Group 8 Gate 1
Project Management Proposal
An entire reverse engineering process for the chainsaw must be completed by December 16, 2011. This process includes a dissection of the chainsaw, a complete analysis of the components and systems, causes for corrective action, and thorough documentation of all the aforementioned. The time line for the for the analysis is broken down into five gates. Within each gate, a plan for work completion is proposed with numerous factors taken into consideration which include:
- Potential issues with dissection
- Other commitments by group members
- Available Lab Times
Proper time management is key to successfully completing a thorough analysis of the chainsaw. The project team has already had to overcome issues during the planning stages as result of losing two members. This in return has resulted loss of several hours of man power and potential capital for various costs throughout the course of the project. The remaining group members listed below play several key roles in the completion of the project.
Group Members and Responsibilities:
\'\'\'Joseph Kisch:\'\'\' Project Manager-
Joseph is in charge of properly managing the completion of the project in its entirety. These responsibilities include maintaining the work schedule laid out in the proposal and overseeing the dissection of the chainsaw is performed thoroughly and safely. Joseph is responsible for final review of all content being presented and that it is accurate as well as the overall perception is exceptional. Along with these duties, Joseph will share an equal role amongst the team with the dissection and analysis of the chainsaw. As project manager, Joseph is the main source of contact. His contact information is displayed below in Table 1:
|\'\'\'Contact Type\'\'\'||\'\'\'Contact Info\'\'\'|
\'\'\'*\'\'\'Note: The secondary email address is linked to his Blackberry so for all emails needing an immediate response, please use this email address.
\'\'\'Austin Snyder:\'\'\' Wiki Coordinator-
Austin is responsible for the primary formatting done on the Wiki page. All charts, graphs, and various figures as well as all content written by the group is inputted and formatted by Austin. Along with his duties coordinating all content being posted, Austin will be playing a vital role as well in the dissection and analysis of the chainsaw.
\'\'\'Dennis Ambrosio:\'\'\' Team Annalist & Dissection Coordinator-
Dennis is primarily overseeing the dissection of the chainsaw. He will be primarily be disassembling the chainsaw and documenting all measures taken. As a result of having the most experience with AutoCAD, Dennis will be responsible for any and all CAD drawings needed for presentation. As Team Annalist, Dennis is responsible for documenting all discussions amongst the group as well the primary outline of all written content being presented.
The strengths and weaknesses of the team members can be found in the Team Overview on the main page.
Group Meetings & Time Management Plan
At minimum, our group is planning on meeting three times a week to work together. Individual work will also be a necessity in order to stay on track. It anticipated that between 36-60 hours of work in terms of Man-power per week will be required for exceptional analysis and presentation. Figure 1 below shows a chart of the anticipated time schedule for each gate and individual component of the gate.
As a result of having an odd amount of group members, all decisions needing to be made within the group will be made on a majority-rules basis. Any significant conflicts and/or issues that may arise will result in the group seeking the advice of Instructors Phil Cormier and Andrew Olewnik, as well as the supporting Teaching Assistants.
In order to successfully reverse engineer the chainsaw, careful planning is vital. Failure to properly document dissection procedures can and will result in conflicts during reassembly.
Without the aid of exploded diagrams, a plan to dissect the chainsaw has been developed with the focus being around accessing and analyzing the centripetal clutch first (as a result that this is the key component for energy transfer in the chainsaw). Dissection will then continue to remove components around the motor in order to make further analysis. Any further dissection done will be done on the basis of observations made during the dissection of the motor and centripetal clutch. It is anticipated that proper dissection and analysis will take two weeks. In order for proper reconstruction, significant notes and photos will be taken as well labeling parts accordingly. From the initial inspection of the chainsaw, the key issue will be the order in which parts are removed. If this is not properly done, the group has the potential to miss something key to the analysis. However, with significant attention to detail, this should not be an issue. Required tools needed for proper disassembly should not be an issue as well. Based off initial observations, the chainsaw should be able to be disassembled with the use of many standard tools including:
- Socket Wrenches (Both English & S.I.)
- Screw Drivers (Both Phillips and Slotted)
- Allen Keys
- Star Keys
- Nut Drivers (Both English and S.I.)
Preparation and Initial Assessment
This model chainsaw is was developed within the last five years and is currently part of Craftsman\'s current line of power tools. When designing the chainsaw, it appears that a major economic concern was keeping the overall cost of manufacturing lower by having the majority of the exterior made out of plastic. This reduces the cost of materials significantly. It appears that the primary global concern is the interpretation of the instructions and safety warnings. The model purchased by the group includes instructions and safety warnings in both English and Spanish. Instruction manuals are available in various languages as well. As a result, the product can be sold globally however the primary market is in the U.S.
The main impact this product has on society is the reduced time it take to cut lumber and strain on the user. As compared to using an axe, the chainsaw can cut wood significantly faster. It also produces smooth straight cuts unlike the rigid cuts from an axe as you can see in Figures 2 & 3.
The intended use of this product is to cut trees, branches and other forms of wood in a timely and affordable manor. Chainsaws in general are intended for both home and professional use. However, the Craftsman 38cc 16" chainsaw is intended for home use. This is the result of the chainsaw being designed for lighter applications such as trimming limbs and cutting small trees rather than full-scale clearing of a forest area. This is the result of a smaller engine and blade size compared to those used for commercial purposes.
