Group 9 2012 Product Dissection

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Contents

Introduction

The purpose of gate 2 is to physically dissect the product. This includes:

  • - A cause for corrective action where we will analyze the mistakes that we made when completeing gate 1, and describe our solution to prevent this from happening again.
  • - A difficulty grading criteria that we will be using to analyze the difficluty of each step during the disecction of our product.
  • - A parts list that provides the name of each component and define it\'s purpose in the gun.
  • - A step by step breakdown of how the entire gun comes apart


Cause For Corrective Action

So far we have had trouble with creating a proper plan for completing the first gate. This forced us to rush to get the work done at the end. So we created this plan as a group to prevent this from happening on gate 2. We made one group meeting for a short time after lecture on the due date of gate 1. This allowed us to get our group completely organized for this upcoming gate. The communication liaison figured out the best time for our group to start the dissection stage. He matched the dissection lab schedule to our group members schedule and found the best fit for the date that we would complete the dissection. We also organized a meeting to work on the written part of the gate and steps of the dissection. We are also planning a visit to the professor’s office hours on Tuesday from 10 am to 12 pm. We want to addresses any of the parts that we were unsure about, as well as get some advice about the best way to improve our weakest parts of the gate. The communication liaison will then create a final meeting to make any necessary improvements, as well as at thorough check of our grammar. As was said in our original plan, “we will add extra meetings each week as we see fit. This will be especially important once we get to the dissection stage of the project, which will require the group to work together for longer periods of time.” So using these extra meetings will account for this extra required time for this gate. We have this plan set because of conflicts that we encountered on our first gate. Due to improper planning and poor communication we ended up working on the gate to close to the due date. This allowed no time to receive any help from TA’s or the professors, as well as not have as thorough check of each group member’s work. So we created this plan which will allow us to have the proper time to do all work initially, as well as have a time set, that works for all members and sufficient time to do final polishing. This will prevent any rushed work from being submitted in the final copy of gate 2, as we ran into with the first gate. Possibly the biggest step towards improving upon our performance on gate 1 is going to office hours. This will eliminate any questions that we have on what is required for certain areas, and will prevent us from submitting work that we aren’t sure about. The chart below outlines each step we need to go through and what the anticipated amount of time is needed to complete it.

Task Time required
Dissection process 1 day
written assesment of dissection process 5 days
visit professor office hours Tesday 10:00 - 12:00
Edit and polish 3 days

By the end of the gate, we were able to follow this overall plan this I feel will lead to a much higher grade than we recieved for gate one.

Product Disecction

Difficulty Scale

Difficulty for the following steps are rated 1 to 3 as shown. The difficulty scale is measured based on the difficulty compared to the other assembly steps. The difficulty was measured based on the amount of time spent, number of tools needed and the force needed.

  • 1: Easy: Minimal effort required. No tools needed and took less than 30 seconds
  • 2: Moderate: Single tool needed and took from 31 seconds to 1 minute and 30 seconds
  • 3: Difficult: Delicate care needed to make sure no parts were broken. Difficult time taking parts apart and removing screws. Took longer than 1 minute and 31 seconds

Tools list

  • Small thin phillips head screwdriver
  • Long flathead screwdriver (for prying)

