Sculpture 3: Process Amphitrite
On this page you will see the process that brought my Amphitrite sculpture to life. It will run through the initial design process, prototyping journey and material research in a chronological order. This page includes all the fabrication files and code for this sculpture.
⚗︎RESEARCH AND IDEATION⚗︎¶
When a whale dies, it doesn’t just vanish — it descends. Slowly, heavily, it falls through the ocean’s layers like a drifting star extinguished, sinking into darkness. This descent marks the beginning of a rare and powerful ecological event called a whalefall — where the end of one life becomes the spark of thousands more.
Upon reaching the seafloor, the whale’s massive body transforms into an island of life in an otherwise barren deep sea. Scavengers like hagfish, sleeper sharks, and amphipods strip away the flesh in a matter of months. Then, a quieter, stranger community takes over — worms that bore into bone, bacteria that feast on lipids, and organisms that thrive on the chemical energy released as the carcass decays.
For decades, sometimes even longer, this one fallen body can sustain entire ecosystems.It offers shelter, food, and a place for reproduction in the vast, nutrient-poor deep. The cycle of decay becomes a cycle of creation.
But this cycle is being quietly disrupted.
As climate change warms the oceans, it alters whale migration patterns, reduces populations, and accelerates the loss of oxygen in deep waters. With fewer whales living long enough to die naturally in the open sea — and more dying from ship strikes, entanglement, or strandings in coastal shallows — the number of true whalefalls has diminished.
The deep sea depends on these rare events. Without them, the organisms that specialize in decomposing bones or surviving on sulfides may vanish. An entire web of life and activity, built around this cycle disintegrates.
A great, introductory video for this phenomena is linked below as well as some of the sources I read when I was entering the topic:
My initial idea for this sculpture was to create a moving "skeletal form" that appears somewhere between animacy and inanimacy, life and death to reflect the cycle of growth and decay in a whalefall ecosystem. I wanted to create a ambiguity for the viewer, are they looking at the slow undulation of a deep sea creature or just matter floating along the waves?
Moreover, I wanted to make it out of a material that would disintegrate as the sculpture moves. As the a person approaches the sculpture its movement would speed up, becoming more agitated and causing a faster deteriation of the piece into dust. This speaks to the dissapearance of whalefall ecosystems as a result of human activity.
I began to collate images of bone-like structure and methods of suspension that give a sense of underwater weightlessness:
I began sketching out my ideas for the shape and form, thinking about suspending individual pieces from fishing line and connecting them with a spine. Perhps, I also I wanted some fabric element to billow and sway with the movement, so the piece appeared to be blossoming.
For the motion, I knew I wanted to create an undulation, the piece hung low- just above the ground- somewhere between crawling and floating. I started to think about ways to make a wave like motion.
⚜︎PROTOTYPING MOTION⚜︎¶
For the motion I was particularly interested in Sinusoidal movements in sea creatures, often referred to as undulatory swimming. This involves a wave-like, oscillating motion of the body or fins, propelling the animal through water.
From here, I started thinking about sine wave machines. I found these amazing examples and became really excited about this mechanism.
I started doing some research and sketching out mechanisms from videos and open source projects to get a bit of a better understanding of how they worked:
Cam Mechanisms¶
From my research I learnt about Cam mechanisms.
What is a Cam Mechanism?
A cam mechanism is a mechanical device that transforms rotary motion into linear or reciprocating motion. It consists of a rotating cam and a follower that follows the cam's profile, resulting in the follower's movement. As well as in mechanics it is often used in simple automata and childrens toys.
This Carnegie Mellow Article by Yi Zhang with Susan FingerStephannie Behrens is a great introduction.
You can change the motion of the follower by changing lots of variables e.g commonly people change the profile of the cam to create different movements for the follower:
Image from TechnologyStudents: https://technologystudent.com/cams/cam2.htm.
Creating a Sine Wave motion with Cam Mechanisms¶
However, with Sine wave machines the motion is created by the incremental rotation of the same cam around an axis.
A sine wave cam profile is created when the follower’s displacement is proportional to the sine of the cam’s rotation angle, creating smooth, oscillating motion.
Each cam has a circular profile. As the cam rotates, it pushes the follower back and forth along a straight line. If multiple cams are rotated by fixed angular increments (e.g. 30° apart), each follower engages its cam at a different point, introducing a phase shift.
These staggered motions combine to produce a continuous sine wave pattern across the system.
Variables that I want to play with are:
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Rotation angle increments which determine the frequency of the sine wave.
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Cam diameter which affects the amplitude of the sine wave.
