Group 17: Gate 1: Project Planning
The purpose of this gate was to plan our dissection and analysis of the Homelite 26cc Line Trimmer. By planning how we will go about dissecting the product in advance, as well as delegating the tasks involved, we hope to set a structure that will be easy to build upon for the rest of the semester.
Project Management: Request for Proposal
Proper analysis of the weedwacker will require a full dissection. The weedwacker will be fully taken apart starting at the point where the motor meets the body. The motor and the rest of the weedwacker including the body, blade and shield will then be dissected and analyzed separately. The team will be divided into two groups one group will be dissecting the motor and the other group will be dissecting the rest of the weedwacker. Dissection of the product should take approximately three hours for the group or fifteen man hours to complete. In order to provide a reference for analysis the dissection will be videotaped, clips of the video will also be used to clarify the analysis report.
\'\'\'Tools required for dissection:\'\'\'
- Nut Drivers
- Pliers (needle nose)
- Screwdrivers (phillips, flat, and torx)
- Allen wrenches
- Ratchet and socket (deep well and standard)
- Possibly torx bits
- Snap ring pliers
The engine poses the greatest challenge for dissection. Its compact complex nature makes it challenging to maneuver tools inside of the engine to take it apart. Also, the engine’s many subsystems will make it difficult to analyze.
The body could also pose a challenge for dissection. The drive shaft is enclosed in a hollow cylindrical aluminum case, which could make it difficult to analyze the mechanisms used in the drive shaft.
The group’s main weakness is an ability to analyze the product with the intent of appropriately fulfilling the project requirements. The group has the mathematical understanding to analyze the product for mechanical function. However, analyzing the product in light of the design process responsible for the development of the weedwacker is a level of critical thinking unfamiliar to the members of the group.
Individually the members of the group possess skills that will help aid in the completion of the project. Jeff Scott has a developed understanding of engine mechanics and will be an asset in the dissection and analysis the weedwacker engine. Ryan Edmondson and Mike Gold are both strong in mechanical and physical assessment, as well as product research. Shawn Milligan is proving superior technical support by managing the group wiki website, as well as handling video editing. Ryan Fiust-Klink is responsible for developing and editing all technical documents produced by the group.
For each gate the work will be divided between the members as equally as possible based on time requirement. All work done will then be reviewed by the group, and then passed on to Ryan Fiust-Klink for editing, then given to Shawn Milligan to be posted to the wiki website.
The group plans to meet on Wednesday’s at 5:00pm in order to discuss assignment responsibilities and progress.
Ryan Edmonson - Technical Analyst
Mike Gold – Technical Analyst
Ryan Fiust-Klink- Report Editor
Shawn Milligan - Wiki Account Manager
Jeff Scott – Project Coordinator
Technical Analyst – check and review mathematical computations used in analysis
Report Editor – read and review all technical documentation for cohesion and completeness
Wiki Account Manager – upload and format all documentation to wiki
Project Coordinator – organize and communicate a plan for project completion
Preparation and Initial Assessment
- \'\'\'Development Profile:\'\'\'The weedwacker was developed in the early1970’s in Houston Texas. It is said the George Ballas, the designer of the original weedwacker, developed his design, to protect the bark of trees he needed to trim around. The weedwacker developed into a versatile lawn maintenance tool, intended to facilitate the removal of foliage. The product is marketable in any region or landscape with a maintainable lawn landscape.
- \'\'\'Usage Profile:\'\'\' The intended use of the product is the removal of unwanted foliage around the user’s property in areas where push and riding lawnmowers cannot reach. The Homelite Mightylite 26vt is for light duty residential use. The weed whacker can be used to remove foliage and edge driveways and sidewalks.
- \'\'\'Energy Profile:\'\'\' The system utilizes chemical potential energy, thermal energy and mechanical energy. Chemical energy, stored in gasoline, is transformed into thermal energy, in the piston cylinder. The thermal energy is then harnessed and converted into mechanical energy.
- \'\'\'Complexity Profile:\'\'\' The three main components of the weedwacker are the motor, the shaft, and the head of the weed whacker. The motor is the most complex component of the product. The throttle, shaft, and weed whacker head are all fairly simple due to their small number of parts and lack of complexity. The component interactions are all very simple due to the fact that they all depend on fittings, couplings, and cables. All of the component interactions rely on very simple mechanisms.
- \'\'\'Material Profile:\'\'\' Plastic, steel and rubber are clearly visibly utilized in the production of the weedwacker. There are most likely some other types of metals used within the weedwacker. Copper could be used in the ignition wire, and platinum or iridium in the spark plug. In addition, the crankcase and cylinder body are most likely made of aluminum or cast iron. Additionally, the air filter could also be made of some kind of cloth or paper.
- \'\'\'User Interaction Profile:\'\'\' The user interfaces with the product through the use of the throttle, pull cord, choke, primer, handle, and kill switch. The starting procedure may not be very intuitive, but there is a step by step set of instructions on the weedwacker’s shaft that guides the user through the starting process. The throttle system is very intuitive because you just squeeze the trigger to increase the speed of the motor/head, and release the trigger to decrease the motor/head speed. The only maintenance required is to change the spark plug once a year so that the product runs efficiently, keep the choke and throttle body clean, change the air filter regularly, and to refill the weedwacker string when it runs out. No oil changes are required because it is a two stroke motor, and the oil is mixed in with the gas. All required maintenance is very simple and virtually any user would be capable of performing it.
- \'\'\'Product Alternative Profile:\'\'\' Alternatives to the gas weedwacker include hedge trimmers and lawn shears. The advantages of these products are that they are cheap and require no gasoline. Other alternatives include electric weedwackers, with the closest competition coming from those powered by wet-cell batteries. The only maintenance necessary to hedge trimmers and lawn shears are is to sharpen them so that they cut correctly. The disadvantage to these products is that they are many times slower than the weed whacker that we plan to dissect. The difference in cost may only be about 40 to 50 dollars considering how cheap a weed whacker can be bought in 2012. Considering the small cost difference and the performance difference, the weedwacker is definitely the best choice for the job with all things considered.