Gate3: Product Analysis

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Contents

Purpose

It is the intent of Gate #3 to provide a detailed analysis of the Black and Decker Variable Speed Orbital Jigsaw JS660 with specific respect to the product's individual components and its subsystems. The gate will also detail a series of design revisions and examine challenges within the group.

Figure 1: Black and Decker Variable Speed Orbital Jigsaw JS660

Project Management: Coordination Review

Cause for Corrective Action

Previous attempts to improve group coherency and productivity have succeeded to an extent. Following the prior gate, our group has encountered a reoccurring issue concerning an even distribution of work between the members. A specific individual within the group failed to complete their assigned portion of the project within the allotted time frame. The magnitude of situation was made increasingly dismal in consideration that the remaining group members were only notified by the individual of concern at a late time prior to a project due date. The specific individual was addressed by the group and has since resigned from the class entirely. This resignation, however, has now provided the group with an additional issue that must be resolved: the distribution of work between the remaining group members. In an attempt to deal with this problem, the project manager has proposed that individual divisions of work be assigned and completed in a timely manner as early as possible prior to the due date of any project. Thus, the group hopes to account for the margin of error for any project by allowing sufficient time to correct mistakes.

Product Archaeology

Component Summary

Figure 2: Parts List
Black and Decker JS660 Parts List
Part Number Part Designation Component Function Manufacturing Processes Implemented Materials Required Part Number (1) Quantity Visual Representation
1

Power Cord

The power cord is the long, black length of wire that extends from the back of the tool and serves to transfer electricity from an external source to the tool.

The copper wire and insulating tubing were created by the shaping process drawing.

Copper

Insulating Material

372067-16

1

Picture 10: power cord

Picture 1: Power Cord

2

Power Cord Clamp

The power cord clamp is a piece of metal which, when screwed into the body, restricts the movement of the power cord.

Stamped

Steel

329301-00

1

Picture 10: Blade Guard

Picture 2: Power Cord Clamp

3

Jigsaw body

The Jigsaw body is the plastic, black and orange exterior casing to the power tool. It consists of two halves. The body serves to contain the internal mechanical components of the jigsaw.

Injection Molding

Plastic

Die (Orange and Black)

N/A

1

Body.JPG

Picture 3: Jigsaw Body

4

Body Screw

The body screws attach the two halves of the Jigsaw body together. They have a 5/16 inch head diameter, and are 3/4 of an inch in length.

Rolling was used to thread the screw. While the head was forged.

Steel

330045-02

8

Shellscrew.JPG

Picture 4: Body screw

5

Reciprocating shaft Assembly

The Reciprocating shaft assembly is the metal extension connected to the blade holder. It is an essential component in the scotch yolk mechanism, which converts rotational to linear mechanical energy.

Forging

Steel

90517289

1

Reciporcatingshaftassembly.jpg

Picture 5: Reciprocating Shaft Assembly

6

Carbon Brushes

The Carbon brushes are black rectangular boxes that complete the circuit to the electric motor. They are clipped into the Jigsaw body.

The plastic outer casing is made from injection molding. The internal spring is made from drawing and bending.

Graphite

Plastic

Steel

N/A

2

Carbonbrush.JPG

Picture 6: Carbon Brushes

7

Armature Assembly

The Armature Assembly is the inner portion of the electric motor. The carbon brushes make contact to the armature in order to complete the circuit for the motor. When electricity is flowing through the system, the armature rotates rapidly within the Field assembly. Thus, the armature assembly serves to create rotational mechanical energy.

Drawing is required to produce the copper wires. Die Casting is used to form the casing. The shaft is made from rolling and then turned. Injection molding was used to create the fan blade.

Copper

Steel

Plastic

N/A

1

Interior.JPG

Picture 7: Armature Assembly

8

Field Assembly

The Field Assembly is the exterior portion of the electric motor. Electricity is transferred to the field assembly by means of two red wires. When power is flowing into the field assembly, the component causes the armature to rotate rapidly through the implementation of magnetic fields. As such, the field assembly serves to create rotational mechanical energy.

Drawing is required to produce the copper wires. Stamping was used to create the multiple plates of the casing. Injection molding was used to create the plastic wire housing.

Copper

Steel

N/A

1

Exterior.JPG

Picture 8: Field Assembly

9

Blade Guard

The Blade Guard is the length of steel which blocks the blade. The blade guard serves to protect the user from accidentally placing an appendage within the path of the blade.

Rolling was used to create the steel, bent to shape, and then plated.

Steel

N/A

1

Picture 10: Blade Guard

Picture 9:Blade Guard

10

Trigger

The trigger regulates the flow of electrical energy within the tool. It is a black, rectangular box within the Jigsaw body.

Injection Molding is used to make the casing. The wires are made from drawing.

Copper

Plastic

585385-00

1

Trigger.JPG

Picture 10: Trigger

11

Power Cord Clamp Screws

The Power Cord Clamp Screws attach the Power Cord Clamp to the jigsaw body.They have a 5/8 inch head diameter and are 1/4 inch in length.

Rolling was used to thread the screws and forging was implemented to form the head.

Steel

370748

2

Triggerscrew.JPG

Picture 11: Screw

12

Base Plate

The Base Plate is the steel plate the jigsaw body rests upon. It serves to provide a stable platform for the tool during operation.

Stamped and bent to shape

Steel

90517431

1

Bp.JPG

Picture 12: Base Plate

13

Angle Adjustment Lever

The Angle Adjustment Lever is the steel handle which adjusts the base plate angle.

Stamped and and then the threads where tapped

Steel

90529814

1

Aal.JPG

Picture 13: Angle Adjustment Lever

14

Angle Adjustment Handle

The Angle Adjustment Handle is the black thumb tab attached to the end of the Angle Adjustment Lever. It serves to provide an easy point for the user to grip the angle adjustment handle.

