Group 7 - Black & Decker Jigsaw Gate 3
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Contents |
Coordination Review
Cause for Corrective Action
As the project progresses we are realizing how our strengths and weaknesses truly affect the quality and therefore grades of our gates and group assignments. Our goal is to consistently improve from gate to gate. We have had one major problem throughout our project and that is editing. Previously we decided to implement a change to deal with our editing problems. We assigned everyone the role of editor to aid our overtaxed editor. We are sticking with this solution but also are adding another change as well. Our first gate was choppy and didn’t flow very well. For the second gate, we had everyone send their individual parts to Mark Rutecki and John Bossung. Once in their hands, each part was checked over for completion and then used like a puzzle piece to complete the gate. If a section didn’t answer the question completely, it was revitalized and worked on until it did. We still have avoided any sort of intergroup conflict. We are functioning quite well. Our biggest enemy is time. Since we are all in the same classes, we all have the same workloads. This is good for scheduling meeting but is detrimental if everything is due at the same time. For instance, this last week every group member had at least 2 exams on top of their normal workload. To handle the inevitable procrastination of Gate 3 we held emergency meetings prior to our workload getting out of hand. These meetings helped us to follow the schedule laid out by our Gantt Chart as closely as possible. It is important that we keep on time to maximize the editing time available.
As we near the end of the semester more group challenges are brought to light with respect to the presentation. We were able to agree to a presentation date but we haven’t been able to decide who is going to present yet. We want to make the presentation a group effort with its completion but since only a limited number of members will be allowed to present we are planning on taking it to a vote. When the Gantt Charts timeline tells us to start working on the presentation, we will hold a meeting and vote on who will present to the class. This is the fairest and best way to ensure that the presenter is qualified and skilled enough.
Product Evaluation
Component Summary
| Components | ||||||||
|---|---|---|---|---|---|---|---|---|
| Part # | Part Name | Part Function | Material | Reason For Material | Manufacturing Process | Picture | Quantity | Complexity |
| 1 | Armature Assembly | The assembly of the motor and it's components | Steel, Copper Wire | Steel: Strength, Copper Wire: Conductivity, Flexibility | Steel: Machined, Pressed, Copper Wire: Extruded |  |
1 | 0.90 |
| 2 | Field Assembly | Provides the power to the motor, allowing it to rotate | Steel, Copper Wire | Steel: Strength, Copper Wire: Conductivity, Flexibility | Steel: Machined, Pressed, Copper Wire: Extruded |  |
1 | 0.35 |
| 3 | Switch Assembly | The control switch for the oscilating blade | Plastic, Copper Wire | Plastic: Inexpensive, Copper: Conductivity, Flexibility | Plastic: Injection Molded, Copper Wire: Extruded |  |
1 | 0.30 |
| 4 | Clamshell Set | Houses the motor, wiring, and most of the components in the jigsaw | Plastic | Inexpensive | Injection Molded |  |
2 | 0.05 |
| 5 | Brush and Spring | Transmits power to the field assembly | Plastic, Carbon | Plastic: Inexpensive, Carbon: Durability | Plastic: Injection Molded, Carbon: Spring |  |
2 | 0.60 |
| 6 | Brush Box | Holds the brush and spring | Plastic | Inexpensive | Injection Molded | |
2 | 0.10 |
| 7 | Thrust Plate | A major component of the motor assembly | Steel | Strength, Durability | Stamped | |
1 | 0.15 |
| 8 | Counterweight | Provides a counterweight allowing the thrust plate to hold the motor parts together | Steel | Weight, Durability, Stability | Die Cast | |
1 | 0.10 |
| 9 | Gear Assembly | This gear assembly is used to aid the rotor in moving the saw blade | Steel | Durability | Forged by Stamping |  |
1 | 0.65 |
| 10 | Roller | A major component of the motor assembly | Steel | Durability | Machined | |
1 | 0.25 |
| 11 | Actuator | A locking gear mechanism | Plastic | Easy to mold, Inexpensive | Machined |  |
2 | 0.20 |
| 12 | Gear Assembly | This gear assembly is used to tighten the locking screw | Plastic, Steel | Plastic: Weight, Easy to mold, Inexpensive, Steel: Strength, Durability | Plastic: Injection Molded, Steel: Machined |  |
1 | 0.35 |
| 13 | Shoe Assembly | Gives the user a plate to manipulate for more control of the product | Steel | Strength, Durability | Pressed |  |
1 | 0.45 |
| 14 | Blade Support | A support for the blade assembly | Steel | Little Flexibility | Pressed |  |
1 | 0.15 |
| 15 | Locking Screw | A locking mechanism used to hold the shoe assembly in place | Steel | Strength | Die Cast, Thread Rolled |  |
1 | 0.20 |
| 16 | Guard | A safety mechanism providing a guard for the user from the dangerous blade | Plastic | Inexpensive | Injection Molded |  |
1 | 0.15 |
| 17 | Button Lock | A mechanism that allows the user to lock on the speed of the blade | Plastic | Inexpensive | Injection Molded | |
1 | 0.35 |
| 18 | Elbow | A support for the shoe plate | Plastic | Inexpensive | Injection Molded |  |
1 | 0.20 |