Product Parts List

MainPartsPicture.png
NumberedPicture.png


Part # Description Image
1 \'\'\'Axle Rod\'\'\': Provides an axis of rotation for the Dart Advance Drum to allow rotation to occur.
AxleRod.png
2 \'\'\'Magazine Housing\'\'\': Forms the outer shell of the magazine to give rigidity and form to the Magazine unit.
MagazineHousing.png
3 \'\'\'Dart Advance Drum\'\'\': Holds 25 darts at the ready to be fired by the gun. This unit is spring loaded to allow for the darts to be continuously loaded into the firing chamber after each shot Is fired.
DartAdvanceDrum.png
4 \'\'\'Rapid Feed Assist Knob Spring\'\'\': The spring holds the Rapid Feed Assist Knob in full extension as to allow for the Dart Advance Drum to spin freely underneath and allows for a smooth, uninterrupted rotaion.
RapidFeedAssistKnobSpring.png
5 \'\'\'Magazine Housing Cover\'\'\': Connects to the Magazine Housing to provide protection from the outside world, as well as holds the whole entire magazine apparatus together.
MagazingHousingCover.png
6 \'\'\'Rapid Feed Assist Knob\'\'\': This knob is connected to the Dart Advance Drum with a spring and once the spring is compressed, it allows for the user to turn the drum manually to clear out any jams that may occur during rapid fire.
RapidFeedAssistKnob.png
7 \'\'\'Push Rod Lock\'\'\': When the cocking arm push rod is pulled back to release the dart, this device locks it in place as to keep the potential energy from being released in the spring.
PushRodLock.png
8 \'\'\'Firing Barrel\'\'\': After the dart has been fired by pulling the trigger, the dart travels down the rifled barrel in order to maximize the distance the dart can be fired.
FiringBarrel.png
9 \'\'\'Muzzle\'\'\': This part keeps the pointed edge of the barrel hidden from touch of the user as well as being esthetically pleasing.
Muzzle.png
10 \'\'\'Outermost Casing\'\'\': These two parts combine in order to protect the inner workings that load and fire each dart. They were also individually designed and painted to be esthetically pleasing to the user.
OutermostCasing.png
11 \'\'\'Stock\'\'\': The stock of this Nerf gun is simply available for attachment parts. Off the Nerf Website, there are multiple attachments for sale that provide the user with added support when firing the gun.
Stock.png
12 \'\'\'Firing Chamber\'\'\': This chamber is where the dart is held when the user compresses the cocking mechanism. The spring is compressed on the backside of this part. When the trigger is pulled the spring releases and hit the backside of the part and releases the dart into the barrel at a certain acceleration
FiringChamber.png
13 \'\'\'Firing Spring\'\'\': This particular spring is main component to firing the dart. It is the spring connected to the part of part 12, as explained in part 12’s description.
FiringSpring.png
14 \'\'\'Holding Bracket\'\'\': The holding bracket spring loads the trigger. It holds the spring at full potential so it can be fired when the trigger is compressed by the user.
HoldingBracket.png
15 \'\'\'Trigger\'\'\': This part when compressed releases the firing chamber from loaded position. It also has an attached spring which returns it to neutral position.
FiringTrigger.png
16 \'\'\'Cocking Arm Pushrod\'\'\': This part pushes the firing chamber system into firing position, and locks it in place at full spring potential.
CockingArmPushRod.png
17 \'\'\'Cocking Arm Foregrip\'\'\': This is where the user holds the front of the gun. This also gives leverage on cocking system so user can load.
CockingArmForegrip.png
18 \'\'\'Drum-Magazine Holder\'\'\':This part is held into the side of the gun with plastic clips. It contains the system that holds in place and allows the release of the drum-magazine with the press of the release button.
DrumMagazineHolder.png


\'\'\'Parts list provides a part number for each part removed, which is referenced in the product dissection chart.\'\'\'


Problems Faced During Dissection

We faced only a few small problems when we dissected this product. We had trouble keeping track of we each little part was inside, because when the outer casing is pulled off, everything comes out of place easily. Be sure to be very gentle when you reach this step, because everything wants to pop out right away, especially anything that has a spring attached. Also we should have been more gentle with all of the parts. We didn\'t actually break anything, but since it is plastic, it was very possible. So be very gentle with all of the parts when you dissect.