Injection molding

Plastic

90514276

1

Blackthumbtab.JPG

Picture 14: Angle Adjustment Handle

15

Handle Screw

The Handle screw secures the Angle Adjustment Handle to the Angle Adjustment Lever. This screw has a 3/16 inch head diameter and is 9/16 inches in length.

Rolling was used to thread the screws and forging was implemented to form the head.

Steel

330019-41

1

Tabscrew.JPG

Picture 15: Handle Screw

16

Detent Spring

The Detent spring is contained within the base plate assembly. It permits the insert to move and lock within the base plate assembly.

Stamping was used to cut the spring to size, then bent to shape, then heat treated

Spring Steel

90521871

1

Bpspring.JPG

Picture 16: Detent Spring

17

Lock Plate

The Lock Plate is the metal plate within the base plate assembly. It holds the insert, detent spring and angle indicator within the base plate assembly.

Die Casting

Steel

90521871

1

Lockplate.JPG

Picture 17: Lock Plate

18

Base Plate Bolt

The Base Plate Bolt connects the base plate to the jigsaw body.

Rolling was used to thread the bolt. The head was forged.

Steel

90514219

1

Bpbolt.JPG

Picture 18: Base Plate Bolt

19

Base Plate Washer

The Base Plate Washer is placed along the base plate bolt.

The washer was stamped.

Steel

90514216

1

Bpwasher.JPG

Picture 19: Base Plate Washer

20

Insert

The Insert is the black, plastic piece within the base plate assembly.

Injection molding

Plastic

90514228

1

Innsert.JPG

Picture 20: Insert

21

Angle Indicator

The Angle Indicator is the black, plastic dial which depicts the current base plate angle.

Injection molding was implemented to form the component.

Plastic

90514273

1

Bplateangleindicator.jpg

Picture 21: Angle Indicator

22

Blade Clamp

The Blade Clamp is the piece which holds the blade in place.

Die casting was used to form the component.

Steel

582593-00

1

Bladeclamp2.JPG

Picture 22: Blade Clamp

23

Angle Plate

The Angle Plate is the white, plastic plate that rests on top of the base plate. It provides a level platform to attach the angle adjustment lever to the base plate.

Injection Molding was implemented to form the component.

Plastic

N/A

1

Angleplate.JPG

Picture 23: Angle Plate

24

Blade Support

The Blade Support is the black, steel piece which guides the blade during movement.

Stamping was used to create the shape and then bent to the final shape.

Steel

90517418SV

1

Bladesupport.jpg

Picture 23: Blade Support

25

Pivot Pin

The Pivot Pin is the steel pin within the blade support. It permits the blade support to rotate.

The pin was rolled and then machined.

Steel

90514424

1

Pin.JPG

Picture 25: Pivot Pin

26

Roller

The Roller is the final gear within the gear train leading to the Reciprocating Shaft assembly. It functions to translate rotational mechanical energy to linear mechainical energy.

Forging

Steel

795688-00

1

Rollerr.JPG

Picture 26: Roller

27

Gear Train washer

The Gear Train washer is the small, steel washer within the gear train assembly. It functions to keep the roller is place.

The washer was made by stamping and then heat treated.

Spring Steel

823954-00

1

Wassher.JPG

Picture 27: Washer

28

Dust Chute

It is the black, plastic tube that runs through the angle indicator and channels the material debris from the fan.

Injection Molding was used to create the part.

Plastic

90514401

1

Dustchute.JPG

Picture 28: Dust Chute

29

Special lock plate bolt

The Special lock plate bolt is the long, black bolt within the lock plate. It functions to attach the lock plate to the base plate.

Rolling is used to thread the bolt. The head was forged.

Steel

90514219

1

Specialbbolt.JPG

Picture 29: Special Lock Plate Bolt(1)

30

Cam Gear

The Cam Gear is the primary gear within the gear train assembly. It is connected to the roller. It serves to translate mechanical energy from rotational to linear.

Forging

Steel

N/A

1

Gearr.JPG

Picture 30: Cam Gear

31

Counterweight plate

The Counterweight plate is the large, metal plate within the gear train assembly. It serves to dampen the resonance from the motion of the blade.

Die casting

Steel

N/A

1

Counterweightg.JPG

Picture 31: Counterweight

32

Connecting Plate

The Connecting Plate is the metal piece which connects the armature assembly to the gear.

Die Casting

Steel

N/A

1

Connectingplate.JPG

Picture 32: Connecting Plate

33

Roller Needle Bearing

The Roller Needle Bearing is attached to the connecting plate. It functions to reduce the friction from rotation.

The plastic casing was made by injection molding while the cylindrical rollers were made from grinding.

Plastic

Steel

N/A

1

Rollerneedlbearing.JPG

Picture 33: Roller Needle Bearing

34

Thrust Plate

The Thrust Plate is the metal plate between the connecting plate and the counterweight plate. It provides support between the motor and the gear assembly.

Stamped

Steel

N/A

1

Thrustplatee.JPG

Picture 34: Thrust Plate

35

Snap Ring

The Snap Ring is the metal ring securing the gear to the gear train assembly.

Stamping was used to create the shape and then heat treated.

Spring Steel

N/A

1

Snapring.JPG

Picture 35: Snap Ring

36

Cam

The cam is the black, plastic piece within the smart select assembly. It alters the position of the smart select plate.

Injection Molding

Plastic

90514375

1

Sscam.JPG

Picture 36: Cam

37

Smart Select Casing

The Smart Select Casing is the black, plastic body that houses the components corresponding the Smart Select dial.

Injection Molding

Plastic

N/A

1

Smartselectcasing.JPG

Picture 36: Smart Select Casing

38

Pc Board

The Pc Board is the black, plastic piece which holds the cam in place in the Smart Select Housing.

