Revision as of 21:05, 18 December 2011

Brief Overview

Group 27's project for MAE277 is dissecting, suggested modifying, and analyzing the internal components of the Vulcan EBF-25 by Nerf. This process will be documented throughout the semester in formal reports in the form of five separate gates. The product is sold worldwide through a Hasbro product line. Product assembly is required after purchase. The price is 40 US dollars and batteries are sold separately. Thus, the total cost is around 50 American dollars. Fully automatic and manual fire are the two options for operation of the product. Initially released onto the market in 2008, the Nerf Vulcan now includes two three different colors/style. The Vulcan EBF-25 that will be analyzed is green and orange colored. Its components are almost solely plastic. The five gates are listed below accompanied with pictures and tables.

Team Members

Project Planning:

Project Management

Work Proposal

The disassembly process is as follows: The time required for the total disassembly of the Vulcan EBF-25 is estimated to be between 30 minutes and 1 hour. As disassembly proceeds, the parts as well as any screws or springs will be noted and placed in an organized manner as to make reassembly as easy as possible. In the case that any parts are lost they will be replaced with a suitable alternative or the group will purchase a replacement part. There should be little trouble with the disassembly of the product and the only foreseeable challenges are going to involve the internal components such as the firing mechanism, the electrical components, and the cocking assembly/firing pin.

Remove all components that can be removed without tools:

• Remove the barrel by simply sliding it out (Held in by Friction).(Note – The barrel tip must be removed first which is held in by screws).
• Remove the carrying handle by turning the tabs/pins holding it in and unlock it.
• Remove the ammo box by opening the breech cover and simply sliding it off.
• Remove the ammo box cover by releasing the two tabs.
• Remove the tripod by pressing on the clasps and releasing it from the nerf gun.
• Remove ammo belt by pulling it out of ammo box.
• Remove the battery pack (Note – The battery door must be unscrewed and removed first).
• Pull apart the two halves of the cocking bolt and remove them, allowing for the gun casing to be pulled apart later.

Remove components that require a screwdriver:

• Remove two (2) screws and two plastic pins holding on the breech cover.
• Remove three (3) screws and pull off the power switch cover.
• Remove one (1) screw and pull the front sight out.
• Remove three (3) screws and pull out the barrel tip/cover.
• Remove one (1) screw and release the battery door.
• Remove three (3) screws and release the foregrip.
• Remove twenty five (25) screws and split the gun casing into two halves.
• After removing the outer casing there is access to internal components, the specific disassembly process of said components is currently unknown until the actual disassembly occurs. It is assumed that they will be similar to other steps and be able to be done with a Phillips head screwdriver or be taken apart by hand without tools).
• Remove four (4) screws and detach the tripod release head from the tripod.
• Remove four (4) screws and detach the plastic cover from the tripod pivot point.
• Remove eight (8) screws and separate the tripod into two halves.
• Detach two resistance springs by unhooking one end and then remove two (2) screws to allow the other end of the springs to slide off.
• Remove six (6) screws from front two tripod legs an detach them from the tripod assembly. (Note – In doing so, the gears used in the pivoting motion of the tripod are also exposed and separated.)

Note: All screws use the same size Phillips head screwdriver.

Management Proposal

In order to meet the requirements of this project on time, our group plans on evaluating the work load and then dividing it into five equal sections amongst the members of our group. This way everyone is contributing an equal amount of work and fully participating in the project. In addition, we also will meet on Monday’s, Wednesday’s, and Friday’s for a minimum of two hours a day. The time frame for these days will be either the hours of 3 p.m. to 4 p.m. before class or 5 p.m. to 6 p.m. after class as well as counting any time that we may have in class from 4 p.m. to 5 p.m. If any of these times are inconvenient or if we need more time to work on the project we will meet on Tuesday, Thursday, or on the weekend at a time that is reasonable for all the members of our group. In order to keep all members of our group informed of the meeting times and updates on the project, we will assign roles such as Communications Liaison and a Project Manager. If there are any conflicts with the roles or responsibilities of each group member, the group will meet and discuss the issue and find a sensible resolution to the problem that everyone agrees upon.

The group roles and responsibilities are as follows:

Project Manager

• Organize the division of the assignment into equal parts and convene with the group to decide who will work on which part.
• Keep track of work progress on each part and the project as a whole.
• Make sure work is getting completed on time and is of acceptable quality.
• Review each assignment before submission to make sure that all aspects are thoroughly addressed.
• Make sure everyone attends meetings.

Research & Development/Technical Assistance

• Research the operations of the product as well as the operations of any modifications.
• Thoroughly compare and contrast multiple options when choosing modifications.
• Maintain thorough knowledge of the product and its components in addition to that of the Technical Expert.
• Maintain organized information and record data from the product and the results of modifications.
• Keep members of the group informed of the specifications of the product and its current operational status.

Communications Liaison

• Maintain open communications with instructors and TA’s and is responsible for asking/emailing any questions the group may have.
• Notifying the group members of the meeting times as well as any changes to said times.
• Reminding each group member of which part of the assignment they are responsible for and when it is due by.
• Responsible for proof reading the assignments before they are submitted to make sure that spelling, grammar, and punctuation are correct.
• May be responsible for writing up the final document from the separate parts, depending on the distribution of the work load amongst the group members.

