UNIVERSITY AT BUFFALO

Project 08 The Final Countdown

Andrew Wise

12/14/2009

The complete report chronicling the design of a paintball maker from conception to finished product.

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1 Contents 2 Introduction.................................................................................................................................................................................................... 4

2.1.1 Figure 1 ..................................................................................................................................................................................... 4

3 Problem Statement ........................................................................................................................................................................................ 4

4 Research on Existing Products ........................................................................................................................................................................ 5

4.1.1 Table 1 ...................................................................................................................................................................................... 5

4.1.2 Table 2 ...................................................................................................................................................................................... 6

4.1.3 Table 3 ...................................................................................................................................................................................... 7

5 Project Management ...................................................................................................................................................................................... 8

5.1.1 Gantt Chart ............................................................................................................................................................................... 8

5.2 Bullets .................................................................................................................................................................................................. 9

5.2.1 Figure 2 ..................................................................................................................................................................................... 9

5.3 Clips ................................................................................................................................................................................................... 10

5.3.1 Figure 3 ................................................................................................................................................................................... 10

5.3.2 Figure 4 ................................................................................................................................................................................... 11

5.3.3 Design Table Analysis for Magazines ...................................................................................................................................... 11

5.4 Barrels................................................................................................................................................................................................ 12

5.4.1 Figure 5 ................................................................................................................................................................................... 12

5.5 Marker Design ................................................................................................................................................................................... 13

5.5.1 Figure 6 ................................................................................................................................................................................... 13

5.6 The Conventional Paintball Gun ........................................................................................................................................................ 14

5.6.1 Figure 7 ................................................................................................................................................................................... 14

5.6.2 Design Analysis Table 2 ........................................................................................................................................................... 14

6 3D CAD Modeling ......................................................................................................................................................................................... 15

6.1 CHAMBER ASSEMBLY ......................................................................................................................................................................... 15

6.1.1 Figure 8 ................................................................................................................................................................................... 15

6.1.2 Figure 9 ................................................................................................................................................................................... 16

6.1.3 Figure 10 ................................................................................................................................................................................. 16

6.2 LINE ASSEMBLY .................................................................................................................................................................................. 17

6.2.1 Figure 11 ................................................................................................................................................................................. 17

6.2.2 Figure 12 ................................................................................................................................................................................. 18

6.2.3 Figure 13 ................................................................................................................................................................................. 18

6.3 STOCK ASSEMBLY .............................................................................................................................................................................. 19

6.3.1 Figure 14 ................................................................................................................................................................................. 19

6.3.2 Figure 15 ................................................................................................................................................................................. 20

6.3.3 Figure 16 ................................................................................................................................................................................. 20

6.3.4 Figure 17 ................................................................................................................................................................................. 21

6.4 DRUM MAGAZINE ASSEMBLY ............................................................................................................................................................ 21

6.4.1 Figure 18 ................................................................................................................................................................................. 22

6.4.2 Figure 19 ................................................................................................................................................................................. 23

6.4.3 Figure 20 ................................................................................................................................................................................. 23

6.4.4 Figure 21 ................................................................................................................................................................................. 24

6.5 TRIGGER ASSEMBLY ........................................................................................................................................................................... 24

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6.5.1 Figure 22 ................................................................................................................................................................................. 25

6.5.2 Figure 23 ................................................................................................................................................................................. 25

6.5.3 Figure 24 ................................................................................................................................................................................. 26

6.5.4 Figure 25 ................................................................................................................................................................................. 26

6.6 Barrel ................................................................................................................................................................................................. 27

6.6.1 Figure 26 ................................................................................................................................................................................. 27

6.6.2 Figure 27 ................................................................................................................................................................................. 28

6.7 The Total Assembly ............................................................................................................................................................................ 29

6.7.1 Figure 28 ................................................................................................................................................................................. 29

6.7.2 Figure 29 ................................................................................................................................................................................. 29

6.8 Design Animation .............................................................................................................................................................................. 29

6.8.1 Figure 30 ................................................................................................................................................................................. 30

6.8.2 Figure 31 ................................................................................................................................................................................. 31

6.8.3 Figure 32 ................................................................................................................................................................................. 32

6.8.4 Figure 33 ................................................................................................................................................................................. 32

7 Manufacturing Analysis ................................................................................................................................................................................ 33