Injection Molding

Plastic

90517283

1

Pcboard.JPG

Picture 37: Pc Board

38

Smart Select Plate

The Smart Select Plate is the metal piece within the Smart Select Casing. It alters the movement of the blade in relation to the

Die casting

Steel

90514354

1

Smartselectplate.JPG

Picture 38: Smart Select Plate

39

Duct

The Duct is the plastic, black piece which diverts the dust away from the blade.

Injection Molding

Plastic

90514324

1

Bduct.JPG

Picture 39: Duct

40

Smart Select Dial

The function of this component is to alter the movement of the blade with respect to the dial setting.

Injection

Molding and

Adhesion

Plastic

Rubber

N/A

1

Diall.JPG

Picture 40: Dial

Product Analysis

Complexity Scale

In an attempt to define the relative complexity of each component, we have defined a complexity scale. The scale is divided into two sub sections: Component Complexity and Complexity of Interactions. The scales are defined within a range from 1 to 3. The complexity specifications of each value are defined below.

Component Complexity scale:

1- The component performs a single function within the product. It is likely static throughout operation. This component is generally exhibits simple geometrical shapes which thus causes it to consist of minimal detail design. It is composed of solely a single material which does not need any special material properties in order to perform its function or in order to be manufactured. As such, the component only consists of a minimal number of parts which may be easily assembled together.

2- With respect to the component geometry, the part consists of a combination of several shapes. It requires slightly more detail design in order for the component to function properly. Also, a more complex manufacturing process is required. Hence, the component consists of multiple parts, which must be assembled in a specific order to obtain the desired function.

3- The component performs a vital function within the product, typically undergoes movement, and requires a shape with a higher geometrical complexity and detail design. A complex manufacturing process, or a series of manufacturing processes are typically required to produce the component, and a specific material (or multiple materials) is required in order to perform these manufacturing processes. This results in the component production to be more costly, time consuming, and difficult to perform. The component assembly is likely complex and requires an individual with a good understanding of the intended function.

Complexity of interactions

Define scale:

1- The component is combined with other parts of the tool by the sole means of one or more physical connections. This physical connection may be achieved by the implementation of such joining mechanisms as screws or snap-in locks.

2- The component is combined with additional components by the means of both a translation of energy and a physical connection. The translation of energy may be in the form of electrical energy, signal, rotational mechanical energy, or linear mechanical energy.

3- The component is assembled in the tool by the means of multiple forms of interaction. These interactions may occur in the form of energy flow or a change in the specific quality of the energy type (i.e. electrical or mechanical energy). The physical connection also likely involves rapid motion of one or more parts during operation.



Trigger

caption

Picture 41: Trigger component


Component function
The trigger regulates the blade speed by controlling the amount of electricity allowed to flow to the motor, which allows the speed of the blade to vary with the users preference. The trigger also controls whether the system is open or closed, off or on. Therefore, the tool is unable to operate unless there is a user to operate it. There are two flows associated with the component, Human energy and electrical energy. The Human energy is from direct contact of the user, and the electrical energy is obtained at a 120VAC electrical outlet. A portion of the trigger is located externally on the product within the handle, exposing it to a wide variety of climates. The internal potion is exposed mostly to heat and internal friction within the switch.


Component Form
The basic shape of the inner portion of the trigger is a rectangular cube. It has a vertical axis of symmetry. The external portion, has the shape of a long rectangular cube, but with a slight "S" shape. The shape of the trigger allows for easier product user interaction and comfort. The width of the trigger is proportional to the node of an average human finger, and the longer surface area allows multiple fingers to be used to compress the trigger. This results in more control and less fatigue for the user. The trigger exterior is made out of plastic as well as the inner section, but also consists of a copper component inside to allow the for the flow of electrical energy. The manufacturing decisions could have impacted the choice of these materials because they most likely wanted to make it as easily as possible. Plastic is by far one of the easiest ways to create a component and is why they are used so readily all over the world. The material also would need to be none conductive so the electrical energy flowing through the inner trigger is not transferred to the user. Another advantage of the plastic components can be seen by there cheap cost to produce, which is an economic factor. Plastic also gives the ability for the trigger to function in a wide variety of climates and environments. The light weight property allows for people of varying ages, sizes, and strengths to operate the trigger. All of these property's are some of the attributions that concern the many global factors.
The component has different aesthetic properties. The surface of the trigger is erganomic, with a slight "S" shape for the fingers to fit in, and along with the rough surface allows for better grip by the user. The component is black, which contrasts to the orange shell of the product and allows for a better recognition of use and is clearly visible.


Component Dimensions:

Inner Trigger Portion:

Length: 1.25 in
Width: .625 in
Height: 1.0625 in


Outer Trigger Portion:

Length: 2.125 in
Width: .750 in
Height: .625 in


Weight: Approximately 1 ounce


Manufacturing Process
The component was most likely created by injection molding. This is supported by the details of the trigger. It has a uniform rough surface finish which is typical from a mold that has been sand blasted, as well as rounded/tapered edges allowing for easy removal from a mold. The material choice allowed for this method to be used because this method is an easy way to cheaply produce plastic objects efficiently. The simple shape of the component further supports the use of this manufacturing process. Complex shapes are not easily produced this way because what goes in, must come out. If there are features on the part that would prohibit the removal from a mold then they must be produced in a different manner. The ability to efficiently mass produce this object, the cheap costs, and ease of manufacturing all pertain to economic factors. The generous size of this object aids in being more suitable for human fingers is a societal factor, and the fact that this material can withstand a varying degree of environments is a global factor.
Component complexity

Complexity:2

Complexity of interactions: 2

Power Cord

Picture 10: power cord

Picture 42: Power Cord

Component function

This component functions as a pathway for electrical current, and allows for a range of flexibility. It not only needs to carry electricity, but must also be pliable and flexible to allow for easy use and storage needs. The only flow associated with this component is the flow of electrical energy from an electrical outlet to the product. It is capable of functioning in a wide variety of environments since it is located externally on the unit and is subject to the climate of its location.


