# Motorcycle spotlight pitch mount — build sheet (v13)

Two 3D-printed parts that mount an auxiliary spotlight to a motorcycle and let you
set its **pitch** (horizon → ~15° nose-down) via a serrated half-moon joint.

> **v13 fix:** the M5 clamp hole is bored through the centre of the trough — which
> is a tooth *peak* — so a tooth ridge used to foul the bolt. A flat relief well
> around the hole now gives the bolt a straight seat (side teeth still index pitch).

```
            SPOTLIGHT  (two 13mm recesses, tapped M4)
                 ▲  2× M4 (head recessed in Part A, threads up into the light)
        ┌────────┴────────┐
        │  PART A (light) │   thick toothed block + 2 bosses
        │   \/\/\/\/\/\/   │   ← teeth set the angle (loosen, slide, retighten)
        │   /\/\/\/\/\/\   │
        │  PART B (bike)  │   M5 clamp nut + 3 M5 bike nuts (all side-inserted)
        └───────┬─────────┘   M5 clamp bolt up the middle (button head flush in base)
             ▼  3× M5 (from the bike, into Part B's captive nuts)
            MOTORCYCLE BRACKET (flat)
```

## Specs
| | |
|---|---|
| Footprint | Part B base **38 × 38 mm** ; Part A **34 × 28 mm** |
| Heights | Part A **19 mm**, Part B **14 mm**, assembled ~**27 mm** |
| Pitch range | **0 → 15° down**, indexed every **3°** (0/3/6/9/12/15) |
| Joint | flat serrated half-moon, thick rigid slab, self-locking teeth |
| Adjust | loosen the M5 clamp → slide to a new tooth → retighten |

## Fasteners — only two sizes (M4 + M5)
| Qty/mount | Item | Job | Length |
|----|------|-----|--------|
| 2 | **M4 screw** | light: head recesses into Part A, threads into tapped light | **≈ M4×16** (8 mm in part + your light's thread depth) |
| 1 | **M5 button-head bolt** | pitch clamp, up from base | **≈ M5×18–20** |
| 1 | **M5 nut** | clamp — slides into Part A's +Y side | standard hex |
| 3 | **M5 screw** | bike (3-point mount) → captive nut | **bracket thickness + ~7 mm** |
| 3 | **M5 nut** | bike — slide into Part B's sides | standard hex |

**For both spotlights, double it:** 4× M4, 2× M5 button bolts, 6× M5 screws, 8× M5 nuts.

- **M5 clamp must be a button/low head** (ISO 7380) — the recess in Part B's base is
  shallow so it sits flush and the base bolts flat to the bike.
- **Stainless A2** (or A4 for salt/winter). Threadlocker on the M5 clamp bolt.

## Assembly
1. **Drop the 4 nuts in first:** the M5 clamp nut into Part A's **+Y side slot**; the
   three M5 bike nuts into Part B's **side (±Y) slots** (two from one side, one from the
   other). Each channel has a **retention nib** — push past it and the nut stays put, so
   it won't drop out when you handle the part upside-down for the pendant mount.
2. **Light → Part A:** push the 2× M4 up from underneath through the bosses into the
   tapped light; the heads recess into Part A, well above the teeth.
3. **Set the angle:** drop Part A's teeth into Part B's trough at the tooth that aims
   the light where you want (0–15° down).
4. **Lock it:** M5 button bolt up from the base, through the curved slot and into the
   side-inserted nut — **tighten now, in your hand.**
5. **Mount to the bike:** 3× M5 from the motorcycle side, up through Part B's flat base
   into the captive nuts. Drill 3 holes to match — a triangle, all at the **sides**:
   **2 holes on one side** (at ±10 mm fore-aft, 20 mm apart) + **1 on the other side**
   (centred). The two sides are **24 mm apart across**. They sit at the sides because the
   M5 clamp head sweeps along a **symmetric arc** down the centre (see below).

### Works upright *or* pendant (light hanging)
The clamp head recess is a **symmetric arc**, so it locks the light whether you rock it
up or down — meaning you can bolt the bracket **flat** in either orientation (light on
top, or hanging upside-down below the mount) and still aim it at the road. No need to
angle the bracket.

---

# Printing on a Bambu Lab P1S

The STLs are already oriented — import and slice as-is. For **both spotlights**, just
use **`spotlight_TWO_SETS_v13.stl`** (2× Part A + 2× Part B on one plate).

| File | Prints as |
|------|-----------|
| `spotlight_TWO_SETS_v13.stl` | both mounts — **print this for the pair** |
| `spotlight_BOTH_v13.stl` | one mount (A + B) |
| `spotlight_partA_v13.stl` / `spotlight_partB_v13.stl` | single parts |

## Filament (use the enclosure)
- **ASA — recommended.** UV + heat stable next to a light. Nozzle **250–260 °C**,
  bed **90–100 °C**, enclosure closed, fan low.
- **PETG** — easier alternative. Nozzle **250 °C**, bed **70–80 °C**.
- ❌ Not PLA (softens near the light, creeps under clamp load).

## Slicer (Bambu Studio, 0.4 mm nozzle)
- Layer **0.16 mm** (sharper teeth) or 0.20 mm
- Walls **4–5**, infill **40–50 %** gyroid
- **Brim 5 mm** — matters most for Part A standing on its bosses
- **Supports:** Part B prints support-free; **Part A needs light support** under its
  platform/slab overhang (it stands on two small bosses). Enable support — `tree(auto)`,
  threshold ~40°, **not** "build-plate only". The **teeth point up on both parts**, so no
  support lands on them. (v13 slimmed Part A to 28 mm wide to minimise this.)

## After printing
- **Test the tooth fit first** — Part A should drop into Part B and re-index by tooth.
  Too tight/loose → change `clear` (0.25 mm) at the top of `spotlight_mount.scad`.
- Slide the M5 nuts into the side traps (snug press fit).

## Editing
All dimensions are named variables at the top of `spotlight_mount.scad` (OpenSCAD).
Re-export: `part="Aprint"`, `"B"`, `"plate"` (one mount), `"plate2"` (two mounts).
Views/checks: `"assembly"` (+pitch_demo, explode), `"diagram"`, `"collcheck"`.
Key knobs: `slab_t` (slab thickness), `plat_t` (head/nut room), `pitch_max`,
`tooth_period` (step), `clear` (fit), `hole_spacing`/`light_boss_d` (light).