7.1 Cost Analysis ...................................................................................................................................................................................... 33

7.1.1 Chamber Assembly Cost Analysis ............................................................................................................................................ 33

7.1.2 Line Assembly ......................................................................................................................................................................... 33

7.1.3 Stock Assembly ....................................................................................................................................................................... 33

7.1.4 Drum Magazine Assembly Cost Chart ..................................................................................................................................... 34

7.1.5 Trigger Assembly Cost Chart ................................................................................................................................................... 34

7.1.6 Barrel Cost Chart ..................................................................................................................................................................... 34

7.1.7 Final Cost and Pricing Analysis ................................................................................................................................................ 34

7.2 Total Assembly Drawing .................................................................................................................................................................... 35

7.2.1 Figure 34 ................................................................................................................................................................................. 35

8 Service Analysis ............................................................................................................................................................................................ 36

8.1 Product Life Analysis .......................................................................................................................................................................... 36

8.2 User Manual ...................................................................................................................................................................................... 36

9 Discussion ..................................................................................................................................................................................................... 36

10 Conclusion .................................................................................................................................................................................................... 38

11 References .................................................................................................................................................................................................... 38

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2 Introduction

The use of projectiles as weapons is as old as humanity itself. It started as rocks and spears, then

evolved into axes and bows and arrows, and eventually into firearms. But the transition from the

primitive weapons of natives to automatic rifles was not an immediate one. It happened in a series of

steps. From the musket came the rifle, then from the rifle came the breach loading rifle, then the

repeating rifle, then the bolt-action rifle, then the semi-automatic rifle, and then the automatic rifle over

a period of approximately 300 years. Progress was slow, but methodical.

If one looks at the paintball industry, there has been no such development. Paintball guns started at

semi or full auto and have remained the same ever since, skipping the centuries of research and

developed endured by their lethal counterparts. No one can argue with paintball’s results, when it

comes to firing mechanism, one has to wonder what the industry is still doing with ball-shaped

ammunition. With such fine engineering put into the rest of the gun, this oversight seems lazy.

2.1.1 Figure 1

Figure1: The Tommy Marker

3 Problem Statement

Project 08 will culminate in the design of a paintball rifle which fires conical shaped rounds, much like a

half or full football. From the typical paintball gun, several design features will be changed. The hopper

will be replaced by a drum magazine, most likely loading from the bottom. The barrel itself will be rifled.

The goal of the new design is to make paintball guns more accurate without sacrificing rate of fire, losing

too much in the line of carrying capacity, or pricing the design out of the market.

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4 Research on Existing Products

4.1.1 Table 1

Gun Picture Features Price

Tippmann A5 Paintball Gun with Response

Trigger

Fires up to 15 balls per second

.68 caliber

Field stripped in under 60 seconds

MP5 style sight

$500

JT Tac 5 Ultimate Sleath Marker

Paintball kit

Quick and easy field strip

14" sniper barrel

.68 Caliber

200 round hopper

$100

Brass Eagle Remanufactured T-

Storm Marker

.68 caliber

2 step field strip technology

200 round hopper

$40

Table 1: Three different markers on the market with selected features

These are some gun from various price ranges. Aside from size, there are two features in common in all

three guns: The advanced pistol front grip and the quick and easy field strip. The pistol grip should be

included in my design. The quick and easy field strip also seems to be popular. I will take great care not

to over-design the gun.

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4.1.2 Table 2

Load Picture Features Price

View Loader 200 Road Hopper

200 Rounds $10

Halo B Electronic Paintball Loader

170 rounds

22+ balls per second

20,000 round battery life

$80

Kingman Training Pistol Mag

140 Rounds

Easy to reload $20

Table 2: Three different loading systems on the market with various features

By far the most popular method of loading is the hopper. However, with conical shaped ammo, the

hopper is impractical. The rounds must enter the chamber with a particular orientation. So a magazine

must be the order of the day. This magazine is designed for 9 mm paintball guns. The .68 caliber is about

twice as large. The straight magazine would be too big. I am contemplating a drum magazine.

