Integrated Crutch Attachment Project

Relevant Skills: Solidworks, GD&T, Rapid Prototyping, Iterative Design, Problem Solving, Teamwork

Situation

In our GD&T (Geometric Dimensioning and Tolerancing) class final project, our team aimed to design and prototype an innovative crutch attachment, named "CrutchGuard," to reduce the risk of reinjury for crutch users. This project targeted the significant issue of crutch-related injuries, particularly on wet or uneven surfaces. Annually, approximately 575,000 people in the United States are prescribed crutches, and a notable lack of awareness exists regarding the potential dangers of crutch use under hazardous conditions. Our objective was to address these risks by developing an attachment that enhances stability and safety.

Task

We were tasked with creating a comprehensive design and manufacturing a functional prototype of the crutch attachment. Our responsibilities included:

Developing detailed designs for each component with precise specifications and tolerances.
Selecting suitable materials for both the prototype and the final product.
Manufacturing the prototype using available resources and ensuring it met all design criteria.
Evaluating the prototype and identifying areas for improvement to optimize functionality and user experience.
Documenting the process and reflecting on the overall project to highlight challenges, solutions, and learnings.

Action

Component Design:

Component A: The base component holds the crutch and other parts securely. It features four heat inserts for screw attachment, enhancing stability and grip with an anti-slip rubber surface. The increased surface area mimics the bottom of a shoe, allowing the crutch to stand independently and providing stability on uneven surfaces. Material: PLA for the prototype; a flexible 3D printed material for the final product.
Component B: A support system for the leg with a round design to enable customizable rotational movement, making the crutch more adaptable to different user needs and movements. Material: PLA for the prototype; metal for the final product.
Component C: An adjustable clamp system connected to Component D for stable leg attachment. This clamp can be snap-fit for smaller thicknesses. Material: PLA for the prototype; metal for the final product.
Component D: An addition to the lock mechanism that connects the leg to the clamp, facilitating rotational freedom and ease of connection. Material: PLA for the prototype; metal for the final product.
Component E: A leg component that connects the clamp and bottom parts, designed for future extendability to accommodate various user heights. Material: PLA for the prototype; metal for the final product.

Tolerance Specification:

Component A to B: Interference fit (LN1), diameters 0.35 ± 0.004.
Component B to E: Sliding fit (RC5), diameters 0.23 ± 0.007 to 0.
Component D to E: Sliding fit (RC5), diameters 0.23 ± 0.007 to 0.
Component E to C: Interference fit (LN1), diameters 0.35 ± 0.004.
Component E to E: Interference fit (LN1), diameters 0.35 ± 0.004.

Prototyping:

Fabrication: We utilized a Bambu P1S 3D printer to produce parts with PLA material at a 0.15 mm layer height. Initially, we faced challenges with the Prusa MK3s+ at Jacobs Hall due to limited accessibility and encountered a thermal runaway issue with Prusas in Cory 246. However, the Bambu P1S successfully printed all components.
Off-the-Shelf Components: We sourced M4 shoulder bolts, locknuts, heat inserts, and M6 threaded nuts from Amazon to save time and reduce costs compared to in-house manufacturing.

Final Reflection and Improvements:

Our prototype successfully increased the surface area at the bottom of the crutch, mimicking a shoe to enhance stability and allowing the crutch to stand independently. The grip layer added to the bottom surface increased traction, fulfilling our vision for a viable long-term solution.
We identified several areas for improvement:
- Locking Mechanism: The current permanent locking mechanism, which wraps around the middle section, makes it difficult to detach the crutch quickly. An improved design would feature a temporary mechanism that does not require a screwdriver for adjustments, providing stability when attached and allowing for quick detachment.
- Height Adjustment: Increasing the height that the lock reaches could potentially boost the stability of the crutch.
- Bottom Shape: Modifying the bottom to a curved shape would better simulate the natural circular motion of human walking, smoothing out the crutch’s movement and addressing the rigidity introduced by the CrutchGuard.

Result

The CrutchGuard project successfully produced a functional prototype that met our design specifications and tolerances, providing enhanced stability and safety for crutch users. Despite initial challenges with design feasibility and manufacturing, the final product demonstrated significant improvements in stability and user safety. Reflecting on the project, we identified key areas for improvement, such as a temporary locking mechanism and design modifications for better movement and stability.

The project provided valuable insights into the practical applications of GD&T principles, teamwork, problem-solving, and engineering. By overcoming obstacles and iterating on our design, we learned the importance of flexibility and collaboration in engineering projects. This experience was both unique and educational, demonstrating our ability to apply classroom knowledge to real-world challenges and create a successful, innovative solution for crutch users.