Mote Mounting Kit

Each Bud Industries PN-1324-MB enclosure (6.73" × 4.76" × 2.17") sits on top of a rebar stake, tilted 40° so the solar panel on its lid faces the sun. Three parts per install:

1. Rebar stake — #4 (1/2"), 5 ft (a 10 ft stick cut in half: $4.14/stake at Home Depot's 50+ price) or 4 ft pre-cut (~$6, no cutting). Hammered into the ground with any 3–4 lb hammer. No post driver.
2. 3D printed cap — black PETG X-shaped platform, tilted 40° along the box's length so the lid faces the sun and sheds rain and dust, with a blind socket that drops over the top of the rebar. One hose clamp around the socket's slotted collar locks it.
3. Zip ties — attach the enclosure through its 4 mounting bracket holes at the arm tips. Nothing else: no bolts, no nut pockets (Michael, Oct 29, 2026).

Print this page and check off before heading to the field.

• Coupon plate printed and rod_bore settled against the batch's rebar (15.5 as shipped)
• Printed 110 caps in black PETG (mote-bracket.3mf → Bambu Studio), a hose clamp snugged in each collar groove
• Test-fit one cap on a #4 rebar — drops on, clamp locks it, no turn by hand, no rock
• Test-fit one cap on a PN-1324-MB — 4 holes align
• 110 rebar stakes loaded (#4: 5 ft cut from 10 ft sticks, or 4 ft pre-cut)
• 500+ black UV zip ties packed (4 per install + spares)
• Spare hose clamps packed
• 3–4 lb hammer (or T-post driver) packed
• 1/2" rebar drive cap packed
• Torpedo level packed
• Wire cutters packed
• 5/16" nut driver or flat screwdriver packed (7 mm for the DIN clamp)
• Dataloggers loaded

Checked before publication by three adversarial reference-check agents (prices and sourcing; rebar geometry, mechanics and print; internal consistency), a geometry audit of the .scad/.stl, and a real Bambu Studio slice. Sources are archived in field-tools/mote-mounting-sources/ (claim→file map in its README). Where this section conflicts with the sections above, this section wins.

Confirmed

• Hole spacing 186 × 96 mm is measured from a real PN-1324-MB (commit 60c8b10). The STL's bounding box matches the .scad (v9.0: 208 × 118 × 66 mm; v9.1: 204 × 113 × 75 mm; v10: 161 × 114 × 137 mm as modelled, 204 × 114 × 65 mm on the bed); the only unsupported surfaces in the print orientation were the 4.5 mm screw-hole bridge, the gable roof of the nut pocket and, from v10, the 0.8 mm-high floors of the engraved SUN marker (v11: the clamp groove's square platform-side shoulder, a uniform 50° on the leaning socket, replaces the first two; the slot-end arches face up).
• #4 rebar is 13.7–14.3 mm over the ribs (ASTM A615 minimum deformation height; NCDOT design figure), so v10's 17 mm bore left 2.7 mm of slack and 2.5–3.5° of maximum tilt; v11's 15.5 mm bore leaves 1.2–1.8 mm and 1.2–1.7° before the clamp closes the collar (calc.js section 8).
• (v9 draft, superseded) 3.5 mm is the right M4 pilot in PETG (Covestro: 0.86–0.92 × D). Pull-out is hundreds of times the load; the printed thread strips at ~1.4 N·m, which is why the wrench rule is two fingers.
• (v10) The set screw was structural: at a 56 mph gust the box + cap lift (11 N flat; 11–15 N vertical plus 9–12 N horizontal with the v10 40° lid, see below) more than they weigh (10 N). Between two rebar ribs (≤9 mm apart) the bolt tip was a mechanical stop even after the plastic relaxes; in v11 the clamped fingers keyed into the same ribs take that role.
• Arm stress is 1.3–3.8 MPa with the v10 18 mm ribs (0.7–2 with v9.1's 25 mm) against ~50 MPa for PETG, so creep is not a concern; that is what let the ribs drop from 60 mm to 25 mm and then 18 mm deep. PETG holds shape to ~80°C.
• 1/2" over 3/8" rebar: 3.2× the stiffness, confirmed by surveyors' bent-bar experience; 3/8" saves only ~$1 a stake.
• All prices are live pages fetched Sept 7, 2026. Home Depot prices are store-specific (the fetch resolved to Virginia stores); confirm the Davis store in the app before ordering.