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4.1.3 Table 3

Barrel Pictures Features Cost

Tippmann 16"Straightline rifled barrel kit

Rifled, 16" barrel

.68 Caliber

$170

Small Parts 1 Piece All-American Paintball Barrel

.68 Caliber

Rifled (14-16") Barrel

$55

BT Apex Barrel

Adjust spin on balls

$40

Table 3: Three different barrels on the market with various features

Most barrels I am familiar with don't have rifling. It's just an empty tube. While the adjustable ball spin

sounds cool, the physics are too complicated for me without building a prototype. A rifled barrel was my

first instinct and I shall stick with it. Truth be told, I don't see any difference between the $55 model and

the $170 model.

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5 Project Management

The biggest obstacle in completing this project to my satisfaction will be time management. As the

semester ends, time will get tight as several projects will come due and multiple tests will be scheduled

at the same time. The Gantt Chart, used universally in industry, is a great tool used to by real engineers

to keep their product design projects on track.

5.1.1 Gantt Chart

The Gantt Chart: For all your one-stop project management needs

Before the project can progress, there must be several design decisions made. Several different design

aspects could be incorporated for the final product.

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5.2 Bullets

5.2.1 Figure 2

Figure 1: The Bullet Sketch

The round shown above is the consensus favorite. Initially, a more football shaped round was

considered, but this did not present much of a design improvement as the rounds would still greatly

resemble the ball shape which is precisely what I want to replace. The round is a 68 caliber is about an

inch long. It has a cylindrical section at the back, but is tapered via two arc to a point at the front. This

design should be much more aerodynamic than its predecessor.

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5.3 Clips

5.3.1 Figure 3

Figure 2: The Straight Magazine Design

The straight, spring-loaded magazine is a classic and simple design. About 20 rounds are housed in the

15" magazine which feeds rounds into the gun. As a round is placed into the chamber, the spring will

advance every other round up the magazine. It is fairly fool-proof.

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5.3.2 Figure 4

Figure 3: The Drum Magazine

The other design possibility is the drum magazine. The drum magazine operates under a similar premise

as the straight magazine: the rounds are hand fed into a drum track; after another round is accepted by

the chamber, the non-linear spring in the center of the barrel pushes the rounds along the track and

into up to the chamber. Due to its circular shape, the can hold almost two and a half times as much

ammunition as the straight magazine. It is also shorter and less awkward.

5.3.3 Design Table Analysis for Magazines

Capacity (50%) Reliability (25%) Size (25%) Total

Straight Magazine 20 20 10 50

Drum Magazine 50 15 10 75 Table 4: The Design Analysis Table for the Magazine

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The drum magazine is the loading method of choice for this paintball marker.

5.4 Barrels

5.4.1 Figure 5

Figure 4: The Barrel Design

Barrels come in various lengths. Luckily, however, barrels are interchangeable on most paintball guns.

This decision can be made by the individual shooter for his/her needs and/or preferences. I plan on

offering all four lengths with the same counter-clockwise twist as options.

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5.5 Marker Design

5.5.1 Figure 6

Figure 5: The Tommy Gun

After the design of the drum magazine, the "Tommy Gun" design seemed like a no-brainer. It is an

enduring American symbol of both crime and corruption and law and order. Through its appearances

into movies like The Godfather, Dick Tracy, and Public Enemies, the Tommy Gun remains iconic and

would sell very well. The changes that would have to be made from a convention paintball gun are to

first move the CO2 tank into the stock in line with the chamber and barrel. The CO2 line which runs to

the front of the gun for blowback would now run over the top of the gun versus underneath the gun as

is customary for paintball markers. Also, a second pistol grip must be added to the front for that

authentic gangster look.

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5.6 The Conventional Paintball Gun

5.6.1 Figure 7

Figure 6: The Conventional Design

5.6.2 Design Analysis Table 2

Reputation Firing

characteristics Appearances Total

Tommy Gun 16 25 33 74

Conventional Gun 33 22 10 65 Table 5: the design analysis chart for the gun layout

The top loading gun is standard in the paint ball industry. With the newly designed magazines, this

design essentially mimics the design of every paintball gun ever made. While this might be the wisest

course of action, this option limits my creativity. The Tommy Gun is the ultimate choice.

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6 3D CAD Modeling

6.1 CHAMBER ASSEMBLY

The Chamber Assembly is the most complicated in the entire marker. The assembly consists of fourteen

different pieces and every other assembly either bolts on or screws into it. Every part connects to the

CHAMBER. The chamber is a metallic shaft with two sixty-eight caliber holes running parallel inside. The

top hole is the actual chamber; this is from the bullet will be launched. The second hole, however, is just

as important. This hole houses the valve and springs that allow the marker to function. It is also

important to note that the TRIGGER ASSEMBLY and the LINE ASSEMBLY connect to the CHAMBER

ASSEMBLY via threads and slots in the bottom hole.