Product Dissection

Step Description Difficulty Image
#1 Remove the drum-magazine from the magazine, by pressing the release button and pulling on drum. This part is designed to be removed repeatedly to be reloaded with darts, by younger users. 1
Dissassembly1.jpeg
#2 Remove the drum-magazine locking mechanism by pulling off of the whole part with force using hands. This is made to be removed because it only has clips holding it in place. 1
Dissassembly2.jpeg
#3 remove magazine cover by removing the five screws around the outside that hold it in place. This is made to be removed because the screws are non-permanent fastener. 2
Dissassembly3.jpeg
#4 Remove rapid feed assist knob, rapid feed assist knob spring, and axle rod from center of the drum assembly by simply pulling strait out of the center. This is made to be removed, and is only held in place by screws, but isn’t intended to be removed with frequency of magazine. 2
Dissassembly4.jpeg
#5 Remove the dart advance drum from the housing by pulling straight out. This is designed to be removed because it only slides into place. 1
Dissassembly5.jpeg
#6 Remove the magazine locking assembly from the drum-magazine holder by removing two screws over cover and pulling out parts underneath with hands. This is comprised of several levers and stops that hold, and allow the release of the magazine. Be careful to watch where all of the parts go. This is intended to be removed because it is held in by screws, but shouldn’t need to be removed. 3
Dissassembly6.jpeg
#7 Remove the four clips that fasten the drum-magazine holder to the side of the gun with the removal of one screw at the base of each of the four clips. These are removable because each one just has a screw. 2
Dissassembly7.jpeg
#8 Remove the cocking arm fore grip from the cocking arm pushrod with the removal of 4 screws. The fore grip then pulls apart into two identical halves and off of the gun. This intended to be removed because it is held together by screws. 2
Dissassembly8.jpeg
#9 Remove the stock. This piece is held in by two screws facing inward into the gun. The stock then pulls strait off the end. Be careful when removing because the stock holds all of the firing springs pressure, and will shoot off when screws removed This may not be intended to be removed because it can be difficult to repressurize the spring. 3
Dissassembly9.jpeg
#10 Outer most casing removed by removing the ten screws that clamp the two pieces of the outer casing together. One half of the casing lifts off of the top by pulling off carefully with hands. This is intended to be removed because only screws hold it in. 3
Dissassembly10.jpeg
#11 Muzzle removed from end. This just lifts off the end because it is held in place by the two casings clamping around it so it is intended to be removed. 1
Dissassembly11.jpeg
#12 Remove the trigger, comprised of the trigger and trigger spring by lifting off of where it rests, the spring can separate by pulling off of the back. This is intended to be removed because it is just set into place. 1
Dissassembly12.jpeg
#13 Remove the barrel by simply pulling out of its location towards end of casing. This is intended to be removed because it simply rests between the two halves of the casing. 1
Dissassembly13.jpeg
#14 Remove the firing spring from the back end of the gun by pulling it straight off the end of the firing chamber. This is intended to be removed because it simply pulls out of the back of the gun. 1
Dissassembly14.jpeg
#15 Remove the firing assembly which is comprised of the cocking arm pushrod, the firing chamber the push rod lock, and the holding bracket. This whole assembly removes by pulling it straight off of the outer casing. This is removable because they are just simply placed in there, but to get to them, you need to remove the spring which is difficult to remove. 3
Dissassembly15.jpeg
#16 Each of these four different parts are separated into their individual components. These each just pull apart easily by hand. They take almost no force to separate since they are normally forced together by spring force. These are intended to be removed because they are loosely put together. These parts can no longer be broken apart because they are press fit into place or glued into place, and would require breaking to get them apart. This therefore is the end of the disassembly. 3
Dissassembly16.jpeg

Subsystems

Summary Of System Connections

TimsChart.png

Arrangement of the subsystems:

This Nerf gun is powered via physical means with no electrical parts so all of the systems must be connected directly to one another. The overall process of firing dart from the gun begins with the magazine. This is the first subsystem where the dart is held until it is ready to be fired. Darts are loaded sequentially as needed, and are forced in by a spring force. From this point when the Cocking Mechanism is contracted, this compresses the spring from the Firing Mechanism to prepare the potential energy needed to propel the dart forward as well as allows for the spring loaded Magazine to push the dart into the firing chamber. The whole system then is held in place by the holding braket that wraps around the firing chamber. From this point, the system is then held static until the user pulls the trigger in the Firing Mechanism which releases the holding bracket\'s hold on the firing mechanism. This then releases all of the potential energy at once that was held in the firing spring and converts it entirely into kinetic energy of the dart, thus propelling the dart forward. This arrangment can also impact the performance as well. If each subsystem does not properly line up, then the gun will be much more prone to jamming and not function as smoothly. If the magazine didn\'t line up properly, then the darts would not feed properly in to the firing chamber causing jams. Also, the location of the holding bracket can allow for more firing power. If the firing mechanism is held at full spring compression, as opposed to coming back forward a short distance, then it will allow for more force. Since F = k * x^2, that short distance could amount to a much larger amount of force, meaning a longer firing range. The only real room for freedom in this system is in the cocking mechanism. It just needs to push the firing mechanism back and lock it. So it could just as easily be behind the firing mechainism, or even on top of it.

G.S.E.E. Factors Surronding The Product

\'\'\'Societal:\'\'\' Societal issues concerning the Nerf Gun include safety issues. The gun is designed with no sharp edges so that young children can play with the product avoiding injures. Although the exterior of the gun is safe, if it breaks there are many small pieces inside the gun that can be considered a choking hazard for young children or pets. Another issue involves the safety surrounding the darts. Parents should take caution and make sure children are wearing proper eye protection when using the gun. A final societal issue involves the public’s opinion on products made in foreign countries. Since the gun is made is in China, some citizens may not support or purchase the product. Although it seems like a bad thing, the production of the gun in China is much faster and cheaper, which allows the price of the gun to be lowered. This makes the gun more affordable for kids or families who may not have a lot of excess money. Also, the arrangment of subsystems will effect the societal view of the product. If for instance, the magazine is not properly arranged with the other subsystems, then the gun will not function properly, this means that society will view it as a poor product. So these needed to be arranged so that the gun fuctions well and that the societal view of it is being a quality product. The placement of the cocking mehanism could also be a impact to consider on scoietal factors. If it were to be located on the top of the gun, or behind the firing mechanism, then the gun could function just as well. But, it may be much more uncomfortable to operate, especially under rapid fire mode. So the main consideration was whether or not it is in a position where the user can oper ate it comfortably.

