Carapace: an organic motion sculpture

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Project by Derek Hugger posted 10-28-2018 12:33 AM 2023 views 9 times favorited 22 comments Add to Favorites Watch

Carapace is a wooden kinetic sculpture that simulates the motion of a sea turtle swimming. A complex series of mechanisms allows Carapace to swim up and down, tilt forward or back, and even lift its head up for a breath of air. As each mechanism is carefully linked to the next, each of Carapace’s flowing motions are driven by turning a single crank.

This sculpture has over 600 parts.

Its mechanisms include:
- gears
- hypocycloid reducers (one is single stage, one is dual stage)
- Peaucellier linkages
- cams
- a synchronized gear mechanism (to keep the flippers moving at a constant speed regardless of vertical motion)
- four bar linkages

Here’s a video of Carapace in motion:

If you’d like to make one yourself, detailed woodworking plans are available on my website:

Please leave a comment and let me know what you think!


22 comments so far

View swirt's profile


4772 posts in 3612 days

#1 posted 10-28-2018 01:07 AM

The most amazing kinetic sculptures/machines I have ever seen. Incredible work.

-- Galootish log blog,

View Dark_Lightning's profile


3811 posts in 3750 days

#2 posted 10-28-2018 01:20 AM

WOW. This is incredible! Well done!

-- Steven.......Random Orbital Nailer

View jamsomito's profile


462 posts in 1067 days

#3 posted 10-28-2018 01:33 AM

Wow, amazing.

View PaulDoug's profile


2336 posts in 2344 days

#4 posted 10-28-2018 02:03 AM

Congratulations! That is beautiful. I have always wanted to try one since I first saw his Hummingbird.

-- “We all die. The goal isn't to live forever; the goal is to create something that will.” - Chuck Palahniuk

View FancyShoes's profile


592 posts in 2005 days

#5 posted 10-28-2018 03:55 AM

Great build. Thanks for sharing. Its stuff like this that brings me here.

View Rayne's profile


1311 posts in 2180 days

#6 posted 10-28-2018 04:55 AM

Man, this is beautiful. I may give this is a shot one day. How much were all the parts from McMaster Carr for you?

View therealSteveN's profile


4906 posts in 1215 days

#7 posted 10-28-2018 05:49 AM

WOW, thanks for this, incredible.

-- Think safe, be safe

View Ivan's profile


15605 posts in 3508 days

#8 posted 10-28-2018 09:33 AM

Just incredible

-- Ivan, Croatia, Wooddicted

View Grulgor's profile


29 posts in 503 days

#9 posted 10-28-2018 10:16 AM

I love that,it’s so amazing. i’m wondering how to plan such a project!

View Albert's profile


536 posts in 4230 days

#10 posted 10-28-2018 03:14 PM

One of the most amazing things I’ve seen on LJs. Excellent!

View ClaudeF's profile


1078 posts in 2348 days

#11 posted 10-28-2018 06:15 PM

Wow! Beautiful work from designing to planning!



View AandCstyle's profile


3273 posts in 2898 days

#12 posted 10-28-2018 08:37 PM

Derek, you are one sick puppy! :D I am in awe and jealous of your abilities. Beautifully done!

-- Art

View Ron Stewart's profile

Ron Stewart

166 posts in 3145 days

#13 posted 10-28-2018 08:47 PM

That’s amazing, inspirational, and most definitely unique.

-- Ron Stewart

View Johan_Bengtsson's profile


7 posts in 644 days

#14 posted 10-28-2018 09:19 PM

How do you start the design of your intricate mechanisms? Its a beautiful sculpture.

View Derek Hugger's profile

Derek Hugger

42 posts in 2599 days

#15 posted 10-28-2018 10:48 PM

Rayne – I think all the hardware was somewhere between $400 and $500.

Grulgor & Johan_Bengtsson – I start with animation software. I model some very basic shapes, and then I animate them in the way that I want them to move in real life. Then the fun starts. I begin to think of what kind of mechanisms can drive these motions. I rough in the geometry for the mechanisms and animate those as well. When I’m confident with how everything works, I start work in CAD. From there, I do all the design, geometry detailing, analysis, and simulations. Then, I cut parts and hope that everything works in real life.

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