Component Form

The power cord is a three dimensional cylindrical shape. This component has an axis of symmetry through its core and is flexible. This shape allows for more flexibility of the cord in all directions than other shapes. The component is made out of rubber, copper, and insulators, which are needed because of the electricity flowing through the conductive metal, as well as allowing for flexibility. Most likely the manufacturing decision did not impact the choice in material because there are certain functions that have to be met in order for the cord to perform safely. Some of the global factors that apply to this component are the ability of rubber to withstand a variety of climates and situations as well as operating safely. An economic factor is that the same component can be used for multiple tools and are widely available from multiple manufacturers. The shape and flexibility of the cord allowing for easy storage and use, and the plug type, being specific to US outlets, are all contributing societal factors.
This component is a solid black color, and feels durable, yet smooth, which is appealing to the users touch. The power cord is black most likely to keep the Black and Decker color scheme, and matches the other black components of the product. Aside from the smooth glossy look and feel, the aesthetics provides no functional purpose to the tool.


Component Dimensions:

Length: 6 ft
Diameter: .3125 in


Weight: Approx. 1 lb


Manufacturing Process

This component was manufactured most likely with the drawing method. This is evident in the fact that all the power cords produced for this product are symmetrical throughout its length. The materials that were chosen for this component were chosen on the basis that they are ductile and easy to manufacture. The cylindrical shape of this component also made this manufacturing method a good option. This process being cheap, fast, and efficient applies to the economic factors. The insulating material used is fairly durable and can withstand a reasonable range of temperatures without deformation. This enables the component to function in a wide variety of environments and is thus a global consideration. In addition, the fact that the copper can be recycled is an environmental factor that influences this component. In terms of societal considerations, the malleability of the materials permits the component to be easily assembled within the jigsaw body.


Complexity:2
Complexity of interactions: 1

Jigsaw Body

Body.JPG

Picture 43: Jigsaw Body

Component function

This component houses the inner components of the jigsaw, protect these inner parts, as well as creating a user interaction by allowing the user a method of controlling the object via the handle. Other than the human energy required to move the tool, there are no flows associated with this component. Since the product is exposed to its surrounding environment, it has to be able to withstand a variety of climates.

Component Form

The general shape of this component is a three dimensional cylinder with a handle on top. The cylindrical section is what houses the majority of the inner components, while the handle encompasses the trigger and allows for an easy maneuvering point for the user. It has a line of symmetry, which is the directly along the dividing line of the shell. This component is composed of plastic and rubber. Manufacturing decisions did impact this because plastic is a much easier material to mold into the complex shape needed for the shell; Not only the shape of the exterior, but all of the supports needed to secure all of the internal parts as well. The ease of manufacturing, minimal expenses, and minimal waste are a few economic factors that apply to this component, Also, the ability for this material to be used in a wide variety of environments is one of the global factors that contribute to this part.
Aesthetics are a major portion of this components complexion because it is makes up most of what the eye can see. It is mostly orange with some black, which is an identity of Black and Decker tools, and the shape and surface finish of the component are ergonomically suited to today’s style; not hard edges and straight lines, but rather more curved features with a textured finish. These points are important because it makes the product distinguishable, and the surface finish hides imperfections that the user may impose upon the component. Also, the slight texture not only to hide imperfections, but is more appealing to the eye and seems more durable..


Component Dimensions:

Max Length: 9 in
Max Width: 3.375 in
Max Height: 7.875 in
Handle: 4.5 in


Weight: Approx. 1 lb


Manufacturing Methods

This component likely is manufactured through the implementation of injection molding because of the concave shape and surface finish of the component. The detail and quality of the surface finish is a good indication for the process, as well as some of the circular marks on the inside of the body. The material choice did impact the manufacturing decision because it is easier to create all of the internal supports and sectioning areas needed to house the inner components and it would need to be light. Due to the great flow properties of polymers, they can make complex molds without having the problems that other materials would have. The low cost to produce plastics is a large economic consideration which ultimately translates to the price of the final product. In addition, hard plastic is a durable material which is capable of enduring a reasonable range of temperatures. The ability for the product to withstand a wide variety of environments is a global factor that contributes to the final product. Also, the use of plastic manages to make the final product relatively light in comparison to other, more durable alternatives, such as steel.


Complexity:2
Complexity of interactions: 1

Reciprocating Shaft

Reciporcatingshaftassembly.jpg

Picture 44: Reciprocating Shaft Assembly

Component Function
This component clamps the blade into the product, as well as oscillates it in a vertical motion in order for it to perform the desired function. Mechanical Energy flows through this component, which allows for the oscillation movement. This component is located inside of the product, which is an enclosed space, so there is a build up of heat due to the friction of the oscillation. Also this component is exposed to some debris of the material being cut.
Component Form
The general shape of this component is a three dimensional rectangular bar with an oval section shaped into the center of it. This component is made up of multiple parts, has a line of symmetry down its center axis, and allows the range of motion. The thinner shape of this object allows for it to more easily fit into the interior of the jigsaw shell, as well as a free range of motion without obstruction of the other components. This component is made of steal, which most likely was not impacted by the manufacturing decisions due to a couple of reasons. Steal is a strong and durable material that can withstand deformation due to the heat produced by friction created in this application. Because of the high forces that are imposed on this part, it needs to be able to handle those forces for long intervals and many years of use. It also needs to have a good strength to weight ratio because of the limited space available, so steel is a relatively good fit for this component. Being recyclable at the end of its life cycle is an important environmental factor of this part. Also, the fact that steel is produced globally and abundantly allows for it to be easily obtained and is a global factor which most likely contributed to the choice of this material as well.

This component is located within the tool, so while it doesn't have any aesthetic purposes, it does require a fairly smooth surface to reduce friction. It is gray in color, raw steel, and uncoated because it is located within the product which means out of sight, so there is no reason to color the component for any other reason.


