Dunes&Fishes

01  ||  Introduction

Octopus

This documentation details the octopus sculpture’s production process, design considerations, materials choices, assembly steps, schematics, and 3D printing methods. It serves as a reference for curators and producers to ensure accurate assembly and doubles as a studio journal for recording workflows and experimentations.

Size: 160cm x 160cm x 80cm
Motor: Dynamixel XM430-W350-T
Material: PATH-CF (mechanical)
Material: PLA (Aesthetics)
Printers: Bambu H2D & X1C
Coupling Magnets: N52
Camera Model: xxxxx
Power: 12V
Controls: OpenRB + Arduino
Project Run time: 16 Weeks

Sculpture No.1 || Museum of Marine Life 2248 Series

02  ||  Sculpture Requirements

1. Materials + Printing Techniques

The sculpture requires a material with high tensile strength, impact resistance, and superior layer adhesion to ensure structural integrity and functionality of moving parts during transportation.

2. Hardware

Use only stainless steel or aluminum components to prevent rust and debris. All hardware must be standard, easily sourced items like common nuts and bolts to allow global, hassle-free replacement.

3. Sculpture Size

The sculpture must fit a 29-inch luggage trunk; parts are limited to 50 cm. A flat-pack design is preferred, with all components compactly organized for efficient transport and storage in one trunk.

4. Motor Selection

The sculpture must fit within a 29-inch luggage trunk, limiting parts to 50 cm. A flat-pack design is preferred, with all components compactly arranged for efficient transport and unified storage.

5. Sculpture Movements

The sculpture’s movements stay slow when alone but grow agitated around humans, reflecting its discomfort and symbolising humanity’s role in its extinction, highlighting the tension between people and nature.

6. Electronics and camera

Electronics, including LEDs, camera, and computing unit, must share a single power supply to reduce wiring and components. Prioritise simplicity and house all elements for easy maintenance and replacement.

7. Coding

The code must support OpenRB, Arduino, and Raspberry Pi, with image processing for human detection. Define all adjustable parameters—motor count, movement ranges—at the top to simplify setup, maintenance, and troubleshooting.

8. Aesthetics

Aesthetic components must be detachable, ideally magnet-based, to ensure the sculpture allows quick setup and deinstallation. This is essential for flat-pack efficiency and compact transport, supporting its mobility and exhibition requirements.

9. Power

The sculpture should use a unified power system for all electronics, motors, camera, and control board, powered via a standard wall socket. Avoid batteries; a single power line should support the entire system.

03  ||  Design Consideration

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Why PAHT-CF?

For mechanical parts, a robust engineering filament is essential to withstand impact during transport and wear during exhibition. Among high-performance options like PA6-CF, PET-CF, and PC-CF, PAHT-CF stands out for its balanced combination of mechanical strength, thermal resistance, dimensional stability, and ease of use. It offers stiffness and strength similar to PA6-CF but with significantly lower moisture absorption, improving reliability in varying environments. PAHT-CF is also AMS-compatible, allowing automated spool handling in Bambu Lab printers. Compared to PET-CF, it offers greater impact resistance and interlayer adhesion, making it more suitable for mechanical and load-bearing applications.

Printing Technique

PAHT-CF adheres extremely well to itself, which presents challenges when using it as its own support material—supports can become very difficult to remove cleanly. While materials like PLA or PETG may also bond well with PAHT-CF, they are not ideal support options due to the high printing and chamber temperatures required for PAHT-CF, which can cause lower-temperature materials to soften or dislodge during printing. The most effective approach is to avoid supports altogether by designing parts that do not require them. If supports are necessary, tree supports with minimal contact points are recommended to ease removal and reduce surface defects.

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Mechanical Attributes
1. Filament Brand: Bambu Lab
2. Colour: Matte Black
3. Tensile strength: x–y: 92 MPa
4. Tensile strength z: 47 MPa
5. Breaking elongation x–y: 8.4%
6. Breaking elongation z: 4.1%
7. Impact strength x–y: 57.5 kJ/m²
8. Notched impact strength x–y: 22.8 kJ/m²
9. Impact strength z: 13.3 kJ/m²
10. Density: 1.06 g/cm³
11. Saturated water absorption: 0.88%
12. Composition: PA12 + long-chain PA + carbon fibre

