Gate 2: Nerf Gun Dissection
Cause for Corrective Action
- Although our work and management plan supplied a general guideline for the dissection and phase two in general it lacked necessary specificity. Our work proposal consisted of half hour dissection segments however we did not plan for the time it took to categorize and document each step in the dissection process. The Nerf Vigilon took approximately two and a half hours which was much longer than we planned for. We have corrected this time management and estimation error by reassessing the time it takes our group to analyze and document. Although the only tools we needed to dissect the guns was a screwdriver, a smaller sized Philips heads with a skinnier neck would have made it easier to access and remove the screws without marring the plastic. The internal components of the gun were difficult to keep track of Because we had not planned for them to be so complex or for so many of them. Although the dissection was completed, we did not have a set date or time to complete it which led to the entire group dissecting the two guns in an impromptu meeting after class. We realized during the dissection that it would only take two people to dissect each gun, yet we feel it was beneficial for each individuals understanding that they be present and active during the dissection. We had not planned on splitting up the work load for each gate however we have seen a greater output of work in each group member when it is individually assigned with a due date. By splitting up the assignment based on ability of the individual and availability to accomplish the task we have seen an increase in quality. As far as conflict resolution and need for disciplinary action our group has been fortunate to not have to take any action due to a conflict. Although we feel it is unlikely that the group will have major conflicts the project manager will solve all disputes with a final decision. Seeing that a conflict may arise with the project manager we will contact one of the instructors in order to mediate our conflict. Scheduling has also been somewhat of an issue with our group. We have corrected this by planning on group meetings every weekend seeing as we are all available on the weekends. Group meeting will also be scheduled by the project manager through a comparison of schedules and communication via text messages and phone calls in order to find optimal meeting times. In the unlikely event group members have excess free time and want to work on part of a gate they are free to do the work as long as they present their work to the group at the next meeting and have it edited.
Derivation of Difficulty Scale
To describe how difficult each step is we have to define a meaningful scale. Our products didn’t require any other tools but a screwdriver and a little elbow grease. Some screws were harder to take out than others, and the way certain parts fit together made them difficult to take out. We are going to describe each step as Easy, Medium or Hard.
- Easy is defined as a part that comes off the gun by unscrewing it and being able to remove it with almost no force such as removing the two halves of the casing from each other.
- Medium is defined as a part that is interconnected with other parts but does not require any intense manipulation in order to separate them.
- Hard is defined as a part that is interconnected with other parts and requires unhooking or unclasping in order to separate them.
The difference between hard and medium is that the parts are connected to each other intricately rather than being merely fastened in someway to the casing or connected to each other by a spring. Also a part that is permanently connected to another part will be considered hard on our difficulty scale because of the deconstruction required to separate them. Now that we have our scale we can go through our steps of dissection.
Dissection of the Nerf Vortex Vigilon
|Step Number||Description||Challenges Encountered||Difficulty Level||Picture|
|1||Remove the screws from the main casing of the gun. We have to remove the screws from the sliding mechanism and one screw from the front of the gun. We removed 12 black screws from the main casing of the gun. We first took off the sliding mechanism because that piece was separate from the casing. Next we pulled the casing off of the gun. The two halves of the casing not only serve the purpose of housing the internal components but also give the gun it visual appeal. It seems that although the screws are meant to connect the two halves permanently, they also allow for the consumer to deconstruct the gun if they choose to do so. Rather than melting or riveting the two halves together, Nerf screwed them together possibly because it is cheaper or because they want to allow the consumer access to the internal components.||Only challenge was locating some screws that were not easily seen.||Easy|
|2||One side of the casing which we are going to call the cavity, which we took off in step one has some parts connected to it. To remove those parts we have to remove two black screws from the ammo door. Then we have to take out the screw from the thumb toggle switch that opens the ammo door.Lastly remove two silver screws from the plate holding the spring mechanism for holding the ammo.||No challenge encountered.||Easy|
|3||Once the gun was open we had to start unscrewing the internal components so we can analyze their functions. Remove all silver screws and one black screw from the inside in order to remove the internal components from the casing. There are three silver screws and one black screw. The one black screw is by the main white spring in the front of the gun. Once you remove those screws take out the internal components.||This step was difficult because there are a lot of components and small parts. It took us a while to figure out which screws we needed to take out to unscrew the internal components from the casing.||Hard|
|4||Now that we have removed all of the internal components from the casing we are going to dissect the internal mechanisms.||N/A||N/A|
|5||We started by taking off all of the pieces that are not attached by screws. We took out the spring and the piece that the ammo sits on. We pulled them out. They were held in by a track on the inside of the chamber and the spring was attached to the inside of the ammo holder.||The pieces seemed to fall out and caused for a little bit of a struggle in keeping track where everything belonged.||Medium|
