AIRU 04 — Mechanical Design and 3D Printing

Mechanical design, DFM, print materials, CAD files, tolerances, service mechanisms and supplier checks for AIRU V1.

DFM (design for manufacturability)

Designing parts so they can be produced reliably within the chosen process, material, tolerance, cost, and assembly constraints.

FDM (fused deposition modeling)

A 3D-printing process that deposits melted thermoplastic layer by layer; AIRU uses it for the V1 shell and mechanism parts.

Why is PETG AIRU's first-choice V1 material?

It offers useful toughness, easier printing than ASA, and better heat and impact performance than many display-grade PLA prints.

ASA

A durable, heat- and UV-resistant thermoplastic suitable for functional parts, but generally harder to print because it benefits from enclosure and warping control.

PLA+ limitation for AIRU

It can work for a display-only model but may soften with heat and is less suitable around a running motor or stressed functional joints.

STL file

A mesh of triangles describing surface geometry. It carries shape but normally lacks editable feature history, units metadata, and engineering intent.

STEP file

A CAD exchange format that preserves solid geometry better than STL and is preferable when a supplier must inspect or modify engineering features.

Watertight mesh

A closed surface with no holes or open edges. A watertight model is necessary for reliable slicing and solid-volume interpretation.

Non-manifold geometry

Invalid mesh topology such as edges shared incorrectly, internal faces, or zero-thickness regions that can confuse a slicer.

Slicer

Software that converts a 3D model into printer toolpaths and previews layers, supports, material use, and print time.

Why is a Meshy model not automatically print-ready?

AI-generated geometry still needs real dimensions, separated moving parts, clearances, wall thickness, closed surfaces, and slicer verification.

AIRU V1 presentation envelope

Approximately 262 mm long, 96 mm maximum width, and 51 mm minimum body height in the blueprint pack.

AIRU baseline print settings

The blueprint suggests a 0.4 mm nozzle, 0.20 mm layers, and roughly 15–20% infill, subject to supplier DFM review.

Layer height

The vertical thickness of each printed layer. Smaller layers improve surface/detail but increase print time and do not automatically improve all strength.

Wall thickness and perimeters

The solid outer shells of a print. Functional strength often depends more on sufficient walls and orientation than on very high infill.

Infill

The internal printed structure expressed as a percentage and pattern. It supports walls and affects stiffness, weight, time, and cost.

Support material

Temporary printed structures under overhangs. Supports add time, cost, cleanup, and surface marks, so parts should be oriented or split deliberately.

Print orientation

The direction a part is placed on the build plate; it affects support demand, dimensional accuracy, appearance, and strength across layer lines.

Tolerance vs clearance

Tolerance is allowed dimensional variation; clearance is intentional space between mating parts so they can assemble or move.

AIRU swivel clearance hypothesis

The blueprint suggests about 0.4–0.6 mm printed clearance, but the correct value depends on printer, material, orientation, and fit testing.

Why order a fit-test part first?

A motor cradle and removable-panel test can validate motor diameter, damper seats, M3 holes, snaps, clearances, and surface quality before buying the full shell.

M3 fastener

A metric screw with a nominal 3 mm thread diameter; printed pilot holes and inserts require process-specific sizing.

Snap-fit risk in FDM

Layer direction, notch sharpness, repeated flexing, material choice, and print variation can cause fragile or inconsistent snaps.

Motor cradle

A separate structure holding the proxy motor and four dampers while maintaining clearance so the motor cannot touch the outer shell.

Removable service panel

An access feature that allows inspection or replacement without destroying the shell; it also makes the mechanism visible to judges.

Dustbin twist-release concept

A collar rotates about 30 degrees to release a spring-loaded bottom plate so debris drops into a trash bin.

Silicone O-ring

An elastomeric seal compressed between surfaces to reduce dust or air leakage; groove geometry and compression must be tested.

Tissue-strip leak check

A simple qualitative test using tissue movement around seams to reveal suspected airflow leakage; it is not a calibrated leakage measurement.

Landed cost

The total delivered cost including part price, finishing, shipping, taxes, and customs—not just the online manufacturing quote.

AIRU print-order gate

Do not order the full shell until the cradle/panel pilot fits, the file package passes DFM review, and the complete landed cost remains within the budget guardrail.