Corrected against the first v9 draft

1. Filament and time: the draft carried ~35 g / ~1 hr scaled from v8's unsliced guess; a real slice is 72.5 g / 3 h 25 m (v8 was never sliced either). Print is now a quarter of the kit cost, and the spool count went from 4 to 10.
2. Pan-head M4 bolts can't be turned by the 7 mm wrench, the only driver in the kit: now hex head (DIN 933).
3. Stake: the 4 ft single (listed $5.27, $6.33 at the rendered store) is no longer the plan; a 10 ft stick cut in half at the 50+ price is $4.14 per 5 ft stake and a foot taller.
4. Hardware: "600 + 500 for $18" priced only bolts, at a carton price; set screws are ~$20 per 200 hex bolts, and bolting the boxes is a separate ~$66 upgrade.
5. Fiberglass rod posts are $2–3, not $6–11; they lose on stiffness (a 1/2" rod is floppier than 3/8" steel) and on having no ribs for the set screw, not on price.
6. "UV resistant for years" was vendor copy: natural PETG lost 36% of its tensile strength in a lab UV test. The guide now specifies black PETG (pigment is the UV screen) and names ASA as the tough-at-year-5 upgrade.
7. Mushrooming is the default when a bare sledge hits mild steel, not a bad swing: a 1/2" drive cap and a torpedo level joined the kit; filing the burr is field recovery, not the plan.
8. The fence post's "~$8 when designed" was the March guide's own budget line, not a price; the cheapest post found today lands at ~$18.50.

v9.1, same day

Three of the review's improvement ideas were built in before anything was printed: the platform is tilted 10° (ear = high side = north) because flat panels soiled 3.5× faster than tilted ones across 186 California PV sites (Mejia & Kleissl 2013); the set screw threads into a captured M4 nut instead of PETG (the review measured strip torque below a casual wrench pull, and PETG loses 11–21% of preload in a week); arms went to 18 × 5 mm from 22 × 6 (still >10× margin on stress). Re-sliced: 63.7 g, 3 h 15 m. Geometry re-audited on the mesh: tilt direction, hub clipped flush both sides, rib–hub fusion, pocket clearances, print overhangs.

