Random Projects – Mikias Berhé

Umbrella Hinge

3D Design and Printing

Reparing a Broken Patio Umbrella Hinge with 3D Design and print.

Problem

My Parents patio umbrella hinge connecting the umbrealls’s pole and canopy snapped, leaving the umbrella unusable… so instead of buying a new umbrella which costs $300+ I figure I can design out of the problem.

The Goal: Design and 3D print a replacement part that could withstand daily outdoor use.

First Attempt

The first version is a single body piece that matched dimension but cracked near the neck due to structural weak point.

This failure was caused by two main factors:

Infill orientation problem: The internal structure couldn’t resist the bending stress along the neck
Material Limit: The use of PETG filament required a more smarter design approach than a single body design.

Redesign & iteration

On the second version I split the design into two pieces, the neck that runs through the body of the model and an enclosure. This design choice distributes the load and tension.

Solutions implemented from two observed failures:

Infill orientation problem: Because of wind and everyday use the tension and load direction is not predictable, therefore I changed the infill pattern to a Gyroid pattern which has a complex, wavy pattern that alternates directions with isotropic mechanical properties for high strength in multiple directions.
Leveraging existing materials: Turning the model into two pieces and having two screws connecting the two pieces together with the umbrella pole moved the load and tension distribution from a single point on the neck area to the whole body of the model using the two screws and the metal umbrella pole.

Outcome & Reflection

After 3 months of use and windy weather, the model is still in perfect condition and doesn’t have any single point damage pointing to unbalanced load and tension displacement.

Things I learned from this project

Load and tension distribution: Distributing load and tension through geometry rather than just increasing thickness, reducing time and cost of manufacturing.
Design for material behavior: Understanding each material behaviors and leveraging these materials inside the design and other parts of the item to create a cohesive and cost efficient model.
Tools & Design choices: The original model that came with the umbrella was created using plastic molding technique for mass production and cost cutting. The tool I had available was a 3D printer, so I had to abandon the original models cost cutting design choices (That probably made it weak), that also complicates or prolongs the 3D printing process and partially redesign the model to be 3D printer friendly and much stronger than the original.