NUGGS bottle adapter

The NUGGS bottle adapter (issue #515): the part that turns an off-the-shelf PCO-1881 water bottle into a drop-in habitat module. One printed body, two interfaces — the standard genderless quarter-turn NUGGS port below (80 mm bore, full library defaults), a threaded throat above that takes a stock bottle finish. The animal never passes through this module: the passage narrows to the bottle's own orifice by design, so this is a service module (water/bedding), not a transit module — the 70 mm bore floor governs entrances an animal uses, and the port below it stays full standard.

Turn a PCO-1881 soda/water bottle into a drop-in module of a N.U.G.G.S. hamster habitat: this one printed part screws onto that standard neck finish and plugs into the genderless quarter-turn NUGGS port — no special bottles, no fasteners, no tools. It does not seal on its own; it passes what the bottle's orifice passes, so treat it as a dispenser, not a watertight waterer — pair with nuggs-shutter-valve when you need to gate flow. Swap bottles in seconds; wash and refill the bottle, not the habitat plumbing.

What you get

adapter — the one-part bottle-to-NUGGS adapter (approx. Ø97 × 66 mm): the coupling port below, a PCO-1881 threaded throat above.
coupon — the print-this-first fit checker: the port stub plus four labelled thread rings to find your printer's bottle_tol before you commit to the body (approx. 187 × 97 × 31 mm).

Which bottles fit: PCO-1881 is the standard Coke/Pepsi soda neck — not every "water bottle" uses it. Before you commit filament: if the cap from a Coke bottle fits yours, or the neck measures about 28 mm inside, you're on PCO-1881; when unsure, the coupon is the proof.

Print settings

Material: PLA (dry service) or PETG if you hand-wash warm — family N7 still applies; see Use & care
Layer height: 0.2 mm with a 0.4 mm nozzle — the thread ridges are 3 layers wide; coarser loses the thread
Infill: 15% (all working surfaces are perimeters)
Supports: none needed — steepest surface is the 44° interior funnel
Orientation: as rendered, port down on the coupling sector tips
Seam: random (or rear) — an aligned seam stacks a ridge inside the threaded bore that can catch the bottle at one spot in the turn
First layers: the sector tips print as separate islands and merge into the ring a few layers up — normal for the NUGGS family pose; keep supports off anyway
PETG note: expect some droop on the 44° funnel ceiling — cosmetic only, the flow path is set by the land opening
Print first: the coupon, and set bottle_tol from the ring that grips a real bottle best (see below). The coupon being heavier and slower than the adapter body is intentional: a full throat rehearsal (port stub + bottle rings), not a bug to "fix" (~4 h 57 m / 62.55 g vs the adapter's ~4 h 10 m / 53.16 g)

Parameters

Parameter	Default	What it does
`bottle_tol`	0.25 mm	Thread clearance — the tuning knob; sweep it on the coupon (0.15–0.38) and set what grips
`f_thread_depth`	0.6 mm	Female thread depth; capped near 0.85 by the printable-profile fit inside one pitch
`nuggs_port_tol`	0.30 mm	Coupling clearance (the NUGGS standard default)
`land_opening_d`	22.0 mm	Hole in the sealing floor; never below the bottle's own 21.74 mm orifice
`funnel_deg`	44°	Interior funnel ceiling; keep ≤45° for supportless printing
`shell_h`	16 mm	Full-round wall behind the coupling face

The PCO-1881 table (bottle_thread_od, bottle_thread_pitch, …) is the standard, not knobs — don't tune those; tune the clearance. All parameters are at the top of nuggs-bottle-adapter.scad in Customizer sections; override on the command line with -D 'bottle_tol=0.22'.

Assembly & use

Print and check the coupon first: screw a washed PCO-1881 bottle into each labelled ring and find the tol that grips without cracking or skipping; put that number in bottle_tol and print the adapter.
Screw the bottle into the adapter mouth-down until its lip seats on the land (about 1.8 turns from first contact). The bottle's weight rests on the printed land — the thread only keeps it from unscrewing. Any rotational "label clock" for which way the bottle brand faces the room is fine mechanically; there is no preferred orientation.
Quarter-turn the coupling into any NUGGS port, the same as every module.
If the bottle bottoms out before seating (you feel the tamper ring hit), your bottle's finish runs long — the design clears the standard's 10.8 mm band; a capful of filing on the rim fixes nonstandard ones.

The adapter does not seal: it passes what the bottle's own orifice passes, through a printed land. For wet service see the design's backlog (an O-ring groove variant); for gating flow, pair it with the nuggs-shutter-valve.

Use & care

When you wash the adapter (or the bottle while it stays screwed in), hand-wash it (NUGGS family N7): ≤ 50 °C only, mild unscented dish soap is fine, rinse and dry fully — never a dishwasher (the heated dry cycle exceeds even PETG, and a warped port is a narrowed bore).

The printed bottle thread is the high-cycle joint on bottle swaps — expect on the order of hundreds of turn cycles a year once you're in the rhythm of refills. A ring of plastic dust under the bottle, or a grip that skips when you seat it, means reprint the adapter (~4 h 10 m and ~53 g per CI's printcheck numbers on this design) — cheap compared with a full bottle dropping from the port.

View in 3D

Inspect the real geometry — drag to rotate, scroll to zoom. The model is rendered from this design's own source at its default settings, right in your browser; nothing is uploaded.

Make it fit

This design has 20 tunable parameters. Change them and render your own STL — OpenSCAD runs in your browser, so nothing is uploaded and nothing is installed.

An STL you configure here is ungated. The files this project ships have each passed a printability check and a PrusaSlicer test-slice; your variant has not. Treat it as a starting point, and print the fit coupon first if the design has one.