Technical Expert

• Maintain a full knowledge of the product and all of its components.
• Interface with the manual or any other technical documents before and after work is done on the product.
• Responsible for maintaining the products functions and regular operation.
• Research of modifications as well as their integration into the product.
• Keep track of any changes made to the product as well as their effects.

Financial Adviser

• Maintain an accurate budget for the group.
• Allocate funds appropriately for purchase of modifications or any other necessary items.
• Brainstorm possibly ways to generate funds if needed.
• Make assessment of cost-effectiveness of modifications and research the purchase of the most advantageous product.
• Communicate with Technical group members to plan a budget for obtaining intended modifications or tools.

Product Archaeology

To start to assess the Vulcan EBF-25 we will start from the barrel. The barrel is a long orange plastic tube that is grooved on the inside the long ways. This barrel in essentially useless, the diameter of the barrel is twice the size of the darts. This means that the effects of a barrel that would normally happen as in making the bullet travel farther and more accurate. As we travel from the tip of the barrel down the barrel we run into the plastic structure that surrounds the barrel and makes up the main structure of the gun. The function of this structure on the front of the gun is to give the user some place to hold the gun in order to aim. The top of this structure has aiming sights in the center as well as a clip to attach the guns many accessories such as a scope. Theses clips are also located on the sides. This structure also holds the barrel in place. Moving to the center of the main plastic structure it starts to have many more functions. In the lower part there is a compartment with a door that once unscrewed allows the placement of the batteries to power the product. Below this is a elevated oval surface that allows for the attachment of the tripod. The middle of the structure houses the feeding and setting mechanism for the the dart belt feeder. This feeder sticks out of the center and is shaped like a gear where the spokes of the gear stick out the bottom of the chamber. This gear rotates and feeds the belt through every shot. At this point there is also hole on the left hand side that looks like it was make by a ball being pressed in the side. There is a little lever inside this hole, this hole is where the ammo box is mounted on the product and the little lever holds it in place. Further towards the top of the structure there are holes on both sides that provide a place for the top handle to be mounted. Diagonal and above these is the breach cover which properly positions the darts in the chamber to be fired. This breach cover rotates on it connection to allow it to open the chamber in order for easier loading. Moving further back the gun the plastic structure houses all the firing mechanisms. A orange knob protrudes from each side of the product. This knob is connected to a rod running perpendicular through the gun. Using the knobs the rod is pulled back along a slit in each side of the gun. This motion also cocks the gun manually. That back part of the gun is shaped like a handle to make it easy for the user to hold. Protruding from the handle is a larger trigger about the size of two average fingers. On top of the plastic structure there is a large on/off switch. This switch is covered by a piece of plastic hinged at one end and attached to the main structure. This cover makes it so that during use of the product it is not accidentally turned off.

Attachments	Description	Image
Ammo Box	The ammo box is a rectangular shaped plastic box with a lid that is hinged at the side. On the opposite side there is a protruding pin that allows for the ammo box to connect to the side of the main product. There is also a gap between the lid and the ammo box that allows for the belt of ammunition to feed into the firing mechanism of the Nerf gun.
Ammo Belt	The ammo belt is a series of identical plastic shells. The individual shells hold the dart. The first shell is solid and does not actually fire. It is located at the beginning of the ammo belt and is fed through the gun for alignment purposes. Every shell is linked together via a nylon band.
Top Handle	A U-shaped handle that attaches to the top center of the gun with pressure clips for an easier way to hold the product.
TriPod	The tripod is attached to the bottom of the main product with pressure clips. Gears on the inside make it so that when one leg is extended, the leg on the opposite side also extends. Springs make it so that the legs stay in the folded up position when there is no pressure on top. On the bottom of the tripod there are pieces of rubber to give it grip on multiple surfaces. Two of the legs are longer and face the back of the main body and the center leg is shorter pointing towards the front. The center leg has a hole on each side which corresponds to small pegs on the two outer legs, allowing for the legs to interlock when closed. Where the tripod connects to the main body it can rotate 180 degrees with a spring loaded knob pressed up against a gear.

Gate 1

Development Profile

The Vulcan was released in 2008. The product was sold within developed countries such as the United States, Japan, and European countries. The Nerf product line has been highly controversial in these areas. It is said that such a product sends a message of violence within children in an already violently evolving world. The basis of Nerf products is not to instill violence. The Nerf products are meant to create a safe environment for children to play. The danger involved with the Nerf Vulcan is at a minimum with a chance of injury being very slight.

Usage Profile

The intended use of the Vulcan EBF-25 is purely trivial. This product was made for the enjoyment of children. It provides a safer method for children to play together than with much more dangerous toys such as an air soft gun or a paintball gun. The Vulcan EBF-25 was designed as a toy and should be used as one. Children can find many different games to play with the Vulcan EBF-25, creating endless hours of entertainment for the group of children participating. This product was designed for use at home. The Vulcan EBF-25 can be taken outside as long as the weather is permissible. This product should be kept out of the workplace because it is a toy and unless they work at Habro; it would not be acceptable. The Vulcan EBF-25 performs the job of keeping children entertained. The parents of the children are then able to garner some time to perform tasks around the house and tie up any loose ends. This product must be used with some care as to prevent any injury to the users. If the children are too young to use the Vulcan EBF-25 then they could injury themselves quite easily. The children could choke on the projectiles if they are not watched or told explicitly. Children could also injure one another by striking each other with the guns so care should be taken when giving a child a Vulcan EBF-25.

