Trackless Photocar S1 · simplified flat build · 2026-10-06

Assembly-line build guide

The car is built as modules at seven stations that work side by side. Each module is checked where it is built, then joined on one final line. Every step below has an animated drawing made from the Inventor model.

The modules meeting on the final line, labelled by the station that builds them.S2 Drive: wall modulesS1 Sensors: nosesS7 Final line: bayS4 Electronics deckS3 Steering cornersS2 Drive: rear wheelsS6 Mast (shortened)S5 Body: lids
The modules meeting on the final line, labelled by the station that builds them.

How the line runs

S0 cuts and prints ahead of the line and kits the parts by station. S1 to S6 each build their modules at their own bench and check them before handing them on. S7 joins the modules from the outside, top-down, and tests the car. Only two parts visit two benches: the side walls (S1 fits the sensor stations, then S2 the drive) and the end panels (S5 fits them out, then S4 mounts them on the deck).

One car through the line: bars fill as each station works; arrows are hand-offs.0:001:002:003:004:005:006:00S0Cut and print1 person · 160 minruns aheadlaser and kitting 2.7 h · printer 26-51 h, started the day beforeS1Sensors1 person · 80 minS2Drive1 person · 80 minS3Steering1 person · 80 minS4Electronics deck1 person · 240 minS5Body1 person · 95 minS6Mast1 person · 45 minS7Final line2 people · 120 minwallsend panelsdeckwallsnosescheckwheelswall modulesforkswheelstowerspowercomputepanelswire + power-upend panelsfront lidrear lidmastbaydeck to lidstestscar done at 5:30One car from cut parts to test. In steady state S4 sets the pace: a car every 4 hours.
One car through the line: bars fill as each station works; arrows are hand-offs.
The stations
StationCrewTime per carBuildsHands to
S0 Cut and print1160 minevery laser-cut and printed part, deburred, labeled and kitted for the other stationsevery station
S1 Sensors180 minall eight sensor stations, in the two noses and on the two side walls, each checked on the benchS2 walls, S7 noses
S2 Drive180 minthe rear drive on each side wall (motor, coupler, bearing block, bearing, axle) and the two driven wheels, drilled and hubbedS7
S3 Steering180 mintwo forks with their front wheels, two servo towers with centered servos and couplers, and the kingpin kitsS7
S4 Electronics deck1240 minevery board and power part on the deck, the mast clamp and the end panels, wired and powered up on the benchS7
S5 Body195 minthe two cover lids (LiDAR, E-stop and reset fitted) and the two end panels (fans, disconnect and charge port)S4 end panels, S7 lids
S6 Mast145 minthe owned mast with its limit switches, ball head and cameraS7
S7 Final line2120 minthe battery bay, batteries, deck, steering corners, wheels, mast and covers, then the power-up and drive testsfinished car

Times are planning estimates until the first car is timed. With one car at a time the line takes about 6 hours; in steady state the electronics deck (S4, about 4 hours) sets the pace.

Standards for every station

One joint
A printed corner block, an M4 x 25, a washer and a nyloc nut. The head goes on the face that closes later and the nut on the face that stays open, so every nut can be reached when it is fitted.
Tightening
Run each nyloc until the washer stops turning by hand, then a quarter turn more. A printed block that turns white at the washer is over-tight.
Acrylic
Washer under every head and nut on acrylic. Snug only: acrylic cracks at a hole long before the bolt is tight.
Set screws
Seat set screws on the shaft flat, with a drop of medium thread-locker.
Leads
Tag every lead at both ends with its station number or part reference, and leave a service loop where it crosses a module joint.
Traceability
Every module carries the car number from S0 to S7; each station signs its check on the traveller.
The one joint: a corner block, two M4 x 25 bolts, washers and nylocs, the nuts on the open face.corner block (PETG)M4 x 25 boltwasher + nyloc nutholes 20 mm apart
The one joint: a corner block, two M4 x 25 bolts, washers and nylocs, the nuts on the open face.
Fasteners by station
FastenerPer carWhereBy stationTools
M4 x 25 button head64both bolts of every corner blockS2 8 · S3 8 · S4 8 · S5 24 · S7 162.5 mm hex key, 7 mm nut driver
M4 x 20 button head47KFL08s, noses, rear blocks, servo ears and tower feet, fuse block, relayS2 12 · S3 20 (8 + 12 bagged for S7) · S4 3 · S7 122.5 mm hex key, 7 mm nut driver
M4 nyloc nut + washer111one on every M4 x 25 and M4 x 20with the bolts7 mm nut driver
M4 x 12 button head16Sonic Hubs and Hyper Hubs, into their own threadsS2 8 · S3 82.5 mm hex key
M3 x 6 socket cap12gearmotor faces, into the motor's threadsS2 122.5 mm hex key
M3 x 18 + nut18Sharp sensors (16), charge port (2)S1 16 · S5 22.5 mm hex key, 5.5 mm nut driver
M3 x 25 + nut8 + boardsfans and filters; boards on 5 mm spacersS4, S5 82.5 mm hex key, 5.5 mm nut driver
M2 screw + 2 nuts16ToF boards: one nut as a spacer, one to clamp (see open items)S1 161.3 mm hex key, 4 mm nut driver
M2.5 standoffs and screwskitboards with M2.5 holes; the LD19 on four standoffsS4, S5 4small hex key or driver
M5 x 25 socket cap + nyloc10both mast flanges (8), battery disconnect (2)S4 4 · S5 2 · S7 44 mm hex key, 8 mm nut driver
M8 x 75 hex bolt + nyloc2front wheel axlesS3 2two 13 mm wrenches
S0

