Revision as of 23:39, 28 November 2012

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Introduction

As the final part of the project, this section wraps the entire wiki together. It includes the product reassembly, as well as further analysis of the product. The product reassembly provides step by step instructions on how to put the chainsaw back together. The mechanism section explains how different mechanism provide different motions or interactions within the chainsaw. The final section includes the design revisions on a system level that are believed to make the chainsaw more profitable and appealing the target audience.

Project Management

By this point in the project, all of the problems within the group have been settled. We had our problems, as discussed in previous sections, but they have been worked out and overcome. The only problem facing the project this time is Thanksgiving Break. It prevents the group for meeting for basically an entire week. To overcome this obstacle, each member of the group was assigned a small portion of the project that could be done on an individual basis before the break was over. Then, after everyone was back together we could do the final portion of the project, the product reassembly.

Product Archeology

Tools Needed

• Flathead Screwdriver
• 7/16" Socket Wrench
• 5/16" Socket Wrench
• 1/2" Socket Wrench
• Long 5/8" Socket Wrench
• 5/32" Allen Key
• T20 Torx Head Screwdriver
• T15 Torx Head Screwdriver
• Scissors
• Needle Nose Pliers
• Pliers
• Vise

Table 1 shows a step by step reassembly of the chainsaw. It includes detailed descriptions of the instructions, tools required to complete each step, any notes that we have discovered during our reassembly, a difficulty scale, and a picture or any important or ambiguous part in the step. The difficult scale is on a range from 1-5, 1 being the easiest and 5 being the hardest. The difficulty scale is based on the number of tools required to preform the step, the force need to dislodge a component, the ease of accessing the component, and our personal experience from dissecting the product.