Energy Profile

The Vulcan EBF-25 uses a combination of Kinetic, Spring and Electric Energy to fire the darts quite long distances. The user supplies the Kinetic Energy through a lever that the user pulls back. The Spring Energy is created through the Kinetic Energy from the lever being pulled by the user. The spring compresses from the Kinetic Energy and builds up a quantity of Spring Energy that can then be used to launch the darts. Once the Spring Energy is built up the user can then trigger the gun to fire by pulling the trigger and releasing the spring and transferring the Spring Energy to the dart and then propelling it through the air. The Electric Energy can be used in lieu of the kinetic energy from six ‘D’ batteries. The Electric energy works in the same way that the kinetic energy propels the dart by transferring the energy from the battery to the spring and then to the dart except at a much quicker pace. The batteries can provide much more power than the user can so; the darts can be fired at a much quicker pace. With the electric power, the Vulcan can fire at a rate of three darts per second while the kinetic energy can only fire at a rate of one dart every three seconds.

Complexity Profile

Within the Nerf Vulcan product there are several components present. The forty dollar purchase includes- a tripod stand, 25 darts, a 25 dart clip, an ammunition casing, and the gun itself. The tripod stand consists of three plastic legs, each with rubber on the bottom for grip. One leg is stationary, but the other two are free to move forward and backward. This motion is controlled through two gears, one in each leg thus the legs can only move together. On top of the legs are two plastic pieces. These two are attached to a spring which allows the tripod to “clamp” onto the gun itself. The darts are simply a lightweight Styrofoam with rubber ends. The 25 dart clip consists of 25 dart holders made of plastic, bound together through a woven material. Each holder has a hole drilled through the backside, for the firing mechanism to come into contact with the individual darts. The gun is by far the most complex component. The Nerf Vulcan product has an automatic firing mechanism. This involves a motor, a power supply, a switch, and trigger. The power supply consists of 6 d size batteries. This power supply then goes to what I can imagine is a 9 or 12 volt motor which is activated through the switch on the outside of the gun. And finally the trigger releases the whole interaction of components, firing the darts consecutively.

Material Profile

The Nerf Vulcan product consists of several different materials. The main material is plastic, this accounts for about 75 percent of the product. The outside layer of the gun, tripod, ammunition casing, and most of the dart clip is plastic. Plastic is a relatively cheap material and provides a material that is durable enough for the Vulcan’s uses. All other materials are within the gun with the exception of the woven material used on the dart clip. This material is flexible and durable. This allows for it to be fed through the gun with ease and speed. The only other materials are the small components within the gun. These include screws which can either be a cheap metal or hard plastic. These are used to keep the components in place. The wiring in the gun and the circuit boards are held together by these screws. The wiring is typical wiring; perhaps conduit is involved within the gun, soldered to the circuit boards. These materials are all relatively cheap with the exception of the batteries and motor.

Interaction Profile

The user interacts with the Vulcan EBF-25 by using it as a toy and a tool while playing games with Nerf guns for entertainment purposes. Along with aiming and shooting Nerf darts from the Vulcan EBF-25, the user has to power the cannon with batteries and load the ammo belt that automatically feeds through the cannon. The Vulcan EBF-25 also comes with a deployable tripod that the user can mount it on or remove it. The user can also choose whether to shoot the cannon in semi-automatic or fully automatic modes. The product interfaces are rather intuitive. The principal of aiming and pulling the trigger to use the cannon is rather simple and standard with Nerf guns. Loading the ammo belt is also made simple with each Nerf dart having its own designated spot to be placed in the ammo belt, which then gets automatically fed through the cannon. The most complicated, yet still rather simple, part of the Vulcan EBF-25 is attaching or detaching the deployable tripod. The only regular maintenance that needs to be performed on the Vulcan EBF-25 is making sure it has electrical power by changing the batteries. Although changing the batteries is easy, it does require six size D batteries.

Product Alternative Profile

There are a lot of product alternatives that exist for the Vulcan EBF-25. Along with other guns made by Nerf, for example the Nerf Vortex product line, there are many other companies that produce guns similar to Nerf guns. Nerf also makes a line of water guns that could be considered alternatives called Super Soakers. The main advantage of the Vulcan EBF-25 compared to other Nerf guns is the fact that it is battery operated. This enables the cannon to load itself automatically and allow a faster firing rate. Another advantage that the Vulcan EBF-25 has over other alternative products is the fact that it allows the user to choose a semi-automatic or automatic firing mode. The deployable tripod that comes with the Vulcan EBF-25 is also a feature that is not offered by most alternative products. The only major disadvantage that the Vulcan EBF-25 has compared to other similar alternative products is its size. Compared to other Nerf cannons the Vulcan EBF-25 is rather cumbersome especially when the tripod is attached. Alternatives products in the Nerf N-Strike product line have some similar features compared to the Vulcan EBF-25. For example the Stampede ECS has a folding bipod instead of a detachable tripod, but the Vulcan EBF-25 is one of the few products that has its own automated feeding system. This feature of the Vulcan EBF-25 could be part of the reason that it is more costly than most other products in the N-strike product line. Generally, other cannons in the N-Strike product line range from $19.99-$24.99 but the Vulcan EBF-25 is $39.99 as priced on the Hasbro Nerf website.