|6||We started with the ammo reservoir and the trigger mechanism because those components were the easiest to get at. Remove two screws off the back of the ammo reservoir. There are three black screws.||NO challenges||Easy|
|7||Remove the one black screw holding the trigger to the reservoir. Now we can take off the trigger and the bracket holding the disc chamber.||Finding the location of the black screw was hard to do. We could not tell what was holding it all together.||Medium|
|8||In this step we are going to remove the actual ammo reservoir from the internal components. Remove two black screws next to the disc reservoir and underneath the barrel. Remove the large spring and the orange pieces above it. Remove two more screws on the disc reservoir and you will be able to disassemble the disc reservoir.||No challenges encountered||Medium|
|9||Remove two more screws off the internal components and you will have completely disassembled the internal components. The rest of the components were clipped or fit together. The white spring mechanism and the part that connects it to the chamber is one example of that.||NO challenges encountered.||Medium|
Dissection of the Nerf Speed Load 6
|Step Number||Description||Challenges||Difficulty Level||Picture|
|1||First we unscrewed fourteen screws from the main casing of the gun.||No challenges.||Easy|
|2||Next we unclipped the yellow cosmetic front cover. This required the use of some force. We were then able to remove the four hidden screws that were underneath the cover.||We did not think force would be needed to take apart the gun so we thought there may have been something wrong with what we were doing.||Medium|
|3||Then we removed the clip from the gun. When we took the clip off of the gun some of the internal parts the clip plate was housing came out of the gun.||No challenges.||Medium|
|4||We removed the screws off of the slide mechanism and take the gun apart. Only one side of the casing had internal components attached to it.||No challenges.||Medium|
|5||Next we removed the spring and loading mechanism. There were two screws we had to take out near the tip of the gun. We then were able to carefully remove the casing of the gun. A lot of the pieces were held in place by the casing of the gun. When we opened it up we took the trigger out. It wasn’t attached by screws so we were able to just take it out.||Maintaining organization of the pieces when disassembling the product.||Easy|
|6||Once we took the internal components off taking them apart wasn’t hard. The parts were all either clipped together or in the case of the spring and the barrel, slid onto one another. We started by removing the spring holder part. We then removed the firing mechanism. We separated the firing mechanism to analyze all of the components. No tool required.||No challenges.||Medium|
For these Nerf product the company has designed them to be assembled once and stay that way until the product is discarded. Nerf guns are not designed to be serviced or upgraded, and because of their design they are difficult to disassemble and reassemble. Self tapping screws were used to secure many parts. The screws dig into the plastic and if they were to be unscrewed and re-screwed multiple times it would strip the hole and no longer be able to secure and fasten the parts. Since all internal components are intricately connected and non serviceable the designers had no need to consider disassemble when creating them. Although screws are not technically permanent connecters, they are used as such in these products due to their comparative low cost.
Product Dissection Assessment
Speed Load 6
The first sub function in the gun is the case which is shown as #1 in the image to the left. The case houses all of the components and is connected to certain parts in order to secure them and allow them to withstand the translation of energy through them to the ammo. The cocking mechanism, #4 on the image on the left is connected to the casing by a screw compressing its two halves together around a slot in the case in order to assemble the parts quickly and cheaply. The cocking mechanism is connected on this slot in order to allow the user to pull it back and translate mechanical energy through it smoothly. The cocking mechanism is also connected to the tube and barrel #6 on the left, via a small grey plastic arm. The arm is screwed to both the cocking mechanism and the tube-barrel assembly, but can freely rotate round the screw because the hole in the plastic arm is larger than the threads but smaller than the screw head. This connection was made this way to allow the user to translate mechanical energy to the spring via the cocking mechanism. The spring guide is located in the rear of the gun and is attached to the case by compression between the two halves. The spring guide(#3) forces the spring to stay parallel to the tube and barrel and makes sure the energy stored in the spring will translate to the forward motion of the tube. The tube is connected to the barrel via an air tight seal thanks to an internal o-ring. The tube slide along a plastic track that was included on the barrel during the molding process. The track is lubricated and provides little friction to impede the sliding of the tube. The tube form an air tight connection with the barrel in order to translate the kinetic energy of the tube moving forward into pneumatic pressure in the tube and barrel. This pneumatic pressure will provide the force to eject the projectile. The round chambering mechanism(#5) consists of an internal spring in the integrated clip which forces a round into the chamber when the cocking mechanism draws back the barrel and tube. The chambering mechanism uses the energy stored in the spring when the shooter depresses it to load the round. The chambering mechanism is the sub system which introduces the material into the main shooting function. The spring loaded internal clip is connected to the case by a small plastic pin that was integrated into the casing mold. It is connected in this fashion in order to reduce the amount of screws used and to make the installation of the spring easier during assembly.