Cut and print

1 person · about 160 min per car · builds every laser-cut and printed part, deburred, labeled and kitted for the other stations

Makes every flat and printed part for one car and kits them by station. The printer runs ahead of the line: start it the day before.

Kit for one car
madeStarts from raw stock
boughtTwo aluminum sheets 24 x 36 x 0.125 in (5052-H32); cast acrylic 1/8 in for the windows, masked; 1 kg PETG
filesDXF for each flat part (outline and holes); STL for the four printed designs

Tools: Laser cutter, 292 mm printer, deburring tool and file, labels, kit trays and bags.

  1. S0.1 Print the three plates 15 min + printer

    1. Plate A: both noses upright, with slicer support only under the side tabs.
    2. Plate B: the two rear bearing blocks (no support) and the two servo towers, with support under the top plate so the feet print flat.
    3. Plate C: the 32 corner blocks, lying flat.
    4. PETG at 4 walls and 40% infill: 766 g in all, so one spool covers it with about 200 g to spare. Start plate A first; it is the longest.

    Check: An M4 bolt passes through both holes of every corner block by hand.

    S0.1 Three print plates growing layer by layer: the noses, the blocks and towers, and the 32 corner blocks.A: 2 noses, 13-26 hB: blocks + towers, 8-15 hC: 32 blocks, 5-10 h
    S0.1 Three print plates growing layer by layer: the noses, the blocks and towers, and the 32 corner blocks.

  2. S0.2 Cut the aluminum sheet 50 min

    1. The deck goes at one end, with three fork legs and a fork top in the cut-out beside its rear body and the rest on the other side. One side wall goes beside the deck; the floor and the second wall go across the remaining 14.6 in.
    2. Cut each part's holes and windows before its outline, so nothing shifts before its features are cut.
    3. Deburr every edge and hole; ease the sensor windows and the motor holes.
    4. Mark each part on its inside face: DK, FL, SW (x2), FT (x2), FG (x4).

    Check: An M4 bolt drops through the floor and wall block holes; the 44 mm deck hole passes the mast tube.

    S0.2 The aluminum nest being cut: holes first, then each outline.DK deckSW wallFL floorSW wallOne 24 x 36 in sheet of 0.125 in 5052, 3 mm gaps: 10 parts. Holes and windows are cut before each outline.
    S0.2 The aluminum nest being cut: holes first, then each outline.

  3. S0.3 Cut the body sheet and the windows 35 min

    1. The two cover tops go first, then two rows of side panels, then the two end panels. The 14 in strip left over covers any re-cut.
    2. Cut each part's holes before its outline. Deburr every edge and hole.
    3. Mark each part on its inside face: CTF, CTR, CSF (x2), CSR (x2), EPF, EPR.
    4. Cut the eight 46 x 42 mm window panes from the 1/8 in acrylic with the masking on, and leave it on: it comes off at S1.

    Check: An M4 bolt drops through every corner-block hole; no burrs on the panel edges.

    S0.3 The body sheet: cover tops, side panels and end panels.CTF front topCTRCSF sideCSRCSF sideCSREPFEPRA second 24 x 36 in sheet of 0.125 in 5052, 3 mm gaps: the 8 body panels, with a 14 in strip left for re-cuts.
    S0.3 The body sheet: cover tops, side panels and end panels.

  4. S0.4 Kit by station 60 min

    1. Sort made and bought parts into one tray per station, using the kit list at the top of each station below.
    2. Bag the fasteners per station and write the counts on each bag.
    3. Split the 32 corner blocks 8 / 4 / 4 / 16 to S2, S3, S4 and S5.
    4. Report shortages before the line starts, not at the bench.

    Check: Every tray matches its kit list.

