Reverse Engineering a Hedge Trimmer: A Practical Approach to Incorporate Geometric Dimensioning and Tolerancing (GD&T) Effectively in an Undergraduate Freshman Engineering Course

Geometric Dimensioning and Tolerancing (GD&T), due to the inherent complexity, is a challenging topic to teach and learn, especially at the undergraduate freshman level. Many institutes either cover GD&T on a superficial level or choose to overlook it. Incorporating such a broad subject in an already busy curricula remains a major challenge for many academic institutes, including ours. The knowledge and skill level of our students in GD&T at the beginning of their co-op is a major concern for several employers. These employers have to expend significant resources to train our students and graduates. To address this growing concern, a practical project was incorporated into a freshman introductory engineering course; a Ryobi hedge trimmer Model No. RY39500 was utilized. The students were divided into five groups, and each group was given a mechanical component from the assembly. First, each group was tasked with taking the necessary measurements to create a Computer Aided Design (CAD) model of their component in an effort to commence the reverse engineering process. The CAD model was then additively manufactured using fused deposition modeling. A detailed drawing of each component was created and GD&T concepts and symbols were applied to the drawing following ASME/ANSI Y14.5-2009 standards. The project was very well received by the students. It enhanced their understanding and skills necessary to implement GD&T concepts and symbols both in practice and in preparing engineering drawings. The 3-D printed parts were shared among the groups and the manufactured parts were fit together to replicate the real life assembling.