Component Dimensions:

Max. Length: 4.875 in
Max. Width: 1.5625 in
Width of Rectangular Region: .4375 in
Max. I.D. of the oval: 1.250 in
Min. I.D. of the oval: .4375 in


Weight: approx. 6 oz


Manufacturing Methods
This component was most likely created through a couple manufacturing processes, the first being forged. There is good indication of this when looking at the edge of the part around the upper portion of the oval. There appears to be some missing material which is good evidence of either a cast or forged part. Because of the strength required for this part, most likely it would be forged because cast parts can tend to be brittle. The other process that it appears to have undergone is grinding. This is noted from the surface finish of the metal. There are many uniform scratches all along the surface and all in the same two directions. Also, the shape is very exact and has nice sharp edges. If not grinding, there is definitely another type of machining process used for this component. Due to steel being able to be forged, it most likely contributed to the manufacturing decision. Usually a forged part costs more, but with such a small component being created, it is unlikely that the price difference between casting and forging was that great. Also, as mentioned earlier, forging gives steel much greater strength properties over castings. Since shapes of molds can be created for a large variety, the likely hood of this components shape effecting this method is extremely small. This ties into an economic factor, being a small component is fairly inexpensive. A global consideration is that the required material, steel, is easily obtained in various locations.


Complexity:3
Complexity of interactions: 3

Armature Assembly

Interior.JPG

Picture 45: Armature Assembly

Component function
This component is the part of the motor that rotates the gear train, and rotates the cooling fan. It is turned by an electromagnetic field created by the field assembly, which acts against the permanent magnets attached to it. At this stage of the flows within the system, electrical energy is being converted to mechanical rotational energy. Since this component is located within the jigsaw shell, this component is subject to heat due to the electric current and friction generated within the gear train.
Component Form
The general shape of this component is a three dimensional cylinder, with a varying degree of cylindrical diameters. The armature does have an axis of symmetry down its length, allowing even and balanced rotation to be possibly at high velocities. The shape allows the component to rotate in the most convenient way possible and contributes to the equal distribution of the magnetic field around the shaft. The materials used for this part include steal, plastic, epoxy, copper, and magnets. The manufacturing decision impacted these choices, because of the way some things were connected were dependent on the type of material used. As such, the use of the plastic allowed the bearings and fan to be pressed down tightly, which is an easy and efficient method of securing them. Some good properties of these materials are that they are conductive, insulating and are able to withstand high heat, as well as being light weight in comparison to some of their competitors. The fact that these materials are the most economically friendly materials that can be used in this process is an economic factor, and the fact that most of the materials are recyclable is an environmental factor that influenced the choice of these materials.
This component, since it is located within the jigsaw shell, has no aesthetic properties associated with it. Its color is the natural colors of all of the individual materials; there is no reason to take the time and resources to change the color of these materials. The surface finish of the component is smooth to create the least amount of friction between the rotating pieces of the component. This is solely for functional reasons.


Component Dimensions:

Max. Length: 5.0625 in
Max. O.D. of Magnets: 1.3125 in
Length of the Magnets: 1.4375 in
Diameter of the steel shaft: .250 in


Approx. Weight: 5 oz


Manufacturing Methods
The shaft of the armature was most likely turned due to the need of an exact diameter for all the zero-clearance joining. It is apparent in the exact consistency in diameter, which is only attainable by turning. The blue plastic was probably heated, slide on the shaft and then allowed to cool. This plastic is deformed behind the bearings and the fan, which is evidence that these parts were pressed on. There appears to be epoxy behind and around the copper windings and the magnet, which is evidence that some sort of epoxy was used to hold it all in place. The material choice did impact this decision, since these materials allow for easier assembly and creation. The shape of the component was important in the manufacturing process choice since the exact cylindrical shape of the component can only be attained by turning, and the press fit is a common, effective, and efficient way for securing other objects to a round shaft. An economic consideration that influenced this machining process is the fairly low cost of machining just the one shaft, and then using other means for attaching the other materials.
Complexity:3
Complexity of interactions: 3

Field Assembly

Exterior.JPG

Picture 46: Field Assembly

Component function
This component generates a magnetic field around the armature assembly. Electrical energy flows through this components copper coils in order to create the magnetic force around the motor. It is located within the product, in a closed environment, so the heat due to the resistance in the copper windings and friction from moving components creates a warm environment around the field assembly.
Component Form
The general shape of the field assembly is a three dimensional hollow cylinder. The cylindrical shape is very important in creating an even magnetic field around the armature; any other shape would not allow this. This assembly is made up of steal plates compressed together and copper windings, as well as a plastic sleeve/cradle for the copper windings. These materials were chosen because they are fairly cheap, are able to withstand heat, and are good conductors, and have magnetic properties. The manufacturing decision did not impact these choices since there is a limited amount of materials that will work for this type of operation. The light weight properties of these materials are a societal factor, and the ability for the materials to be recycled is an environmental factor that influenced the decision for these materials.
This component has no aesthetic properties since it is located within the product; there is no need for any to be present. It is the natural color of its components, gray (steel) and copper. It would be a waste of time and resources to color this component a different color. The surface of this component is smooth, which is solely from the manufacturing process and doesn’t really have a function purpose.


