MAXV

A novel solution for wild land firefighters.

Overview

Course: Thesis Project

Focus: Research; Ideation; Mechanical Design; Prototyping; Storytelling

Timeline: August 2020-May 2021

Role: Mechanical Design and Manufacturing Lead

Background and Need

In 2020, the US saw nearly 60,000 wildfires destroy over 10M acres of land, costing the country $2.3B to suppress. This was the 2nd most devastating season on record, and the top 3 most devastating seasons occurred in the last 5 years. It’s estimated that the total financial cost of a wildfire season is actually between $130B-$150B, and it is only getting worse. This year to date, we’ve already doubled the number of acres burned during the same period last year.

Fire is natural and necessary, however, climate change and human activity are creating optimal conditions for fast-moving fires that impact areas more frequently than nature intends. In California, the fire season now runs from June until April, with just one month of reprieve in May.  This exhausting season, coupled with low federal support, puts pressure on already strained wild land firefighters. Thus, our goal was to make fighting fires safer, easier, and more efficient for the firefighters who risk their lives protecting us.

Research and Insights

The goal of wild land firefighters is to contain wildfires and let them burn out on their own by anchoring the fire in a strategic location, manually digging landlines, and flanking the fire until a circle is formed and the fire is pinched off. Firefighters that my team spoke with unanimously highlighted the importance of being as efficient as possible while performing the physically demanding task of creating landlines. There are many ways to improve firefighting efficiency, but our stakeholders drew a key connection between the sharpness of their tools (such as the Pulaski, shovel, and Mcleod), and the ability to complete their tasks quickly and efficiently.

 Ideation and Modeling

After running two co-creation sessions with firefighters from around the country, my team created a list of design elements that would help us define an in-the-field used tool sharpener that would promote more frequent tool sharpening. We ideated around these criteria and started modeling concepts for prototyping.

The following were some of our initial design criteria: our tool must improve sharpening efficiency, be durable and reliable, be lightweight and compact, allow for one-hand use, be low cost, have an ergonomic and safe grip, work in combination with existing files, work for multiple tools, and not require expertise or power.

 Prototyping and Testing

The design for the MaxV began with testing possible abrasive types in conjunction with various ways of holding them. A challenge with sharpening is that different tools have different blade angles. Additionally, there are a variety of personal sharpening styles - for example some firefighters like to push the abrasive, while others like to pull. With this in mind, we found diamond coated abrasives to be the most versatile, as they allowed for multi-directional use. To accommodate different blade angles, we placed them in an adjustable “V” configuration, initially with two bits but eventually adding a second set to help guide the user. This allowed for a simple swiping action that could be performed easily with one hand. When firefighters need to remove more material however, the traditional bastard file still performs the best; so, we ultimately combined the two in an improved ergonomic form factor to offer maximum flexibility for sharpening and honing blades.

We conducted our initial user testing with fellow students and faculty, focusing on refining the ergonomics and safety of the product. After multiple iterations, we had a working design that was ready to be sent out to real stakeholders.

We got excellent feedback from people in the consumer segment, who tested it on multiple gardening tools and commented on its ease of use. And, despite coinciding with the beginning of the wildfire season, we were able to get prototypes into the hands of some of the firefighters we connected with in our initial research and co-creation sessions. They loved having both methods combined into a single tool, and thought it would be very practical in the field. The main point of improvement that was suggested was making the grit of diamond abrasives coarser, which fortunately is an easy fix for future iterations.

MaxV, From the Front Lines to the Front Yard

Mechanism and Product Design

The angle of the abrasive teeth is controlled by the same gear mechanism that’s used in adjustable crescent wrenches. This worm gear design prevents backdriving by the teeth, which means that the angle stays fixed without the need of an additional lock. The double set of abrasive teeth guides proper alignment with the users tool. Not captured in this render is a laser-etched angle read-out that provides an accurate reference for people using the MAXV on a variety of tools.

The diamond abrasives themselves each have a magnetic hexagonal shaft, similar to a drill bit, which enables them to be turned to a fresh side as wear occurs, and eventually be replaced entirely as needed. The quick and guided action of sharpening with the adjustable teeth allows for tool blades to be regularly honed during use.

For the larger nicks and chips that occur less frequently, a bastard file is also available in the MAXV. Featuring both single and double cut sides, the file can be pushed in position using a recessed slider. Firefighters and consumers expressed excitement over the sliding bastard file feature of our design, so we iterated on orientations of the design that would fit seamlessly into our small handle envelope. With this feature, the MAXV remains compact, lightweight, and easily usable, even with the gloves worn by firefighters, landscapers, and forestry professionals.

The file movement is controlled by a spring loaded slider that connects to a carriage that runs inside an indexable track. This allows the user to select an ideal file length that can for any particular task. Bastard files also wear over time, so when a replacement is needed, the handle disassembles easily, allowing for the used file to removed from the carriage and replaced with a new one.

Design for Manufacturability

The MAXV was designed to be compact and durable, and key design decisions were made to ensure manufacturability and assembly at scale. The product contains two major sub-assemblies that house to two sharpening options.

The head sub-assembly includes the diamond files and their holders, controls the movement of the adjustable teeth with the gear train, and includes a protective finger guard. This entire subassembly will be made out of aluminum, to ensure durability and mechanical precision.

The handle sub-assembly connects the 2-part handle to the head with two screws, and houses the retractable file mechanism. The handle was designed to be easy to grip, comfortable to use, and durable for quick use in the field.

Each individual component was designed with a specific material and manufacturing techniques that align its geometry with desired performance metrics. Notably, the head subassembly features multiple aluminium profiles which are screwed and pinned together. These complex geometries will be achieved by machining features into die casted parts. Our handle will be injection molded as two parts out of glass filled polypropylene, which is economic and durable, and also reduce weight. The carriage and sider of our file mechanism will be stamped and formed out of sheet metal. In addition to manufacturability and feasibility, these processes were also chosen to be cost effective at our target volumes.