Product Assembly By Steps
Step	Description	Tool Required	Difficulty of step (1-5)	Important/Ambiguous Part Locations
1	Screw in the black tuning screws labeled "hi" and "lo." Put on the black gasket. Then screw both cylindrical gates back on, being sure each gate is on the proper side. Also, screw the lever assembly (in red) back together. This metal assembly is very small and contains a pin, a lever and a spring.	Flathead Screwdriver	3	Lever system (in red) and various other carburetor parts
2	From the carburetor, screw in the four screws that have washers on them shown in red. Be sure to note the order in which the gaskets, plastic reservoirs, and metal pieces go. This is shown in the picture to the right.	Flathead Screwdriver	1	Carburetor exploded view
3	Very carefully assemble the 20 roller pins around the outside of the crank shaft and screw in the two T15 torx screws holding the rod to the crankshaft. Next, put the two big and two small spacers back on the crankshaft.	T15 Torx Screwdriver	5	Exploded view of rod assembly
4	Re-bolt the crankshaft by holding the crankshaft in a vise while securely screwing in the 7/16" nut, on the brake side, with a socket wrench. The nut is threaded the opposite way so turn it counter-clockwise to screw it in. Be sure to use a lot of force to get it secure. Re-bolt the other 1/2" nut from the other side of the crankshaft holding together the brake assembly and magnet head. The magnet will need to be hammered into place to ensure it remains secure.	7/16" 1/2" Socket Wrench Vise	4	Exploded crankshaft and rod
5	Next connect the carburetor and alternator. From the alternator, connect the grounding wire, and the on/off switch wire. From the carburetor, place the three plastic tubes in indicated slots and the gasket separating the carburetor and the combustion chamber. Use needle nose pliers to put the throttle cable back on by bending the wire to fit through the hole and cramp back on. Screw the 3 torx head screws with a T20 torx screwdriver.	T20 Torx Screwdriver, Needle Nose Pliers	1	Remove three screws. (in red)
6	Put the piston/crankshaft assembly into the combustion chamber. Screw in the four flathead screws, highlighted in red, holding the casing of the crankshaft to the combustion chamber.	Flathead Screwdriver	1	Remove four screws (in red)
7	Replace the casing on the drivetrain as depicted in the image to the right. Screw in the three flathead screws holding the wrap around casing to the drivetrain system.	Flathead Screwdriver	1	Removal drivetrain system from case
8	Replacing the trigger is a tricky step so it is broken into two steps. The trigger should be connected at the top of the wrap around casing by a spring. Use needle nose pliers to bend the spring back in. This spring is highlighted in gold in the image to the right.	Needle Nose Pliers	3	Spring (in gold) being removed
9	Replace the metal wire connecting the trigger and the throttle. The wire is highlighted in red in the picture to the right. Use needle nose pliers bend the cable back on. This step is especially difficult because bending the metal wire requires some force applied with the pliers. The wire is located in a tight space which also makes the process harder.	Needle Nose Pliers	5	Throttle Cable (in red)
10	Put the choke lever on and screw in the flathead screw that it holds it in place. The screws are highlighted in red. The lever is a small black lever plastic piece on the left side near the red engine switch and shown in the picture. Also put the plastic handle back on by screwing in the two flathead screws with a screw driver. Next, put the spark plug wire back on then screw the spark plug on with a long 5/8" socket wrench. This needs to be a long socket so that it can reach the nut portion of the spark plug. A wrench of the same size can be used but it is harder to maneuver in this situation.	Flathead Screwdriver, Long 5/8" Socket Wrench	2	Remove screw (in red) holding on choke
11	Next detach the exhaust. To do this, remove the outer screws with a 5/32" Allen key. These screws are highlighted in red in the picture. This holds on the exhaust cover plate on. Removing the cover plate reveals two more 5/32" screws. Remove them with the Allen key and remove the exhaust.	5/32" Allen Key	1	Two screws (in red) holding on the exhaust cover plate.
12	To put the tanks back on simply slide them back into the closure as shown until the tab shown in red snaps into place.	Table Cover 5/16" Socket Wrench Flathead Screwdriver	4	Tab (in red) located on the bottom of the case.
13	Next, put the starter housing back on. Screw in the four flathead screws. These screws are highlighted in red. Pull the started cord back through the housing and tie it back on to the started handle. Be sure to replace the filter that covers the air intake.	Flathead Screwdriver Scissors	1	Remove four screws. (in red)
14	Put the blade, chain and aluminum handle back on. First, slide the blade on horizontally, allowing you to then put the chain on by wedging it around the blade and the drive wheel. Putting on the chain takes a little work but twisting the chain a little can help ease the step. To put the aluminum handle on, first put it in place then screw in the 5/16" bolt with a socket wrench,located on the top, and the flathead screw with a screwdriver, located on the underside. The bolt is highlighted in red.	5/16" Socket Wrench Flathead Screwdriver	3	Removing bolt and screw to take off aluminum handle. (in red)
15	Turn the brake handle 180 degrees so that it can be put on. From the brake assembly, use pliers put on the pivot lever. This lodges the spring and the black lever. Then screw in the two flathead screws using a screwdriver highlighted in red. To put on the brake assembly which is located on the chain side of the chainsaw, screw in the 7/16" nut, and 7/16" bolt using a socket wrench.	7/16" Socket Wrench, Flathead Screwdriver	1	Removing two screws, a nut and a bolt. (in red)

Table 1: Step by step dissection of chainsaw.

Mechanism

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Design Revisions

Change #1

Ease of Use

Reasons for Redesign

Chainsaws may not be the most complicated product on the market to use but in order to expand the target audience of those who are purchasing them, it would be beneficial to have a simple to use chainsaw in order to convince a new group of people to buy the product. This chainsaw could become much easier to use with a few small changes including electric start as well as placing clearly marked instructions on the product itself so that customers don't need to look through the manual to understand how to use the product for its most basic uses.

Design Considerations

Easier to use chainsaws would expand the number of people who could work in fields that required chainsaw use as it lowers knowhow that most chainsaw users must currently have. Making the product more intuitive would close on the reputation that chainsaws are difficult to use or only for those who are "handy". This new chainsaw would be something that could be picked up and used by someone who has never used a chainsaw before without needing to read the manual.

With this more intuitive chainsaw being in the hands of less experienced users it is only proper to assume that users will have little experience maintaining them correctly, therefore when an issue arrises they will take their chainsaw strait to a mechanic to fix it. This will result in higher cost of ownership as well as a rise in demand for small appliance maintenance.