| 20 | Shaft Assembly | An assembly attached to the motor to allow for movement | Steel, Felt | Strength, Durability | Steel: Cast, Felt: Cut |  |
1 | 0.75 |
| 21 | Blade Clamp | Holds the blade in place | Steel | Strength | Die Cast |  |
1 | 0.70 |
| 23 | Bearing Sleeve | Cylindrical Support | Steel | Durability | Die Cast |  |
1 | 0.70 |
| 24 | Cord Protector | A safety mechanism providing a guard from electrical leakage | Plastic | Insulation, Flexibility | Injection Molded | |
1 | 0.10 |
| 25 | Cord, 8 ft.,18-2 | The cable that supplies the electrical energy from the outlet to the product | Plastic, Copper Wire | Plastic: Flexibility, Insulation, Copper Wire: Conductivity, Flexibility | Plastic: Injection Molded, Copper: Extruded | |
1 | .10 |
| 26 | Lead Wires | Wires connecting the various parts of the machine | Plastic, Copper Wire | Plastic: Flexibility, Insulation, Copper: Conductivity, Flexibility | Plastic: Wrapped, Copper Wire: Extruded | |
2 | 0.05 |
| 28 | Screw | This screw hold the two pieces of the clam shell together | Steel | Strength | Thread Rolling |  |
7 | 0.10 |
| 44 | Gel Grip | A comfortable and stable grip allowing the user extended control of the product | Plastic, Gel | Comfort | Injection Molded, Filled |  |
1 | 0.20 |
| 45 | Baseplate | A component used to hold the gel grip in place | Rubber | Durability | Stamped | |
1 | .10 |
Complexity/Interaction Scale
The complexity rating of each component can be found in the component summary following the product evaluation, also known as Table 3-1. This table tabulates every single component within the jigsaw and gives each component a complexity rating based on a defined scale. The defined scale to each components complexity is a factor of it’s function, the geometry of the component, the material it is made of, the reasoning for that material, it’s manufacturing process. Our scale was based on a rating from 0.00 to 1.00.The rating of 0.00 being the lowest and therefore very simple, and 1.00 being the highest and therefore intensely complex. The components to receive the lowest ratings included the brush box, thrust plate, counterweight, roller, actuator, blade support, locking screw, guard, elbow, cord protector, the cord itself, lead wires, the screws, gel grip, and the base plate. These all received extremely low complexity ratings on account that their parts are non-moving, they are all easily made and easily molded from their respectable materials, are all easily replaceable, and have a rather simple component function. The more complex components include the field assembly, switch assembly, brush and spring, gear assemblies, shoe assembly, and the button lock. These components are more complex because they provide a higher level function to the jigsaw, and are all moving or rotating pieces that help make the jigsaw work efficiently. These components are harder to make as their geometry needs to be more specific and their material needs to allow them to work in specific conditions. The most complex components in the jigsaw include the armature assembly, shaft assembly, blade clamp, and the bearing sleeve. These components perform the highest level functions, are vital to the efficiency of the jigsaw, and are extremely intricate and difficult to manufacture.
The majority of component interactions within the jigsaw are not complex, with the exceptions of the armature and field assembly which make up the motor, the gear assemblies’ which make up the transmission, and blade assembly. These are the only complex component interactions because they have to take in one form of energy and convert it into another form of energy for the next component. The motor assembly takes in electrical energy and turns it into rotational energy for the transmission to convert it again into rotational energy for the blade assembly to convert it into kinetic energy to oscillate the blade and cut materials. These types of interactions will receive higher ratings of complexity compared to lower interaction components. Complexity of interaction also depends on the amount of parts the component transfers mass, signals, or energy to. If the part sends energy to multiple other parts then that part will receive a higher interaction rating. The scale for interaction complexity is from 0 to 1 with decimals as the in-between ratings. The overall ratings will depend on the complexity of the flow transfer as well as the quantity of flow transfers that deal with an individual component.
Product Analysis
Bearing Sleeve
- Component Function
The bearing sleeves main purpose is to provide support for the blade assembly when it oscillates up and down. The bearing sleeve ensures that there is minimal to no horizontal movement. It keeps all motion vertical. This component does not perform multiple functions because when in place it is stationary. Two different flows are associated with the Bearing Sleeve. First is the flow of kinetic energy which is present when the blade assembly moves up and down. There is also a mass flow which is the steel of the shaft assembly as it flows up and down as long as the Jigsaw is being used. When the Jigsaw is fully assembled, the bearing in held in place by a plastic socket built into the clamshell set. From that position it doesn’t move at all. It is not visible at all if the Jigsaw is assembled.