    S0.4 Trays filling per station, with each station's fastener bag.S1 Sensors2 side walls2 noses8 window panesfastener bag16 M3 x 1816 M2S2 Drive2 bearing blocks8 corner blocksfastener bag12 M4 x 208 M4 x 258 M4 x 1212 M3 x 6S3 Steering2 fork tops4 fork legs2 servo towers4 corner blocksfastener bag8 M4 x 2520 M4 x 208 M4 x 122 M8 x 75S4 Electronics deck1 deck4 corner blocksfastener bag8 M4 x 253 M4 x 204 M5 x 25board screwsS5 Body2 cover tops4 side panels2 end panels16 corner blocksfastener bag24 M4 x 258 M3 x 252 M3 x 182 M5 x 254 M2.5S6 Mastparts bag2 limit switches2 hose clampsS7 Final line1 floorfastener bag16 M4 x 2512 M4 x 204 M5 x 25
    S0.4 Trays filling per station, with each station's fastener bag.

S0 check before hand-off

  • 64 made parts, all labelled: 18 aluminum, 8 acrylic, 38 PETG.
  • Aluminum deburred; acrylic still masked.
  • Fastener bags counted for every station.

Hands off: Trays to S1-S7. The two side walls go to S1 first.

S1

Sensors

1 person · about 80 min per car · builds all eight sensor stations, in the two noses and on the two side walls, each checked on the bench

Builds all eight sensor stations: one on each side wall and three in each nose. A station is a clear pane outside the wall, a Sharp distance sensor and a ToF board inside, held by the same four bolts.

Kit for one car
made2 side walls (SW), 2 noses (NS), 8 window panes (W)
bought8 Sharp GP2Y0A21 with cables; 8 VL53L1X ToF boards (two 4-packs); foam seal tape
fasteners16 M3 x 18 + 16 M3 nuts; 16 M2 screws + 32 M2 nuts (16 are spacers)

Tools: 2.5 mm and 1.3 mm hex keys, 5.5 mm and 4 mm nut drivers, the sensor test rig.

  1. S1.1 Side-wall stations first 20 min

    1. Do the two walls first: S2 is waiting for them.
    2. Peel the pane's masking. Run seal tape round the window on the pane's inner face, outside the four holes.
    3. Pane on the outside face. From inside, the Sharp goes in with its lens in the large window and its tabs flat on the wall. The ToF goes in with its sensor in the small window and an M2 nut behind each screw as a spacer.
    4. 2 x M3 x 18 through pane, wall and Sharp tabs; 2 M2 screws through pane, wall, spacer and ToF board. Nuts inside, snug only.
    5. Tag the leads: station 2 on the right wall, 6 on the left.

    Check: Pane flat with no gap; both sensors square in their windows.

    S1.1 A side-wall station from inside: pane outside, Sharp and ToF inside, four bolts.acrylic pane outsideSharp GP2Y0A21 insideToF VL53L1X insidenuts inside
    S1.1 A side-wall station from inside: pane outside, Sharp and ToF inside, four bolts.

  2. S1.2 Nose stations 40 min

    1. The same fit at all three stations of each nose: the front face and both chamfers.
    2. The nose is open at the back, so every nut is reached from behind.
    3. Tag the leads: front nose 7, 0, 1; rear nose 3, 4, 5.

    Check: Three panes flat, six sensors square, twelve nuts snug.

    S1.2 A nose from behind: three panes, six sensors and twelve nuts through the open back.3 panes outsidesensors from inside12 nuts, open back
    S1.2 A nose from behind: three panes, six sensors and twelve nuts through the open back.

  3. S1.3 Check every station on the bench 20 min

    1. Connect each station to the test rig and hold a white card square in front of it at 10, 30 and 60 cm.
    2. Both sensors must follow the card, and all eight stations should read alike. A station that reads short usually has a fingerprint on the pane or a sensor not seated in its window.

    Check: 8 of 8 stations read; leads tagged 0-7.

    S1.3 Bench check: one card at three distances, two readings per station.station on the test rig10 cm30 cm60 cmwhite cardreadingSharp 2.3 VToF 100 mmpassSharp 0.9 VToF 301 mmpassSharp 0.5 VToF 598 mmpassHold the card square to the station at 10, 30 and 60 cm.Both sensors must track it; all eight stations should read alike.Typical values shown; the first station checked sets the band (fit check 8).
    S1.3 Bench check: one card at three distances, two readings per station.

S1 check before hand-off

  • Eight stations built and read on the bench.
  • Leads tagged 0-7 at both ends.
  • No cracked or scratched panes.

Hands off: Walls to S2, about 20 minutes in. Noses to S7.

S2

Drive

1 person · about 80 min per car · builds the rear drive on each side wall (motor, coupler, bearing block, bearing, axle) and the two driven wheels, drilled and hubbed

Turns the two side walls into drive modules: motor, coupler, bearing block, bearing, axle and the four wall blocks. It also prepares the two driven wheels.

