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OHIO University Mechanical Engineering Concept Design Report

Photo Press Mechanism

One Stop Photo Shop

Matthew Becker

Alex Carrier

Brandon Foggie

Andrew Knipp

Sebastian Osorio

Tim Smoot

01/12/2012

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1.0 Concept Generation

1.1 Problem Statement for Concept Generation

The purpose of this project is to create a system so the customer, Kara Moore, can cut and round an entire sheet of eight 2.5” x 3.5” photographs at once. The reason such a device is in demand because the current process, done by hand, is very time consuming and during peak photography season she is not able to complete her picture orders in a timely manner without the help of volunteers. This device aims to reduce the amount of time needed to process an entire sheet of pictures, allowing her to provide her services to more customers. She also desires the device to be safe and easy to use, easy to maintain, not damage the pictures, and to be of a reasonable size and weight so that it may be used on almost any tabletop surface.

The design team has researched the market for similar products and patents, and failed to find one that met each of her criteria. The closest available products were too expensive, intended for use in an industrial setting, or they are designed to only cut one picture at time. The team also looked at devices that perform similar tasks but are applied for different uses. It was decided by the team that the best option was to design a system that combined aspects of the devices currently in use with the team’s own ideas to create a device that suits the customer’s needs.

The team’s needs statement is as follows, taken from Section 2.2 of the Project Proposal Report:

Design and fabricate a safe system that is capable of cutting and rounding the corners of multiple wallet sized pictures which come in a single sheet of eight pictures. The overall process of cutting and rounding needs to be quick and easy to perform. The system needs to be highly efficient and not damage the pictures as well.

1.2 Patent Search

Patent search results can be found in Section 3.1 of the Project Proposal Report.

1.3 Concept Generation

The team came up with several concepts which can be used to solve our problem statement. The designs were based on our patent and product searches combined with our own creativity. The concepts generated were focused on the mechanism itself, the tray which the sheet of pictures will sit on, and the arrangement of the blades used to cut the pictures.

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Figure 1.1: Rack and Pinion Gear Lever Press

A rack and pinion gear lever press system as shown in Figure 1.1could be used to accomplish this task. Similar to a drill press, the pictures would be secured to a mounted base and a picture die cutter would be lowered via rack and pinion lever to cut the pictures. After the cut is made, the reverse motion would be performed. The die cutter would be located in a plastic shell that is attached to the press. If a different cutting pattern was desired, the blade die could be removed from and a different one can take its place. To ensure that the press does not move around during operation, the entire system would be decently weighted. Conversely the system will be light enough so that it can be used on a desktop.

Figure 1.2: Crank-Press

The crank press as shown in Figure 1.2 consists of a crank attached to a rack and pinion to apply the necessary force needed to cut the photos. The tray where the photo sheet sits can be easily removed using a group of rollers, allowing the quick and easy exchange of photos. The system

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is operated by turning the crank clockwise to lower the die cutter and cut the photos. After cutting the pictures, the crank would be turned counterclockwise to raise the die cutter, and the photos can be removed.

Figure 1.3: Simple Lever Hinge

Preliminary design concept for the simple lever hinge, as seen in Figure 1.3, involved three different subsystems: a frame, lever, and the blades. The frame consists of a top plate and a bottom base. The bottom base has a tray with a set place for the pictures. The shape of the frame is a rectangle with a footprint just larger than the 7”x 10” picture sheets. The lever would be attached to the frame along the top of the top plate. At the end of the lever there is a hinge to help with the cutting motion. The blades will also be attached to the bottom side of the top plate. The blades would be surrounded by a foam layer which is used for two purposes. The main purpose of the foam is to contact the picture sheet first and to keep the sheet in place at all times through the cutting motion. The second purpose of the foam is for added safety, the customer will never be exposed to the blades and therefore less likely to cut themselves.

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Figure 1.4: Spring Loaded Press, A: Top Portion. B: Bottom Portion C: Complete Assembly. D: Location of Springs

The Spring Loaded Press seen in Figure 1.4 is another potential solution to the problem at hand. It would use a system that contains a top portion of the press that contains a set of blades that uses a blade matrix. The blade matrix would be designed in a way that has blades that are made in a 2.5” X 3.5” shape, the same exact way the pictures will look like when cut. The top portion of the press in Figure 1.4-A would have four shafts attached to it at every corner of the press making sure when it is engaged there is even distribution across the pictures. The bottom portion of the press in Figure 1.4-B would be slightly larger. The reason for the increase of weight on the bottom would be to hold the press in place when engaging the top portion. The bottom portion will have an indented platform to hold the pictures down while the cutting process is performed. This will allow for ease of inserting and removing the picture sheets. The bottom portion of the press would also contain four holes for the shafts to enter when engaging with the top portion. These holes will contain four springs as well. These springs will be used to automatically reset the top portion to its original position after the user makes the desired cut. The total assembly can be seen in Figure1.7-C and the locations of the springs can be seen in 1.7-D. Advantages to this process are it would keep a low profile close to the pictures, simplicity of use, and an automatic reset due to the springs. Disadvantages to this process are spring fatigue, increased input force due to the springs acting against the person performing the task, and spring back force.

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Figure 1.5: Slotted Lever Mechanism

The slotted lever mechanism, as seen in Figure 1.5consists of a lever attached to the bottom of the frame by hinges and to the top of the frame by a sliding pin. The bottom part of the frame consists of a sliding tray system to serve as a cutting surface and as a method to insert and remove the pictures. The bottom section also has two hinges on the back corner of the device to serve as a pivot point for the lever. The top part of the frame has a slot on each side with a pin running through both. This pin connects the top frame to the lever and also allows the force applied at the end of the handle to be transmitted to the frame. The top frame also holds the blades for cutting the pictures. The top and bottom are held together by four short links attached near the corners. Each link has an adjacent spring which allows the device to open back up on its own force. When force is applied to the handle the pin slides within the slots on the top frame. After reaching the center point of the frame, the force is transmitted to the frame and forces the blades down onto the pictures. The user must overcome the force of the springs in this motion but it serves as a reset and holds the top of the frame in place while the picture sheet exchange is occurring.

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Figure 1.6: Four-Bar Mechanism

The four bar mechanism, seen in Figure 1.9, consists of a bottom panel and a top panel connected by two linkages on each side. The bottom panel which is rectangular in shape has a thin slit where the pictures are slid in. The bottom panel also has a grid that is 10”x7” with individual 3.5”x2.5” rectangles, the size of each individual picture. The bottom panel also slides to another chamber which contains holes with a radius for the rounding of the pictures. The top panel contains the same grid as the lower panel except this matrix holds the blades. The blades are securely connected within the top panel so that they cannot be seen without closing the machine and pulling on the outside lever. The top panel also consists of a lever, which is used to shut the mechanism so that both top and bottom grid panels match up. Once the mechanism initially closes, more force is required to then release the blades. The blades are released in two steps. The first sets of blades released are the straight blades, which are used for cutting the sides of the pictures. Once this action has occurred, the second sets of blades are released, which round the corners of the pictures. Then the lever would be slid back up and the pictures can be removed from the bottom panel.