- Component Form
The bearing sleeve is of a cylindrical shape. The top edge of the cylinder is flattened as well as the bottom and there is a rectangular whole running through one flat edge to the other. There are 3 axis of symmetry on the bearing sleeve and it acts in 3 dimensions. The bearing sleeve needs to be shaped the way it is to perform its function in the Jigsaw. The rectangular cut out secures the shaft in the bearing sleeve and the cylindrical shape allows it to easy fit into the socket in the clamshell which therefore secures the shaft to the clamshell.
Max Height = 1 cm
Max Width = 0.8 cm
Max Length = 2 cm
Estimated Weight = 23 g
- Material
The bearing is made out of steel. The material choice of steel was impacted by manufacturing decisions in a couple ways. Steel manufacturing has a substantial base all over the world. It is a well versed practice that has been around for quite some time. It is relatively cheap, durable and strong. Steel is necessary for the component because of its strength and durability. The bearing comes is in a high friction zone and this means the steel has to be able to keep its shape under high temperatures. Combined with a little grease the steel also has a low enough coefficient of kinetic friction to not impede the cutting function. Global factors of the choice to use steel are that steel is available all over the world as long as there is some sort of steel mill or mini mill around there. This is also an environmental factor because there isn’t going to be a shortage of steel any time soon. Economic factors include steels price and its durability. To keep the price of the Jigsaw lower its components need to be cheap but they can’t just break. Socially, steel might be necessary because it isn’t affected by heat as much meaning the Jigsaw will be less likely to break or burst into flames while in operation.
- Aesthetics
The bearing has very few aesthetic characteristics besides color and surface finish. The bearing isn’t visible in any way so it doesn’t have any sort of aesthetic purpose. The color of the bearing is grey for the sole purpose that that is most convenient. No additional money was spent on the color of the bearing because that would have been illogical and wasteful. The bearing has a very smooth surface finish. Combined with grease, this aids the blade assembly with its sliding action. It allows for a lower coefficient of friction. The surface finish is for functional reasons as well.
- Manufacturing Methods
The bearing sleeve was created by a forge and some sort of die cast. It might have been stamped together. This is evident because there are two lines running in parallel down the width of the bearing. The lines appear to be from where two shapes were pushed together or where a mold was removed. Material choice defiantly impacts the decision of how to create the part because steel is not an easy material to work with. It is a huge process to work with steel because of its high melting point. The shape of the bearing is easy to mimic and would have impacted the method of manufacturing because it is perfect for a die cast or a forge. Global aspects affect the manufacturing process because steel needs to be worked on in some sort of steel mill which though all over the world, aren’t necessarily close by. Manufacturing steel is expensive which will affect the price of the Jigsaw. Forging the bearing doesn’t have many societal factors because it doesn’t impact the people that use the Jigsaw that much. It affects the workers of steel mill but not the consumers of the product. Environmental factors, though present, were probably not considered because price and quality generally comes before the environment.
- Component Complexity
The Bearing Sleeve is more complex. Our complexity scale rates it a 0.7. Please see the above section for more info on our complexity rating The interactions are more complex as well and again we rate it a 0.7.
Shaft Assembly
- Component Function
The shaft assembly’s function is to move the blade up and down. It is the final task that leads to the job of cutting. Besides moving the blade up and down, the shaft assembly is part of the conversion of rotational motion of the gears and motor to linear vertical motion of the blade. The major flow associated with this component is kinetic energy. Energy is passed from the gears to the shaft assembly which then is transferred to the blade. The shaft assembly completes most of its function in the enclosed area of the clamshell. There is a minimal amount of the shaft assembly that operates outside of the clamshell and that is where it is attached to the blade.
- Component Form
The shaft assembly is relatively flat with a rectangular shape. About halfway down the shaft is an extruded middle in the shape of an ellipse. There are three separate elliptical holes in the shaft one which is similar and in sync with the elliptical extrusion. This component has one axis of symmetry and is primarily in 3 dimensions. The shaft is shaped the way it is to aid in the movement of the blade. The main elliptical whole in the middle of the shaft is used to transmit rotational motion to linear motion by allowing a shaft from a gear to rotate around and move the shaft assembly up and down. It also has two relatively flat portions to allow for the bearing sleeves to fit around it.