Heat Resistance
1. Heat deflection temperature (0.45 MPa): 194 °C
2. Heat deflection temperature (1.8 MPa): 170 °C
3. Vicat softening temperature: 220 °C
4.Melting temperature: 225 °C
5.Glass transition temperature: 70 °C
6.Crystallisation temperature: 140 °C

3D Printing Perimeters
1. Melt index (280 °C, 2.16 kg): 14.4 g/10 min
2. Nozzle temperature: 260–290 °C
3. Bed temperature: 80–100 °C
4. Drying requirement: 80 °C for 8–12 hours
5. Cooling fan: 0–40%
6. Recommended nozzle sizes: 0.4 mm, 0.6 mm, 0.8 mm
7. Hardened steel nozzle required
8. Printing speed: Under 100 mm/s
9. Chamber temperature: 45–60 °C
10. Max overhang: ~70°
11. Max bridge length: ~40 mm
12. Annealing: 80–130 °C for 6–12 hours (in convection oven only)

Chemical Properties
1. Odour: Odourless
2. Flammability: Flammable
3. Solubility: Insoluble in water
4. Chemical resistance: Resistant to oils, greases, fuels
5. Not resistant to acids, alkalis, strong solvents
6. Lower water absorption than older PA-CF (0.88% vs 1.7%)

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Why PLA?

PLA is chosen for its ease of printing and aesthetically pleasing finish, which is particularly suitable for sculptures with organic forms that require support structures. PLA excels in this regard, as it can support itself and allows for easy removal of supports without damaging the piece. While PETG is sometimes considered due to its higher strength, PLA offers a more refined, matte appearance—unlike PETG, which tends to have a slight sheen, even in matte variants. In the context of visual arts, aesthetics are crucial, and PLA delivers a professional, high-quality look, whereas PETG may appear glossy or feel like inexpensive plastic.

Printing Technique

PLA enables the printing of complex shapes and detailed undercuts, largely due to its compatibility with tree supports and the ease with which supports can be removed. This makes it especially suitable for intricate or organic designs where clean surface quality is important. PLA’s ability to act as its own support material further simplifies the process. However, its mechanical limitations must be considered. PLA is brittle and lacks strength under stress or abrasion, making it unsuitable for parts that interact with mechanical components.

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Mechanical Attributes
1. Filament Brand: Kexcelled
2. Colour: Matte White/Black 
3. Tensile strength: 36–42 MPa
4. Tensile strength z: not specified
5. Breaking elongation x–y: 2–4%
6. Breaking elongation z: not specified
7. Impact strength x–y: 38–42 kJ/m²
8. Notched impact strength x–y: 6–9 kJ/m²
9. Impact strength z: not specified
10. Density: 1.40–1.45 g/cm³
11. Saturated water absorption: very low (PLA is not hygroscopic like nylon)
12. Composition: PLA (polylactic acid), matte modifier blend

Heat Resistance
1. Heat deflection temperature (0.45 MPa): 61 °C
2. Heat deflection temperature (1.8 MPa): not specified
3. Vicat softening temperature: 57 °C
4.Melting temperature: ~160 °C
5.Glass transition temperature: ~60 °C
6.Crystallisation temperature: not applicable (amorphous polymer)

3D Printing Perimeters
1. Melt index (190 °C, 2.16 kg): 7–12 g/10 min
2. Nozzle temperature: 190–230 °C
3. Bed temperature: 30-60 °C
4. Drying requirement: not mandatory but 45–55 °C for 3–6 hours
5. Cooling fan: 50–100%
6. Recommended nozzle sizes: 0.4 mm, 0.6 mm
7. Hardened steel nozzle required: no (not abrasive)
8. Printing speed: 40–80 mm/s
9. Chamber temperature: not required
10. Max overhang: ~60–65°
11. Max bridge length: ~20–30 mm
12. Annealing: not required but can be done at 80–100 °C for increased strength

Chemical Properties
1. Odour: Odourless
2. Flammability: Flammable
3. Solubility: Insoluble in water
4. Chemical resistance: low; sensitive to alcohols, alkalis, and solvents
5. Not resistant to acids, alkalis, strong solvents
6. Lower water absorption than nylon; no drying needed for typical use

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Why Choose Dynamixel?