Effect on Target Audience and Price

With nothing but new features being added to the chainsaw it would come at a higher cost. Not only would redesign be an obvious cost but the additional features would only be additions to the everyday chainsaw so cost of supplies would also come into play. When a product becomes more intuitive it becomes able to be used by a larger target audience however those who currently know very well how to use modern chainsaws will not prefer these more intuitive chainsaws as they will have a higher cost. This being said it is safe to assume that the target audience of this new chainsaw will be new to the chainsaw market. People buying their first chainsaw will be very attracted to this product and would likely buy a chainsaw with these features in the future as well. At first sales would be slow but as time progresses this market will eventually include the majority of those buying chainsaws. Cost of these features would likely decrease over time as they become standardized. This is very comparable to the automatic transmission in modern cars.

Change #2

Safety

Reason for Redesign

As easy to use as a chainsaw may become, several people are scared to use chainsaws because they are very powerful and have a reputation of being dangerous. Misused, a chainsaw will easily sever limbs if not severally wound people. A chainsaw could be made safer by giving it new features such as a safety switch similarly to what is found on guns, as well as a blade guard that is automatically moved out of the way when the trigger is pulled. One more way to make chainsaws safer would be to put an accelerometer in the blade that would detect kickback and deploy the guard when it is detected.

Design Considerations

According to the US consumer Product Safety Commission, there are approximately 100,000 chainsaw related injuries annually. The largest cause of which was due to kickback. With safety features in place to prevent these injuries hospitals country wide would have much less traffic. This would not only decrease the number of deaths due to chainsaw related incidents but free up hospitals to prevent deaths due to other causes.

Economical-

With more features being introduced to the chainsaw it would have a higher likelihood to malfunction. With the

Environmental-

Similarly to the example posed previously, longer strokes would be more efficient on fuel. This would mean that less octane would be burned and therefore less CO2 would be emitted to the environment. With the ever growing concern of greenhouse emissions in mind, this chainsaw would have a much smaller carbon footprint than previous models.

Effect on Target Audience and Price

This price of this chainsaw would be a bit more seeing as it would require more materials. The longer stroke requires the entire engine to be larger as the circular radius of the path that the piston rod travel would have to be larger in order to move the piston a further distance. The longer the stroke is, the larger the radius of the circular path that the piston rod is traveling. Looking back at the group's engineering analysis section, it is noted that an increased radius would result in a higher torque and therefore higher horsepower. So the engine would not only be quieter and more efficient, but also have higher torque. The target audience for a product like this would be almost everyone who would buy a normal chainsaw; however, this model of chainsaw would necessarily have a larger engine and therefore be a bit heavier than a normal chainsaw. This being said, it is more likely to target those who are more physically fit and who are looking to boost performance. This product would largely target yard work companies that wouldn't mind paying a little extra to have a much higher quality chainsaw.

Change #3

Ergonomic Rubber Grip Handle

Reason for Redesign

The current handle system attached to the Eager Beaver chainsaw is simply an aluminum handle screwed into the chainsaw by 2 screws on either side. If the handle were to be altered to fit the shape of a hand and coated with a rubber exterior, there would be several positive effects. Seeing as the chainsaw is often used for an extended period of time, it would increase comfort of the user immensely. Holding a heavy chainsaw by a metal handle given that the vibrations of the chainsaw would travel up the users arm and cause discomfort. Rubber would act as a shock absorbent material that would fit into the users fingers and spread out the surface area. This would result in the most comfortable user experience by the user. The new handle would no longer be removable as it would be a part of the body, so serviceability of the engine would have to be slightly altered so the body could still come apart.

GSEE Considerations

Societal-

People who work for yard work companies would be using this device for several hours at a time. With a metal handle this would cause much discomfort and in some cases medical damage may be caused by extended exposure to vibrations up the users arm. This new ergonomic handle would help prevent this from happening.

Environmental-

Although little rubber is needed to make this handle, it is noteworthy to keep in mind that rubber is made in part from oil which is a limited resource. It is possible that rubber may become an impractical resource to use on this handle over time.

Effect on Target Audience and Price

The shift in target audience would not be very significant since almost anyone who uses a chainsaw would prefer a more comfortable handle but it would particularly target those who use chainsaws for many hours a day and do not want to have sore arms. This being said, the price tag of this chainsaw would be slightly higher than it would have been previously since there would be a necessary raise in cost of production given more supplies used.

US Consumer Product Safety Commission article- http://www.cpsc.gov/CPSCPUB/PREREL/prhtml80/80023.html