Component Dimensions:

Max. Length: 2.875 in
O.D.: 2.250 in
I.D.: 1.4375 in
Length of the steel portion: 1.500 in


Approx. Weight: 6 oz


Manufacturing methods
The field assembly was created through the implementation several different manufacturing processes. The steel body of the component is made from multiple little, stamped out, steel plates that are compressed together. It appears that the plastic cradle and copper windings are holding these plates together, but it is not certain. The copper windings then run throughout the steel portion going back and forth wrapping around the plastic. Because of the properties of these materials, it probably did have an impact on the manufacturing decisions. The steel plates are much easier to form rather than trying to make such a complex shape out of a piece of stock or even molding the part. Also, this method probably has to due with the internal design that is not visible for the copper windings. The shape however most likely did not have any impact. In terms of economic considerations, the plastic cradle was primarily chosen due to its minimal cost. In addition, the lightweight nature of the cradle factors in a societal consideration with regard to the increased ease of use for the consumer. The fact that the materials required for the production of this component widely obtainable in various countries presents an global consideration. This also would permit Black and Decker to acquire the component from foreign manufacturers. Since these manufacturers are capable of producing the component at a decreased cost, the availability of the materials provides an insight into an additional economic consideration. The decreased cost of the component, along with other components, could possess the possibility of reducing the overall cost of the product. This would permit the jigsaw to be sold to a wider economic market.
Complexity: 3
Complexity of interactions: 2

Base Plate Assembly

Bpassembly.JPG

Picture 47: Base Plate Assembly

Component function
The base plate gives the tool a solid foundation for the product to rest and operate on, and it also determines the cutting angle for the product. Human energy is flowing into the product, since the user is controlling the direction and movement of the cutting, as well as through the angle lever arm, which controls the angle adjustment of the base plate assembly. The base plate is located externally of the jigsaw shell, so it is exposed the the climate of the surrounding environment.
Component Form
The basic shape of the base plate assembly is a 3 dimensional rectangle. The large surface area of the base plate directly correlates with its function; a larger surface area allows for a steadier base and therefore more control and higher accuracy. The base plate assembly is a combination of smaller parts that function together. These components are either steel, plastic, or spring steel. These materials needed for the base plate itself needed to be ductile enough for the manufacturing process that was performed in order to achieve the necessary shapes. The fact that these materials are durable in varying environments is a global factor, and the lighter weight of these materials is a societal factor that contribute to the functionality of this component.


This component has a rough finish, along with a coating for appearance and corrosion prevention. This type of finish allows to hide any imperfections, be it from the manufacturing process or from the use of the product. This finish is for both function and aesthetic reasons; it helps hide imperfections and makes it more eye appealing, and the coating allows it to move more freely with less friction. It is silver in appearance from the coating that was applied to it.

Component Dimensions:

Length: 6.9375 in
Width: 2.8125 in
Max. Height: 0.8125 in
Thickness: 0.0625 in


Approx. Weight: 6oz


Manufacturing Methods
The base plate assembly was first stamped out and then was likely heated and pressed to form the drastic bend for the angle of movement as well was the other deformed features in the component. This is evident in the edges. They are rounded on one side and sharper on the other which is good evidence that a material was stamped out. The material did have an impact on the process choice. Since the steel is easily manipulated without machining, it was easier to use this method, which is cheaper and easier, rather than machining it. The simple shape of the base plate also allowed this method to be implemented. The low cost of this process is an economic factor that influenced this choice in manufacturing process. The ease of the manufacturing processes involved in the production of this component represents a societal consideration with regard to the skill level of the manufacturing companies' employees. From a general perspective, as the the complexity of the manufacturing methods decreases, the required capital to fund the production of the part also decreases. This essentially means that, due to the relative simplicity of the manufacturing methods involved during production, the component will cost less than a more complex alternative. This decrease in cost may subsequently be translated to the consumer in order to permit the exploitation of a wider economic market.
Complexity: 2
Complexity of interactions: 2

Counter Weight

Counterweightg.JPG

Picture 48: Counterweight

Component function
This component carries momentum to the blade, as well as acts as a counter balance to the vibrations created by the other components. This decreases the amount of vibration that reaches the user, which in turn lessens the fatigue rate of the user. There is mechanical energy flowing through this component from the gear train, and since this component is located within the jigsaw shell, it is in a heated environment due to friction among other components.
Component Form
The general shape of this component is a 3 dimensional rectangle, (LxWxH) and weighs about 14 oz. There are no notable features except that it has a line of symmetry with respect to its rectangular shape. The shape has no real effect on the function of this component, since it's function is primarily based on the density of the object and how well it is able to counter act the vibrations of the product. It is made of steel, which is good for this component because it is able to withstand heat well and is fairly dense. The Manufacturing decision had no impact on this choice of material. The steel being recyclable is an environmental factor, being easily accessible in general is a global factor, and its abundance and comparatively low cost is an economic factor that influenced the choice of this material.
This component has no aesthetic purpose because it is located within the shell and has no need to. It is the natural color of steel, gray, and is not colored because that would be a waste of time and resources. Its surface finish is smooth in order to minimize any friction creating between it and any other close moving part. This is for a functional reason solely.


Component Dimensions:

Length: 2.6875 in
Width: 1.8125 in
Thickness: .250 in
Notch: .125 in x .250 in
Max. I.D. of the oval: 1.250 in
Min. I.D. of the oval: .8125 in


Approx. Weight: 14 oz


Manufacturing Methods
This component was most likely die cast, which was determined from the rounded edges of the plate, smooth finish, and parting lines. The material choice did have an impact on this decision because it is much faster and efficient to cast a part than to machine it. The shape allowed casting to be an option due to its simple geometry and small size as well, also making it a prominent choice. The comparatively low cost of steel is an economic consideration. In addition, the relative simplicity of the die casting, as a whole, provides a reduction in the cost of the part in comparison to the capital required to produce a forged or machined counterweight. This cost reduction may be then translated to the final price of the product in order to allow the jigsaw to appeal to a more economically diverse market.
Component complexity
Complexity:1
Complexity of interactions: 2

Gear Train

Gt.JPG

Picture 49: Gear Train

Component function
The gear train converts rotational mechanical energy to translational mechanical energy, as well as gearing down the rpm's from the motor, which inversely increases torque. There is a flow of rotational energy going into this component, and a flow of translational energy coming out of this component. This gear train is also located within the jigsaw shell so there is heat surrounding it due to the friction between the components, as well as heat from the motor.
Component Form
The general shape of this component is a three dimensional cylinder. The shape of the gears of the gear train is coupled to the function. Since the parts are rotating around a central axis, the distance between the gears' central axis needs to be constant to allow the gears to be in continuous contact with each other. The parts of this component are made of steel, which did not impact the decisions for the manufacturing because they needed something strong and durable, yet affordable. The steel is resistant to wear and is able with withstand high heats, which made it ideal for this component. The low cost of steel is an economic factor, and the ability to easily attain steel is a global factor that contributed to the choice of this material.
This component has a smooth finish on the gear teeth to minimize the friction between the parts, and is the natural color of molded steel part. It would be a waste of time and resources to color it. There is no aesthetic purpose associated with this component because it is located within the jigsaw shell, so the finish is solely for functionality.