Through extensive experience with stepper motors, hobby servos, and various actuators, we have found Dynamixel motors to be the most robust and versatile solution for kinetic sculpture. Our work demands compact design, precise control, and reliable long-term performance. Dynamixels offer both angular and continuous rotation mode in a single unit, along with integrated position feedback, reducing the need for additional sensors or circuitry. This simplification minimises failure points and streamlines the overall circuitry. Additionally, their ability to daisy-chain multiple units over a single communication and power line benefits complex configurations if needed.

Dynamixel Models:  XM430-W210-T || XM430-W350-T

Considerations for Maintenance

From previous projects involving multiple actuators, we have learned that motor replacement can be one of the most time-consuming maintenance tasks. With earlier systems, replacing a single motor often required 20–30 minutes due to manual shaft alignment and position recalibration. Dynamixel motors greatly simplify this process. Their have built-in position feedback and clearly marked alignment indicators allow us to pre-calibrate the motor’s orientation before installation, eliminating guesswork and repetitive work. As a result, replacements should be completed in under two to three minutes. For systems with twenty or more motors, this translates to significant time savings and improved on-site maintenance efficiency.

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Why M2.5 and M4 Stainless Steel Bolts?

To meet the project’s objective of standardising hardware, we have selected M4 and M2.5 stainless steel bolts as the primary components, together with stainless steel inserts and nylock nuts. We chose M4 over M3 due to its significantly greater holding strength—approximately 200–300% higher—especially for lengths exceeding 60 mm, where torsional stress becomes problematic. This substantial increase in strength justifies the slight increase in diameter. Furthermore, M4 nuts integrate more reliably into 3D-printed cut-outs, requiring only about 0.2 mm tolerance. This simplifies precision fitting and reduces assembly issues, ensuring greater consistency and accuracy across all hardware and components throughout the project.

Tools and setup

By standardising on M4 and M2.5 hardware, we reduce the variety of components required, which significantly decreases storage demands. Fewer bolt sizes and nut types mean fewer assembly tools are needed, reducing complexity during both storage and use. This also minimises the need for different driver heads, spanners, or torque tools, as a single set of tools can handle most of the assembly tasks. When setting up, we no longer need to bring an excessive range of tools or hardware, allowing for lighter and more compact toolkits. This makes on-site assembly faster, reduces the chance of missing essential tools, and improves overall reliability during installations.

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Fitting into a 29-Inch Trunk Luggage

In this series, all sculptures are designed to fit within a 29-inch trunk-style luggage for ease of storage and transport. This approach provides distinct benefits over traditional wooden crates, including lower shipping costs, simpler handling, and greater portability. Each trunk is dedicated to a specific species; for example, the octopus, represented by a single sculpture, occupies one case, whereas the seahorse, with three aesthetic variations, requires all pieces to fit within a single trunk. A 29-inch trunk accommodates components up to 50 cm with protective padding, while its square design maximises space efficiency. Unlike crates, luggage eliminates bolting, reducing labour and setup time.

Benefits of Standardised Storage

Using a standard 29-inch luggage across all sculptures ensures consistency in packing, storage, and transport, simplifying logistics. Uniform sizing allows efficient stacking during shipping and eliminates the need for custom layouts when arranging cargo, reducing freight costs. Organisation features, such as internal dividers or mounting systems, can be reused across the entire series, avoiding the need to redesign or rebuild for each piece. Similarly, packing materials like foam inserts and protective padding can be standardised, reducing material waste and preparation time. One drawback is reduced flexibility, as smaller sculptures still occupy the same size case, slightly increasing overall storage volume.

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Why slow movements?

The sculpture’s slow, deliberate movements evoke a sense of calm and elegance, encouraging viewers to engage with the work in a more contemplative manner. Rapid or abrupt motions often appear mechanical and can induce unease, disrupting the illusion of organic behaviour. By contrast, gentle, almost imperceptible movement introduces an intriguing element of suspense, prompting observers to pause and question whether the sculpture is in motion. This ambiguity aims to heighten the audience’s perceptual awareness, compelling them to analyse the subtleties of motion.

Mechanical Considerations

Mechanically, slower movement significantly reduces wear on components, ensuring greater durability and reliability. This effect is further supported by the use of metal and nylon sleeves, which minimise friction and extend the lifespan of moving parts. To avoid direct stress on motor shafts, the design incorporates belt drives, gearboxes, and worm gears, distributing torque efficiently and reducing axial pressure. By operating at lower speeds, we aim to deliver higher torque, improving mechanical stability while lowering energy demands.

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