Max height = .4 cm
Max Width = 10.7 cm
Max Length = 3.3 cm
Estimated Weight = 100 g
- Material
The shaft assembly is made out of steel. Manufacturing decisions impacted this choice in similar ways that the bearing sleeve was impacted. Steel is used all around the world for many different purposes from beams to eating utensils. Manufacturing steel is a practice that has been around for a while and isn’t going anywhere fast. Steel is needed on the shaft assembly for a couple reasons. It is very strong and therefore will be less likely to bend or break when under pressure when the blade starts cutting. More important than that is its high melting point. There is going to be a large amount of friction on the shaft assembly because of its rapid motion. This will cause large amounts of heat and the steel won’t become deformed because of this. The four factors impacted this decision in a couple ways. Globally, steel is present in most places and there are mills around the world. Socially, steel had to be used because of its higher quality. Other materials wouldn’t be able to take the strain that steel can which would cause the Jigsaw to break and then the users wouldn’t be satisfied. Economically steel is costly to use but it pays off because it don’t really break that often. To replace a broken shaft assembly would be much more expensive than having to replace a broken blade so the shaft has to be stronger than the blade.
- Aesthetics
This component has almost no aesthetic purpose. The shaft assembly is connected to the blade and that is the only part that is visible to the user. The component is colored gray because that is the color steel was when the component was created. Changing the color of the shaft would be counterproductive and a needless expenditure of money. The surface finish is quite smooth even though it looks a little rough. Combined with a little grease the shaft has very smooth. This finish is purely functional because the smoother the shaft the lesser the frictional force.
- Manufacturing Methods
Like the bearing sleeve, the shaft assembly was manufactured by forging. This would be the most time efficient way to create the part. It wouldn’t be practical to create the part using any other way because steel isn’t very conducive to other forms of manufacturing. Choosing steel defiantly affects the decision because steel needs to be forged at steel mills. Shape also impacted the decision of what manufacturing process to use because the shape of the shaft is quite simple and wouldn’t be hard to put in the form of a die. In deciding what type of process to use, global factors would be considered as to where the closest steel mill was and other location factors like that. Environmental factors would be ignored for the most part because there really isn’t that much impact that each shaft would have on the environment. As long as local pollution regulations were in check at the steel mill there would be little impact on the environment. Societal factors and economic factors run hand in hand. If the product is going to be higher quality, more expensive components will need to be used like the steel. If shortcuts are taken then the Jigsaw would lose its integrity and though it would be cheaper, could break easier which would negatively affect the user.
- Complexity
This component is more complex and is given a 0.75. See the above section for a more detailed explanation of our complexity scale. The interactions between this component and the rest of the product are more complex and are given a 0.75.
Gear Assembly
- Component Function
This gear assembly’s purpose is to change the gear ratio from the speed of the motor to a speed that can be easily used. The ultimate task of the gear assembly is to aid in the conversion of rotational motion to linear motion. These multiple functions performed are related because changing the gear ratio needs to occur in order to convert the motion direction. The main flow through this component is kinetic energy. The gear is spun at higher speeds and as it rotates it causes the shaft assembly to oscillate up and down. Nothing else flows through this component. The gear assembly completes its function entirely inside of the Jigsaw. The environment is not suitable for most things. It is dark and dank with no light penetration and lots of grease. It will be loud from all the moving parts and there are probably an assortment of odors depending on what is being cut and how long the Jigsaw has been running.
- Component Form
The gear assembly’s base shape is of a classic gear but it has some interesting physical properties not found on many gears. There are gear notches all around the circumference of the gear and there is a shaft extending from the center of the circle. This shaft also has a smaller circle extruded out of the gear with it. There are 3 holes running through the gear and there are ridges gouged out of the one side as well. The other side of the gear has a shaft extending out of it but it is not extended from the center of the gear. It is around a centimeter off from the center and is what helps in the conversion of motion. The gear has one axis of symmetry. This gear is primarily in 3 dimensions. The shape of the gear is directly related to its function. If any part of this component’s shape was changed its functionality would be destroyed and the overall function of the jigsaw would be affected too. Gears need teeth for their function and if the shafts were changed other parts of the Jigsaw would be affected.
Radius = 2 cm
Width = 1 cm
Shaft lengths = .7 cm and 1.5 cm
Max width = 3.7cm
Estimated Weight = 180 g
- Material
The gear assembly is created out of steel. Manufacturing has a huge impact on the decision of steel because steel is not an easy material to manufacture. It has a high melting point and needs to be forged in a steel mill. It is necessary for the gear assembly to be created out of steel because the gear assembly will encounter large amounts of torque while completing its task. Also, it will be rotating at high speeds and will encounter substantial friction. This will lead to lots of heat and the gear can’t be allowed to have any sort of deflection or failure. The different global, societal, economic, and environmental factors influenced choosing steel considerably. Though steel is able to be shipped to most factories it generally needs to be worked on at a steel mill. Combined with where the Jigsaw is assembled, this affects the global factors. Socially steel is work intensive for the factory or mill workers but it is less work intensive for the user of the Jigsaw. The Jigsaw is stronger and more durable with the steel gear which is much more beneficial for the user. Environmental factors of using steel are relatively small. Besides pollution at steel mills, using steel for the gear assembly isn’t to detrimental to the environment. All these factors can be put together to see the economic factors. Using steel has its increased costs which will raise the price of the Jigsaw but will also increase its life.