As in all common combustion engines, electrical, mechanical, and chemical energy are all vital in order for the engine to run. The same goes for the two stroke engine on the chainsaw as well. Initially, mechanical energy is required to make the engine turn over. The operator rapidly pulls on the rip cord to get the chain saw started. To keep the engine running, a combination of chemical and electrical energy create the combustion required in order for the piston to oscillate. A chemical reaction occurs between the gasoline-oil mixture and air when ignited by a spark plug. The pressure from the reaction forces the piston upward which in return creates mechanical energy to rotate the crank shaft. As the crank shaft rotates the centripetal clutch which is screwed onto it rotates as well. When the clutch spins fast enough it opens and connects with the drum around it that also is drive gear for the chain. When the drive gear rotates it moves the chain along with it. After combustion occurs, the engine emits the exhaust which as a result, loses energy in the form of heat. The throttle on the chainsaw uses mechanical energy as well. When the user pulls on the trigger, a small metal bar moves as well which is attached to a lever operating an air valve on the carburetor. In order to control the velocity at which the chain spins, the throttle controls the amount of air flowing into the piston cylinder which pulls the appropriate amount of fuel with it. As a safety precaution as well, the kill switch uses electrical energy to cease the operation of the engine. The kill switch grounds out the flow of electrons in the engine. This grounding does not allow the spark plug to produce spark which as a result prevents the combustion cycle to continue.
Without dissection of the chainsaw there a three components of the chainsaw necessary for it to function properly. The engine, the clutch, and the chain. The engine is a 38 cc two stroke engine which is fairly simple compared to larger engines like in lawn mowers or cars. The engine converts chemical energy in the fuel to mechanical energy through the crank shaft which turns the clutch. At low rpm’s and idle speed the spring on the clutch holds down the arms. When the rpm’s increase the arms are pulled out and lock onto the other half of the clutch called the clutch drum. The clutch drum is also connected to the drive gear. The clutch is fairly simple. It screws onto the crank shaft and the clutch drum rotates freely around the crank shaft. The drive gear pushes the chain around the chain bar so it can cut material. The chain is also very simple. It looks and works much like a bike chain however sharpened pieces are also put it for cutting. The interaction between all the components are also simple. When the crank shaft turns the clutch turns with it. When the clutch turns at the right speed the clutch drum turns with it. And when the gear turns the chain turns with it.
Without any significant investigation on the internal components on the chainsaw, it has been observed that on the outside, plastic is primarily used in order to protect all the vital internal components. As a result of part of the engine block being visible externally, it has been determined that it is made out of aluminum. It has also been the determined that the chainsaw blade and chain are made out of carbon and steel as well.
The interaction between the operator and the product itself is relatively simple. The user starts the engine through the use of the ripcord. The amount of energy required to start the engine is reduce by allowing the user to control the air flow to the carburetor through the use of the choke switch. The priming bubble allows the user to pump gas through the fuel line in order to remove air in the line. With the engine running, users engage the blade through the use of the throttle. The device can easily be turned off through the use of the kill switch. The blade can also be disengaged without the engine having to be shut off through the use of the chain break. There are safety measures required in order to allow for safe operation. For example in Figure 4, if a the operator tries to cut a piece of wood with the tip of the blade, the chainsaw has a greater ability to kickback towards the operator. The kickback is the result of the chain rotating clockwise so when the user goes to cut wood with the edge of the blade, instead of the blade penetrating the wood, the force from the chain will make the blade bounce back into the user Therefore it is important to cut near the center of the blade.
Moderate but straightforward routine maintenance is required to keep the chainsaw operating at an optimal level. First off, as a result of the two-stroke engine, a specific ratio of gas and two stroke engine oil must be mixed together before filling the gas tank. According to the instructions for the Craftsman 16” 38cc chainsaw, the gas to oil ratio is 40:1. Proper lubrication of the chain is required as well. Therefore the chain oil levels must be properly managed. Even though the chain is lubricated, the chain will still get dull eventually. As a result, the chain must be replaced periodically, depending on the amount of use and hardness of wood being cut. The air filter will eventually need to be replaced as well. This part can be easily order off of Craftsman\'s website Finally the tension of the chain must be kept tight at all times. Craftsman designed a system for the user to easily do this without having to keep taking the chainsaw apart. A dial on the side allows for the tension in the chain to be increased and held with ease.
\'\'\'Product Alternative Profile:\'\'\'
An alternative to a chainsaw is an axe. One main advantage to an axe is that it is much less dangerous and complicated than a chainsaw. An axe does not need any outside maintenance such as filling it with oil and is more portable. An axe has no internal mechanisms or engine and is a very basic tool and can be used for basic wood cutting. One disadvantage to an axe is the need for the users own mechanical energy and skill when cutting down a tree or branch. Unless a person is a skilled axe man, a chainsaw is much easier to use because it does not need a swinging motion or any physical energy besides holding it and applying pressure. The difference in the cost of a chainsaw and axe will vary but for most cases, a new chainsaw will cost more than a new axe. A chainsaw for home use can be priced in the one hundred to two hundred dollar range and an axes cost is roughly in the fifty dollar range.