6.1.1 Figure 8

(A) (B)

Figure 7: 8(A) shows the Chamber; 8(B) shows the Chamber from a different angle

The chamber is itself was difficult to make not because the techniques were difficult (The several

extrusions, rounds, holes, and helical sweeps needed for the part have long since been mastered.), but

rather because there was no room for error. Not only did everything have to fit but it had to fit in the

right place. Several revisions were made to the individual features, parts, and pieces of the assembly so

that they would all work in harmony.

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6.1.2 Figure 9

(A) (B)

Figure 8: 9(A) shows the chamber assembly constructed; 9(B) show an exploded view of the assembly

6.1.3 Figure 10

Figure 9: The Assembly drawing for the Chamber Assembly with individual part drawings for each component

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6.2 LINE ASSEMBLY

THE LINE ASSEMBY is crucial is the product. Without the compressed CO2 tank, the bullet is a squib,

doomed never to leave the barrel. Most of the half of a dozen or so pieces in the assembly were

modeled easily, but the expansion chamber was more intricate. Not only did the part require features to

be modeled on the inside and the outside, but it also need to convey a sort of elegant symmetry. On

most markers, the expansion chamber also doubles as a second handle on the front of the gun. Here,

the expansion chamber is purely functional, but I did not want to lose that artisan-like styling.

6.2.1 Figure 11

(A) (B)

Figure 10: 11(A) shows the threaded stem on the expansion chamber; 11(B) shows the symmetrical, elegant nature of the part

The finger holes were made by revolving a circle about a center axis and making a cut. The cut was then

patterned four times for four fingers. As no accurate dimensions could be ascertained, the process was

an exercise in trial and error. Several different depths and diameters of circles were test until the perfect

fit was established.

The threaded protrusion that connects to the line expansion chamber was made in a three step process.

First, a sketch was made of a circle on the edge surface of the part and an extrude cut was made.

Second, a revolved protrusion was made at the bottom of the newly created hole to create the stem.

Finally, a helical sweep added the threading. The piece looks more akin a vase than a hunk of cold, hard

steel.

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6.2.2 Figure 12

(A) (B)

Figure 11: 12(A) shows the constructed line assembly; 12(B) shows an exploded view of the assembly

The assembly went together smoothly. The toughest part was creating the right dimensions for the line.

While reality affords a builder some flexibility and some give in the line, ProE is not as forgiving. Precise

dimensions are required or else the assembly will look badly.

6.2.3 Figure 13

Figure 12: The assembly drawing for the Line Assembly with part drawings for individual components

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6.3 STOCK ASSEMBLY The Stock Assembly was hardly considered for Phase 1 and Phase 2. Vaguely the designer knew that the

stock was needed if the marker was ever to look like a Thompson Machine Gun, but little thought was

given as to how. The stock needed to go behind the chamber in such a way so as not to disturb the

hammer, which would move back and forth repeatedly given the weapons fully automatic nature. The

solution became the stock mount. The stock is not assembled to the gun itself, but rather another piece

(the stock mount) that attached to the gun. The stock mount is designed to slip seamlessly over the

chamber assembly. Quite a bit of comparing back and forth went on between the chamber and the

stock during its creation. The stock mount mimics the profile perfectly and has been given 1/16” wall

thickness all the way around. It attaches to the barrel with a screw on top and a pin on the side. The

chamber insures that the stock will not move left or right and the screw and pin make sure the stock will

not move forward or back. The stock mount attaches to the stock by slipping into a hole with the same

profile as the mount in the stock. Basically, the process used to create the mount of the chamber was

repeated to alter the stock off its mount.

6.3.1 Figure 14

(A) (B)

Figure 13: 14(A)&(B) show the stock mount from different angles; Notice how the mount mimicks the contour of the chamber

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6.3.2 Figure 15

(A) (B)

Figure 14: 15(A) shows the stock mount installed on the chamber assembly; 15(B) shows the stock mount entering the stock

The assembly went together surprisingly smoothly considering the small tolerances allowed, though

perhaps this should have been expected. Aside from the stock and the stock mount, there are only a few

screws, washers, and nuts. It would be very hard to screw that up.