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Figure 1.7: Angled Blade Matrix

The picture die cutter could consist of a matrix of intertwined angled blades, as seen in Figure 1.7. There would be a total of 7 right triangle blades, with three being equal to the width of the picture and 4 being equal to length of the picture. The blades would be fixed to either a plastic or wood backing. To ensure there is an equal distribution of cutting force across the photos, the blades would be arranged in a flip-flop pattern throughout the die. To produce the rounded corners, 36 small rounded blades would extend past the straight angled blades. This causes the die to cut the rounded corners first, then as the die is pressed further into the photos the straight blades follow through and make the remaining cuts.

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Figure 1.8: Indented Tray Base

To ensure that the sheet of pictures is held in place and is in the same exact spot for every repetition, an indented tray base could be used as seen in Figure 1.8. The tray would have an indented surface area equal to the 8 picture sheet cut out from a cutting board. If you are looking at the tray from the front, the farthest left corner of the indented surface will serve as the origin for all sheets of pictures, whether it is the two, four, or eight size picture sheet. When the picture sheet is placed in this lower elevated area, it will not have any room to move around, thus eliminating alignment difficulties. The tray would be able to slide in and out of the mechanism, so the user does not have to put their hands in the path of the blades when placing the pictures. Also, the indented area would be tapered as shown in Figure 1.8. These two designs to the tray allow for an easier and safer removal of the pictures and any resulting scrap.

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2.0 Concept Screening and Evaluation

2.1 Concept Screening

Customer feedback was our upmost priority in this project. Kara Moore, the client, did not have much input on the design of this mechanism. Since our customer was indifferent towards the design of the actually finished product, she did have a few design requests. She was contacted several times throughout the process and gets most of her pictures sent from Nations Photo Lab and Bay Photo, which produces eight pictures per sheet. If she needs a rush order she will go to the local Sam’s Club and print off a set of two pictures per sheet. She did ask if it was possible to not only cut eight pictures but a pair of two. This was the only requirement on the design of our mechanism that our client requested.

Since the group had many different design concepts, a screening process was used to take the best individual features of each to aid in development of a single and final design concept. To evaluate these features a pros and cons list was made for each including the three main subsystems which were the frame, the cutting mechanism, and blades. These lists can be found in Tables 2.1, 2.2, and 2.3 respectively.

Table 2.1: Pros and Cons List for Frame

Frame Pros Cons

Square Easy to Fabricate Bad Aesthetics

Safety Issues (Sharp Corners)

Rounded Good Aesthetics Harder to Fabricate Improved Safety More Expensive to Fabricate

Indented Tray on Platform Less Movement of Pictures Picture Size Restricted

Easier to Load Pictures Increase of Cost Hold Pictures Tighter

Flat Tray on Platform Less Expensive Type of Mechanism to Hold

Pictures Down Picture Sizes can Vary

Increased Set Up Time

Based on Table 2.1 the One Stop Photo Shop Team decided on a square frame with an indented tray. A square frame would be much easier to fabricate and the corners which could be a safety issue, could be de-burred and if necessary a rubber coating could be applied to the outside of the frame. Rounding the frame corners did not pose a hard problem, but due to the added difficulty of fabrication, it was eliminated. The indented tray was chosen mostly because of the ease of

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loading the pictures along with little to no movement of the pictures. The picture size is restricted, but our client Kara Moore, mostly uses Nations Photo Lab, so the size should stay standard. This will also aid in lowering the time to perform the cutting process. The flat tray was ruled out because an extra mechanism would need to be added to the device and could potentially create more design issues.

Table 2.2: Pros and Cons List for Cutting Mechanisms

Cutting Mechanisms Pros Cons

Spring Loaded Press Fig. 1.4

Automatic Reset Spring Fatigue Simplicity of Use More Input Force

Low Profile Spring Back Force

Slotted Lever Mechanism Fig. 1.5

Less Force (Lever) Harder to Fabricate Even Force Distribution More Components

Weight Concerns

Double Four-Bar Mechanism Fig. 1.6

Less Force (Lever) Larger Footprint Even Force Distribution More Components

Weight Concerns

Crank Mechanism Fig. 1.2

Low Profile Slower Cutting Motion

More Components

Weight Concerns

More Torque Needed

Difficult Gearing

Simple Lever Hinge

Fig. 1.3 Simplicity of Use Blade Setup Difficult

Safety Issues

Rack and Pinion Press Fig. 1.1

Smooth Cuts Very Heavy (Weight Concerns) Simple for Interchangeable

Blade Complex System Simplicity of Use

Table 2.2 presents the pros and cons to the actual cutting mechanism of the system. The crank mechanism and rack and pinion press were eliminated from our types of cutting mechanism moving forward with this concept screening. The reason for most of these eliminations comes straight from the pros and cons list, as well as concept screening talked about within the group. The crank mechanism does fit the low profile setting that the group would like to see, but the negatives outweigh the positives. This includes the slowest cutting motion of all the concepts, as

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well as the weight concerns and difficult gearing. The rack and pinion press would provide smooth cuts of the pictures and would be very simple to use. This mechanism would not be feasible for our client because of the weight concerns. One of our main concerns is that Kara can have portability with this mechanism and the weight of the rack and pinion press would eliminate this. The spring loaded press, slotted lever mechanism, double four-bar mechanism, and simple lever hinge will be evaluated into more detail in Section 2.3.

In Table 2.3 there is a subsystem of blades, and included into this subsystem are even smaller divisions broken up into orientation and mounting. Straight blades were chosen by the group based on deliberations throughout the quarter. Straight blades seem to be the most reasonable to buy and would fit onto any of our mechanisms that are still left. The rounded corners of the blades would need to be purchased and added onto the straight blades, but that is the case for the angled blades as well. Angled blades were not chosen because of the complexity of the fabrication as well as being more expensive. The team thinks that with enough force applied to the pictures the straight blades can achieve a clean cut comparable to the angled blades. The machine die would not be feasible for the project due to how expensive it would be as well as the fabrication would be even more complex than that of the angled blades.

The mounting process of the blades cannot be evaluated at this time because this depends on which mechanism is chosen. Not all mounting processes will work on every mechanism. There will be however a foam material that encompasses the blades to have short exposure of the blades. This will provide improved safety for the user of this machine. It will serve the purpose of holding the pictures in place before the blades penetrate the pictures.