Kit for one car
made2 rear bearing blocks (RB), 8 corner blocks; the 2 walls arrive from S1
bought2 FIT0185 gearmotors, 2 couplers 6-8 mm, 2 KFL08, 2 REX axles 88 mm, 2 Hyper Hubs, 2 L-faster wheels
fasteners12 M3 x 6; 12 M4 x 20; 8 M4 x 25; 8 M4 x 12; 20 M4 nylocs and washers

Tools: Drill press, 4.5 mm drill, centre punch, 8 mm pin, 2.5 mm hex key, 7 mm nut driver, the keys supplied with the couplers and bearings.

  1. S2.1 Drill and hub the driven wheels 20 min

    1. Start here while S1 finishes the walls.
    2. Clamp the wheel flat on the drill press with an 8 mm pin through its bearing.
    3. Mark the 32 mm square from the bore centre (16 mm each way), centre-punch, and drill 4 x 4.5 mm through the metal hub, clear of the 22 mm bearing seat (fit check 1).
    4. Seat the 1313 Hyper Hub on the drilled face; 4 x M4 x 12 from the tire side into its threads.

    Check: The hub sits flat and the wheel runs true on a REX shaft.

    S2.1 Four holes on the 32 mm square, then the Hyper Hub on the drilled face.32 mm square4.5 mm holesgoBILDA 1313 Hyper Hub4 x M4 x 12 from below
    S2.1 Four holes on the 32 mm square, then the Hyper Hub on the drilled face.

  2. S2.2 Motor on the wall 15 min

    1. Wall on the bench, inside face up. Set the gearmotor's face over the 16 mm hole, shaft through.
    2. From outside, 6 x M3 x 6 into the motor face. They reach 2.8 mm into its 3 mm holes (fit check 4).
    3. Slide the 6-8 mm coupler onto the motor shaft, set screw on the flat.

    Check: Motor face flat on the wall; coupler square to it.

    S2.2 Gearmotor from inside, six face screws from outside, coupler on the shaft.gearmotor (inside)6 x M3 x 66-8 mm coupler
    S2.2 Gearmotor from inside, six face screws from outside, coupler on the shaft.

  3. S2.3 Bearing block, KFL08 and axle 25 min

    1. Bridge the printed block over the coupler: 4 x M4 x 20 from inside the wall out through its feet, nuts on the feet. Heads inside keep the tails clear of the rear nose.
    2. KFL08 on the block's outer plate: 2 x M4 x 20, nuts inside the bridge.
    3. Slide the 88 mm axle through the KFL08 into the coupler. Tighten the coupler on the axle, then the KFL08 set screws, through the block's open top and bottom.

    Check: Axle turns with the motor, no end play.

    S2.3 Bearing block over the coupler, KFL08 on the block, axle into the coupler.bearing blockKFL08 flange bearing88 mm axleset screws
    S2.3 Bearing block over the coupler, KFL08 on the block, axle into the coupler.

  4. S2.4 Wall blocks 20 min

    1. Two floor blocks inside the bottom edge and two ledge blocks outside the top edge, each on its horizontal M4 x 25 only.
    2. Floor blocks have the vertical hole at the bottom and ledge blocks at the top. S7 fits the vertical bolts.

    Check: Blocks flush with the wall edges.

    S2.4 Floor and ledge blocks hung on their horizontal bolts.floor blocks (inside)ledge blocks (outside)H bolts only
    S2.4 Floor and ledge blocks hung on their horizontal bolts.

S2 check before hand-off

  • Both walls: motor, coupler, block, KFL08, axle and four blocks.
  • Motor and sensor leads tied clear of the axle.
  • Both wheels drilled and hubbed.

Hands off: Left and right wall modules and both driven wheels to S7.

S3

Steering

1 person · about 80 min per car · builds two forks with their front wheels, two servo towers with centered servos and couplers, and the kingpin kits

Builds each steering corner as three bench pieces: a fork with its wheel and kingpin, a servo tower with a centred servo, and a bag of bearing hardware for the final line.

Kit for one car
made2 fork tops (FT), 4 fork legs (FG), 2 servo towers (ST), 4 corner blocks
boughtRUTU wheel pair, 2 M8 x 75 bolts and nylocs, 4 spacers 10 mm, 4 M8 washers, 2 Sonic Hubs, 2 REX kingpins 64 mm, 2 couplers 4001, 2 MG996R servos; 4 KFL08 for the kits
fasteners8 M4 x 25; 8 M4 x 12; 8 M4 x 20 for the ears; 12 M4 x 20 bagged for S7; 28 M4 nylocs and washers

Tools: 2.5 mm hex key, 7 mm nut driver, two 13 mm wrenches, servo tester.

