4040 T-slot extrusion
Four times the second moment of area of 2020 for twice the mass. This is what a gantry that must not deflect uses.
The role it plays
Structure is a stiffness-per-gram competition. Aluminium extrusion is cheap and modular but its bolted joints creep. Carbon is stiffer per gram and fails without warning. Printed parts win on geometry freedom and lose on layer adhesion. Match the material to the load path, never the other way round.
Typical use: CNC gantries, heavy robot bases, camera rails.
What the numbers actually mean
The headline figure is 40 × 40 mm (profile), with 8 mm T-slot as the next most load-bearing number (slot). At $16 in the structure tier it sits cheap enough to prototype with and replace without regret, which is the correct way to learn a new subsystem.
How it compares
Same subsystem, closest alternatives. The primary spec column is usually the one that decides it.
| Part | Price | Primary spec | Second spec |
|---|---|---|---|
| 4040 T-slot extrusionStructural profile | $16 | 40 × 40 mm | 8 mm T-slot |
| 2020 T-slot extrusionStructural profile | $8 | 20 × 20 mm | 6 mm T-slot |
| 16 mm carbon fibre tubeComposite tube | $25 | 16 mm | 1 – 2 mm |
| PA-CF printed structural parts3D-printed composite | $40 | ~70 – 100 MPa (depends on print) | ~150 °C (annealed) |
Where it shows up
Platforms in this atlas that use something in this class: ALOHA 2.