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Table 2.3: Pros and Cons List for Blades with Subsystems Including Orientation and Mounting

Blades Pros Cons

Orientation

Straight Simple to Fabricate

Would Need Rounded Corners Cheap to Fabricate

Separate Pieces

Angled

Cleaner Cut Hard to Sharpen Separate Pieces Hard to Fabricate

More Expensive/Complicated Would Need Rounded Corners

Machined Die Would Cut Desired Shape Fabricate instead of Buy

Rounded Corners Expensive Total of One Piece Hard to Sharpen

Mounting

Compression Less Expensive Safety/Fall Out

No Hardware Needed Hard to Repair

Weld Permanent No Need to Replace

Inexperience

Hard to Sharpen

Nut/Bolts (Hardware)

Easy Replacement More Components Easy to Obtain More Expensive

Could Become Loose

Lose Tolerance

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2.2 Data and Calculations for Feasibility and Effectiveness Analysis

Material Properties:

𝐵𝑢𝑠𝑡𝑖𝑛𝑔 𝑠𝑡𝑟𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝐶𝑜𝑎𝑡𝑒𝑑 𝑃𝑎𝑝𝑒𝑟 �250𝑔𝑚2

� = 43.5 – 94.27 𝑃𝑠𝑖.

𝐵𝑙𝑎𝑑𝑒 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 = .01 𝑖𝑛.

𝐶𝑢𝑡𝑡𝑖𝑛𝑔 𝐴𝑟𝑒𝑎 = .65 𝑖𝑛.2

𝑆𝑝𝑟𝑖𝑛𝑔 𝐷𝑖𝑠𝑝𝑙𝑎𝑐𝑒𝑚𝑒𝑛𝑡 = .5 𝑖𝑛.

𝑇𝑜𝑡𝑎𝑙 𝑆𝑝𝑟𝑖𝑛𝑔 𝐹𝑜𝑟𝑐𝑒 = 5 𝑙𝑏𝑓.

Formulas:

𝐶𝑢𝑡𝑡𝑖𝑛𝑔 𝐹𝑜𝑟𝑐𝑒 = (𝐴𝑟𝑒𝑎) 𝑥 (𝑆ℎ𝑒𝑎𝑟 𝑆𝑡𝑟𝑒𝑛𝑔𝑡ℎ) (Formula 2.1)

𝑀𝑜𝑚𝑒𝑛𝑡 = (𝐹𝑜𝑟𝑐𝑒) 𝑥 (𝐿𝑒𝑛𝑔𝑡ℎ) (Formula 2.2)

𝐻𝑜𝑜𝑘𝑒′𝑠 𝐿𝑎𝑤 = 𝐹 = (𝐾) 𝑥 (𝐷𝑖𝑠𝑝𝑙𝑎𝑐𝑒𝑚𝑒𝑛𝑡) (Formula 2.3)

Equations:

𝐶𝑢𝑡𝑡𝑖𝑛𝑔 𝐴𝑟𝑒𝑎 = �(5)𝑥 �(7𝑖𝑛. ) 𝑥 (. 01𝑖𝑛. )�� + �(3) 𝑥 �(10𝑖𝑛. ) 𝑥 (. 01𝑖𝑛. )�� = .65𝑖𝑛.2

𝐶𝑢𝑡𝑡𝑖𝑛𝑔 𝐹𝑜𝑟𝑐𝑒 = (. 65𝑖𝑛.2 ) 𝑥 (94.27 𝑃𝑠𝑖) = 61.3 𝑙𝑏𝑓.

𝑀𝑜𝑚𝑒𝑛𝑡 𝐴𝑟𝑚 𝑙𝑒𝑛𝑔𝑡ℎ = 61.3 𝑙𝑏 − 𝑖𝑛. = (10 𝑙𝑏𝑓) 𝑥 (𝐿𝑒𝑛𝑔𝑡ℎ)

𝑀𝑜𝑚𝑒𝑛𝑡 𝐴𝑟𝑚 𝑙𝑒𝑛𝑔𝑡ℎ = 6.13 𝑖𝑛.

𝐻𝑜𝑜𝑘𝑒′𝑠 𝐿𝑎𝑤 = � 5𝑙𝑏𝑓4 𝑠𝑝𝑟𝑖𝑛𝑔𝑠

� = (𝑘)𝑥 (. 5𝑖𝑛. ) → 𝑘 = 2.5 𝑙𝑏𝑓.𝑖𝑛.

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Figure 2.1: This figure represents the total cutting area which is seen as the blades.

The most important calculation for project feasibility is the cutting force required to cut the photo paper. Using formula 2.1 and the area shown in Figure 2.1, we found our maximum cutting force to be 61.3 lbf. In order to decrease the input force of the user we implemented the use of a lever. Introducing a lever to the design would create a moment arm. In our design specifications we stated the maximum input force from the user should be no more than 10 lbf. To achieve this, our design would require a 6.13 in. moment arm. Our current design has a foot print of 12 in. x 10 in. Installing a 6.13 in. long lever would be on the top surface would be feasible.

In our conceptual design we implemented four springs that are wrapped around four guide pins. The purpose of the springs is to allow the press to automatically reset to its raised position after use. Estimating the weight of the cutting die and handle to be 5 lb., we would need a total spring force of 5 lbf. The spring displacement is .5 in. This is equal to the distance between the die and the cutting tray. Using Hooke’s Law (Formula 2.3), we found the spring constant for each spring to be 2.5lbf.

in.. The spring force would have miniscule effects on the input force. The weight of the

handle and die would counteract most of the spring force. With a total input force of 10 lbf, our conceptual design would be effective and easy to operate. Figure 2.1 depicts the total cutting area of the blades.

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2.3 Concept Development, Scoring, and Selection

2.3.1 Mechanism Design Selection

After applying the data collected in Section 2.2 and to the concepts that passed the concept screening in Section 2.1, the team decided to narrow down the remaining mechanism concepts using a weighted concept scoring chart, as seen in Table 2.4. The Die Cutter Steel ID Card Paper Trimmer was included to compare our concepts against current products on the market. Each concept was given a score between 1 and 5, judging the idea’s durability, usability, safety, and portability. The assigned weights were determined in Section 2.1 of the Project Proposal Report.

Table 2.4: Concept Scoring Chart - Mechanism

Mechanism Weight

Simple Lever Hinge

Spring Loaded Press

Slotted Lever

Mechanism

Double Four-Bar

Mechanism

Die Cutter Steel

Manual ID Card

Fig. 1.3 Fig. 1.4 Fig. 1.5 Fig. 1.6

Durability 0.385 5 4 3 3 5

Usability 0.15 3 4 5 5 2

Safety 0.08 4 5 3 2 4

Portability 0.385 5 5 4 2 4

Weighted Totals 4.6 4.5 3.7 2.8 4.1

Continue? Yes Yes No No

Durability was judged by the expected lifetime of the system, taking into account joint fatigue, number of expected individual parts, and how easy the maintenance was expected to be. For example the Single Lever Hinge scored a 5 because it has one joint, while the Double Four-Bar scored a 3 because it has 8 joints and more moving parts.