  1. S3.1 Forks 30 min

    1. Fork top face down on the bench. Stand both legs on it and fit a corner block on the outer face of each leg, away from the wheel.
    2. Each block: one M4 x 25 through the plate, one through the leg, washers and nylocs on the block.
    3. Sonic Hub on the top with 4 x M4 x 12 up through the plate into its threads. Push the 64 mm kingpin into the hub and tighten the hub's clamp.

    Check: Legs square to the plate and parallel to each other.

    S3.1 Fork: two legs, two corner blocks, the Sonic Hub and the kingpin.two identical legsblock outside each legSonic Hub64 mm kingpin
    S3.1 Fork: two legs, two corner blocks, the Sonic Hub and the kingpin.

  2. S3.2 Front wheels 20 min

    1. Measure the RUTU hub across its bearing faces first (fit check 11): at 35 mm use a washer each side, at 38 mm none.
    2. Spacer and washer each side of the wheel between the legs; M8 x 75 through both legs, nyloc inside.
    3. Tighten with two 13 mm wrenches until the legs just clamp the spacers.

    Check: Wheel spins freely with no side play.

    S3.2 Front wheel between the legs on spacers and washers, M8 axle and nyloc.RUTU 6 in front wheelspacer + washer each sideM8 x 75 + nyloc
    S3.2 Front wheel between the legs on spacers and washers, M8 axle and nyloc.

  3. S3.3 Servo towers 30 min

    1. Centre each servo on the tester (1500 µs) before it goes in.
    2. Drop it into the tower upside down, spline toward the deck, ears on the tower top: 4 x M4 x 20, nuts under the top.
    3. Push the 4001 coupler onto the spline (fit check 5) and leave its kingpin clamp loose. S7 tightens it with the wheel straight.
    4. Bag each corner for S7: 2 KFL08, 2 M4 x 20 for the bearings, 4 M4 x 20 for the tower feet, 6 nylocs and washers.

    Check: Servo still centred after fitting; recheck on the tester.

    S3.3 Centred servo into its tower, ears bolted, coupler on the spline.centred at 1500 µsMG996R, spline down4001 coupler
    S3.3 Centred servo into its tower, ears bolted, coupler on the spline.

S3 check before hand-off

  • Two forks with wheels and kingpins.
  • Two towers with centred servos and loose couplers.
  • Two bearing kits, marked L and R.

Hands off: Forks, towers and kits to S7, marked left and right.

S4

Electronics deck

1 person · about 240 min per car · builds every board and power part on the deck, the mast clamp and the end panels, wired and powered up on the bench

Builds the whole electronics layer on the deck plate at the bench, where every board is easy to reach. It is wired and powered up before it goes near the car. The R4 wiring plan is unchanged.

Kit for one car
madeDeck (DK), 4 corner blocks; end panels arrive from S5
boughtEvery board and power part on the deck, the LD19's USB adapter, one SHF40, 2 grommets 7/8 in, fuses, wire, connectors, USB cables
fastenersBoard spacers with M3 x 25; M2.5 standoffs; 3 M4 x 20; 8 M4 x 25; 4 M5 x 25; nylocs and washers

Tools: Hex keys, nut drivers, crimpers, heat gun, multimeter, current-limited bench supply.

  1. S4.1 Power parts 60 min

    1. Deck top up on bench blocks, so the nuts underneath are reachable.
    2. Fuse block (2 x M4 x 20) and drive relay (1 x M4 x 20) first. Then, on spacers: motor driver, the four bucks, the stop-latch relay module and the current monitor.
    3. Lay each delivered part on its holes before fitting (fit check 3). The fuse block and relay are the first to check.
    4. Grommets in the two 22.2 mm cable holes.

    Check: Every nut under the deck seats flat.

    S4.1 Power parts onto the deck, one by one.fuse blockdrive relaymotor driver6 V servo buck5 V compute buck5 V sensor buck5 V mast buckstop-latch relaycurrent monitor
    S4.1 Power parts onto the deck, one by one.

  2. S4.2 Compute, I/O and mast clamp 60 min

    1. Orange Pi in its heatsink case, USB hub, Pico, servo board, USB-I2C bridge, Qwiic hub and the I2C boards (ToF mux, two ADCs, I/O expander, IMU), then the level shifter and the LD19's USB adapter.
    2. The second SHF40 over the 44 mm mast hole: 4 x M5 x 25, nuts under the deck. Leave its clamp screw open.

    Check: IMU flat and square to the deck edges.

    S4.2 Computer, controllers and I2C boards, then the mast clamp.Orange Pi Zero 3USB hubPicoI2C boardsQwiic hubservo boardlevel shifterLD19 USB adaptermast deck clamp
    S4.2 Computer, controllers and I2C boards, then the mast clamp.