- Aesthetics
Aesthetics have a small impact on the creation of the gear assembly. It wouldn’t really be considered beautiful unless someone was impressed by steel. The gear doesn’t have an aesthetic purpose because it is completely hidden at all times unless the Jigsaw is taken apart. The gear is gray. In some places it is a different shade of gray where grease has stained it. The gear is gray because that was the most convenient color for it to be without spending more money on its creation. The surface finish on the gear is smooth on the areas that come in contact with other components which is for functionality in decreasing friction.
- Manufacturing Methods
The gear assembly was forged by stamping. The main cylinder has a stamping mark ringing it on both sides. Also, the shafts appear to be pressure fit into premade holes in the cylinder. The raised cylinder section appears to have been stamped onto the main cylinder. Using steel affects the manufacturing decision because steel has limited manufacturing uses. It is mainly used at a steel mill but can also be stamped and machined. Shape also impacts the manufacturing method used because the gear is in the base shape of a circle with teeth lining the circumference. Global factors used in this decision are the availability of steel manufacturing plants or mills. It might not be efficient to use steel if it needs to be shipped across the world to make. Socially the steel industry goes up and down but is constantly around. There will constantly be people making steel but they might not be as widespread in a time when steel is down. Environmentally, steel mills provide pollution through heat and waste pollution. They use huge amounts of energy. Economically, stamping steel is cheaper than actively forging it because the part doesn’t need to be quite as hot.
- Complexity
This component moderately complex and is given a .65 on our scale. See the above section to see our complexity scale in more detail. The interactions of the gear with other components are moderately complex as well. It is rated a .55 on our scale.
Screw
- Component Function
The screw on the outer part of the jigsaw has the main purpose of supporting the two main chassis shells together. The screws provide a stable environment for the jigsaw to function. The screw is meant to be durable because it operates outside the main plastic shell. This means the screw must be able to hold the two plastic chassis parts together under normal operating temperature based on the extreme climates of the region it’s being used in. An arbitrary range of operating temperature would be -15 degrees Celsius to 90 degrees Celsius. The jigsaw should not be operated in a wet environment because of its electrical components, but the screws may encounter a humid environment that they must perform in.
- Component form
The screw is very standard for this type of component. The head of the screw is rounded and the screw driver docking type is Phillips. The screw is doesn’t have axial symmetry about any line because of the pitch of the thread on the screw. This pitch is essential to creating thread friction in order for the screws to stay in place.
Length: 2.1 cm
Head Width: 0.7 cm
Width: 0.3 cm
Height: .7
Estimated Weight= 2 grams
- Material
The screw is made out of steel. The basic demands that the screw must fulfill are to not wear under climate conditions, not distort under load, and not affect the overall cost. The screw looks to be coated with a material other than steel to prevent wear caused by screw driver heads and also moisture. The main problem with screws is their tendency to be stripped over time by screw driver heads. Steel provides durability to avoid this defect. Steel is a widely used material around the world, because of its abundantcy and also its properties. The economic factors the play into the choice are the relatively low cost of the base material and also the relatively low cost to form the screw into its shape.
- Aesthetics
The screws are placed inside premade depressions in the plastics chassis so they are barely visible by the user. They have a smooth finish on the head and the thread part in sharp at the edges, but smooth between the threads. This smooth surface between the threads has a purpose of allowing the screw to be snugly and easily screwed in by the assembler. The screw doesn’t have a feasible aesthetic purpose in the overall design of the jigsaw. The screw is black which is probably because it should standout or reflects light to draw attention to it.
- Manufacturing Methods
The screw is made by the technique of thread rolling. This process falls under forming and shaping. The screw is rolled over two dies while it is still hot enough to be shaped. The original blank of the screw was probably made my stamping. The evidence of this is the smooth surface finish and the economic practicality of this process and the shape of the screw. The process of thread rolling was chosen for the screw because that is the most typical way to produce a thread for screws on a large scale manufacturing process. Using the process of stamping out the blank of the screw and thread rolling the screw could be made anywhere in the world because any steel mill could perform this process. The price of making a screw using these methods would be very economic because for a large scale production these methods would cost the least for the shape require of the screw. Societal and environmental factors don’t really weigh in because they don’t change by a lot for different manufacturing methods for screws and the factors a screw does have are legible to society. The environmental impact occurs in the heating of the steel because that process will burn hydro-carbons, but this factor is inevitable.