Usability was mostly judged by how much effort would be required to operate the device. Other factors included how fast the process was, how intuitive it was, and any ergonomic concerns. The Spring Loaded Press scored a 4 due to its fast cycle time and automatic reset. It would have been a 5, but this design lacked the mechanical advantage of a lever and thus would require a greater input force. The Die Cutter Steel Manual ID Card product was given a 2 for usability because it can only cut one photo at a time.

Safety was judged by what level of threat the device presented. This included how much the process exposed the blades and the likelihood that it may pinch or smash body parts when in use. The Double Four Bar Mechanism scored a 2 in safety due to it multiple pinch points. While the Spring Loaded Press was given a 5 due to its minimal blade exposure.

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Portability was judged by the size and weight of the proposed mechanism and by how likely it may break while in transit. The Spring Loaded Press was given a 5 because of its low profile, while the Double Four-bar mechanism scored a 2 in portability due to its larger footprint.

Figure 2.2: Final Conceptualized Design Drawing.

What was unknown was exactly how to implement the lever to the spring loaded press mechanism. After much deliberation among the team members, it was decided that a backing piece would be required to make the lever hinge effective, as seen in Figure 2.2. A bar lever parallel to the length of the mechanism would be placed above the system, with arms sloping down on each end attaching to a hinge on the back side. Attached below the lever would be a pressing block that the lever uses to push down on the surface of the blade box in the spring loaded mechanism.

Pressing down on the lever will force the blade box toward the tray, opposing the force of the springs and compressing the blades onto the photo sheet. The input force would then be decreased, allowing the springs to elevate the blade box up to its original position. As an added safety measure, the frame would be secured to the table top surface using clamps. This will negate the possibility of a violent spring-back force causing the system to shake off the table.

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2.3.2 Blade Mounting Design Selection

The final design feature to be evaluated was how the blade system would be attached to the frame. The mounting process was briefly discussed in Section 2.1 of the concept screening. It was stated in the section that the mounting process could not be discussed until further action was taken on what mechanism would be chosen. This was done because not all mounting processes could work on every mechanism. Now that the concepts are narrowed down to two choices, the spring loaded press and the simple lever hinge, the mounting of the blades can be discussed. The mounting processes include the compression fitting, welding and fasteners which included nuts and bolts and set screws. The team decided on using a weighted concept scoring chart seen in Table 2.5. Each concept was given a score between 1 and 5, judging the price, lifecycle, maintenance and production.

Table 2.5: Concept Scoring Chart - Blade Mounting Process

Categories Compression Weld Fasteners Price 3 4 2

Lifecycle 2 2 4 Maintenance 4 1 3 Production 5 2 5

Totals 14 9 14 Continue? Yes No No

The welding process was eliminated because there were too many negatives compared to positives. There can be no replacement of the blades at any time added along with inexperience among the group and a hard setup. It would be difficult to keep tight tolerances on the blades if welding was the mounting process. During team meetings, this was discussed in detail and even though the compression fitting and fastener mountings tied in the score the team believed that the compression fitting would be a better choice. The reason for this is because for compression fittings the tolerances can be made tighter which is something that is important due to the fact that there is no space in between the pictures themselves. It will provide ease of replacement for our client, Kara, because instead of removing all of the fasteners that would be contained in every blade she would be able to pop the compression blades in and out easily. The maintenance of taking the blades in and out and the fact that the tolerances can be made tighter were the main deciding factors in choosing the compression fitting as the mounting process the team will use instead of the fastener mounting process.

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The first kind of mounting housing for our blades which is shown above is the hole and screw system which involves drilling holes in both the blades and the blade mount. Then after the holes are drilled in inserting screws to each intersection to make sure the blade will not move while performing the cutting operation. This system is not convenient or plausible for the fact that it will take a lot of time to machine holes through each blade and then line them up perfectly with the blade housing, it also requires a lot of extra hardware that is not necessary. Finally this kind of system could become loose very easily over a certain amount of usage and the blades could become a hazard to the user as well as not accurately cutting out the pictures.

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The next kind of system to attach the blades would be to weld the blades to the housing itself as shown above where the blue line represents the welding marks. This kind of system compared to the fastening system with screws would take less time to make and would last much longer therefore not causing any harm to the customer or the picture quality. The problem with welding is the potential affect that it could have on the blades and the mounting housing for the blades. Welding could possibly cause both the blade and housing to melt and could cause deformities in the way the blades are mounted which would ruin the way the blades are supposed to cut.

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The last choice for connecting the blades to the blade housing would be to use a compression fit where the blades are stuck in place due only to the small differential in thickness of the blade in comparison to the gap in the blade mount. This operation can only be done by machine but would make a long lasting fit that would leave no footprint or any signs of how the blades are mounted as compared to the welding and screw system which both change the aesthetics of the machine.

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3.0 Final Concept Design

The final concept design that was chosen was the simple lever hinge combined with the spring loaded press. These two concepts had the highest total scores when compared to the other ideas based on their durability, usability, safety, and portability. The simple lever hinge was weak in usability and safety, which the spring loaded press was stronger in. Also the simple lever hinge was stronger in durability than the spring loaded press. The combination of these two concepts creates a design that is most suited to our client’s specifications when compared to the other concept ideas and currently available products.

Figure 3.1: Final Concept Design

The reason for the combination of these two concepts, seen in Figure 3.1, is because it gives the best of both worlds. The spring loaded press design allows us to have four round bars attached to both the top and bottom plates. Each of the bars will be surrounded by a spring, which will automatically reset the top plate to its original position after being lowered to make the perforated cut. The simple lever hinge design helps overcome the higher net force required to press down on the springs. In order to translate the arcing motion of the lever to the vertical

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motion of the spring loaded press, the lever consists of a single rectangular bar that presses down on a semi-circle bar on top the top plate, behaving similar to a cam. By pushing down on the semi-circle bar, the top plate and blades are pressed towards the bottom plate onto the photo tray. The lever hinge is located on top of a solid back piece connected to the bottom plate. The back piece also provides weight to balance the system. Attached to the back piece are two plates which cover the exposed right and left sides of the mechanisms to reduce the number of pinching points on the device. Underneath both the back piece and the bottom plates will be rubber feet or suction cups so prevent minimize movement during operation.