  3. S4.3 End panels 30 min

    1. When S5 hands them over: two corner blocks at each end, vertical bolts first, nuts under the deck.
    2. Stand each panel against its blocks: 2 x M4 x 25 through the panel into the blocks, nuts behind.
    3. Front panel: intake fan. Rear panel: exhaust fan, battery disconnect and charge port.

    Check: Panels square to the deck.

    S4.3 Rear end panel onto its two corner blocks.2 corner blocksrear end panelpanel bolts
    S4.3 Rear end panel onto its two corner blocks.

  4. S4.4 Wire and power up 90 min

    1. Wire to the R4 wiring plan. The leads that drop into the bay stay long and tagged: battery to the disconnect, both motors, the eight sensor stations.
    2. Close the E-stop loop with a jumper plug for the bench test.
    3. Bench supply at 12.8 V with a 2-3 A limit on the battery input; switch on at the disconnect.
    4. Check each rail: 6 V for the servos, 5 V for compute, sensors and mast. Boot: the computer starts, the Pico and the USB-I2C bridge show up, and an I2C scan finds every board.
    5. The drive relay pulls in with the jumper fitted and drops out when it is pulled.

    Check: Bench log filled in: rails, I2C scan, relay.

    S4.4 Bench power-up: supply, disconnect, fuses, each rail checked, relay test, I2C scan.bench supply12.8 V, 2-3 A limitdisconnectrear end panelfuse block20 A per circuit6 V servo buckservo board6.0 V ✓5 V compute buckcomputer + USB hub5.0 V ✓5 V sensor buckSharp, ToF, I2C boards5.0 V ✓5 V mast buckmast5.0 V ✓drive relaycoil through E-stopmotor driverno motors on the benchE-stop loopjumper plug at S4relay pulls in; drops out when the jumper is pulledboot · I2C scan finds every board ✓
    S4.4 Bench power-up: supply, disconnect, fuses, each rail checked, relay test, I2C scan.

S4 check before hand-off

  • All rails in range.
  • Every board found on the bus.
  • Relay follows the E-stop loop.
  • Bay leads tagged and long enough.

Hands off: Deck module to S7, with its bench log.

S5

Body

1 person · about 95 min per car · builds the two cover lids (LiDAR, E-stop and reset fitted) and the two end panels (fans, disconnect and charge port)

Builds the two aluminum lids and the two end panels. The end panels go to S4 first; the lids go to the final line.

Kit for one car
madeFront and rear end panels, 2 cover tops, 4 side panels, 16 corner blocks
boughtLD19, E-stop, reset button, 2 fans 40 mm and filters, battery disconnect, XT60E-M, 2 grommets 5/8 in, seal tape
fasteners24 M4 x 25 and nylocs; 8 M3 x 25; 2 M3 x 18; 2 M5 x 25; 4 M2.5 standoffs and screws

Tools: 2.5 mm hex key, 7 and 8 mm nut drivers, small nut drivers, a clean mat for the lids.

  1. S5.1 End panels 30 min

    1. Front panel: intake fan inside, filter outside, 4 x M3 x 25.
    2. Rear panel: exhaust fan and filter the same way; battery disconnect through the 32 mm hole on 2 x M5 x 25; XT60 charge port on 2 x M3 x 18.
    3. Air runs front to back: check each fan's arrow before it is bolted.

    Check: Fans spin freely; the disconnect turns both ways.

    S5.1 Rear end panel: fan and filter, battery disconnect and charge port.outside facefan + filterbattery disconnectXT60 charge port
    S5.1 Rear end panel: fan and filter, battery disconnect and charge port.

  2. S5.2 Front lid 40 min

    1. Top face down on the mat. Stand the side panels on it and join each top edge with two corner blocks inside: one bolt through the top, one through the side.
    2. Two foot blocks outside the bottom edge of each side panel, on their horizontal bolts only. S7 bolts them to the deck.
    3. LD19 on four M2.5 standoffs on the top; grommet in its lead hole.
    4. Seal tape along the bottom edges.

    Check: LD19 turns freely; the lid sits flat on a table.

    S5.2 Front lid: side panels, top-edge blocks, foot blocks and the LD19.top-edge blocksfoot blocksLD19 on standoffs
    S5.2 Front lid: side panels, top-edge blocks, foot blocks and the LD19.

  3. S5.3 Rear lid 25 min

    1. Built the same way. E-stop and reset button in the two 22 mm holes, heads above and contact blocks below; grommet in the camera lead hole.
    2. Give the E-stop a firm palm strike: the lid must not flex.

    Check: E-stop latches and releases; reset clicks.