v10, Sept 10

The tilt became a solar tilt: 40° about the box's short axis, so the platform slopes along the box length and the low edge is a narrow end (v9.1: 10° about the long axis, chosen for drainage). Fleet latitudes from the motes table: 33–46°N with 456 of ~600 units at 37–40°N, plus 26–35°S in Australia. Angle. The lid panel charges a battery that is full for most of the year, so the objective is the worst month, not the year. A PVGIS v5.2 sweep of Fresno, Davis, Red Bluff, Yakima and Mildura at 25–48° (pvgis-sweep.mjs, results archived in pvgis-sweep.json): against 30°, 40° is −0.7 to +0.7% annual and +8.1 to +11.5% in the worst month at every site; 48° is −3.1 to −0.3% annual and +12.4 to +18.3% worst month. 40° takes most of the winter gain at no annual cost and keeps the socket 5° inside the 45° no-support print limit; 48° (the "latitude + 10°" table in the Campbell Scientific SP65 manual, footnoted there to a Solarex design aid) would put it at or past that limit and add 10–15% more height. The annual optimum itself is 32–38°N / 27–32°S on PVGIS; Jacobson & Jadhav 2018 (Solar Energy 169:55–66; their northern and southern fits give 28–34°N and 25–30°S) runs 2–4° low, as the paper itself says its fits are rough. A first draft of this section argued that a steep panel loses diffuse light in fog season; the reference check refuted that with PVGIS's own Central Valley December data (~40% diffuse, steep panel still ahead) and it is withdrawn. Geometry. Three consequences the 10° design hid, all caught on the mesh before anything was printed: a flat seat under a 40° lid would break through the lid by 0.6 mm at the low edge of the bore, so the seat is lowered 7.1 mm, enough that the lid keeps its full 5 mm measured through the tilted wall (6.6 mm vertical on the mesh; a vertical 5 mm would have been only 3.8 mm through the wall); a rib's root edge leans outward by the tilt as it goes down, so ribs rooted at r = 7.5 mm would leave the hub wall 12 mm down, and even a 25 mm rib rooted on the axis would put its corner 17 mm from the axis, 3 mm outside the wall — the ribs now start on the socket axis and are 18 mm deep (37% of the old stiffness, still ~40× the plate; arm stress 1.3–3.8 MPa against ~50 for PETG), with an assert in the .scad; and ribs and bosses overlap 1 mm into the platform, because with the pivot no longer an integer CGAL left the four rib-top strips (779 mm²) as a second, unfused surface on the first export. The nut pocket's hex is phased by the tilt so its vertex still points up in the print orientation (face normals 30° and 90° from the print vertical on the mesh, not 0°). The final export is one solid, every edge shared by exactly two triangles; the low arm tips now just touch the plane of the socket mouth (0.3 mm below it). Re-sliced: 62.2 g, 3 h 11 min (v9.1: 63.7 g, 3 h 15 min). As modelled the cap is 161 × 114 × 137 mm; on the bed 204 × 114 × 65 mm. Wind. The 40° lid turns the 56 mph load into 11–15 N vertical plus 9–12 N horizontal (ASCE 7-16 Fig. 27.3-4 monoslope free-roof coefficients, whole-lid average 1.5–2.0 at 30° used as an envelope at 40°; h/L ≈ 6 is outside the figure's range, so this is a conservative extrapolation, and the gust factor is omitted — calc.js section 7). That horizontal component, on top of the broadside drag, takes the #4 stake's bending stress from 21 to ~70 MPa at 56 mph and to ~210 MPa at 96 mph against a 420 MPa Grade 60 yield, so the stake margin at the extreme gust is now about 2× where it was 7×; the bolt tip between two rebar ribs is still the stop, and Lee's field unit is still the wind verdict. Install. The rule changed: the low end faces south (north south of the equator); the ear no longer marks anything, so "SUN" and a chevron are engraved into the top of both low arms — a 40° panel facing away from the sun gets no direct beam at noon from early November to early February at 38°N, worse than flat, and silently. Two v9.1 items the review corrected: the set screw is now the M4×16 the box bolts already use (the head seats on the ear 17.5 mm from the socket axis, so a 12 mm tip stops at 5.5 mm — at or short of the bar's rib crest once the bar has been pushed to the far wall, with no bite below the crest and no travel left after creep; 16 reaches the core between ribs and stands 3–4 mm proud), and the bench list gains the three PG7 glands and the antenna port on the box base, which nobody has checked against the centre disc and arms.