Figure 3.2: Top Plate Construction: Blade Arrangement [A], Blades With Foam [B]

The top plate houses the blades so they are not exposed, as seen in Figure 3.2. The blades will be arranged in a way so that when they are in contact with the photo sheet, each of the photos on the sheet will be cut at once. Surrounding the blades will be a compressible foam material, helping to keep the picture sheet in place during operation and to reduce the risk of the user cutting them self.

Figure 3.3: Photo Tray Sliding Procedure: Fully Outside [A], Halfway [B], Fully Inside [C]

The bottom plate serves as a base which holds the photo tray. The photo tray can slide in and out of the bottom plate, as seen in Figure 3.3, allowing the user to place the photo sheet onto the tray without their hands being in the path of the blades.

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Figure 3.4: The Final Concept Design while it is not engaged [A], and is engaged [B]

By pushing the top plate toward the bottom plate, the blades are compressed onto the photo sheet on the photo tray, as seen in Figure 3.4. This creates a perforated cut according to the blade pattern. Once the input force is decreased the springs will elevate the top plate to its original location. The picture sheet can then be removed from the device by sliding the photo tray out and the pictures and waste can be removed. Each freshly cut picture can then be placed aside and the waste can be thrown away. A new, uncut picture sheet is then placed on the picture tray and the process can be repeated.

Maintenance of this device would be minimal. With proper material selection, the blade sharpness and spring elasticity should meet or exceed the life expectancy of this mechanism. Due to the nature of performing perforated cuts and having the photo cutting tray be removable, paper waste remaining in the system should be minimal and may require very little cleaning for the duration of the device’s lifespan. Any cleaning that needs to be performed could be as simple as using a small dry rag or paper towel and a can of compressed air. If the hinge shows signs of needing lubrication; a can of 3-in-1 oil or WD-40 can be used to return the hinge to its original state.

Because of the uniqueness and simplicity of the design and because it meets each of the needs of our client, Kara Moore, the team believes that this is the best solution to our task.

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OHIO University Mechanical Engineering Concept Design Report

Photo Press Mechanism

One Stop Photo Shop

Matthew Becker

Alex Carrier

Brandon Foggie

Andrew Knipp

Sebastian Osorio

Tim Smoot

11/13/2011

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1.0 Concept Generation

1.1 Problem Statement for Concept Generation

The purpose of this project is to create a system so the customer, Kara Moore, can cut and round an entire sheet of eight 2.5” x 3.5” photographs at once. The reason such a device is in demand because the current process, done by hand, is very time consuming and during peak photography season she is not able to complete her picture orders in a timely manner without the help of volunteers. This device aims to reduce the amount of time needed to process an entire sheet of pictures, allowing her to provide her services to more customers. She also desires the device to be safe and easy to use, easy to maintain, not damage the pictures, and to be of a reasonable size and weight so that it may be used on almost any tabletop surface.

The design team has researched the market for similar products and patents, and failed to find one that met each of her criteria. The closest available products were too expensive, intended for use in an industrial setting, or they are designed to only cut one picture at time. The team also looked at devices that perform similar tasks but are applied for different uses. It was decided by the team that the best option was to design a system that combined aspects of the devices currently in use with the team’s own ideas to create a device that suits the customer’s needs.

The team’s needs statement is as follows, taken from Section 2.2 of the Project Proposal Report:

Design and fabricate a safe system that is capable of cutting and rounding the corners of multiple wallet sized pictures which come in a single sheet of eight pictures. The overall process of cutting and rounding needs to be quick and easy to perform. The system needs to be highly efficient and not damage the pictures as well.

1.2 Patent Search

Patent search results can be found in Section 3.1 of the Project Proposal Report.

1.3 Concept Generation

The team came up with several concepts which can be used to solve our problem statement. The designs were based on our patent and product searches combined with our own creativity. The concepts generated were focused on the mechanism itself, the tray which the sheet of pictures will sit on, and the arrangement of the blades used to cut the pictures.

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Figure 1.1: Rack and Pinion Gear Lever Press

A rack and pinion gear lever press system as shown in Figure 1.1could be used to accomplish this task. Similar to a drill press, the pictures would be secured to a mounted base and a picture die cutter would be lowered via rack and pinion lever to cut the pictures. After the cut is made, the reverse motion would be performed. The die cutter would be located in a plastic shell that is attached to the press. If a different cutting pattern was desired, the blade die could be removed from and a different one can take its place. To ensure that the press does not move around during operation, the entire system would be decently weighted. Conversely the system will be light enough so that it can be used on a desktop.

Figure 1.2: Crank-Press

The crank press as shown in Figure 1.2 consists of a crank attached to a rack and pinion to apply the necessary force needed to cut the photos. The tray where the photo sheet sits can be easily removed using a group of rollers, allowing the quick and easy exchange of photos. The system

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is operated by turning the crank clockwise to lower the die cutter and cut the photos. After cutting the pictures, the crank would be turned counterclockwise to raise the die cutter, and the photos can be removed.

Figure 1.3: Simple Lever Hinge

Preliminary design concept for the simple lever hinge, as seen in Figure 1.3, involved three different subsystems: a frame, lever, and the blades. The frame consists of a top plate and a bottom base. The bottom base has a tray with a set place for the pictures. The shape of the frame is a rectangle with a footprint just larger than the 7”x 10” picture sheets. The lever would be attached to the frame along the top of the top plate. At the end of the lever there is a hinge to help with the cutting motion. The blades will also be attached to the bottom side of the top plate. The blades would be surrounded by a foam layer which is used for two purposes. The main purpose of the foam is to contact the picture sheet first and to keep the sheet in place at all times through the cutting motion. The second purpose of the foam is for added safety, the customer will never be exposed to the blades and therefore less likely to cut themselves.

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Figure 1.4: Spring Loaded Press, A: Top Portion. B: Bottom Portion C: Complete Assembly. D: Location of Springs

The Spring Loaded Press seen in Figure 1.4 is another potential solution to the problem at hand. It would use a system that contains a top portion of the press that contains a set of blades that uses a blade matrix. The blade matrix would be designed in a way that has eight blades that are shaped in the same way the pictures are. The top portion of the press in Figure 1.4-A would have four shafts attached to it at every corner of the press making sure when it is engaged there is even distribution across the pictures. The bottom portion of the press in Figure 1.4-B would be slightly larger. The reason for the increase of weight on the bottom would be to hold the press in place when engaging the top portion. The bottom portion will have an indented platform to hold the pictures down while the cutting process is performed. This will allow for ease of inserting and removing the picture sheets. The bottom portion of the press would also contain four holes for the shafts to enter when engaging with the top portion. These holes will contain four springs as well. These springs will be used to automatically reset the top portion to its original position after the user makes the desired cut. The total assembly can be seen in Figure1.7-C and the locations of the springs can be seen in 1.7-D. Advantages to this process are it would keep a low profile close to the pictures, simplicity of use, and an automatic reset due to the springs. Disadvantages to this process are spring fatigue, increased input force due to the springs acting against the person performing the task, and spring back force.