Component Dimensions:

Max. Width(not including the shaft): .6875 in
Width of the gear teeth: .3125 in
O.D.: 1.5625 in
Length of shaft: .4375 in


Approx. Weight: 7 oz


Manufacturing Methods
This part appears to be forged, which would have been impacted by the material choice because other methods could be used. Due to the small size, a forged part of this nature would be fairly inexpensive and has benefits over casting. Some indication of this is the surface finish is not quite as nice as a die cast part, and the chamfered holes are not very even which is also an identifying factor. It was also machined to tightly press a pin into it as well as for the roller needle bearing to be inserted. The shape impacted the method selection as well because it was a simple and small enough shape that could easily be forged. The low cost and efficiency of forging is an economic factor that contributed to the choice of this manufacturing method. The availability of the materials in various countries permit the component to be manufactured by a variety of produces. This is a global consideration. Within the realm of societal considerations, the fact that the piece of the gear train are fairly easily assembled together provides the capability for the part to be produced by employees with a limited skill set. In addition, this factor also increases the ease of the assembly process.
Component complexity
Complexity: 2
Complexity of interactions: 3

Dial

Smartdial.JPG

Picture 50: Smart select dial

Component function
The smart select dial allows the setting of the blade to be changed in order to accommodate different materials. Human energy flows through the dial component, and since it is located on the exterior of the body it is subject to the external environment that varies depending on location.
Component Form
The general shape of this component is a three dimensional cylinder, and has an axis of symmetry. The shape of the component does not correlate with the function of the dial though. The dial is made up of plastic and rubber, and the manufacturing decisions probably impacted these choices because they are easy to make and work with. These materials are light, rigid, and are durable in a large degree of environments. The ability of these materials to withstand corrosion is a global factor, and the relatively low cost of the materials is an economic factor that influenced the choice of these materials.
The component has a plastic base with a rubber grip around the outside of the dial. This is to allow a better grip on the dial as well as to be aesthetically pleasing to the eye and touch. The dial also has ridges around its rim to enhance the product user interaction. The dial component is black to contrast with the orange of the jigsaw body shell, as well as to maintain the trademark colors. The finish is for both a functional and aesthetic purposes.


Component Dimensions:

Max. Width: .625 in
Width of the dial: .3125 in
O.D.: 1.500 in


Approx. Weight: .5 oz


Manufacturing Methods
The parts of this component were injection molded. This is evident in the tapered edges on the dial as well as some identifying markers on the inside of the dial such as marks from were the plastic was injected. Then, there was a type rubber that was somehow adhered to the outside of the cap, most likely with an adhesive of some type. The material choice allowed for this process to be used, which is relatively cheap and easy with plastics in general. The shape also impacted the method selected since it is a small and simple shape, and was able to use injection molding. The low cost and efficiency of these manufacturing processes with these materials distinguish an economic consideration. In addition, the relative simplicity of assembly and availability of plastic represent societal and global considerations, reflectivity. Together, these factors provide the possibility for Black and Decker to outsource the manufacturing process to an external or foreign company. This practice may allow Black and Decker to save a substantial sum of capital and can subsequently result in the reduction of the final product's price. Hence, a more diverse economic range of consumers may purchase the jigsaw.
Component complexity
Complexity: 1
Complexity of interactions: 2

Solid Modeled Assembly

In consideration of the motion of the blade during operation, the components of the scotch yoke mechanism were chosen to be modeled by a CAD software. The mechanism is the means by which the tool converts the rotational mechanical energy of the electric motor to linear mechanical energy. As such, the system represents a fundamental aspect of the internal components within the jigsaw. When the tool is engaged, the electric motor rotates the cam gear. The roller, which is attached to the cam gear, fits within the slot in the reciprocating shaft assembly. The rotating motion of the gear in addition to the sliding motion capable from the slot produces linear motion of the reciprocating shaft assembly. (2)


The CAD package chosen to model the components was AutoCad 2011. The program was chosen in an attempt to utilize the prior experience a group member possessed with the program. In addition, the software provided the capability to demonstrate a detailed representation of each component. The packaged CAD files can be downloaded at the following link: Jig Saw CAD Files Package.


Table 1: Solid Modeled Components List
Figure 3: Cam gear

Figure 3: Cam gear

Figure 4: Reciprocating Shaft Assembly

Figure 4: Reciprocating Shaft Assembly

Figure 5: Roller

Figure 5: Roller

Table 2: Solid Modeled Assembly
Figure 6: Component Assembly

Figure 6: Component Assembly

Engineering Analysis

The Black and Decker Variable Speed Jigsaw JS660 implements a scotch yoke mechanism in order to translate mechanical energy from rotational to linear. The result of this mechanism creates a oscillatory motion of the blade, which in the case of the jigsaw is used to remove material. This oscillatory motion subsequently transfers to the linear displacement and linear velocity of the device. In terms of the components previously mentioned, the scotch yoke mechanism, in its simplest form, consists of the reciprocating shaft assembly, roller and cam gear. The specific arrangement of the components is detailed within Figure 2. Within the realm of the design process the stroke length and blade velocity must be determined. In an attempt to determine the linear displacement and linear velocity of the blade from the scotch yoke mechanism, engineering analysis will be applied. The linear displacement of the system corresponds to the stroke length of the blade. The problem statement for this engineering analysis is specified as the following:

Determine the stroke length and linear velocity at any given time by calculating the linear displacement and velocity of the scotch yoke mechanism.