    S5.3 Rear lid: E-stop, reset button and the camera lead grommet.E-stopreset buttoncamera grommet
    S5.3 Rear lid: E-stop, reset button and the camera lead grommet.

S5 check before hand-off

  • End panels to S4 first.
  • Both lids square with seal tape fitted.
  • LD19, E-stop and reset leads tagged.

Hands off: End panels to S4, about 30 minutes in; lids to S7.

S6

Mast

1 person · about 45 min per car · builds the owned mast with its limit switches, ball head and camera

Prepares the owned mast as one drop-in module, so it goes in last and nothing waits for it.

Kit for one car
ownedThe mast
bought2 limit switches, 2 hose clamps, ball head, camera (C920e until the production camera is chosen)

Tools: Nut driver for the hose clamps.

  1. S6.1 Switches, ball head and camera 45 min

    1. Measure the tube against the SHF40 bore (fit check 2).
    2. Clamp the two limit switches with the hose clamps where the mast's travel ends; the model has them 885 and 905 mm above the tube foot.
    3. Ball head on top and the camera on it, level.
    4. Run the mast to both ends: each switch must click before the mast stops.

    Check: Both switches actuate; camera lead dressed down the tube with releasable ties.

    S6.1 Mast: limit switches on hose clamps, then the ball head and camera.mast shown shortenedlimit switchesball head + camera
    S6.1 Mast: limit switches on hose clamps, then the ball head and camera.

S6 check before hand-off

  • Switches set at both ends of travel.
  • Camera level and its lead dressed.

Hands off: Mast to S7.

S7

Final line

2 people · about 120 min per car · builds the battery bay, batteries, deck, steering corners, wheels, mast and covers, then the power-up and drive tests

Two people put the modules together from the outside, top-down, then test the car.

Kit for one car
modulesWalls and wheels (S2), noses (S1), forks, towers and kits (S3), deck (S4), lids (S5), mast (S6)
madeFloor (FL)
boughtSHF40 floor flange, battery pad, 2 batteries, 2 straps, terminal boots
fasteners4 M5 x 25; 16 M4 x 25; 12 M4 x 20 for the noses; nylocs and washers

Tools: Hex keys, 7 and 8 mm nut drivers, laptop for the tests, charger.

  1. S7.1 Battery bay 20 min

    1. Floor flange on the floor: 4 x M5 x 25, nuts on top.
    2. Stand both wall modules on the floor edges: one M4 x 25 up through the floor into each floor block, nut on top of the block.
    3. Lower each nose in from above, tabs inside the walls: the rear one cannot slide in past the rear-block bolt heads. 4 tab bolts through the walls and 2 bolts up through the floor each, nuts inside.

    Check: Bay square: diagonals equal.

    S7.1 Battery bay: floor flange, wall modules and noses.floor flangefloor-block boltsnose bolts
    S7.1 Battery bay: floor flange, wall modules and noses.

  2. S7.2 Batteries 10 min

    1. Rubber pad between the walls; both batteries upright, terminals up, positive toward the front.
    2. Two straps through the floor slots and over the batteries. Terminal boots on; nothing connected yet.

    Check: Batteries do not shift when the car is tipped by hand.

    S7.2 Pad, batteries and straps.rubber pad+ terminals forwardstraps
    S7.2 Pad, batteries and straps.

  3. S7.3 Deck on 15 min

    1. One person holds the deck above the bay while the other connects the battery leads to the disconnect, the motor leads and the eight sensor leads through the grommets, by their tags.
    2. Lower the deck onto the walls and noses: 4 x M4 x 25 down through the ledge blocks, nuts under the overhang.

    Check: No lead pinched at the deck edge.

    S7.3 Deck module lowered onto the bay and bolted to the ledge blocks.leads through firstledge-block bolts
    S7.3 Deck module lowered onto the bay and bolted to the ledge blocks.

  4. S7.4 Steering corners 15 min

    1. KFL08 under the wing and KFL08 on top, sharing the kit's 2 x M4 x 20.
    2. Push the fork's kingpin up through both bearings and tighten the KFL08 set screws.
    3. Tower over the kingpin with the coupler on it: 4 x M4 x 20 through the feet and the wing.
    4. Point the wheel straight ahead, then tighten the coupler's kingpin clamp.

    Check: Wheel turns lock to lock without binding.

    S7.4 Steering corner: bearings on the wing, fork from below, tower from above.KFL08 pairfork from belowservo towerclamp the coupler
    S7.4 Steering corner: bearings on the wing, fork from below, tower from above.

  5. S7.5 Rear wheels 5 min

    1. Slide each wheel's Hyper Hub onto its axle and tighten the hub's clamp screw.

    Check: Wheels clear the walls and bearing blocks.

    S7.5 Rear wheel onto its axle.wheel onto the axle
    S7.5 Rear wheel onto its axle.