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Figure 1.5: Slotted Lever Mechanism

The slotted lever mechanism, as seen in Figure 1.5consists of a lever attached to the bottom of the frame by hinges and to the top of the frame by a sliding pin. The bottom part of the frame consists of a sliding tray system to serve as a cutting surface and as a method to insert and remove the pictures. The bottom section also has two hinges on the back corner of the device to serve as a pivot point for the lever. The top part of the frame has a slot on each side with a pin running through both. This pin connects the top frame to the lever and also allows the force applied at the end of the handle to be transmitted to the frame. The top frame also holds the blades for cutting the pictures. The top and bottom are held together by four short links attached near the corners. Each link has an adjacent spring which allows the device to open back up on its own force. When force is applied to the handle the pin slides within the slots on the top frame. After reaching the center point of the frame, the force is transmitted to the frame and forces the blades down onto the pictures. The user must overcome the force of the springs in this motion but it serves as a reset and holds the top of the frame in place while the picture sheet exchange is occurring.

Figure 1.6: Four-Bar Mechanism

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The four bar mechanism, seen in Figure 1.9, consists of a bottom panel and a top panel connected by two linkages on each side. The bottom panel which is rectangular in shape has a thin slit where the pictures are slid in. The bottom panel also has a grid that is 10”x7” with individual 3.5”x2.5” rectangles, the size of each individual picture. The bottom panel also slides to another chamber which contains holes with a radius for the rounding of the pictures. The top panel contains the same grid as the lower panel except this matrix holds the blades. The blades are securely connected within the top panel so that they cannot be seen without closing the machine and pulling on the outside lever. The top panel also consists of a lever, which is used to shut the mechanism so that both top and bottom grid panels match up. Once the mechanism initially closes, more force is required to then release the blades. The blades are released in two steps. The first sets of blades released are the straight blades, which are used for cutting the sides of the pictures. Once this action has occurred, the second sets of blades are released, which round the corners of the pictures. Then the lever would be slid back up and the pictures can be removed from the bottom panel.

Figure 1.7: Angled Blade Matrix

The picture die cutter could consist of a matrix of intertwined angled blades, as seen in Figure 1.7. There would be a total of 7 right triangle blades, with three being equal to the width of the picture and 4 being equal to length of the picture. The blades would be fixed to either a plastic or

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wood backing. To ensure there is an equal distribution of cutting force across the photos, the blades would be arranged in a flip-flop pattern throughout the die. To produce the rounded corners, 36 small rounded blades would extend past the straight angled blades. This causes the die to cut the rounded corners first, then as the die is pressed further into the photos the straight blades follow through and make the remaining cuts.

Figure 1.8: Indented Tray Base

To ensure that the picture is held in place at the same spot for each use, an indented tray base could be used as seen in Figure 1.8. The tray would have a surface area equal to the 8 picture sheet cut out from a cutting board. When the picture sheet is placed in this lower elevated area, it will not have enough room to move around, thus eliminating alignment difficulties. To further decrease the likelihood the picture sheet would move around, the surface could have a sticky or grip-like property to it. The tray would be removable, so the user does not have to put their hands in the path of the blades when placing the pictures. This would also allow for easy removal of the pictures and any resulting scrap.

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2.0 Concept Screening and Evaluation

2.1 Concept Screening

Customer feedback was our upmost priority in this project. Kara Moore, the client, did not have much input on the design of this mechanism. Since our customer was indifferent towards the design of the actually finished product, she did have a few design requests. She was contacted several times throughout the process and gets most of her pictures sent from Nations Photo Lab and Bay Photo, which produces eight pictures per sheet. If she needs a rush order she will go to the local Sam’s Club and print off a set of two pictures per sheet. She did ask if it was possible to somehow cut the pair of pictures as well as the set of eight if need be. This was the only request on the design of our mechanism that our client spoke on.

Since the group had many different design concepts, a screening process was used to take the best individual features of each to aid in development of a single and final design concept. To evaluate these features a pros and cons list was made for each including the three main subsystems which were the frame, the cutting mechanism, and blades. These lists can be found in Tables 2.1, 2.2, and 2.3 respectively.

Table 2.1: Pros and Cons List for Frame

Frame Pros Cons

Square Easy to Fabricate Bad Aesthetics

Safety Issues (Sharp Corners)

Rounded Good Aesthetics Harder to Fabricate Improved Safety More Expensive to Fabricate

Indented Tray on Platform Less Movement of Pictures Picture Size Restricted

Easier to Load Pictures Increase of Cost Hold Pictures Tighter

Flat Tray on Platform Less Expensive Type of Mechanism to Hold

Pictures Down Picture Sizes can Vary

Increased Set Up Time

Based on Table 2.1 the One Stop Photo Shop Team decided on a square frame with an indented tray. A square frame would be much easier to fabricate and the corners which could be a safety issue, could be de-burred and if necessary a rubber coating could be applied to the outside of the frame. Rounding the frame corners did not pose a hard problem, but due to the added difficulty of fabrication, it was eliminated. The indented tray was chosen mostly because of the ease of

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loading the pictures along with little to no movement of the pictures. The picture size is restricted, but our client Kara Moore, mostly uses Nations Photo Lab, so the size should stay standard. This will also aid in lowering the time to perform the cutting process. The flat tray was ruled out because an extra mechanism would need to be added to the device and could potentially create more design issues.

Table 2.2: Pros and Cons List for Cutting Mechanisms

Cutting Mechanisms Pros Cons

Spring Loaded Press Fig. 1.4

Automatic Reset Spring Fatigue Simplicity of Use More Input Force

Low Profile Spring Back Force

Slotted Lever Mechanism Fig. 1.5

Less Force (Lever) Harder to Fabricate Even Force Distribution More Components

Weight Concerns

Double Four-Bar Mechanism Fig. 1.6

Less Force (Lever) Larger Footprint Even Force Distribution More Components

Weight Concerns

Crank Mechanism Fig. 1.2

Low Profile Slower Cutting Motion

More Components

Weight Concerns

More Torque Needed

Difficult Gearing

Simple Lever Hinge

Fig. 1.3 Simplicity of Use Blade Setup Difficult

Safety Issues

Rack and Pinion Press Fig. 1.1

Smooth Cuts Very Heavy (Weight Concerns) Simple for Interchangeable

Blade Complex System Simplicity of Use

Table 2.2 presents the pros and cons to the actual cutting mechanism of the system. The crank mechanism and rack and pinion press were eliminated from our types of cutting mechanism moving forward with this concept screening. The reason for most of these eliminations comes straight from the pros and cons list, as well as concept screening talked about within the group. The crank mechanism does fit the low profile setting that the group would like to see, but the negatives outweigh the positives. This includes the slowest cutting motion of all the concepts, as

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well as the weight concerns and difficult gearing. The rack and pinion press would provide smooth cuts of the pictures and would be very simple to use. This mechanism would not be feasible for our client because of the weight concerns. One of our main concerns is that Kara can have portability with this mechanism and the weight of the rack and pinion press would eliminate this. The spring loaded press, slotted lever mechanism, double four-bar mechanism, and simple lever hinge will be evaluated into more detail in Section 2.3.