Thus, by adjusting the cam's size and the rotational spacing between cams, you can precisely control the shape, frequency, and amplitude of the resulting sine wave motion.
I began to sketch out ideas for the mechanism, taking notes from the projects I had seen in my research. This instructables project was also particularly useful because of the detailed technical renders: Kinetic Sculpture: "Sine Machine".
Adventures with Grasshopper¶
Discussing this mechanism with my mentors, we decided that creating a grasshopper definition would make it easy to change parameters such as cam diameter and rotation angle and prototype the movement quickly.
We quickly made a simple definition you can use to flexibly adjust the parameters of the cam:
- Diameter of the Cam (Amplitude)
- Angle of Rotation (Increments between cams or wave frequency)
- Axel Hole Diameter and Diameter of connecting holes. (Hardware dependant)
- (A) OR Offset distance between the cam’s rotational center (axle) and where it connects to the next cam (linkage point). (Offset affects the height of movement of the follower and therefore also affects the amplitude.)
Here is a short screen recording to show the definition in action.
YOU CAN DOWNLOAD THE GRASSHOPPER FILE FOR THIS DEFINITION HERE: 1.
I used this as a tool to create my first set of cams to prototype the motion. I used the parameters:
CAM RADIUS: 50
A or OFFSET DISTANCE: 0.6
ANGLE: 30 (12 CAMS PER WAVE CYCLE)
RADIUS OF HOLES: 3
I also created a version of the cam with an offset profile so that it can be sandwiched between two of the wider cams and create a groove for the follower to slot into without falling from its path
Finally, it was important to design a frame from which I could test different distances and pivot angles of the follower relative to the cam surface. As I did with my other sculptures, I aimed to make a prototype system as adaptable as possible to test and evaluate different outcomes.
Iteration 1¶
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I decided to do 12 cams which meant 24 normal cams and 12 offset needed to be cut from 5mm cardboard
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I laser cut the frame from 4mm ply.
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I used super glue to adhere the offset cams between 2 of the normal cams, lining up the holes.
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I used 6mm wooden dowel as my axels and followers. I cut the followers to 30cm lengths here, drilled a small hole in them about 5mm down and used a length of wire to create a loose hinge around the pivot pole.
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I used M6 screws to connect each cam, always connecting the central hole of the cam to the 30 degree angled hole of the following cam.
Here you can see my final prototype for Iteration 1 and you can download the lasercut files for this iteration here: 2.
First Test with Electronic Integration.¶
To move the prototype I just needed to rotate the axel.
I had already done a lot of the hard graft with stepper motors to get my 2nd sculpture Philomel up and running. Because of this a lot of the electronics for this work were already figured out. The stepper would be an appropriate way top rotate the axel as it provides continuous rotation and can be programmed for speed control. I had seen stepper motors used in a similar way in this project by Riley Cox to rotate a belt.
I started by testing Iteration 1 straight away with the NEMA 17 stepper motor and driver set up I had worked out previously. I used my code for continuous 30 RPM rotation. You can find all the documentation for this set up here on my Philomel Page. I simply taped the stepper to the axel at first to see what would happen:
I was immediately IN LOVE! I was so happy with the movement and could already envision the magic I could create with this mechanism.
✠TESTING FORMS AND MOVEMENTS✠¶
I took the working prototype as an opportunity to test some suspended forms. I wanted to see which kinds of structures were best for translating the sine wave motion through and also to see how variables from the suspension effect the movement created.
I could immediately see how many possibilities I had with this mechanism. But it was clear that structures with a connecting "spine" made the movement look clearer as the suspended materials couldn't spin or twist and distract from the shape of the wave.
⚔︎SCALING UP- Iteration 2⚔︎¶
Next, it was time to scale up the whale! I knew the piece had to be bigger than the Daphne and Philomel to make sense in the space. So it was important for me to see if the motion would still work scaled up.
This time I used my grasshopper definition to create cams with these parameters and I cut 2 wave cycles so 24 cams (48 ordinary diameter and 24 offset to piece together). This gave me the length of just under a meter.
CAM RADIUS: 50
A or OFFSET DISTANCE: 0.6
ANGLE: 30 (12 CAMS PER WAVE CYCLE)
RADIUS OF HOLES: 3
My process became very playful at this point, trying out things in space to see what began to work.
I played around with shape as well, making a cardboard skeleton with a connecting spine to see how the full piece might move.
The mechanism still moved by hand crank at scale, even when weighted with 24 coat hangers! But I could tell that there was much more friction in the system and it took a lot more force to turn the axel, particularly because the weight was bending it at the center.