v11, Oct 29

Lee's bench fit (issue 128, Oct 29). The box sits well, the four holes line up, zip ties hold, the cap drops onto the bar — and spins freely on it. His print predates v10 (no nut pocket, nothing to thread into), but the finding stands against v10 too: a 17 mm bore over a ~14 mm bar is 3 mm of slack, and a single M4 tip on a round bar is two line contacts with plastic creeping under them, fiddly to fit (a nut fished into a pocket inside the bore) and weak in yaw. The options he and Michael weighed: a heat-set insert (slow to assemble), a hose clamp (useless around a rigid socket — it needs a part designed to flex), a smaller bore (the drive cap keeps the bar top round). v11 does the last two at once and drops the insert. The bore is 15.5 mm (0.6–0.9 mm of radial play over A615 #4 rebar, 1.2–1.7° of tilt play before clamping, calc.js section 8); the lower 44 mm of the socket is split into four fingers by 2.4 mm slots with round ends (2 mm would leave 0.3 mm of slot on a 16.1 mm bore with the thinnest bar; the .scad asserts the slots stay open); a 1.2 mm deep groove near the mouth with a 13.5 mm flat floor, a 45° lead-in on the mouth side and a square platform-side shoulder seats a worm-drive hose clamp (SAE 12, 1/2–1-1/4", or DIN 3017 20–32 mm with its 7 mm hex head; groove OD 24.6 mm, mouth lip 27 mm). Two of the bug audit's catches live in that sentence: a size 10 clamp tops out at 26.99 mm and cannot pass the 27 mm lip, and the first cut's two 45° flanks inside a 13.5 mm opening left an 11.1 mm floor under a 12.7 mm band, so the band would have ridden the flank edges; the platform-side flank, the one that faces the bed in the print, read 5° on one side of the 40° lean and 85° on the other as a chamfer, and is square now. The hub OD stays 27 mm so the rib-root corner keeps its margin (hub_wall is derived now, 5.75 mm). Closing a finger 0.9 mm at the clamp is a ~1.4% root strain (~29 MPa) imposed by the clamp, so the plastic relaxes rather than fails, and the steel band keeps the preload; once the fingers have conformed to the rebar's deformations, yaw is a form lock, not friction, and a relaxed or cold band does not undo it. The wind's yaw torque on the lid is ~0.6 N·m at 56 mph and ~1.7 N·m at 96 mph (section 7's tilted-lid envelope, CN 2.0; the bug audit halved an earlier flat-plate figure) against ~2.1 N·m of friction at a light 200 N band tension and ~10 N·m at 800 N, after the ~270 N the band spends closing the four fingers on the thinnest bar (calc.js section 8). The set-screw ear, the nut pocket and the M4 set screw are gone, and so are the hex-nut bosses under the four tips (Michael, Oct 29: the boxes are zip-tied, nothing else) — each tip is a plain 5 mm hole, and without the bosses the low tips clear the socket's mouth plane. Mesh. Two CGAL traps caught on the first v11 export, each leaving 32 edges shared by four triangles: a slot built as a cube touching a tangent cylinder, and a groove revolved separately from the $fn = 80 hub (coincident facet seams, last-bit-different vertices) — each slot is now one hull, and the hub is one revolved profile with the groove in it. The export is one solid, every edge shared by exactly two triangles; the audit's collar checks (every slot open from the mouth to z = 45.2 on its centreline, the 2.4 mm width, the groove as the wall's one gap at z 8.25–21.95 at r = 12.5 with a 13.6 mm floor under the 12.7 mm band, the wall under the groove floor one run from the mouth through the rib root, nothing where the ear stood) replace the hex-pocket and ear checks. A third catch of the bug audit is older than v11: the audit's print-frame transform was a bare z-flip — a reflection — so the print-oriented STL and the sliced .3mf of v10 and of the first v11 export were mirror images, and every cap would have printed "SUN" backwards (the chevron is symmetric, so the cue survived); it is a 180° turn about X now and the .3mf is re-sliced from it. Seat lift 6.5 mm (6.6 mm vertical cover on the mesh, 5 mm through the tilted wall); area steeper than 45° in the print orientation 245 mm² (the SUN-marker floors and the groove's platform-side shoulder; the slot-end arches face up). As modelled 159.5 × 114 × 135.9 mm; on the bed 204 × 114 × 64.6 mm; the low tips sit 0.9 mm above the mouth plane now that the bosses are gone. Re-sliced: 55.8 g, 3 h 3 min (v10: 62.2 g, 3 h 11 min). Kit. One SAE 12 stainless clamp per cap at ~$1.56 (Bolt Depot #28246, a bulk 100 + two bags of 10, ten spares) replaces a $0.10 bolt and a $0.03 nut, and the 200 bolts + 500 nuts bought for set screws drop out: ~$746 for 110 (~$6.80/install) against v10's ~$605. A coupon plate (three collar-only pieces at 15.5 / 15.8 / 16.1 mm, part = "coupon" in the .scad; 52 g and 2 h 26 min for the three, ~50 min for one) settles the bore against the batch's rebar before the first 3-hour cap. Tools: the 7 mm wrench gives way to a 5/16" nut driver or a flat screwdriver (or stays, with the DIN clamp).

Open: Lee's v11 reprint and bench fit (drop-on, clamp lock — no turn by hand, no rock — tip pocket, gland clearance) and the wind/winter field unit, tracked in issue 128 — print the v11 .3mf, and paint-pen a witness mark across the cap-to-bar joint on the field unit so yaw or settling after the first storm is a photo, not a feeling. Rebar Grade 40 vs 60 is irrelevant here; either drives the same.