In Table 2.3 there is a subsystem of blades, and included into this subsystem are even smaller divisions broken up into orientation and mounting. Straight blades were chosen by the group based on deliberations throughout the quarter. Straight blades seem to be the most reasonable to buy and would fit onto any of our mechanisms that are still left. The rounded corners of the blades would need to be purchased and added onto the straight blades, but that is the case for the angled blades as well. Angled blades were not chosen because of the complexity of the fabrication as well as being more expensive. The team thinks that with enough force applied to the pictures the straight blades can achieve a clean cut comparable to the angled blades. The machine die would not be feasible for the project due to how expensive it would be as well as the fabrication would be even more complex than that of the angled blades.

The mounting process of the blades cannot be evaluated at this time because this depends on which mechanism is chosen. Not all mounting processes will work on every mechanism. There will be however a foam material that encompasses the blades to have short exposure of the blades. This will provide improved safety for the user of this machine. It will serve the purpose of holding the pictures in place before the blades penetrate the pictures.

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Table 2.3: Pros and Cons List for Blades with Subsystems Including Orientation and Mounting

Blades Pros Cons

Orientation

Straight Simple to Fabricate

Would Need Rounded Corners Cheap to Fabricate

Separate Pieces

Angled

Cleaner Cut Hard to Sharpen Separate Pieces Hard to Fabricate

More Expensive/Complicated Would Need Rounded Corners

Machined Die Would Cut Desired Shape Fabricate instead of Buy

Rounded Corners Expensive Total of One Piece Hard to Sharpen

Mounting

Compression Less Expensive Safety/Fall Out

No Hardware Needed Hard to Repair

Weld Permanent No Need to Replace

Inexperience

Hard to Sharpen

Nut/Bolts (Hardware)

Easy Replacement More Components Easy to Obtain More Expensive

Could Become Loose

Lose Tolerance

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2.2 Data and Calculations for Feasibility and Effectiveness Analysis

Material Properties:

𝐵𝑢𝑠𝑡𝑖𝑛𝑔 𝑠𝑡𝑟𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝐶𝑜𝑎𝑡𝑒𝑑 𝑃𝑎𝑝𝑒𝑟 �250𝑔𝑚2

� = 43.5 – 94.27 𝑃𝑠𝑖.

𝐵𝑙𝑎𝑑𝑒 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 = .01 𝑖𝑛.

𝐶𝑢𝑡𝑡𝑖𝑛𝑔 𝐴𝑟𝑒𝑎 = .65 𝑖𝑛.2

𝑆𝑝𝑟𝑖𝑛𝑔 𝐷𝑖𝑠𝑝𝑙𝑎𝑐𝑒𝑚𝑒𝑛𝑡 = .5 𝑖𝑛.

𝑇𝑜𝑡𝑎𝑙 𝑆𝑝𝑟𝑖𝑛𝑔 𝐹𝑜𝑟𝑐𝑒 = 5 𝑙𝑏𝑓.

Formulas:

𝐶𝑢𝑡𝑡𝑖𝑛𝑔 𝐹𝑜𝑟𝑐𝑒 = (𝐴𝑟𝑒𝑎) 𝑥 (𝑆ℎ𝑒𝑎𝑟 𝑆𝑡𝑟𝑒𝑛𝑔𝑡ℎ) (Formula 2.1)

𝑀𝑜𝑚𝑒𝑛𝑡 = (𝐹𝑜𝑟𝑐𝑒) 𝑥 (𝐿𝑒𝑛𝑔𝑡ℎ) (Formula 2.2)

𝐻𝑜𝑜𝑘𝑒′𝑠 𝐿𝑎𝑤 = 𝐹 = (𝐾) 𝑥 (𝐷𝑖𝑠𝑝𝑙𝑎𝑐𝑒𝑚𝑒𝑛𝑡) (Formula 2.3)

Equations:

𝐶𝑢𝑡𝑡𝑖𝑛𝑔 𝐴𝑟𝑒𝑎 = �(5)𝑥 �(7𝑖𝑛. ) 𝑥 (. 01𝑖𝑛. )�� + �(3) 𝑥 �(10𝑖𝑛. ) 𝑥 (. 01𝑖𝑛. )�� = .65𝑖𝑛.2

𝐶𝑢𝑡𝑡𝑖𝑛𝑔 𝐹𝑜𝑟𝑐𝑒 = (. 65𝑖𝑛.2 ) 𝑥 (94.27 𝑃𝑠𝑖) = 61.3 𝑙𝑏𝑓.

𝑀𝑜𝑚𝑒𝑛𝑡 𝐴𝑟𝑚 𝑙𝑒𝑛𝑔𝑡ℎ = 61.3 𝑙𝑏 − 𝑖𝑛. = (10 𝑙𝑏𝑓) 𝑥 (𝐿𝑒𝑛𝑔𝑡ℎ)

𝑀𝑜𝑚𝑒𝑛𝑡 𝐴𝑟𝑚 𝑙𝑒𝑛𝑔𝑡ℎ = 6.13 𝑖𝑛.

𝐻𝑜𝑜𝑘𝑒′𝑠 𝐿𝑎𝑤 = � 5𝑙𝑏𝑓4 𝑠𝑝𝑟𝑖𝑛𝑔𝑠

� = (𝑘)𝑥 (. 5𝑖𝑛. ) → 𝑘 = 2.5 𝑙𝑏𝑓.𝑖𝑛.

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Figure 2.1: This figure represents the total cutting area which is seen as the blades.

The most important calculation for project feasibility is the cutting force required to cut the photo paper. Using formula 2.1 and the area shown in Figure 2.1, we found our maximum cutting force to be 61.3 lbf. In order to decrease the input force of the user we implemented the use of a lever. Introducing a lever to the design would create a moment arm. In our design specifications we stated the maximum input force from the user should be no more than 10 lbf. To achieve this, our design would require a 6.13 in. moment arm. Our current design has a foot print of 12 in. x 10 in. Installing a 6.13 in. long lever would be on the top surface would be feasible.

