OpenTrek
Undergraduate Thesis Project // 2024-2025
An open-source posterior gait trainer made from 3D printed parts, PVC, and hardware.
Designed to be shared, built, and revised.
OpenTrek
Undergraduate Thesis Project // 2024-2025
An open-source posterior gait trainer made from 3D printed parts, PVC, and hardware.
Designed to be shared, built, and revised.
01
Scope & Context
The American healthcare system is often restrictive and difficult, frequently denying people access to the care they need.
I spent a semester researching alternative ways people access medical devices when traditional systems fail, and how digital fabrication technology like 3D printing plays a role.
Research
I spent a few months reaching out to people within organizations involved in creating low-cost assistive technology.
From site visits, to interviews, and eventually volunteer opportunities, I learned a lot.
In my research, I discovered two approaches to the design of low-cost assistive technology.
Global & Digital
This approach is globally driven, capitalizing on the decentralized nature of 3D printing. It is limited by a lack of customizability and scale.
Local & Analog
This approach is locally driven and community based, using low-cost materials and higher skilled labor to build or modify large, custom devices for people in need.
I wanted to discover how we might combine both models, leveraging the customizability of the local model with the reach of the global one.
My Project
I began volunteering with ARISE Adaptive Design, which is in Syracuse. My goal was to apply insights from my research to something real.
A family from Albany had reached out about getting a low-cost alternative to a posterior gait trainer (pictured right) for their child. I took on the project.
Design Goal: Build a posterior gait trainer that is:
Low Cost & 3D-Printable
Make a gait trainer from 3D printed parts, PVC, and hardware, keeping costs low.
Shareable
Make the gait trainer easily shared beyond the community it was created within. This means designing for ease of assembly and with future editing in mind.
Pivoting
The gait trainer should have two independently moving sides, mimicking a stride. An experimental feature, proposed by the OT of the child being designed for.
02
Ideation & Prototyping
Sketching
The sketching process was done alongside prototyping, and was an invaluable tool for communicating ideas to those at ARISE.
Prototype 1
Prototype 2
Prototype 3
Prototype 4
Simplifying the System
With each connector iteration, I sought to simplify the assembly process, increase part strength, and improve aesthetics.
Final Prototype
The final prototype was constructed from 3D printed parts and furniture grade PVC. The wheels and skids were salvaged from another walker.
03
Final Design
Final Metrics
24 Hours
Machine Time
Takes ~24 hours to print on a P1S. Can be split over multiple machines.
$100
Material Cost
Includes furniture grade PVC, parts printed in ASA, and some sourced hardware.
44
Fasteners Used
40 M4x35mm, 4 M6x50mm
2 Hours
Fasteners Used
*this is how long it takes me, but I’ve made like 5 of these
Designed for streamlined assembly
Small orientation features are modelled into the parts, reducing confusion and streamlining the assembly process.
Designed specifically for 3D printing
Each connector is printed on a clearly defined face and requires no support, increasing clarity and reducing complexity for future users.
Designed with hardware sourcing in mind
95% of fasteners on this model are M4x35mm socket head cap screws.
This means a future user can source their hardware easily, buying a bulk package of a single type of screw.
04
Designing for Fabrication & Assembly
It's one thing to hit "print." It's another thing to do all this.
Fabrication Difficulties
Drilling
Drilling a cylindrical object like PVC is hard, especially when every hole has to be accurate.
Cutting
Cutting any stock to equal lengths without some assistance is hard. This is compounded by the fact that PVC is round, and doesn’t stay still on a table.
Assembly
Once everything is cut and drilled, a lot of parts look similar. Putting everything together the right way isn’t easy.
Process Analysis
Every time I made a prototype, I took extensive footage and notes.
Printed tools make it easier
I designed and iterated on several 3D printed jigs, which interface with low-cost materials like scrap wood and PVC to allow users to perform operations more easily.
Jigs in Action
Each jig is printed in PLA or PETG. The first jig is screwed to any scrap material and used to cut repeated lengths. The second clamps to equal lengths of PVC and is used as a drill guide,.
Keeping Track
Even with everything cut to the correct length, it’s still hard to put everything in the right place.
A set of LEGO-inspired instructions, paired with color dot stickers from the dollar store, help users keep track of everything during the assembly process.
05
Parametric Design
Connectors
Every aspect of the connectors is designed parametrically, from the wall thickness, to the diameter, and even the fastener hole distance from the inner wall.
This means future adjustments can be made for different materials, whether it be wood dowels, aluminum pipe, or simply thicker PVC.
Assembly
The entire assembly is also driven by parameters that a user can edit.
Entering a new height, width, or depth parameter will generate an entirely new model with an appropriate cut list.
