power switch INPUT terminal          22 AWG yellow  10 cm
  12  Meter thin RED            -> microswitch COM                      22 AWG red     10 cm
  13  Microswitch NO            -> power switch INPUT terminal          22 AWG red     10 cm
               (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.
  The Pi - 18 AWG (up to 3 A at 5 V)
  14  Converter OUT +           -> Pi pin 2 (5 V)                       18 AWG red     60 cm
  15  Converter OUT -           -> Pi pin 14 (ground)                   18 AWG black   60 cm
               18 AWG is too thick for the little pin plugs: solder it to a female jumper lead's
               short wire about 5 cm from the Pi, heat-shrink over each joint.
               !! 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.
  16  Cooler fan                -> Pi pins 4 (red), 6 (black), 8 (blue)  its own lead
               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.)
  17  Printer USB               -> a BLACK Pi USB port.  Library drive -> the lower BLUE port.
  18  Mesh radio                -> the upper BLUE Pi USB port, 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.
  Ends:        ring terminals on the battery bolts; blue female spades (16-14 AWG) on the power
               switch - its INPUT terminal takes runs 2, 11 and 13 together in one spade (or a
               piggyback spade); crimped butt splices or solder at the splices; heat-shrink over
               every joint so nothing bare can touch the can.
  Route:       the Pi's power pair 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.
  Solar, after an event (not wired in storage): controller BATT+ -> 20 A fuse (near the battery)
               -> battery +, BATT- -> battery -, both 12 AWG, about 1 m; the panel on its own leads.

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 x 8 mm screws), inline blade fuse holder with a 7.5 A
  fuse, TOBSUN EA25-5V converter (12 V to 5 V, 5 A).
  Printer: DFRobot DFR0503 V2.0, the USB one (9-24 V). NOT the older serial-only one (5-9 V).
  Wire: about 1.5 m each of 16 AWG red and black; about 60 cm each of 18 AWG red and black and
  two female jumper leads for the Pi; about 30 cm each of 22 AWG red and yellow; ring terminals,
  blue female spades, butt splices, heat-shrink. Solar, later: 12 AWG red and black, 20 A fuse.
  Inserts: 4 x M2.5 (3.5 mm across, 4 mm long), 2 x M3 (4.6 mm across, 5.6 mm long).
  Screws (socket head): 4 x M2.5 x 6 mm with 2 washers (2 Pi, 2 converter), 2 x M2.5 x 8 mm (the
  Pi's cooler corners, from under the base), 2 x M3 x 6 mm (mesh radio), 2 x M2 x 8 mm
  (microswitch). Zip ties, VHB foam tape, a soldering iron for the inserts.
  The Pi's cooler (GeeekPi Armor Lite): leave out its own two M2.5 x 6 screws. The M2.5 x 8
  screws take their place, from under the base, through the Pi into the cooler.
  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. 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 converter (TOBSUN EA25-5V) as measured: 51.7 mm long over its plate, 48.5 wide, 19.8
  thick, the ears 63 across with 3.33 mm holes about 56.3 apart, 18.35 mm from the far end.
  Another converter needs the riser's frame changed (make_can_parts.py, CV).
  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; an M3 x 6 mm screw into the insert in either post at the USB end
  then shuts it in, its head on the board's corner. 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.