I was pretty happy with this scale but unfortunately when I connected the NEMA 17 motor it would not rotate the Axel at all The motor did not have enough torque to move the system with all the extra weight.
☸︎ELECTRONIC UPGRADES- NEMA 23☸︎¶
I decided my best chance at getting the axel moving was to switch to a motor with significantly more torque output.
After consulting Michelle Vossen's Final Project Documentation aka the bible! I saw that she had similar issues to me. She switched to the Nema 23HS8430.
The Nema 23HS8430 has a 1,9Nm Holding torque and a 3A rated current so has a lot more holding force and I thought this would be my best chance.
The motor driver I am using (see my Philomel Documentation), the DRV8825 has a max current of 2.2 Aso I could not give the NEMA 23 its full rated current of 3A with this. However, other motor drivers looked quite complicated to switch out at this point and were all pretty expensive. So, I decided to just ensure I used a heatsink on my DRV8825 and current limit it properly and run it below its rated current.
I knew I wouldn't get full torque from my motor (maybe around 50% or less), but it would still work. I hoped this would still be enough torque to move my system!
I calculated my Vref again using the same formula but with the NEMA 23's current limit of 2.2A this time.
Vref = 2.2 A / 2
Vref = 1.1V.
I then connected the NEMA 23 up into a circuit exactly the same as the NEMA 17 I had used previously: Documentation Here.
In the video below you can see the NEMA 23 working with:
- The Continuous 30 RPM code
- The sensor interaction, mapping distance to different RPMs.
- The serial monitor readings.
⛽︎THE UNSTOPPABLE POWER OF GEAR RATIOS⛽︎¶
To be extra sure I got the mechanism moving and help out my under powered motor, I decided to use the gear ratios to increase the torque in my gear system.
Gear ratios help increase force (torque) because they trade speed for strength
If the stepper motor has a gear that is 3× smaller than the gear on the axle, the motor must spin 3 times to turn the axle once. This setup multiplies the motor’s torque by 3, making it easier to rotate heavy loads, even though the axle will turn more slowly.
I decided to make one gear with 40 teeth and another with 12 teeth meaning I have a ratio of 1:3.3.
In theory multiplies my motor’s torque by 3.3 compared to no gears.
I generated these gears using stlgears.com and lasercut them from 4mm transparent acrylic.
HERE IS THE .DXF LASER FILE FOR THE 2 GEARS: 3
Designing Gear connectors¶
Then I had to work out how to connect the gears to the axel and the motor securely so that the gears wouldn't become misaligned from vibrations or movement.
I started modelling in Rhino and 3D printed prototypes in Transparent PLA Filament until I found the perfect fit. They had to be secure enough with press fit, but e further secured with a threaded insert and grub screw.
This is the video I used to learn how to design for a threaded insert and how to heat set it into your 3D print:
I ended up with something like this which attachs nicely to my laser cut gears with M2 screws and nuts.
You can download the .stl files for these connectors from sketchfab below:
- This connector is between the 40 tooth gear and the axel pole. I used a 10mm aluminium pole as my axel and therefore the inner bore is a very tight press fit for this diameter:
- This is the connector for the 12 tooth gear to the NEMA 23 stepper motor. It has a 6.35 inner bore to have a secure press fit onto the motor:
Motor Mounting Frame¶
Finally, to get iteration 2 up and running I needed to find a way to mount my new motor onto the frame securely.
The mounting points had to be a precise distance from the axel so that the gear attached to the motor and the gear attached to the axel would align perfectly.
To work this out I mocked it up in Rhino and created another adaptable test frame to laser cut from 4mm ply.
You can download the lasercut file for this frame here: 5.
Testing Iteration 2 with Motor:¶
My set up for this iteration was very rough and ready! Serious mad inventor vibes! I suspended both frames with wire from a beam in the Textile lab and glued the breadboard on the wall above.
I switched out my wooden dowel axel for 5 x 10mm aluminium poles securing the frame at all 4 corners also. I simply speared and glued the old cardboard cams onto their new axel.
I set up the new gear mechanism and mounted the motor onto the frame with screws.
We were ready to switch her on:
I was ecstatic that my gear ratio and motor set up seemed to alleviate all my friction problems with ease! Swapping out my wooden dowels for aluminium poles also helped with the general structure and keeping things aligned.
However, I wasn't super pleased with the movement in the skeletal structure beneath the mechanism. I thought that there was too much swaying and twisting in the individual pieces that the overall wave motion was a bit lost and it didn't give me the feeling I wanted.