6.3.3 Figure 16

(A) (B)

Figure 15: 16(A) shows the Stock Assembly exploded; 15(B) shows the assembly constructed

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6.3.4 Figure 17

Figure 16: The Assembly Drawing for the Stock Assembly with part drawings for the individual components

6.4 DRUM MAGAZINE ASSEMBLY

The Drum Magazine Assembly is brutally complicated. As I have never seen a paintball gun with a drum

magazine, I knew from the start that this project would be my own design. I had hoped to find some

inspiration on the internet, but information on drum magazine was few and far between.

The premise of my design is essentially this: paint bullets are fed into the magazine from the top along a

track which runs just inside the outer edge of the magazine; the inside the magazine the rounds

encounter resisted provided by an arm at the end of a circular spring; the when the magazine is placed

into the gun assembly, the spring and arm will force the rounds down the track and eventually into the

gun one at a time. To better accomplish my design goals, several pieces additions were made to the

main part. In the track, a circular ramp was made to better help the rounds reach the chamber; a trap

was created so the one end of the spring would always remain stationary; small indentations were made

so the magazine would stay in the gun; the edges were chamfered to better help the magazine enter the

gun. Generally, I am happy with the magazine. However, it is comically oversized when compared with

the rest of the gun. It was the only way to even get capacity up to forty-eight rounds. Most paintball

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guns come with hopper which can hold 200 balls. The problem is all the empty space in the magazine,

but I am unable to find a design with a more efficient use of such a valuable resource.

6.4.1 Figure 18

(A) (B)

Figure 17: 18(A)&(B) show the main part of the magazine assembly from different angles; Note the hole on top where the rounds are loaded and the slit in the track where the spring advances the rounds

The other part of this assembly which is remarkable is the paint bullet. This design is hardly

revolutionary or complicated, but because of the pre-design emphasis put on the round I feel it should

be discussed. The design is simple: Instead of a ball, why do markers not propel something shaped like a

bullet. For my efforts, I have created a sixty-eight caliber paint bullet. The round is an inch long, which

makes it approximately one and one half times the size of a conventional paint ball. However, the

pointed tip and sleek design should make the marker more accurate and help the effective range.

Another feature incorporated into the design that is an improvement to the paintball is the small jut into

the back end. When the paint bullet is fired, the pressure will enter the jut and cause the wall to expand

outwards. The wall will adhere its shape to the rest of the barrel and create an airtight seal leading to

better range and more accuracy.

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6.4.2 Figure 19

(A) (B)

Figure 18: 19(A) shows the backend of the bullet; Notice the indentation; 19(B) shows the sleeker, more aerodynamic shape of the round

The actually assembly goes together easily. Attention needed to be paid to the orientation of the front

and back pieces of the magazine because it does indeed matter. The pattern feature in the ProE made

putting the paint bullets into the assembly quick and easy. Without Pattern, the bullets would have been

a nightmare.

6.4.3 Figure 20

(A) (B) Figure 19: 20 (A) shows an assembly view of the Drug Magazine; 20(B) shows an exploded view

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6.4.4 Figure 21

Figure 20: The assembly drawing for the Drum Magazine with part drawings for each individual piece

6.5 TRIGGER ASSEMBLY

The trigger assembly is one of the more involved pieces in the design. Unlike my initial ideas about a

marker works, the trigger assembly only interfaces with the pressure tank and valves indirectly. When

the marker is cocked, a small arm is wedges itself into a rut on a seal in the chamber assembly. When

one pulls the trigger, he/she simply dislodges the arm from the rut and the rest has nothing to do with

the trigger assembly. Also in my design, when the trigger remains pulled, it can keep the arm from

interfacing with the rut. Thus, the marker re-cocks and fires immediately. This is an example of a full-

automatic weapon.

The trigger handle is the main enchilada, so to speak, in this assembly. Its modeling took patient care. It

has an oddly shape cross-section and no set width. This necessitated the creation of multiple features

and the repetition of commands. The handle also has three finger grips of which I am particularly proud.

They were made much like the expansion chamber, but without the benefit of symmetry. Also, the grips

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were made on a crooked axis. In addition, this is one of if not the only time in the entire course of MAE

377 that I made a revolve that did not go 360 degrees. This only went 180.