\'\'\'Global:\'\'\' Global concerns surrounding the product include the durability of the plastic casing of the gun. The plastic is durable enough to survive a beating from young children. This beating includes battling the elements such as being left outside in the rain. The gun is durable enough to be used in both warm and cold climates with no change in performance. When making the arrangment of the subsystems specifically, the design needed to allow enough space to that the system is able to slide without getting stuck, and allows the gun to fuction, even when temperature expands or contracts the materials.

\'\'\'Economic:\'\'\' The economic factors that affect the subsystems within the Nerf gun are related highly to the production processes used as well as the relation of the subsystems to one another. First of all the components are designed to be as small and compact as possible as to not be wasting materials and since less overall materials are then used in the production process, this then drops the cost of the product down; to in turn a lower the cost for the consumer. As well as using less materials, the company Mattel, also decided it would be worth their while to have this product manufactured in China. This allows for the least possible cost of labor, which also lowers the final cost for consumers as opposed to having this Nerf gun produced elsewhere such as the United States because if it were to be made here the cost would be driven up drastically since the cost of labor is far more expensive in the US instead of in China. Whe nyou consider the arrangement of the subsystems on an economic scale, the main factor is tolerences. The tolerences of all of the parts need to be tight enough to allow a goo performance. But, the tighter the tolerences are made, the more failure there is in production. So Nerf designed the tolerences to be large enough to be able to reduce the cost of production, but also tight enough to allow function with minimal problems.

\'\'\'Environmental:\'\'\' Some of the major environmental factors that influence the creation of the subsystems are heavily in relation to Mattel’s decision to drive cost down in their economic design choices. It is pretty common for children’s toys to be created out of plastics because this material is extremely cost efficient but yet is still durable enough to withstand a decent amount of abuse from children. This choice does have its downfalls though because plastics are made from fossil fuels which our planet is running out of; as well as the fact that plastic is not biodegradable so this also is not good for the environment because plastics will be around forever in landfills. Another negative note about using plastics to create the toy instead of using a far more durable material such as metal, is that plastic toys are not really meant to be taken apart for repair so if the Nerf gun does break, the consumer is more than likely to just throw the product out and buy another rather than attempt to fix what’s broken and this is not eco-friendly.

Arrangement of Subsystems

Within the toy, many subsystems are constantly interacting with each other and are only able to interact effectively with each other once there is an outside force applied. Due to a lack of battery system in the toy, all created energy comes solely from a human exerting a force on the cocking mechanism. The design of this toy was created as it was to closely resemble that of an actual weapon, but without it being lethal. With the stock located on the butt of the gun, the user is able to comfortably press against the gun as to avoid any recoil. In traditional “real” weapons, the clip or drum holding the ammunition is typically found mounted on the bottom of the gun with a direct feed to into the chamber. This also is dictated by the location of the firing chamber. The darts need to be loaded directly into the firing chamber, the magazine has to be loacated right there. With the Rampage Blaster the 25-dart drum magazine is a side mounted system as to make the toy more comfortable and ergonomic compared to other models. With the introduction of a side mounted drum magazine system, the rest of the interior of the gun had to be adjusted. The direction at which the firing chamber’s port is facing where the darts are fed needed to be adjusted to remain in line with the feed coming from the drum magazine. These two sub systems must always be in sync with each other in order for the gun to properly load and reload each dart after it’s been fired. Before each dart can be fired though, the cocking arm pushrod must be pulled back and released to compress the firing spring that is attached to the firing chamber inside the main portion of the toy. For this to function, the holding bracket as well as the trigger will have to be located right at the apex of the cocking arm pushrod\'s motion so that it can hold the maximum energy, as well as be far enough forward to hold the mechanism. This series of events allows each dart to be fired with minimal interruption such as jams or misfires. If the subsystems combined were to be shifted from one spot to another, the only rising issue would be that of addressing a new shape for the overall body of the weapon. This in turn means that no sub system must be held towards a certain direction in “space” (upside down, sideways) but must turn or rotate as precisely as it’s subsystem connector. If one subsystem were to move on its own, then it would require that every other subsystem moves along with it.

References

1.http://sgnerf.blogspot.com/2012/04/nerf-n-strike-elite-25-dart-drum.html