Complexity: The screw is a very basic component and our scale rates its complexity rates it a .1.
The interactions are minimum between other parts because it is located outside the jigsaw. We rate it a 1.
Counterweight
- Component Function
The function of the Counterweight is to provide a counterweight allowing the thrust plate to hold the motor parts together. This component helps to perform multiple functions, as without it, the thrust plate would be off balanced, and the motor would not run as smoothly. There is minimal flow throughout this component as its function is to balance motion and flow in general. It moves up and down so there is a little kinetic energy but it isn’t transferred anywhere. The component functions in a high friction environment within the casing of the jigsaw.
- Component Form
The general shape of the component is a hexagon with a rounded rectangular bottom, and a flat triangular top. The rectangular shape merges with the triangular top at a 30 degree angle shortening the length at the top in comparison to the length at the bottom. It is a symmetric shape with six holes bored into it allowing for different components to pass through the counterweight. It is primarily two dimensional as all of the function lies within the length and height, and is not really affected by the width, with the exception that added width allows for extra stability. The component has a length of 4.6 cm at the bottom, a length of 2.8 cm at the top, a height of 8.7 cm, and a width/thickness of .55 cm. The component shape allows it to fit snugly into the casing, and the holes bored into the steel allow it to oscillate up and down along with the movement of the gear. The component is rather heavy compared to other pieces of the jigsaw and is one of the heaviest parts besides the motor and transmission. It weighs about 500 grams
Length at top = 4.6 cm
Length at bottom = 2.8 cm
Height = 8.7 cm
Width/Thickness = .55 cm
Estimated weight = 500 g
- Material
The counterweight is made from steel. Manufacturing decisions impacted this as they need a strong and durable material that is easy to mold into a specific shape. A specific material property is needed for it to function as steel can withstand a lot of heat, which is vital to its function where it creates a lot of friction. Steel is readily available, does not concern society, is rather cheap, and has no adverse effects on the environment
- Aesthetics
The component does not have any aesthetic properties and does not need them as it is not visible on the product. It is grey colored as it should be because it is made of steel, and it has a yellowish, shiny surface finish as it is lubricated. The surface finish is for functional purposes as the lubrication of the counterweight allows the oscillation to flow more smoothly and efficiently.
- Manufacturing
The manufacturing method of die casting was used to design the counterweight. This is supported by the fact that there is a small riser mark that circles the edge of the component. Being steel, material choice has a big affect on the manufacturing process chosen. Steel can be manufactured in a limited number of ways. Shape also impacted the method chosen because of the counterweights relative simplicity. It is 2 dimensional and only has a couple shapes and holes in it. Globally, die casting steel isn’t done everywhere. There are steel mills in set areas around the world. They aren’t to mobile but can be found in different places around the world. Die casting something is less manually intensive than other processes which socially affects the factory workers. Environmental concerns go hand in hand with all sorts of factories or manufacturing plants. Where there is something industrial, there is pollution. All these factors can affect the economic factors because all them can affect the price of the component which directly impact the price of the Jigsaw.
- Complexity
This component is not complex and is given a 0.1 on our complexity scale. Look above to find our complexity scale. The interactions of the counterweight are minimal and therefore it is given a 0.15
Thrust Plate
- Component Function
The function that the thrust plate performs is to hold the parts of the motor together. It helps to perform multiple functions as without it, the connection between the motor and the gear assembly would not be made smoothly, and the motor would not run efficiently. The thrust plate works hand in hand with the counterweight to balance the flow of energy and to stabilize the other components in the Jigsaw. There is no energy flow on this component besides it moving up and down. The component functions in a high friction environment within the casing of the jigsaw.
- Component Form
The general shape of the component is a thin, rounded rectangle. It is axis symmetric, and has six purposefully bored holes into the plate. The component has a length of .028 meters at the top and bottom, a height of .052mm, and a width/thickness of virtually nothing. The components shape is coupled with the way it performs as it fits within the casing, takes up virtually no space within the jigsaw, and also as the holes bored into the plate holds the gear assembly in place for the motor to work properly. The thrust plate is virtually weightless and may be the lightest component within the jigsaw at about 5 grams.
Length = 2.8 cm
Height = 5.2 cm
Thickness = virtually nothing like a piece of paper
Estimated weight = 5 g
- Material
The thrust plate is made from steel. Manufacturing decisions impacted this as they need a strong and durable material that will not break even when it is extremely thin such as in this case, and a material that is easy to mold into a specific shape. A specific material property is needed for it to function as steel can withstand a lot of heat, which is vital to its function where it creates a lot of friction. Steel is readily available, does not concern society, is rather cheap, and has no adverse effects on the environment. The component does not have any aesthetic properties and does not need them as it is not visible on the product. It is grey colored as it should be because it is made of steel, and it has a yellowish, shiny surface finish as it is lubricated. The surface finish is for functional purposes as the lubrication of the thrust plate allows the gear assembly to rotate with a minimal amount of friction.
