The Mechanisation of Nature: Oil Spills

Ideation
I began with research, primarily of mechanisms. I identified key movements that interested me and evaluated them for ease and applicability. From this I sketched ideas. I decided on a bird concept, with a focus on showing three movements: wings moving up and down, head bobbing, oil ripple.

Gears
I created 2:1 ratio gears to make the wings move correctly with the crank. I decided on a crank-slider mechanism to link the movements together. I developed CAD starting with the gears, only modelling a select portion of it so I could test without wasting material and printing time.

Design for Assembly and Testing
I designed for assembly, and within the size of the printer. I did this through multiple ways: splitting parts into sections that could be snapped together, making parts removable so they can be replaced and put together, avoiding interlocking pieces

Before printing out fully, I tested small versions of mechanisms, taking a modular approach to building my creation. At this point, I tried different printer brand, and it made a big difference, with greater accuracy, more removable supports and higher quality finish.

Linkages
The target bar had a rapid change in velocity, so I designed the linkage to be at a wider angle to lessen this, and used software to test out different lengths and positions to achieve the movement I wanted.

Adjustments were made to make it better, such as reducing friction and extending the axles to make them more stable.

Cams
To make the movement of the oil realistic, I studied how a still body of water reacts to being 'hit' by something, both videos and graphical representations. I aimed for the oscillations to die down each cycle.

I created displacement diagrams and applied dynamic considerations to the profiles, and using Autodesk Inventor I created follower motion schemes. The pressure angles were too large so I changed motion paths to reduce pressure angles. Each cam was then tested, printed and adjusted as needed.