Nerf Vortex
Super Soakers
Nerf Stampede ECS

Conclusion

The Vulcan EBF-25 should prove to be a great system to study the properties of Mechanical Engineering. It will be a challenge for the group to understand and document all of the processes that went into developing this product. The group will have to find consistent methods for developing a complete and accurate study of the Vulcan EBF-25. As long as the group works together and communicates well, there is no doubt that Vulcan EBF-25 will be broken down and understood.

References

http://www.hasbro.com/nerf/en_US/shop/details.cfm?guid=66BDFA34-19B9-F369-1008-581BEF4B304A&product_id=26121&src=endeca

http://nerfguns.org/nerf-vulcan-ebf-25

http://www.hasbro.com/shop/details.cfm?guid=5C7A77E6-19B9-F369-10F7-51414DF5A649

Gate 2

Gate 2 consists of the removal and documentation of the components within the Nerf Vulcan EBF-25. This process is displayed thoroughly below, complete with descriptions and images of the 17 steps involved. Our group also documented the difficulty of each step, ranging from easy to medium difficulty. The tools used include three screwdrivers- one small flat head (1/8"), one small philips (1/8"), and one large philips head (1/4").

Attachments	Description	Image
Step #1	Assemble all parts of the Nerf Vulcan EBF-25
Step #2	Removal of Outer Components Handle - Pull on both sides of the connecting joint to remove from the top of the Vulcan EBF-25 (Easy Difficulty). Tripod - Squeeze both attachment clips and pull away from the main body (Easy Difficulty). Ammunition Holder - Pull up and out from main body of gun (Easy Difficulty). Cocking Bolts - Remove one of the bolts by oulling away from gun, then slide it through the gun (Hard Difficulty).
Step #3	Detachment of the Breach Cover This process involves the removal of two screws with the use of a philips head screwdriver (Easy Difficulty).
Step #4	The breach cover is then removed by removing two plastic components. This is done through a small flat head screwdriver. The screw driver is used to pry the components out of place (Easy Difficulty).
Step #5	Battery Door Removal With the removal of one screw, the battery door is unattached from the main body. Next, just pull away from the gun (Easy Difficulty).
Step #6	Front Grip Removal Removing three screws from the main body results in the detachment of the front grip from the Vulcan EBF-25 (Easy Difficulty).
Step #7	Small Components Removal The sight is removed using a small flat head screwdriver. This is accomplished through the unscrewing of one screw (Easy Difficulty). Once the barrel and casting are removed, the switch cover is no longer attached to the gun (Easy Difficulty).
Step #8	Barrel and Casing Removal The removal of the barrel and casing is completed through the unscrewing of 12 large screws, and 3 small screws. This process is completed with the use of a small and large philips head screwdriver (Medium Difficulty).
Step #9	Main Body Disassembly Remove casing of main body by removing 18 large screws and two small screws with respective Phillips head screw drivers. Pull one of the casings away from the main part of the gun and remove the battery clip away from the casing as well as the plastic shield that keeps wire away from feeding mechanism (Medium Difficulty).
Step #10	Main Body Removal Remove the other half of the main body by unscrewing 10 small screws located around the main body, this is done using the large philips head screwdriver. You now have the main firing component of the gun. It retains the electric motor, cocking mechanism and main spring located inside of it (Medium Difficulty). Feeder gear will fall out of the firing mechanism when the second half of the main body is removed with a large alignment spring attached to it (Easy Difficulty).
Step #11	Electric Motor Detachment Remove Electric motor by unscrewing 4 screws with the Phillips head screw driver. Carefully remove the electric motor without harming any of the wires (Medium Difficulty).
Step #12	Basic Internal Disassembly Remove two small alignment springs on both sides of the gun by unscrewing two screws on both sides of the gun (Easy Difficulty). Remove the gear cap and the release pin will come out as well. By removing three screws from the gear cap (Easy Difficulty).
Step #13	Cocking Lever Disassembly: Part 1 Remove three screws to begin to take apart the cocking lever. The lever is made of a few plastic pieces and some springs. Remove these pieces to begin to take apart the cocking lever (Easy Difficulty). Remove two black screws to take off part cocking lever (Easy Difficulty).
Step #14	Cocking Lever Disassembly: Part 2 Remove eight screws to take off the main body of the firing mechanism and remove the entire cocking mechanism which will be in three pieces. The spring retainer will most likely fall off during this process which is no problem (Medium Difficulty). Remove the retention spring by sliding it off the main part of the spring (Easy Difficulty).
Step #15	Main Spring/Feeder Rotator Disassembly Pull out and away from the gun to remove the air chamber of the main cocking mechanism to reveal the main spring (Easy Difficulty). Remove the main spring mechanism by pulling it away from the gun (Easy Difficulty). Remove the feeder rotator by pulling it away from the gun (Easy Difficulty).
Step #16	Trigger Components Removal Remove four small silver screws on the right half of the gun to remove the trigger structure and trigger. The trigger mechanism can then be removed by pulling away from the gun. The gear cover can also be taken off by pulling away from the gun. This reveals four sets of gears used to help power the device (Medium Difficulty).
Step #17	Removal of Internal Gears The gears can then be removed separately from top to bottom (Easy Difficulty). Note: Keep the order of the gears intact.