In our conceptual design we implemented four springs that are wrapped around four guide pins. The purpose of the springs is to allow the press to automatically reset to its raised position after use. Estimating the weight of the cutting die and handle to be 5 lb., we would need a total spring force of 5 lbf. The spring displacement is .5 in. This is equal to the distance between the die and the cutting tray. Using Hooke’s Law (Formula 2.3), we found the spring constant for each spring to be 2.5lbf.

in.. The spring force would have miniscule effects on the input force. The weight of the

handle and die would counteract most of the spring force. With a total input force of 10 lbf, our conceptual design would be effective and easy to operate. Figure 2.1 depicts the total cutting area of the blades.

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2.3 Concept Development, Scoring, and Selection

2.3.1 Mechanism Design Selection

After applying the data collected in Section 2.2 and to the concepts that passed the concept screening in Section 2.1, the team decided to narrow down the remaining mechanism concepts using a weighted concept scoring chart, as seen in Table 2.4. Each concept was given a score between 1 and 5, judging the idea’s durability, usability, safety, and portability. The assigned weights were determined in Section 2.1 of the Project Proposal Report.

Table 2.4: Concept Scoring Chart - Mechanism

Mechanism Weight Simple

Lever Hinge Fig. 1.3

Spring Loaded Press

Fig. 1.4

Slotted Lever Mechanism

Fig. 1.5

Double Four-Bar Mechanism

Fig. 1.6 Durability 0.385 5 4 3 3 Usability 0.15 3 4 5 5

Safety 0.08 4 5 3 2 Portability 0.385 5 5 4 2

Weighted Totals 4.6 4.5 3.7 2.8 Continue? Yes Yes No No

Durability was judged by the expected lifetime of the system, taking into account joint fatigue, number of expected individual parts, and how easy the maintenance was expected to be. Usability was mostly judged by how much effort would be required to operate the device. Other factors included how fast the process was, how intuitive it was, and any ergonomic concerns. Safety was judged by what level of threat the device presented. This included how much the process exposed the blades and the likelihood that it may pinch or smash body parts when in use. Portability was judged by the size and weight of the proposed mechanism and by how likely it may break while in transit.

The slotted lever and double four-bar mechanisms scored the lowest, so the team decided to remove them from consideration. Features of both the spring loaded press and the simple lever hinge are desirable, so it was decided that these two mechanisms would be combined. The main desired features from the spring loaded press were its low profile and its ability to reset the blades to a neutral position above the cutting tray. To account for the counteracting force from the springs, the lever hinge will be implemented to create a mechanical advantage, lowering the required input force.

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Figure 2.2: Final Conceptualized Design Drawing.

What was unknown was exactly how to implement the lever to the spring loaded press mechanism. After much deliberation among the team members, it was decided that a backing piece would be required to make the lever hinge effective, as seen in Figure 2.2. A bar lever parallel to the length of the mechanism would be placed above the system, with arms sloping down on each end attaching to a hinge on the back side. Attached below the lever would be a pressing block that the lever uses to push down on the surface of the blade box in the spring loaded mechanism.

Pressing down on the lever will force the blade box toward the tray, opposing the force of the springs and compressing the blades onto the photo sheet. The input force would then be decreased, allowing the springs to elevate the blade box up to its original position. As an added safety measure, the frame would be secured to the table top surface using clamps. This will negate the possibility of a violent spring-back force causing the system to shake off the table.

2.3.2 Blade Mounting Design Selection

The final design feature to be evaluated was how the blade system would be attached to the frame. The mounting process was briefly discussed in Section 2.1 of the concept screening. It was stated in the section that the mounting process could not be discussed until further action was taken on what mechanism would be chosen. This was done because not all mounting processes could work on every mechanism. Now that the concepts are narrowed down to two choices, the spring loaded press and the simple lever hinge, the mounting of the blades can be discussed. The mounting processes include the compression fitting, welding and fasteners which included nuts and bolts and set screws. The team decided on using a weighted concept scoring

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chart seen in Table 2.5. Each concept was given a score between 1 and 5, judging the price, lifecycle, maintenance and production.

Table 2.5: Concept Scoring Chart - Blade Mounting Process

Categories Compression Weld Fasteners Price 3 4 2

Lifecycle 2 2 4 Maintenance 4 1 3 Production 5 2 5

Totals 14 9 14 Continue? Yes No No

The welding process was eliminated because there were too many negatives compared to positives. There can be no replacement of the blades at any time added along with inexperience among the group and a hard setup. It would be difficult to keep tight tolerances on the blades if welding was the mounting process. During team meetings, this was discussed in detail and even though the compression fitting and fastener mountings tied in the score the team believed that the compression fitting would be a better choice. The reason for this is because for compression fittings the tolerances can be made tighter which is something that is important due to the fact that there is no space in between the pictures themselves. It will provide ease of replacement for our client, Kara, because instead of removing all of the fasteners that would be contained in every blade she would be able to pop the compression blades in and out easily. The maintenance of taking the blades in and out and the fact that the tolerances can be made tighter were the main deciding factors in choosing the compression fitting as the mounting process the team will use instead of the fastener mounting process.

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3.0 Final Concept Design

The final concept design that was chosen was the simple lever hinge combined with the spring loaded press. These two concepts had the highest total scores when compared to the other ideas based on their durability, usability, safety, and portability. The simple lever hinge was weak in usability and safety, which the spring loaded press was stronger in. Also the simple lever hinge was stronger in durability than the spring loaded press. The combination of these two concepts creates a design that is most suited to our client’s specifications when compared to the other concept ideas and currently available products.

Figure 3.1: This is the Final Concept Design while it is not engaged [A], and is engaged [B]

The reason for the combination of these two concepts, seen in Figure 3.1, is because it gives the best of both worlds. The spring loaded press design allows us to have four round bars attached to both the top and bottom plates. Each of the bars will be surrounded by a spring, which will automatically reset the top portion of the tray to its original position after being lowered to make the cut. The top portion houses the blades so they are not exposed, and the bottom tray will hold the pictures. The simple lever hinge design helps overcome the higher net force required to press down on the springs. It includes a backing piece that would be required to make the lever and the hinge effective. The lever would be a bar parallel to the mechanism length placed above the system. Attached to the lever would be a pressing block which pushes down on the top tray, which in turn pushes the blade box toward the bottom tray. By pushing on the bottom tray, the blades are compressed onto the photo sheet. Once the input force is decreased, the spring will elevate the top portion of the tray to its original location, where our client can unload the freshly cut pictures and insert a new uncut sheet of pictures. Because of the uniqueness and simplicity of the design and because it meets each of the needs of our client, Kara Moore, the team believes that this is the best solution to our task.