As with the Speed sixth the Vigilon has a case(#2) which houses all of the internal components and is in some way connected to all of the parts that perform the sub functions. The cocking mechanism(#3) in the Vigilon is similar to the Speed Six in that it was attached to the case through a slot. The cocking mechanism is directly connected to the chambering mechanism(#4) through a plastic pin that feeds through a hole on the rear of the chambering plastic piece. This connection was made so solid due to the force the user will be putting on the mechanism when they pull back on the slide. The chambering mechanism is also the mechanism which translates the mechanical energy of the cocking mechanism into the potential energy stored in the spring(#6). The part of the mechanism which is connected to the cocking mechanism slides back which pulls back a white plastic rotation arm(#5) that has a spring coiled around its turning axis. The chambering mechanism is pulled back which interacts with the white piece of plastic by drawing the arm back and translating the translational energy into potential in the coiled spring. The arm is not physically attached but rather set in a slot on the underside of the sliding part of the chambering mechanism in order to be able to slide back while raising and lowering slightly due to the change in angle the plastic arm undergoes. This connection was made to be free floating because this will be the motive force that throws the disc forward when released. The arm is held in place by a small inclined plane that the arm can push past on the way back but becomes temporarily locked in place when the plane is pushed back over by a small spring. This small plane is forced back to the side when the trigger(#1) is pulled via a second small plane that the trigger force into the first plane. The connection between the trigger and the second plane is riveted together due to the shear force the consumer may put on it and the amount of time the trigger will be pulled. There is a circular arm in the cavity the disc travels through on its way out of the barrel slot. This arm put spin on the disc as it is leaving which adds to the discs flight time. Each of these sub systems are placed in their location in order to perform the actions needed to launch the projectile.
Certain Factors Discovered
- Society and Nerf fans have greatly influenced Nerf guns and how they are made. The Speedload six was designed to meet consumer demands and societal issues. The gun needs to be safe for children. Safety is always a huge factor that influced the design such as the restrictor on the air compressor which sets an upper limit for the velocity of the projectile. The Speedload Six solves these problems in a very interesting way. For safety it has doesn’t shoot fast enough to hurt people. This was accomplished by the internal systems of gun. The spring used isn’t strong enough to store the energy needed to make the projectile go fast enough to harm someone. They did this specifically so that when the dart was shot it also wouldn’t hurt. The weaker spring doesn’t create much air pressure and the restrictor makes sure the projectile doesn’t get launched fast enough that it can hurt people. At the same time the spring stores enough energy to still shoots fast enough for kids to have fun with it.The Vigilon accomplishes the safety concern a little bit differently. The goal of the Vigilon was to create a gun that shoots farther than the traditional dart gun. They couldn’t keep the ammo a dart because to make that go far enough, they would have to increase the speed of the dart to a dangerous level. They used a disc instead. To get enough spin on it they used a different kind of spring. They used a wind up spring attached to a lever that flings the disc, instead of using pneumatics and traditional springs. There is an internal circular arm which causes rotatation on the disc and increases flight time.
- The Speedload Six is a very simple gun. When we took it apart there were not a lot of parts in it. That makes the gun very economical and easy to make. It is cheaper to manufacture and easier to put together. This makes the gun cheap and easy to use. Another economic factor is that both guns are made from the same plastic and use the same screws. Since the company uses standardized parts they can buy in bulk and pass the saving on to the customers. When we opened up both guns we noticed that all of the plastic used for the internal components of the gun we the same. They are all orange industrial grade plastic. Another similarity between the two guns was the screws. Every screw used on both guns was a long black self-taping screw, a small black self-taping screw or a medium length silver self-taping screw. Using the same plastic and the same types of screws for all of their guns saves them a lot of money on parts and manufacturing.
- Since nerf has production factories all over the world, the connection types they used had to be common and readily available in most developed geographical regions. Although machines could be designed to assemble the entire gun, because global wages vary so greatly it is profitable and feasible to design the connections to be hand assembled. Since screwing a small plastic part to another one is delicate work and takes dexterity, having the guns assembled in a third world industrial country is the cheapest method. If cheap labor was not available, the screw connected pieces may have been molded together instead.
- The environmental concerns of the world today affect almost every product and Nerf is no different. When we opened up the Speedload six we found out that minimization of material and waste was how they affected Nerf. The amount of plastic used on the Speedload six was minimized such as empty parts of the cavity created by the casing. They found a way to condense all the internal components so they would fit and perform while not using too much plastic or making the guns to heavy. Less plastic saves them money on production material and on gas for shipping due to the lower weight. The reduction in carbon emissions helps out the environment in a positive way by not adding unnecessarily to global warming. Since the same plastics were used for the casings and the internal components of both guns the company is able to cast all of the parts on site. Because all casting can be done in one place not having to ship certain parts to other factories in order to be assembled the company save more money and reduces shipping emissions further. When there is no need to use multiple forms of plastic waste is minimal and excess landfill space is not consumed.