Cause for Corrective Action

Our group has been very successful with our work and management plans. Every member of the group has taken care of their tasks on time and with relative ease. Our technical expert, Ryan Tomala, has displayed prime knowledge of all the parts of the Vulcan EBF-25 while removing all of its components. Our Project Manager, Tom Petersen, has performed an excellent job by scheduling meetings when everyone can attend and making sure all of the work is being done on time. Our Financial Advisor, Jason Cukierski, has made sure that we have everything that we need or will need for each step of the project and makes sure that it is cost effective as possible. Our Communications Liaison, Robert Hanes, has done a wonderful job in keeping in touch with the TAs and professors by attending office hours and making sure that everyone knows which part of the assignment they are responsible for. Our Research and Development/Technical Assistant, Corey Bice, has thoroughly researched our product, which has greatly helped the disassembly of our product and made sure that everything was kept track of. Our work for Gate 2 started a few days later than anticipated but it was of no problem because our team worked more quickly than was forecasted. We predict that Gate 3 is going to take a lot of work, so our group is going to have to make sure to begin to work on it as early as possible.

Gate 3

Project Management: Coordination Review

Cause for Corrective Action

Our group has been working very well together and we have made sure that we have addressed any problems. For gate 3 we were a bit confused on how to show the components being assembled in sequence. We solved this problem by attending office hours to find out how exactly we were supposed to do the assembly. The TA showed us how to put all the parts together in an assembly drawing. Our group almost had the right idea but we had forgotten a few key components since taking MAE 177. Another problem has been dividing the work into equal workloads. We were able to solve this problem by spending a portion of the group meeting deciding who would do each part and how they would do it. In gate 3, we had to break to figure out how we were going to finish it in time. We did this by breaking up each category and assigning to one group member who would send it to another group member to check it over to make sure it was satisfactory. For example, Ryan was assigned to do the solid modeled assembly part of Gate 3 and then he sent it to Jason to make sure that it was done correctly. Another problem that the group had to deal with was the large number of tests that took place in the two weeks before Gate 3 was due. We knew of this problem before all of the tests so, we made sure to work on Gate 3 before the tests so we would have enough time to make corrections before the due date. The group does not have any outstanding challenges at this time and we will continue to deal with any problems in the future with diligence and perseverance.

Product Archaeology: Product Evaluation

Component Summary

The product was created as a result of several factors and assessments. These consist of component function, component form (geometry, material, and appearance), manufacturing methods, and component complexity.

Manufacturing Methods

The product was created as a result of several factors and assessments. Of these, the main analytical interpretations consist of the Manufacturing Methods and the Four Factors involved. There are many methods for manufacturing. However, for the specific product of the Nerf Vulcan EBF-25 the main method is injection molding. This process is used for the external plastic coverings, small components (including the trigger, sight, barrel, internal firing mechanism, and gears), tripod, ammo box, and ammo belt. These components were formed through a mold, filled with a green plastic. This is apparent through the plastic material used, the various shapes within the product, and the fact that plastic is a great material for injection molding. The Vulcan EBF-25 uses plastic throughout, roughly 95%. Therefore, injection molding is the best manufacturing process. In addition to injection molding, the manufacturing process of drawing was used. This is evident in the wires. Wires are formed and shaped through the drawing process.

The Four Factors

Economic Factors:

The price of the Vulcan EBF-25 was a large factor in deciding the process for manufacturing. Injection molding was the obvious choice for the plastic parts due to the high volume of parts needed for each gun. This would minimize the cost of each gun and would make it affordable for any child who wanted one.

Societal Factor:

The way in which society views the manufacturing process had a large impact on which manufacturing process was chosen. If society had a negative view on the process then they would most likely choose a different process so Habro would not receive any negative media attention.

Global Factor:

If a product looks 'cool' or not was a large determining factor in deciding which manufacturing process to use. If the product does not look 'cool', then it would be a large turn off to the customers due to the nature of the product. Injection Molding was the obvious choice due to the fact that coloring the individual components would be much easier.

Environmental Factor:

If the process was detrimental to the environment then Hasbro would want to choose a different process to avoid receiving any negative media attention. Injection molding is better for the environment because there is only one mold needed for each part so there would be less pollution.