6.5.1 Figure 22

(A) (B)

Figure 21: 22(A) shows the handle; 22(B) shows the a detailed close up of the grips

Another interesting feature of the assembly is the safety. It stops the marker from shoot by wedging

itself under the trigger so that the trigger cannot be squeezed back. Its odd shape allows the safety to be

safely pushed left or right without falling out of the gun.

6.5.2 Figure 23

(A) (B) Figure 22: 23(A) shows the safety; 23(B) show the assembly from another angle

The assembly fits together easily. There were no constrain-related issues.

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6.5.3 Figure 24

(A) (B)

Figure 23: 24(A) shows the trigger assembly constructed; 24(B) shows the assembly in an exploded state

6.5.4 Figure 25

Figure 24: the assembly drawing of the Trigger Assembly with part drawings for each individual component

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6.6 Barrel

The Barrel might have been included in the chamber assembly, but I decided to leave it separate. The

barrel connects to the rest of the gun by screwing into the chamber. As an improvement over most

paintball guns, this barrel is rifled. This was accomplished with one helical sweep patterned down the

barrel several times. This feature will put a stabilizing spin on the bullet and help increase its accuracy.

The other notable feature on the barrel is its foregrip, a trademark of the original Thompson. This was

created with extrusions, revolutions, and several rounds. The idea was to design the grip for the

contours of the hand. Thus there are four finger indents and the handle is tampered toward the bottom.

The entire feature is rounded so that there is not a flat edge anywhere. The measurements were loosely

based on my own hand. If I had had access to a research and marketing team, the design might have

been of a different size.

6.6.1 Figure 26

(A) (B)

Figure 25: 26(A) shows a straight on look at the barrel; 26(B) shows the barrel from the side

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6.6.2 Figure 27

Figure 26: The part drawing for the barrel with highlighted dimensions

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6.7 The Total Assembly

The entire assembly is a combination of the aforementioned parts and sub-assemblies. It all comes to

together in a fairly cool looking design.

6.7.1 Figure 28

(A) (B)

Figure 27: 28(A) is the Tommy Marker fully assembled; 28(B) is the Tommy Marker in an explode view

6.7.2 Figure 29

(A) (B) Figure 28: 29(A) is a front view of the assembly; 29(B) is a back view

6.8 Design Animation

One of the appealing features of ProE and of most quality 3-D software in general is the animation

capability. Any sub-assembly can be made to move so as to mimic the product’s functionality. For my

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Tommy Marker, I created two animations. The first animation included a 360 degree rotation on the

non-exploded assembly. This was done using the “View@Time” feature. I selected a front view, a back

view, a side view, and then another front view in sequence to create the effect. If I had only used two

front views and a back without a side view, the assembly would have only rotated 180 degrees and then

reversed direction and gone back the same way another 180 degrees creating a very lame sequence.

The animation also includes a look the totally exploded assembly view for the marker. Every piece and

not just the sub-assemblies explode apart showing just how complex this project really was.

6.8.1 Figure 30

Figure 29: A screen shot from the assembly animation; Look at all those parts...

The next part of the animation showed the individual sub-assembly being reconstructed and shown

being installed on the model. Because many of the pieces in these assemblies are very small, different

views at different levels of zoom were required. The entire sequence came out nicely.

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6.8.2 Figure 31

Figure 30: The close up views of the sub-assemblies going on the part in order

My second animation displayed the functionality of the marker. Using “Transparency@Time” feature, I

was able to hide parts such as the chamber and handle that obscured or out and out hid the vital inner

workings of the assembly. The animation allowed me to demonstrate the fully automatic nature of the

Tommy Marker and I was able to display the function and method of the trigger.

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6.8.3 Figure 32

Figure 31: The zoomed in few of the safety function; See how the safety keeps the shoot from pulling the trigger

The Animation also allowed me to showcase my magazine design:

6.8.4 Figure 33

Figure 32: the screenshot from the animation that showcases the magazine design

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7 Manufacturing Analysis

7.1 Cost Analysis

7.1.1 Chamber Assembly Cost Analysis

Chamber $10.00 1 $10.00

Chamber Valve $0.50 1 $0.50

Firing Spring $0.10 1 $0.10

Pressure Spring $0.10 1 $0.10

End Seal $0.50 1 $0.50

O-Rings $0.15 2 $0.30

Low Pressure Chamber $1.00 1 $1.00

T Pipe Adapter $2.00 1 $2.00

Plastic Pin $0.05 1 $0.05

Metal Pin $0.20 1 $0.20

Hammer $3.00 1 $3.00

Cock Seal $2.00 1 $2.00

Magazine springs $0.15 2 $0.30

Magazine Arms $0.10 2 $0.20

Slots $0.05 2 $0.10

Chamber $10.00 1 $10.00

Sub-Total = $20.35

7.1.2 Line Assembly

Unit Price QTY Total Price

Line $1.00 1 $1.00

Tank $10.00 1 $10.00

Tank Mount $1.00 1 $1.00

Screws $0.10 2 $0.20

Expansion Chamber $0.50 1 $0.50

Washers $0.05 2 $0.10

Sub-Total = $12.80

7.1.3 Stock Assembly

Unit Price QTY Total Price

Stock $10.00 1 $10.00

Stock Mount $1.00 1 $1.00

Screws $0.10 3 $0.30

Washers $0.05 3 $0.15

Nuts $0.10 2 $0.20

Sub-Total = $11.65

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7.1.4 Drum Magazine Assembly Cost Chart

Unit Price QTY Total Price

Drum Part $3.00 1 $3.00

Back Part $0.50 1 $0.50

Spring $0.25 1 $0.25

Arm $0.15 1 $0.15

Bullets $0.20 48 $9.60

Screws $0.10 5 $0.50

Washers $0.05 5 $0.25

Nuts $0.10 5 $0.50

Sub-Total = $14.75

7.1.5 Trigger Assembly Cost Chart

Unit Price QTY Total Price

Handle $5.00 1 $5.00

Trigger $0.50 1 $0.50

Cocking Arm $0.50 1 $0.50

Slots $0.10 2 $0.20

Safety $0.25 1 $0.25

Screws $0.10 2 $0.20

Washers $0.05 2 $0.10

Springs $0.15 2 $0.30

Sub-Total = $7.05

7.1.6 Barrel Cost Chart

Unit Price QTY Total Price

Barrel $15.00 1 $15.00

7.1.7 Final Cost and Pricing Analysis

Part Cost

Chamber Assembly Cost $20.35

Line Assembly Cost $12.80

Stock Assembly Cost $11.65

Drum Magazine Assembly Cost $14.75

Trigger Assembly Cost $7.05

Barrel Cost $15.00

TOTAL COST $81.60 Labor Cost (EST) $244.80

Total Manufacturing Cost $326.40 Markup (50%) $163.20

TOTAL PRICE = $489.60

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The total price for consumers is much higher than had anticipated. It does not price the gun out of any

market place, but I wanted my gun to cost more toward the lower end: $100-$200 tops. The major

contributing factor to the high price of the gun is the labor cost. Not being a businessman in any sense of

the word, I have no idea what my sunk cost or variable labor costs are in relationship to an individual

product. After further review, the law of diminishing returns states that more the products I make, the

less my cost per part. So if this design were mass-produced, it would cost less to make than it would to

make one prototype. Therefore, this price may come down based on expected business.

7.2 Total Assembly Drawing

The individual assembly and part drawings can be found in their respective sub-heading of the 3D

modeling section. The following assembly drawings are of the entire assembly broken apart into the

respective subassemblies.

7.2.1 Figure 34

Figure 33: The Total Assembly Drawing

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8 Service Analysis

8.1 Product Life Analysis

How long the product will last may not be entirely dependent on how often the shooter uses the gun.

Most of the parts in the assembly are made from durable steel: the chamber, the barrel, the hammer,

most of the magazine, and handle included. I foresee at least two years of use for the avid gamesman

and as much as ten for the novice as far as these parts are concerned. The one part I am very concerned

about the durability of is the drum magazine spring. A common failing of magazines is that of the failure

of the spring. With the magazine loaded, that spring is under constant stress and strain. If the magazine

is fully loaded all the time, I suspect the spring might last as little as three months and probably no more

than a year. This life can be extended obviously by not leaving the magazine loaded when stored. This is

should not cause any hardship because there is no conceivable instance when one would need to have a

paintball gun ready to go at a moment’s notice.

8.2 User Manual

The user manual has been done separately. Please see the other bound report.