- Aesthetics
The thrust plate has almost no aesthetic properties. It is not enjoyable to look at unless someone is particularly attracted to steel. The only aesthetic property is that it is a little shiny and has minimal glint and glamour when a light is directed at it. The component has no aesthetic purpose because it can’t be seen by anybody. The thrust plate has a smooth surface finish which is for functional purposes to decrease friction.
- Manufacturing
The thrust plate was created by stamping. This is evident on its incredibly thin shape. To use any other sort of manufacturing process would be impractical and inefficient. Since the thrust plate is made out of steel, material has a sizable impact on the manufacturing choice. Steel has a limited number of manufacturing methods that can be practically preformed on it. Shape also played a part in the method choice because of the thrust plates’ small thickness. If the thrust plate were thicker, easier manufacturing methods might have been used. There are global factors affecting this decision because steel generally needs to be manufactured at a mill or a bigger plant. These facilities aren’t located everywhere. Social factors of manufacturing the steel using stamping are that using steel can be dangerous to the factory workers. Steel needs to be quite hot before it can be used and with great heat comes greater risk of injury. Environmental concerns go hand in hand with all sorts of factories or manufacturing plants. Where there is something industrial, there is pollution and this probably isn’t considered in the overall production of the Jigsaw. All these factors can affect the economic factors because all them can affect the price of the component which directly impact the price of the Jigsaw.
- Complexity
This part is not very complex and has a rating of 0.15. See the above section on complexity rating for more detailed information. The interaction between other components is kept to a minimal and is rated a 0.23.
Solid Modeled Assembly
The CAD package I used to solid model the components was Auto Desk Inventor 2011. We chose this CAD package because it could fulfill the solid modeling of this project and our group was familiar with this program. The reason why I chose the components I modeled because our group analyzed these components for our component summary. The engineering process our group completed analyzing a function of our jigsaw involved all the parts we solid modeled. The assembly of the gear, counter weight, bearing sleeve, and scotch yolk are an important part of the jigsaws main function. We used the sub-function of this assembly in our engineering analysis problem so further visual aid to this analysis was also beneficial. We found the dimensions of all four components and modeled them to their actual size.
| Part Name | 3D Model |
|---|---|
| Scotch Yolk |  |
| Gear Assembly |  |
| Bearing Sleeve |  |
| Counter Weight |  |
Table 3-2: Solid Modeling- This is the documentation of 4 of our components as solid models.
Engineering Analysis
- Introduction
- Using the engineering process an engineer would evaluate the best way to make the mechanical energy transfer from the motor to the blade optimal, via gears. The first step in the engineering process would be to identify the need, in this case this would be finding the optimal gear ratio of the gears in the Jigsaw. Next the engineer would break down the function of the gear transfer into its basic function of transferring a torque ratio to another gear and determine what type of performance the Jigsaw should have with the gear specifications. The performance standards will be discussed later after the theoretical analysis. Next the engineer will look at the basic concepts of the gears and the limitations the parameter of the gears will have based on space, economic factors of materials, and availability of materials. This is the step where the theoretical analysis to the problem will occur. An example of this theoretical analysis can be seen in the next section. When the final dimensions are in place the engineer will have to validate his/her design by doing physical test as mentioned in the discussion of the theoretical analysis. After the final dimensions meet performance and safety standards the product could be put into production with the given specifications of the gear assembly.
- Function
- The drive shaft of the Jigsaw is connected to a large gear. When this gear ratio is bigger there is greater torque in the larger gear. The larger gear applies mechanical energy to the scotch yolk blade assembly, but the amount of force that the scotch yolk receives depends on the torque of the larger gear. The overall performance of the Jigsaw depends on the ability to apply force to the blade to cut wood, but at the same time oscillation speed of the blade cutting the material back and forth must be conserved for the Jigsaw to function. For example the blade could have a large force pushing it through a piece of wood but if there isn’t enough blade speed back and forth the process of cutting the wood may be very long. This function can be analyzed using different gear ratios and calculating the torque. The power loss based on those gear ratios must also be calculated for the given dimensions of each gear conditions. This power loss will be elaborated more in the discussion after theoretical analysis. Calculating the best torque and power loss won’t give results that tell if the Jigsaw will perform to specifications of cutting quality. The equations of the analysis will give you theoretical outcomes but there must be testing in order to achieve a definitive analysis that can be verified.