Product Analysis

Component	Description	Number within Final Product	Image
Ammo Box	Function Hold the ammo belt and attaches to the side of the product. Materials Plastic Manufacturing Process Injection Molding.	1
Handle	Function Attached to top of product to make it easier to carry. Materials Plastic Manufacturing Process Injection Molding.	1
Cocking Pin	Function It goes through the main firing mechanism and sticks out of each side of the gun. It manually cocks the gun when pulled back. Materials Plastic, Metal. Manufacturing Process Injection Molding, Forming.	1
Tripod	Function Allows the gun to be mounted to a surface so that the user doesn’t have to carry the product Materials Plastic. Manufacturing Process Injection Molding.	1
Breach Cover	Function A structure that goes over the breach and helps guide and load the darts. Materials Plastic. Manufacturing Process Injection Molding.	1
Barrel	Function To make the product look more like a gun. It does not guide the dart in any way. Materials Plastic. Manufacturing Process Injection Molding.	1
Barrel Casing Half	Function Holds the barrel in place and attaches the barrel to the gun. It also provides a place for the user to hold the gun when attached to its other half. Materials Plastic. Manufacturing Process Injection Molding.	2
Main Body Casing Half	Function When attached to its other half it encloses all the major components of the product. Materials Plastic. Manufacturing Process Injection Molding.	2
Battery Case	Function Hold the batteries in the product and allows the power from the battery to transfer to the products electric motor. Materials Plastic, Metal. Manufacturing Process Injection Molding, Forming.	1
Electric Motor	Function When given power from the batteries it moves the gears inside the gun. Materials Plastic, Metal, Copper Wiring. Manufacturing Process Injection Molding, Forming, Drawing.	1
Gear Shaft	Function When given power from the batteries it moves the gears inside the gun. Materials Plastic. Manufacturing Process Injection Molding.	1
Dart Feeder Rotator	Function When the gun is cocked this part rotates the dart feeder by the feeder pressing up against the slanted groves of the rotator. Materials Plastic. Manufacturing Process Injection Molding.	1
Main Spring System	Function This part includes the main spring which when compressed stores the energy used to propel the dart. It also includes a rubber seal at the front to create an air tight seal in the main spring chamber so that when the energy from the spring is released the air in the chamber is pushed by the rubber seal. Materials Plastic, Metal. Manufacturing Process Injection Molding, Forming.	1
Main Spring Chamber	Function It is a hallow tube that the main spring system goes inside of and it provides a channel for the pushed air to go. Materials Plastic. Manufacturing Process Injection Molding.	1
Gears	Function It pushes back the gear shaft after being acted upon by the motor. Materials Plastic. Manufacturing Process Injection Molding.	7
Gear Cover	Function Provides a protective casing over the gears and also helps hold the gears and the motor in place. Materials Plastic. Manufacturing Process Injection Molding.	1
Trigger	Function In manual firing mode it pushes on the trigger pin releasing the cocked spring. In automatic mode it connects the batteries to the electric motor and keeps the trigger pin open. Materials Plastic. Manufacturing Process Injection Molding.	1
Trigger Pin	Function When the product is cocked to holds the compressed spring back. Materials Plastic. Manufacturing Process Injection Molding.	1
Trigger Cover	Function Holds the trigger in place. Materials Plastic. Manufacturing Process Injection Molding.	1
Main Mechanism Cover	Function Encloses all of the parts of the main firing mechanism. Materials Plastic. Manufacturing Process Injection Molding.	1
Gear Shaft Guide	Function This guides the gear shaft into the gears and prevents it form popping out of place. Materials Plastic. Manufacturing Process Injection Molding.	1

Solid Modeled Assembly

Using the Inventor 2012 3D Drafting Program, our group modeled an internal assembly of the Nerf Vulcan EBF-25. This assembly consisted of four components- the seven gears, the main spring, gear shaft, and dart feeder rotator. Images of the assembly are shown below.

Assembly 3D
Assembly Front

Engineering Analysis

A key component of the Vulcan EBF-25 is the main firing spring. Without the main firing spring the Nerf gun would be absolutely worthless because it could not perform its main function, which is to shoot darts. It would not matter if electrical or kinetic energy was applied to the rest of the gun; the dart would not be able to be fired because it supplies the spring energy, which is the main energy that powers the dart through the air. The engineering analysis process would be used to find out which spring would be most appropriate for the Vulcan EBF-25. The engineers would not want a spring that would be too strong for the children using the Vulcan EBF-25. If the spring was too strong the product could fire darts with too much velocity and might become a liability for the Hasbro. The first step would be stating the Problem, and the problem is finding the right spring for the Vulcan EBF-25. Then a diagram would be drawn up showing the different forces on the main firing spring and how each one would effect the spring. Making some assumptions such as no energy is lost from the spring to the dart would be the next viable step in the analysis process. Then any relevant equation would be brought up such as the energy equation for a spring (U=1/2k(X2(^2)-X1(^2))), Hooke’s Law (F=-kx) and Conservation of energy (Ein=Eout). The calculations would then be performed to find the appropriate strength of the spring for the Vulcan EBF-25. Once an appropriate strength for the spring has been found the spring then would undergo a series of rigorous tests to make sure that it would live up to Nerf’s standards. Some of the tests could be making sure that it is durable enough and that the gun can fire as quickly as needed with the spring. If the spring does not pass these tests then the process will be need to be looked at and make sure that it is corrected. This step is the solution check and it must be done or the reputation of Hasbro could be damaged. The last step would be to present the spring to the person or persons in charge and discuss why it is the most appropriate spring for the Vulcan EBF-25.

Design Revisions

The Nerf Vulcan EBF-25 is a well rounded product. Its components (in sequence and parallel) accomplish the aspects involved with a projectile launcher. However, the design could be improved. These improvements involve three major components- the main spring, power source, and motor. The improvements involved with each aspect is explained in detail below.

Main Spring:

One component of one of the major subsystems that operates within the Vulcan EBF-25 is the main spring. We found that the main spring that comes standard with the Vulcan EBF-25 was rather frail to begin with but obviously strong enough to do the job of launching a dart. While testing the Vulcan EBF-25 we found that when lofted at approximately a 45-degree angle with the ground the darts were only launched about 25 feet at maximum, with some darts barely reaching 20 feet. So not only is the power of the spring unimpressive, it is rather inconsistent as well. Incorporating a stronger spring into the product would improve the users experience with the product by allowing it to shoot farther on average and having an almost negligible rise in production and retail prices thus providing a better product for the consumer.