9 Discussion

Project 08 was by far the most labor intensive of the semester. It dwarfed all of the other projects

in size, scope, complexity, and work required combined. After its completion, it is still hard to really

gauge the success of the assignment.

One of the ways this project certainly will be judged via design analysis. In this regard, I would have

to say my project is a qualified success. There is no doubt that I designed and modeled a paintball

gun. However, I am not entirely pleased with my design. There are numerous flaws which I would

love to correct if given more time, not least of which is the pricing problem discussed earlier. In

addition, magazine is gargantuan when compared to the rest of the marker. The Thompson used a

similar drum magazine, but its magazine had a higher capacity and a smaller diameter. I think if I

had it to do over again, I would try a double track inside the magazine. This would effectively

double the capacity and allow for the possible reduction in the size of the magazine. The magazine

also lacks some ergonomic features which I would like to address. For instance, how would one

carry extra clips in a “fire fight”? I thought the perhaps I would add a clip to the back cover of the

magazine that could be fastened to a jacket or vest.

Another part that I felt badly about was the chamber. Functionally for firing, the chamber requires

no apology but I always felt my magazine interface for loading and reloading to be clumsy and ill-

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conceived. I think a better way is to have the magazine attach to the chamber itself rather than the

out of place arms that detract from the gun’s ascetic qualities. I feel this way would be much more

solid and allow the shoot to feel that the magazine is much more a part of the gun rather than a

wayward attachment.

The other part I think should be changed in my design is the location of the air tank. The best place

for it to make a Tommy Gun is to hide the tank in the stock. Perhaps even a custom tank could be

made for the marker in which the stock is a functional CO2 tank. Honestly, this change would have

been made in this design, but I still am very wary to change to many things related to the pressure

assembly. My knowledge of fluids and the calculations needed to design a marker is simply not

adequate to make those decisions at this time. Perhaps in the future or with the help of a more

experienced aerospace engineering student, this change could be made effectively.

Aside from the actual design, my project will also be graded on the quality of the CAD modeling. For

this subject, I could not be more proud. The modeling I completed for this project is by far the best I

have completed to date. Nothing else even comes close to volume of pieces or the complexity.

There are a few details I wish I had more time to incorporate: a sight on the top of the chamber,

more o-rings, and a shapelier foregrip grip just to name a few. But as I compare Project 08 to even

Project 07 in which I modeled a dart gun, there is no comparison. My handles are more ergonomic;

my pieces fit together better and on the first try; more details were included; the complexity was

greater; there were more parts that has to fit; I could even take an idea for a part in my brain and

make it in ProE. I felt very good about the CAD aspect of this project.

As for problems encounter during the completion, the animations were a pain. I have done

animations before. I even like to think I am fairly adept with them, but this time around they just

took too long. To do my two animations for a grand total of about one minute and forty-five

seconds, I spent about sixteen hours. The problem was that ProE took over twenty minutes to get

an animation after I had changed something. After that, ProE would crash or change my views

arbitrarily or lock bodies together despite the one part one body setting or any other travesty that

an experienced engineering student can imagine. The problem (I think) was that program good not

handle so many parts moving at once. I shudder to think how many hours ProE would have taken to

render my videos, if it could do it at all.

Project 08 has taught me, if nothing else, that I am a master of ProEngineering Wildfire 4.0 Student

Edition. There is nothing in this program that been cover in this course I cannot do. If someone

would have told me at the beginning of the semester that I would model a paintball gun and in the

end it would not look like a piece of crap, I would have laughed. I might not be the greatest

designer in the world yet, but now I seem to know my CAD. I would have like to run my design

through Mechanica or any of the other design analysis functions ProE has, but that is a subject for

another day.

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10 Conclusion

While my skills as a designer might still need practice, the Tommy Marker is without a doubt the

best CAD model I have ever created. Complete with conical shaped ammunition, a drum magazine,

and fully automatic, the Tommy Marker will set nostalgic paintballers back less than $500. In the

course of the design project, I learned valuable CAD skills, time management skills, web design

strategies, design skills, forward thinking techniques, stress-reduction methods, and that I am

skilled with ProE.

11 References LarryWillis.com 14 December http://www.larrywillis.com/bullet-shape.html The Official Tommy Gun Page 14 December 2009 http://www.nfatoys.com/tsmg/ Paintball Discounters.com 14 December 2009 http://www.paintball-discounters.com/get_list_366.htm