⚘TRYING A NEW SKELETAL FORM⚘¶
So to help this I decided to try a different kind of structure where all the "bones" were flat on the same horizontal plane, giving them more of a neutral start point to highlight the movement.
I made the shape from the previous "coat hanger" type form but made it smaller and connected them all up with the Sketch tool in rhino.
You can download the lasercutting file for this test here: 5.
I suspended this piece via fishing line through each central hole along the spine. I tied the other ends of the line to the follower.
Once suspended I also glued pieces of transparent binbag to the underside to test if I could make a more billowing form and heighten the movement.
I was really happy with the way this version moved! The connecting spine and flat top surface really helped to emphasise the wave movement and I loved how it kind of looked like a puppet of chinese liondog. This version felt much more alive and I was happy to proceed with this structure.
♐︎MATERIAL UPGRADES AND MACHINE HARDWARE DESIGN♐︎¶
The next step was to get the machine away from cardboard and hot glue and into something a bit more pretty!
I drew out the machine and started identifying all connecting points between hardware and everything I would need to make the machine work smoothly, reliably and in a stronger material.
I sketched some machine hardware and a frame as changes to be made.
Redesign the Frame¶
**A crucial first step was to redesign the frame so that it would stay straight and square whilst suspended and the mechanism is moving.
My aims for the frame were:
- Simplify the holes, keep only the ones I need.
- Integrate a top piece to the frame. This would need to be held via L Brackets to keep both side parts of the frame (and therefore the motor and gears) at right angle. This would keep everything aligned and reduce the weight on the axels and metal poles.
- Design stoppers to hold the frame in place on the axel and metal poles. This will also pull in the bottom of side frames and keep it from slipping out of a right angle with the top piece.
- Include 4 points for suspension.
- Cut it out of transparent acrylic for aesthetics and durability.
I bought some L brackets from the hardware store and got to work making a mock up of the frame from cardboard to work out where I would need to laser holes for screws in the acrylic.
I then made this into a Rhino File, including the motor mounting holes and holes for the axel and poles.
I laser cut the two side pieces of the frame out of 4mm Transparent Acrylic and 3 copies of the top piece from 2mm Transparent acrylic so I could layer it up and make a thick piece that was more resistant to bending.
You can download the lasercut file for the final frame here: 6.
Designing Stoppers¶
Next, I designed some chunky stoppers to hold the frame in its position along the metal poles and keep it square despite movement.
I also wanted to put these on either side of the Cam worm to ensure that everything stays tightly sandwiched together without the need for glue.
EVERYTHING ABOUT MY DESIGN IS DISASSEMBLABLE SO THAT IT CAN BE TRANSPORTED AND REPURPOSED INTO OTHER WORKS.
I designed these stoppers to be very similar to the gear connectors just with a slighly chunkier stop to give it weight and a wider contact surface with the frame:
You can download the stoppers from Sketchfab below. I printed them with 1.75mm Transparent PLA filament as I did all the hardware for this piece.
YOU NEED TO PRINT 18 OF THESE FOR THE FULL MECHANISM
Designing Hinges, Follower End pieces, Spacers and Dowel stoppers.¶
Next, I had to design and fabricate solutions to anything I had fixed with hot glue, wire or sheer will power! I wanted to make them elegant and aesthetic solutions, so I got to work designing.
Hinges¶
These were designed to fit onto the axel (10mm) loosely so the follower could pivot up and down easily and then have a very tight press fit onto the end of the follower (3mm). I had replaced the wooden dowels I was using as followers with 3mm stainless steel rods. These were much more sturdy and aesthetic.
Follower End pieces¶
These were designed to fit on the end of the followers to stop the fishing line tied to the ends of each follower sliding off and also to have an aesthetic function.
Spacers¶
These were designed to hold each Cam in place and hold the correct amount of space between each Cam. Their full length is 12mm and I used 2 between each Cam set to create a 24mm spacer either side.
With these spacers correctly sized between the cam and the chunky stoppers secured on the very end, there is a tight pressure between each cam which is designed to hold everything together without the need for glue.
Dowel Stoppers¶
Finally, these are designed to press fit on to either side of a 6 mm x 550mm dowel which I used to connect each cam (via its central point to the next cams 30 degree point.) The stoppers hold the cams rotation angle in place whilst allowing me me to take the dowel out again and take the cam worm apart.
I cut 20 of the 6mm x 550mm dowels. This measurement ensures a press fit connection betweem the cams which keeps the cams straight and pressed together.