Power Source:

One of the first things to be noticed about the Vulcan EBF-25 is the excessive size of the battery compartment. The main reason for the battery compartment being so large is to account for the size of the six size D batteries used to power the Vulcan EBF-25. One of the best ways to improve the power source for the Vulcan EBF-25 would be to replace all six D-batteries with one rechargeable 9.6 Volt battery pack. Since the six D-batteries provide approximately 7-9 Volts, not only would a single rechargeable 9.6 Volt battery pack provide more voltage but would take up less space as well. In addition the user would not have to go through the hassle and expenses of buying, changing, and properly disposing of batteries when they run out. So not only would the consumer benefit from this redesign but the environment could possibly benefit as well.

Motor:

Another design revision that could be made to improve the Vulcan EBF-25 would be to use a different electric motor. Using a better, more efficient electric motor that could power the gun and still launch the darts at the same rate would reduce the battery usage for the Vulcan EBF-25 thus saving the consumer more money. Although this would drive up production prices making consumers pay more for the initial cost of the Vulcan EBF-25, the recurrent costs of continually replacing the batteries would be lower which is relatively high compared to the cost of the product.

Gate 4

Project Management: Critical Project Review

Cause for Corrective Action

Our group continues to work well together through all of the struggles and growing pains. One of the problems that we have dealt with was when we received our gate 3 grade. Our group believed that we were unfairly graded, so we attended office hours to talk to Mr. Olewnik about getting a re-grade. We also wanted to make sure that we were going to get a better grade on gate 4 as compared to gate 2. Another problem that we are going to have to deal with is making sure gate 5 is going to be completed on time. Gate 5 is due during finals week so it is going to be difficult to make sure that everyone does their part during that chaotic time. Another problem will be choosing the group member who is going to give the final presentation. Everyone will have to do their part to create the five minute presentation and we will have to decide which group member will do the best job of giving the presentation. Our group will have to continue to persevere through the most difficult time of the semester in order to finish the project and have a good grade.

Product Archaeology: Product Explanation

Product Reassembly

Attachments	Component(s) and Description	Image
Step #1	The Gears Insert the gear in the order that corresponds to the same order found in disassembly and to match the picture. To insert the gears simply place them on the pegs in the gear box of the main body. Easy Difficulty
Step #2	The Trigger The trigger and its components go on next. Place the trigger with the smooth towards the front of the gun on the peg at the rear of the main body. The trigger pin then is placed into the grooved directly above the trigger and should sit flat. Easy Difficulty
Step #3	The Gear Cover The gear cover is placed on top of the gears with the longest peg from the main body as well as some of the small gears sticking out of the cover. Make sure the four screw holes line up and screw in a small black screw for each hole using the small screwdriver. Follow the same procedure for the trigger cover. Easy Difficulty
Step #4	The Gear Cover continued Attach the cocking mechanism extender to gear shaft guild through the slit in the cover with 2 large screws using the large screwdriver. Also attach the second gear cover by placing it over the exposed gears lining up the screws holes and screwing it in with 2 small screws with the small screw driver. Easy Difficulty
Step #5	The Feeder Rotator To attach the feeder rotator place on the main body on the lower front into the groves lining up the screw holes. The main spring mechanism can be put back together by first sliding the main spring into the air chamber. Then place the retention spring on the front of the air chamber and place the main spring mechanism above the feeder rotator with the compression spring towards the front. The mechanism should sit flat with the groves lining up with the gears in the back. Medium Difficulty
Step #6	Internal Components of the Cocking Mechanism To finish the internal workings of the cocking mechanism place the gear shaft with the grooved parts by the gear in the main body so that it lays flat in between the feeder rotator and the main spring mechanism. Then place the gear guide guard under the gear guide with the holes lining up with the holes on the back half of the feeder rotator. In those two screw holes screw in a large screw in each with the large screw driver. Medium Difficulty
Step #7	The Electric Motor Place the motor in the area with a hole, the gear attached to the motor goes in this hole and then just screw the part into place with the small screws and screwdriver. Easy Difficulty
Step #8	The Alignment Springs Attach the alignment springs on each side by hooking one half to a hook and then the other to a screw that screws into a hole an inch further towards the front of the gun. Hard Difficulty
Step #9	The Attachment of the Firing Mechanism to the Main Body Attach the firing mechanism cover by placing it over the front half of the main body aligning the screw holes and placing the spring retainer on front to the compression spring. Then screw 8 small screws into the 8 holes with the small screw driver. In order for the compression spring to fit in it has to be compressed while the cover is being attached. Hard Difficulty
Step #10	The Attachment of the Firing Mechanism to the Main Body continued Place the main firing mechanism into the main body cover with the trigger by the handle then screw them together with 10 small screws in the empty screw holes. Then run the wires from the motor, the yellow button goes in a slot in the front of the main body and the other two go to the battery compartment. Lay the other half of the main body casing over the assembles part of the casing to line up the screw holes and then screw together with the small screws using the small screwdriver. Easy Difficulty
Step #11	The Barrel and Casing: Part 1 Assemble the barrel and casing by screwing the two halfs of the casing together with the small screws then slide the barrel into the hole in the assembles casing. Next screw the barrel cap on the front of the gun with a small screw. Easy Difficulty
Step #12	The Barrel and Casing: Part 2 Attach the barrel and casing to the main gun assembly by sliding them together like a puzzle and then screwing them together with big screws and the big screw driver in the two screw holes where the parts over lap. Easy Difficulty
Step #13	The Battery Cartridge Slide the battery cartridge into the space on the bottom of the gun and use a big screw to secure it down in the one screw hole. Easy Difficulty
Step #14	The Breach Cover The reattachment of the breach cover requires two steps. First, place the two plastic pieces on the holes within the breach cover. Then with the breach cover in place, tighten two screws with the Philips head screw driver. Easy Difficulty

