Kai Scott - Product Insight

During my internship at Product Insight, I had the opportunity to contribute to projects across various stages of the product development process, from early problem definition and prototyping to testing and improving previous projects. Product Insight’s consultant-driven approach gave me exposure to a wide range of challenges and methodologies.

I supported the team by updating and improving CAD models and engineering drawings to resolve assembly and manufacturing issues, designing an assembly fixture to streamline a large-scale assembly process, and creating a dynamic testing fixture to analyze material properties under harsh environmental conditions.

Project 1: Robotic Gantry Improvements

This project focused on redesigning components of a robotic gantry used in harsh environments. Improvements were implemented based on lessons from the first build, with a focus on assembly accessibility, mechanical reliability, and ease of manufacturing.

Collaborating closely with the mechanical design and manufacturing teams, I modified existing parts, assemblies, and drawings to streamline installation, improve reliability, and reduce error-prone procedures.

I have selected one of the more complex reworks to share.

Problem A: Fastener Access

The spring-tensioner boss, seen in the image, houses a spring connected to a timing belt pulley. The spring is preloaded to a determined value to tension the timing belt. The original design integrated the spring tensioner boss into the main frame, blocking access to eight bolts. This prevented proper torquing of fasteners during assembly. Cable routing options were also limited by this design.

Solution A: Removable Tensioner Boss

To restore fastener access, I redesigned the tensioner boss as a removable component.

The updated design:

• Retains all mechanical function

• Includes a mounting flange for installation

• Allows torque wrench access to all fasteners

Problem B: Jam Nut/Nut Access

During a discussion with the manufacturing team, a second issue was identified: there was no effective method to hold the preload nut in place while torquing the jam nut inside a recessed bore. The concerns included:

Inaccurate spring preload settings
Poor nut retention under high vibration
Risk of mechanical failure in demanding environments

Design Requirements:

The solution must secure the preload nut to maintain spring tension in high-vibration environments
Preferably, the solution does not require custom or specialty tools

Explored Concepts and Limitations:

Crow’s Foot Wrench

- Not enough clearance in the bore for even the lowest-profile options

Injector-Style Socket

- Bore access may allow entry, but angular misalignment between the nuts prevents removal

Face-Drive Fastener

- Inspired by angle grinder nuts; could work with a pin wrench, but would require both a socket for torquing and wrench for retaining while jamming

Castle Nut with Cotter Pin

- Lacks fine adjustment, risking over- or under-tensioning of the spring

Lockwire

- Provides security but significantly increases assembly time and introduces a specialty process

Solution B: Nut Locking Tab

After evaluating multiple approaches, a nut-locking tab was selected for its simplicity, reliability, and ease of use.

The tab captively retains the preload-nut from rotation, secured in position by the bolt. This achieves the same properties as a lock-nut; keeping the preload-nut at its specified torque in harsh environments.

Features:

• 12-point star cutout allows 30° rotational capture

of the nut

• Additional 31° slotted mounting hole allows full

360° retention

• Eliminates need for a jam nut, simplifying

assembly and improving fastener security

Problem C: Part Count/Assembly Time

The tensioner, pulley, and spring system required assembly from multiple angles in a constrained space, resulting in:

• A high part count

• Time-consuming and error-prone assembly

• Limited tool clearance due to other surrounding components

The image shows the original assembly process, requiring component installation from various sides in confined spaces. The next goal was to make the entire pulley/tensioner assembly a separate subassembly, simplifying the assembly process.

Solution C: Pulley/Tensioner Subassembly

By enlarging the pass-through opening and

separating the tensioner into a pre-assembled

unit:

• The entire spring-pulley system can be

assembled outside the main gantry frame

• Installation becomes a drop-in process, reducing

time and complexity

• Risk of assembly errors is reduced

Imaged on the right is the new pulley/tensioner

subassembly.

Bungee Lifecycle Test Fixture

To evaluate the feasibility of replacing steel cables with bungee cords in a product, I designed and fabricated a low-cost test fixture to simulate demanding real-world operating conditions.

Design Objectives

Replicate service conditions, including a temperature range from –40 °C to 75 °C.

Apply 25% elongation per cycle to the bungee cords.

Enable high cycling speeds (RPM) to accelerate testing while maintaining realistic strain profiles.

Achieve 75,000 test cycles per specimen to validate multi-year service life expectations.

Fixture Development

Developed a mechanical cycling system capable of repeatedly stretching bungee cords under controlled elongation in a wide temperature range

Designed for durability and ease of monitoring to support extended multi-day test runs without intervention.

Outcome

The completed fixture allowed the team to conduct accelerated lifecycle testing of bungee cords, providing critical data on durability and performance under harsh operating conditions. This work enabled an informed comparison between bungee cords and traditional steel cable solutions, guiding future material and design decisions.

Trigonometry - equations to convert motor torque to linear force

Force over cycle count graphs, indicating a minor reduction in tension force over cycle count