ENGR 100
Engineering Design Portfolio

Coursework Overview

Entries are grouped by assignment rather than assigned to unverified calendar weeks. Each records the objective, approach, and current outcome.

Lab 01 — 3D Modeling from Orthographic Drawings

Objective: Develop 3D CAD models from provided orthographic engineering drawings and produce dimensioned drawing views.

Methods: Used Onshape sketches on reference planes, dimensions and geometric constraints, extrusion and fillet operations, then generated orthographic views.

Results: Documented a modeled part and its related drawing in the submitted Lab 1 report. This exercise strengthened the connection between a 2D engineering drawing and a 3D solid model.

Lab 02 — CAD Modeling Basics

Objective: Continue developing 3D visualization and dimensioned engineering drawing skills.

Methods: Used Onshape to build and document geometry based on orthographic reference drawings. The submitted file is named “LAB 2.1,” but this portfolio groups it as Lab 2, consistent with the course numbering correction.

Results: Additional drawing pages are present in the submitted report. These examples show the continuation of the CAD modeling and technical presentation exercises.

Note: the original Lab 2 file retains a “CAD LAB 1” cover heading; the original has not been altered.

Homework 03 — Lower-Leg Anatomy and AFO Research

Objective: Study lower-leg anatomy and existing assistive devices as research for a personalized ankle-foot orthosis (AFO) addressing foot drop.

Introduction: My experience with MS-related foot drop makes this project personally relevant. The research asks how a support device might improve toe clearance while remaining practical to put on, wear and use.

Anatomy reviewed: Knee structure and movement; ankle dorsiflexion and plantar flexion; and the foot and toe joints that contribute to walking and support.

Existing designs: The report compares two prosthetic examples (Össur Pro-Flex LP and PROPRIO FOOT) with two braces (Ottobock 28U90 and Allard ToeOFF 2.0). Prostheses replace a missing body part; orthoses support an existing one.

Design considerations: Footwear compatibility, comfort, hand dexterity, seated positioning and toe clearance are proposed priorities. This is a literature review, not a fabricated or clinically validated brace.

Outcome: The research established a foundation for future AFO design and highlighted trade-offs between support, motion and everyday usability.

Figures are reproduced from my HW3 report; their original source captions and references remain in that report.

Homework 02 — Zipper Buddy

Objective: Create a small device with a moving feature that makes a zipper tab easier to grasp and pull.

Introduction: I designed a pear-shaped wire attachment, resembling a broad safety-pin loop, using bent clothes-hanger wire. The narrow end attaches to a zipper pull while the large loop offers a more accessible gripping surface.

Methods: I developed the idea as a sketch, built a physical wire prototype, tested it in everyday use, and then modeled the concept in Onshape to document the geometry more clearly.

Results: The Zipper Buddy worked very well during actual use. The main limitation was that it could sometimes be awkward to grab when the loop was oriented unfavorably. This was a minor usability issue, not a failure of the concept.

Summary / next iteration: The prototype met its functional goal. A thin rubber coating or grip sleeve may improve tactile grip and ease of handling; this remains a proposed improvement, not a tested modification.

Testing note: Performance is reported from practical use. No cycle count or quantified load data is claimed.

Design progression

Testing observation: The tool performed well in use. Occasionally it was awkward to grab when the loop was not oriented conveniently; a thin rubber coating remains a possible grip improvement, not a tested change.

Lab 03 — WHILL C2 Wheel Reverse Engineering

Objective: Reverse engineer the front omnidirectional wheel of my WHILL C2 power chair and develop an approximate CAD representation of its visible geometry and assembly.

Introduction: The wheel has alternating large and small rollers and overlapping contact geometry that allow sideways motion. It is an especially useful study of mechanical packaging, rotating parts and geometric repetition.

Methods: Photographed the wheel, took accessible measurements without removing it, studied the related WHILL patent, and began an Onshape front-view sketch. Construction geometry divides the circumference into ten positions at 36°, with five repeating groups at 72°. Roller positions and simplified outlines have been explored in 2D.

Assembly observations: The visible construction suggests inner and outer support plates connected by five through-fasteners secured with nuts, alongside central hub and bearing elements. Hidden details remain tentative.

Measured and assumed dimensions

Patent figure visual reference — correct WHILL patent

These visual references are taken from the correct patent page for the wheel studied in this project: US11938752B2 / application US17/774,603. I used these figures to interpret the hidden support structure, axle region and alternating roller layout.

Measurement note: The physical wheel was measured at approximately 10 inches across, and the tire is marked 257 × 63. Roller lengths measured were 3 inches (small) and 2¾ inches (large). Other dimensions used in the CAD model, including estimated bore and outer roller diameters, should be treated as assumptions unless directly measured.

Why both are used: The patent figures help reveal the hidden structure and repeating roller/support pattern, while my own photographs and rough measurements help ground the CAD model in the actual wheel on my chair.

Current results: Initial 2D CAD layouts show the circular reference geometry, radial pattern and representative roller envelopes. A finished 3D model, verified roller profiles and exact hidden dimensions are not yet complete.

Summary / next steps: Refine the roller curves, build a simplified support plate and hub, and use circular patterns to create a complete representative assembly. The goal is a documented engineering approximation, not a manufacturable replacement wheel.

Patent reference: US11938752B2 — WHILL omnidirectional wheel. Patent drawings inform the architecture; dimensions marked as assumptions are not measurements supplied by the patent.

Major Design Project — Assistive Arm Concept

Project: Upper-limb assistive/prosthetic design concept developed around a remaining upper-arm attachment area and a modular wrist/terminal interface.

Design considerations: User attachment, weight, gravity assistance, range of motion, removable attachments and practical mounting points.

Planned development: Rough physical concept → CAD refinement → fixture-based verification → design iteration. These are planned phases; no unperformed tests are presented as completed results.

Safety: Any load-bearing or body-mounted prototype would need appropriate supervised evaluation before use.

Onshape — Progress Screenshots

These are real screenshots from my current reverse-engineering workflow, showing the development of the wheel’s front-view roller layout.