Design Revisions

• Cocking Mechanism:

One design revision at the system level would be to redesign the cocking mechanism. To make it more efficient, we would make the cocking mechanism easier to cock back. We could do this by making the bolts in the cocking mechanism less resistive to the force required to cock the gun while still maintaining its full power. The Vulcan EBF-25 is mainly handled by children under the age of fourteen so, making the cocking mechanism easier to cock back would improve the overall performance of the product. The cocking mechanism is rather difficult to pull back even when handled by an adult. Through testing the product we have concluded that the cocking mechanism would be difficult for a child to apply a force necessary to cock back the gun. This addresses a societal concern for the Vulcan EBF-25; children could potentially hurt themselves from being too tired from cocking back the gun. This redesign would also address a global concern because the product would gain a more favorable view in a society’s culture. This redesign would bring more joy and children would get more enjoyment out of the Vulcan EBF-25.

• Barrel Length:

One design revision at the system level would be to reduce the overall length of the firing barrel. The length of the firing barrel is there purely for aesthetics only; it serves no purpose in the overall function of the gun. When we removed the barrel we tested the gun by firing it and found that the darts went exactly the same distance. Reducing the length of the firing barrel would improve the overall performance of the Vulcan EBF-25 by making it more maneuverable because the gun would be less long. This would also reduce the number of products broken from use because the barrel is the weakest part of the Vulcan EBF-25 so, by reducing its length the durability of the barrel would increase. This change would address an economic concern for the product, because it would reduce the overall price of the Vulcan EBF-25 since there is less material being used in the product. This redesign also addresses an environmental concern because it would reduce the overall emissions required to produce the product since there is less material being used. Since the Vulcan EBF-25 is becoming more maneuverable, it is also becoming a safer product to use because children are less likely to run into objects with a smaller gun. This redesign therefore addresses a societal concern since it is becoming safer.

• Motor:

A third design revision at the systems level would be to use a different motor or change the existing motor in a way to increase operating speed and power threshold levels. The current motors used in the Vulcan EBF-25 have been known to eventually burn out over time or burn out even quicker if any modifications are performed to increase battery power supplied to the motor thus increasing shooting rates. Although the motor can handle the extra power from the batteries temporarily, after a longer period of time the motor will eventually burn out because it is only designed to operate on about 9 Volts of battery power. So this factor somewhat limits the performance capabilities and modification potential of the Vulcan EBF-25. Using a bigger or better motor that can operate normally at a power level higher than 9 Volts, without burning out, will move the gears quicker and allow the Vulcan EBF-25 to shoot more darts per second. This revision would be considered a social design consideration because the manufacturers would be producing a better performing product that is more fun to use for the consumer at a reasonably small rise in production and market cost. Utilizing a motor that could operate safely at 12 Volts and could shoot at about five or six darts per second (compared to the currently claimed three darts per second) would almost double the performance rates of the Vulcan EBF-25 for the cost of a small increase in production price.

Design Revisions

To define a meaningful scale for difficulty we determined it by the amount of effort that needed to take place in order to do the task. The scale is done on an easy, medium, or hard basis. The easy parts would include using basic tools for basic function such as screwing a screw or such things as pushing one part into another using a moderate amount of force. Medium parts would be something like holding a part a certain way while it is screwed into place. A hard assembly part would be something that one would have to hold under tension, hold multiple parts at once while being screwed in, or thread a part through or around stationary parts. The product was most likely assembled by workers on an assembly line with numatic screwdrivers. The assembly is the same as the disassembly just in the reverse order and only using a small and large Philips head screwdriver.

Gate 5

To start our analysis of the NERF Vulcan EBF-25 our group did a large amount research to find background information regarding the product. From there, we began planning our procedure for analysis and the disassembly process. Using the background information from our research, we created the product profiles, which helped organize our research in a manner that we could use it effectively throughout our disassembly and analysis. The next step in the analysis process was to begin the actual disassembly. To start, we removed the exterior components on the product that often get removed during regular use anyway. This includes the tripod, top handle, manual cocking bolt, ammunition holder, and battery door. Proceeding from there, we removed the mainly aesthetic, plastic body pieces that form the exterior casing to the Vulcan EBF-25 mostly simply loosening the screws. This left the basic internal assembly exposed for disassembly. The rest of the components of the internal assembly were removed by simply unscrewing screws and compressing to remove internal springs. During the disassembly, our group learned exactly what functions the main components perform during the operation of the Vulcan EBF-25.