Final Cams¶
The last thing to do was to lasercut the Cams for the final mechanism. I decided it would look really nice to have the cams made of transparent acrylic so I got some 4mm and 2mm.
The inner offset cam is cut from the 4mm acrylic. This is sandwiched between the other two pieces to create a groove big enough for the 3mm steel rod follower.
The normal sized cams are cut from the 2mm.
I made 20 cams as to have one and a bit wave cycles. The motion will therfore have a flick up at the end, like a tail!
You can download the .dxf laser file for the final cams here: 7.
☼BUILDING THE UPGRADED MECHANISM☼¶
The final result looked stunning. I was so happy with all the material upgrades, it suddenly looked like something I could present!
⚐TESTING NEW HARDWARE AND MATERIALS WITH ELECTRONICS¶
I hooked up the electronics to the new mechanism and mounted the motor.
Thankfully, mercifully, miraculously she worked!
So very pleased:
⍣BIO FABRICATION⍣¶
The finally step was to make the skeletal structure. I knew from the beginning that I wanted it to be made out of a material that would disintegrate as it moved. I wanted a fragile, biomaterial with its own temporality that would change throughout the life of the work.
I decided to try Aluin crystalisation, we had explored this technique during Textile Scaffold week and it was a completely magical... and quite easy process.
I was particularly interested in the fact that the Aluin crystals could be redissolved, meaning that as the piece disintegrated I would be able to reconstitute it again and agin by redissolving the crystals. This reflected the cycle of the whalefall ecosystem poetically and perfectly.
Material Tests¶
I first created a scaffold for the crystalsthat would give me the shape of the skeleton I wanted.
I decided to test lasercutting slithers of acrylic and sewing these on to an organza lasercut of the skeletal form I had tested previously.
In theory, this would give a porous and flexible material for the crystals to grab on to and still make it soft enough to move in the wave shape. The acrylic would also give the form a bit of structure and shape, stopping the fabric from going limp and drooping under the weight of the crystals and giving me somewhere to attach the fishing line on to in a consistent location.
In Rhino I simply made an offest of my original design and added some holes so I could easily sew the two pieces together. I laser cut the wider piece from white organza and the smaller individual pieces from transparent acrylic (2mm).
Then, I followed the same process from Textile Scaffold week. You can find the full recipe and process documented here. I left it in for about 1 hour and then removed it before the crystals could become too stiff.
I liked the effect a lot and thought the way the crystals played with the light would add another dimension to the final piece.
❥Crystalising the Skeleton❥¶
Digital Fabrication¶
Commiting to the crystals I created a full scale laser file for laser cutting the acrylic and organza.
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I needed 1m length of each.
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The shape has 20 bones, one per cam. They are each spaced in the same intervals as the cams on the axel (5.5cm between each suspension point).
You can download the .dxf laser cutting file for these parts here: 8.
Sewing the Scaffold¶
Next, was the incredibly labourious task of sewing each piece of acrylic onto the organza. It is important this is sewed on really well other wise the acrylic is so much heavier than the fabric that it pulls off easily.
I also sewed in some fishing line from which to suspend the skeleton in the aluin bath.
Aluin Bath¶
To crystalise my full skeleton was quite the task given it is 1m long.
I scaled up the recipe to use 2.5kg of Aluin Crystals and 4 litres of water at a 70g: 100ml ratio.
I dissolved this in two big pots and poured it into a large storage container which I had prepped by suspending my skelton about half a centimeter above the bottom using fishing line and duct tape.
I couldn't fit the whole skeleton in the storage container so I had to crystalise it in two halfs, repeating the process.
I left the skeleton in the bath for 2 hours each time until the acrylic was completely covered with crystals.
The results were amazing! I was so happy with the fact that all the fabric and acrylic were concealed by the crystals and that the whole structure was still flexible:
☑︎FINAL CONSTRUCTION☑︎¶
The home stretch with this work was connecting the skeletal structure to the mechanism.
It is important that all the fishing line strings are the same length so that the whole skeleton is on the same horizontal plane. This helps keep the phasing difference created by the mechanism correct and the wave motion more clear.
My lovely assistant Irja (Fabacademy Intern extraordinaire) helped me sew each string through the hole in the acrylic whilst the skeleton was flat on the floor. Then, pulling the string taunt, we let out a measure and tied it to the end of the follower. When all the strings were attached and of similar tension it was ready to go!
Finally, I transferred all the electronics to protoboard and glued it next to the motor on the frame, running the sensor down to rest at chest height.
That completes the process! Please see my Project Page for the final result,installation and interaction with this work!
