# Mr. Palm Tree — Print & Materials Guide (v0.2)

## The material problem, stated honestly

These parts live outdoors in a NYC heat wave: **95–100°F+ air, direct sun
(dark plastic surfaces reach 60–70°C / 140–158°F), constant water mist, and
all-summer UV** — while the mount parts carry real wind loads. That kills the
default hobbyist answer:

- **PLA is disqualified.** Glass transition ~55–60°C. A PLA tree softens and
  sags on the exact day it's needed most. (Sustained-load creep starts well
  below Tg.) Do not use PLA for ANY part of this, including "just the fronds."
- **Nylon is disqualified.** It's hygroscopic — it absorbs water, swells, and
  loses stiffness. Wrong polymer for a misting device.
- **PP is disqualified for large parts.** Water-inert but warps badly at this
  size and is too floppy for the mount.

## Filament decision matrix

| Filament | Heat (Tg / HDT) | UV | Water | Big-part printability | ~$/kg | Verdict |
|---|---|---|---|---|---|---|
| PLA | ~55–60°C — sags in sun | poor | ok | easiest | $13–18 | ❌ excluded |
| **PETG** | ~75–80°C — passes in light colors | fair–good (1 season; clearcoat for more) | **excellent** (bottle plastic, ~0.1% absorption) | easy, fast, no enclosure | **$15–22** | ✅ **all decorative parts; budget structural** |
| **ASA** | ~100–105°C — passes with margin | **excellent** (car-mirror plastic) | excellent | needs enclosed printer | $20–30 | ✅ **structural mount set (production spec)** |
| ABS | ~100°C | poor (chalks/embrittles) | good | enclosure + fumes | $15–20 | ⚠️ only if painting; ASA is ABS-done-right |
| PETG-CF / ASA-CF | same Tg, far stiffer, much less creep/warp | good/excellent | excellent | needs hardened nozzle | $30–40 | 💪 optional upgrade: legs, hub plate, sleeve |
| Nylon (PA) | high | good | **absorbs water** | hard | $30+ | ❌ excluded |

*(Tg/HDT values are typical vendor-datasheet ranges — verify against the
specific spool's datasheet before a production run.)*

## The recipe

**Two-tier build:**

1. **Pilot / this-week build (cheapest, fastest, any open-frame printer):**
   everything in **PETG, light colors only** (tan trunk, light green fronds —
   palm colors are conveniently low-solar-gain). Light colors run ~15–20°C
   cooler in sun than black; that's the difference between passing and
   sagging for PETG. One season of UV is fine; rattle-can UV clearcoat buys
   more.
2. **Production / season-after-season spec:** the **load path in ASA**
   (bonnet collar ×2, arch legs ×4, hub plate, riser sleeve, crown hub) —
   ideally legs/hub/sleeve in **ASA-CF** — and the **cosmetics in PETG**
   (trunk shells, fronds, ring clip, topper). ASA needs an enclosed printer
   (Bambu P1S/X1, Prusa Core One class).

**Free thermal bonus:** when the mister runs, evaporative cooling keeps every
part well below air temperature. The design case is the unit parked OFF in
full sun — which is exactly why the load path gets ASA.

## Settings (speed-optimized)

Global: **0.6 mm nozzle, 0.3 mm layers** — roughly halves print time vs
0.4/0.2 and makes *stronger* walls at this scale.

| Part | Qty/unit | Material | Walls | Infill | Notes |
|---|---|---|---|---|---|
| bonnet_collar | 2 | ASA | 5 | 35% gyroid | brim; bridges over bore are short |
| arch_leg | 4 | ASA(-CF) | 6 | 40% gyroid | print flat, no supports |
| hub_plate | 1 | ASA(-CF) | 5 | 35% gyroid | supports only under clevises |
| riser_sleeve | 1 | ASA | 5 | 35% gyroid | lugs get seams — orient seam away |
| crown_hub | 1 | ASA or PETG | 5 | 30% gyroid | supports in angled sockets |
| trunk_shell | 18 (9 segs ×2) | PETG tan | 2–3 | 8% gyroid | the volume driver — run these as farm plates |
| frond (skeletal) | 8 | PETG green | 4 | 15% | breeze variant — near-zero shade, near-zero sail |
| frond_shade_root | 8–16 | PETG green | 3 | 15% | webbed shade variant, ~85 g / ~1.2 h each |
| frond_shade_tip | 8–16 | PETG green | 3 | 15% | ~70 g each; laps 28 mm onto root, 2 zips |
| ring_clip | 1 | PETG | 4 | 20% | — |
| topper | 1 | PETG green | 3 | 10% | — |
| nozzle_clip | 8 spares | PETG | 4 | 20% | — |

**Budget cut:** 5 trunk segments on the lower half + tan-painted PVC above
saves ~1 kg PETG and ~8 printer-hours per unit (real palms have smooth upper
trunks — it reads fine).

**Shade crown note:** the default build is now the 16-frond double-ring shade
crown (`frond_rows=2`, `shade_fronds=true`) — adds ~2.5 kg PETG and ~20
printer-hours vs skeletal, **and requires the aluminum riser + 14 mm legs**
(see DESIGN.md §3b). The 2-row `crown_hub` is 36 mm taller; set `frond_rows=1`
for the budget/breeze build.

## Per-unit totals (ESTIMATES — verify on first article)

- Plastic: ~2.6 kg PETG + ~1.0 kg ASA ≈ **$60–85**
- Printer time @ 0.6 mm on a fast CoreXY: **~40–55 h/unit**
  (mount set ~12 h, shells ~2.5 h/pair, fronds ~1 h each)
- Farm math: 20 printers ≈ **8–10 complete units/day**

## Hardware interfaces

- All bolted joints: **M5 stainless + nyloc** (collar ears ×4, clevis pivots ×8).
- PVC screws: **#8 × 3/4" stainless self-tappers** (sleeve ×2, crown hub ×2).
- Collar bores: line with **3 mm EPDM foam tape** — absorbs casting variance
  between hydrant models and protects the paint.
- Tolerances: `clr = 0.3` is tuned for a calibrated 0.6 nozzle; test-fit the
  riser_sleeve↔hub_plate bayonet first and adjust `clr` before batch runs.