Theoretical Analysis
- Problem Statement
- What gear ratio will give you a maximum torque while giving an acceptable mechanical energy loss between the gears?
- Diagram
Fig 3-8: This is the Diagram for the flow of energy and also the gear interaction.
- Assumptions
- the jigsaws motor output has a constant mechanical energy output each test
- the coefficient of friction is constant for the gear surfaces touching.
- Governing Equations
- Discussion
- The engineer doing this analysis would have to measure the values specified in governing equations step. From those values he would then make educated estimates on the dimensional values of the larger gear that would create a higher torque. The engineer would then have to validate the assumptions made in this analysis. He must test the mechanical energy output of the motor in terms of Joules and see if there is any fluctuations in power generated over multiple prolonged uses. Then the coefficient of kinetic friction must be found based on the two materials in contact for the gears. From those values the engineer would calculate the power loss and torque on the gears for the dimensions used. The next step would be to make a chart of power loss vs. torque and find the plot point that will give you a minimum power loss and maximum torque based on acceptable power losses. The answer to this analysis problem is very sensitive because it does not mean these dimensions should be used for manufacturing final design specifications.
- In order to find the maximum torque and minimum power loss of the gears that will be best, there also must be physical tests of the saw to determine its cutting ability; this will be the verification plan for the calculations. A test will be set up using the jigsaw at all the gear dimensions and have every other variable remain constant. A robot arm will have to apply a constant force pushing the Jigsaw across a piece of uniform wood. This test would hold every variable constant to then observe jigsaw performance. A base requirement for time and quality of cut will be established based on the expected performance of the Jigsaw. The dimensions of the gears that don’t meet the quality of performance
Design Revisions
Design Revision 1
Our first design revision is to switch the Jigsaw from being powered by an electrical outlet to being powered by a battery. This would be a very complex revision which would involve a complete rewiring of the Jigsaw to account for Direct Current since it is currently wired for Alternating current. Besides rewiring, the orange clamshell component would have to be restructured to allow for a batter pack attachment. This would further increase the magnitude of the revision. The electric power cord could be removed but a battery charger would have to be included in the jigsaw package. Socially, his revision would exponentially aid the mobility of the Jigsaw as it would no longer be restricted by the power cord. The user could take the Jigsaw around and not have to worry about being plugged into an outlet. There would be some negative economic changes though. There would be minimal environmental effects from this change. Batteries are not very good for the environment because of their recyclability and the heavy metals they use. They aren’t horrible for the environment so it would be a small factor but the increased product waste after the Jigsaw is thrown away. The price of the Jigsaw would increase substantially as more components are necessary and their interactions would become more complex. This change would change the type of consumers who buy the Jigsaw. The higher price would drive away some customers but the added mobility would bring in people who work a lot outdoors away from electricity.
Design Revision 2
The second design revision our group conceptualized is an added scale to measure the cutting angle of the jigsaw. This would change the base plate by adding a scale in degrees from vertical the angle of the cut for the jigsaw. This change to the base plate will not be drastic, rather just adding to the original component design. The jigsaw would now be able to make angled cuts in the units of degrees, an international unit. This will help create better global use for the product because degrees will be used anywhere in the world. Economically adding a scale to measure the angle of cut won’t be that costly. The only thing added would be hash marks or some type of dial to turn the angle of the blade to a specific degree. This wouldn’t change the overall design of the product which won’t create a huge cost increase. Adding an angle measuring apparatus won’t affect the environmental factor that go into the production of the jigsaw. Socially the added angle measuring apparatus will improve the ergonomics of the jigsaw by making angled cuts easier and more precise. The overall added serviceability of the product and the negligible added cost makes this design revision a overall smart addition to the design.
Design Revision 3
The third design revision involves the horizontal precision of the cuts made by the jigsaw. An added laser to the front of the jigsaw will add precision to cuts by making sure the jigsaw stays in line with the target cut destination and doesn’t make a curved cut to the cut destination. In order to add a laser to the jigsaw without affecting many components the laser will have to be attached by a clip to the blade guard and be removable. This way the laser can be removed and the cost of redesigning the jigsaw to accommodate the later won’t be excessive at the cost of the consumer. Globally the added laser will ensure a straight cut no matter where you are. Economically this added design revision will add consumer marketability for increased profits, but won’t add a lot of cost to the manufacturing process. The original jigsaw is relatively cheap so adding a detachable laser guide could make this feature optional. An optional laser guide will give the consumer the option of paying more for a straighter cut, or pay less for the original design of the jigsaw. The laser could also be sold separately from the jigsaw, but very easily added to the blade guard. Socially the laser will add better ergonomics by aiding the ability of the user’s sight of line on every cut they make. Overall the design revision would boost sales of the product with minimum production cost increase.