  6. S7.6 Mast 10 min

    1. Drop the mast through the deck clamp into the floor flange and tighten the deck clamp.
    2. Plug in the mast's leads.

    Check: Mast vertical; clamp tight.

    S7.6 Mast down through the deck clamp into the floor flange.mast drops indeck clamp
    S7.6 Mast down through the deck clamp into the floor flange.

  7. S7.7 Lids 15 min

    1. Plug in the LD19, E-stop, reset and camera leads before each lid seats.
    2. Lower each lid over its half of the deck: 4 foot bolts down through the foot blocks and the deck, nuts under the overhang.

    Check: Seal tape unbroken; no lead pinched.

    S7.7 Both lids on, eight foot bolts.foot boltsplug leads first
    S7.7 Both lids on, eight foot bolts.

  8. S7.8 Power-up and drive tests 30 min

    1. Disconnect on. The computer boots and every rail is in range.
    2. Press the E-stop: the drive relay drops and the wheels stop. Reset restores drive.
    3. Steer lock to lock; the wheels sit straight at centre.
    4. Drive the taped course both ways; both encoders count.
    5. The LiDAR spins; each ToF and Sharp sees a hand at 20 cm. The mast runs to both switches and the camera gives an image.
    6. The charger connects at the rear port. Write the car number on the deck.

    Check: Every test passed and signed on the traveller.

    S7.8 Final tests: drive the course, E-stop, then the checklist.E-STOP1. power on: computer boots, all rails good2. E-stop drops drive; reset restores it3. steering: lock to lock, straight at centre4. drive the course both ways; both encoders count5. LiDAR spins; 8 ToF and 8 Sharp read a hand6. mast to both limit switches; camera image7. charger connects at the rear port8. foot bolts checked; car number on the deck
    S7.8 Final tests: drive the course, E-stop, then the checklist.

S7 check before hand-off

  • All eight tests passed.
  • Foot bolts and mast clamp checked.
  • Car number recorded with its S4 bench log.

Hands off: Finished car.

Open items before the first car

ToF screws
The BOM lists M2 x 10 for the ToF boards, which is too short. The stack is pane 3.2 + wall 3.2 (nose 4) + spacer nut 1.6 + board 1.6 mm, plus 1.6 mm for the nut. That calls for M2 x 12 in the walls and M2 x 16 in the noses. Check the M2 kit's lengths before the first car.
Mast flanges
Measure the mast tube. The SHF40 pair and the 44 mm deck hole assume a 40 mm tube (fit check 2).
Front wheels
Measure a RUTU hub across its bearing faces before S3 sets the washers (fit check 11).
Board holes
Lay the delivered fuse block, relay and boards on the deck file before cutting (fit check 3).
Driven-wheel hub
Confirm the drilled hub face on the first wheel and the M4 x 12 length (fit check 1).
Qwiic hub
It has no Amazon source: buy SparkFun's direct, or chain the boards.
Radio in a metal box
With both aluminum lids on, check the app's Bluetooth link and the WiFi range against the bench (fit check 10). If they drop, the Orange Pi's antenna has to come outside the box.

What changed in the design for the line

The mast drops in last
A second SHF40 clamps the mast on the deck and the floor flange only locates it. The mast is its own module (S6) and goes in after the deck, so no station waits for it. Batteries come out without touching the mast top.
Fewer corner blocks
Two blocks per side join the floor to the walls and the walls to the deck, down from three, because the noses tie both ends. That is 4 blocks and 8 bolts fewer, 32 blocks in all.
Every nut seats
Twelve deck holes in eight parts had nuts landing on a wall top or inside a nose wall. Those parts moved a few millimetres, so S4 never finds a bolt that cannot be fitted.
Kits by station
One joint and two M4 lengths (x 25 through a block, x 20 elsewhere) let S0 bag fasteners per station by count.
Modules close on open faces
Walls get their sensors, motors and blocks while they are loose plates. Lids are built upside down on the bench, and the deck is wired before it meets the car.
Aluminum lids and end panels
They were 1/8 in acrylic. Now they are 0.125 in 5052 from a second sheet, with the same files, holes and corner blocks. Aluminum does not crack at a bolt or under an E-stop strike. Acrylic is left only in the eight windows.

Considered and not done

One M4 length everywhere
With M4 x 25 at every joint, the rear foot bolts' tails hit the rear nose and two sensor windows.
Printed forks
The forks carry the front wheel loads. Aluminum plates from the same sheet cost nothing extra and add no printer hours.
One-piece lid
The mast passes between the two lids. A single lid would have to come off over the mast, so the mast would come out first.
No sensor windows
The panes keep dust and fingers off the sensors, and the same four bolts hold pane and sensors, so they add no parts to fit.