Figure 7: Scotch Yoke Mechanism (3)

Assumptions

The system requires a series of assumptions in order to simply the analysis process. The validity of these assumptions in relation to the final solution will later be discussed in relation to the inclusion or disregard of various variables. The assumptions for the analysis problem are specified as follows:

  • Assume no Friction (i.e. Drag, static, or kinetic)
  • Disregard any External Loads
  • Assume the gear and the roller are perfectly circular.
  • Assume constant voltage and amperage to ensure constant angular velocity (strokes per min)
  • Neglect the effects of gravitational acceleration on the components of the mechanism
  • Assume constant inflow of electrical energy (trigger depression remains constant)
  • Assume there is no wear on the components during operation
  • Assume rigid bodies


Governing Equations:

The displacement of the mechanism along a distance (x) is given by the following:

[Eq.1]
x = (R)sin(θ) where θ is given by (ωt)

The derivative with respect to time of the displacement of the scotch yoke mechanism provides its linear velocity.

[Eq.2]
v = (R)(w)cos(ωt)

Provided that the strokes per minute of the jigsaw is given within the specifications of the tool, the angular velocity may be calculated. Since each stroke is equivalent to a change in angle of π, the angular velocity (ω) may be determined from the following:

[Eq.3]
ω = (Stroke/Minute)((1 Minute)/(3600 s))(π/Stroke)

Discussion:

Provided that the governing equations are correctly implemented during the calculation process, the resulting solution of the linear displacement and velocity will be in the form of a trigonometric function that varies with respect to time. In the case of Equation 1, the maximum linear displacement is provided by the amplitude of the function. Thus, the value of the displacement is equivalent to the radius of the large gear. By consequence, the maximum linear velocity of the blade is detailed by the amplitude of Equation 2. Thus, the value of the velocity is given by the product of the radius of the large gear and the angular velocity. The validity of the solutions must then be considered in relation to the assumptions made to simplify the calculations. The subsequent inclusion of friction in the model would not, however, affect the stroke length of the blade since the amplitude is only dependent upon the radius of the cam gear. Yet, the linear velocity is dependent upon friction since the inclusion of the force would result in a decrease in the angular velocity of the gear. Since the maximum velocity of the blade is given by the product of the radius and the angular velocity, a decrease in the angular velocity would understandably result in a decrease in the linear velocity of the assembly.

Design Revisions

Design Revision 1
Laser Guiding System

In an attempt to enhance the user-friendly aspect of the product, it is suggested that a laser guiding system should be added to the product. The components of the system would consist of the laser itself, and the control switch. As such, the system would be able to project a guiding laser over the desired surface and thus facilitate increased accuracy and an ease of motion with respect to the tool. A representative visual example of the revision, for an alternative power tool supplier, is depicted in Figure 8. The system deals primarily within the realm of societal concerns. It possesses a special significance in consideration of the target audience: household handymen. In the likelihood that the average consumer possesses minimal to zero prior experience within the span of craftsmanship, the laser guiding system would dramatically improve the performance of the tool by increasing the precision of cuts. In addition, since there is a reduction in the scrap or waste materials for a particular project, the consumer is capable of saving money. This is an economic consideration. By consequence, and within the realm of environmental concerns, the revision will reduce the expected waste from a project.

Figure 8: Laser Guiding System


Design Revision 2
Battery

In an attempt to increase the mobility of the product, it is suggested that a design revision should exchange the power cord for a battery. This is an altercation of the tool at the component level. The purpose of the design revision exists by consequence of the household handymen, who, once again, are the primary audience. The exchange of the power cord for a battery would increase the ease of use of the product since the tool would no longer be constrained by the confines of the length of the cord. As such, the proposed design revision deals primarily within the range of societal concerns. In consideration that the household handy man is constantly working on one or multiple projects, he or she would gain the ability to quickly and easily move the jigsaw between areas. In addition, there is always a likely hood for accidents while working with power tools. Since stretching a power cord along the length of a room filled with other power tools, saw blades, and nails represents a possible safety hazard, the introduction of the battery actually decreases the likelihood for the user to encounter harm. From a global perspective, the design revision to the product provides the opportunity for the manufacturer, Black and Decker, to distribute the product around the globe with minimal altercations. The charging station for the battery would simply have to be changed to fit the corresponding external power source of the nation. Hence, the battery design revision denotes an increase in the ease of use of the product for the intended consumer.

Figure 9: Battery


Design Revision 3
Light Source

In an attempt to increase the safety of the product and to enhance the function, it is suggested, as a design revision, for a light source to be added to the jigsaw. This is an altercation of the power tool at the component level. The addition of a light to the front of the jigsaw would, quite literally, illuminate the area surrounding the blade. In consideration that the rooms of any building are rarely well lit, the design revision would brighten the area and reduce the probability for the user to encounter an unknown hazard. As such, the increase in safety for the operator deals within the realm of societal concerns. By consequence of the illuminated work area, the user would be less likely to perform an incorrect or inaccurate cut through a material. Thus, the design revision would reduce the expected waste from a project for both the experienced and inexperienced handyman. This consideration deals with the range of economic concerns as the reduction of waste from a project represents a reduction in the cost for any particular project. This same consideration deals with environmental concerns. The reduction of scrap parts from a job signifies an increased efficiency in the usage of the world's resources. Thus, the design revision would not only increase the safety of the user but also reduces the cost associated with a project for the user.

Figure 10: Light Source. Please note that the diagram is intended to only provide a representative view of how a light source could attach to a power tool. In the case that the attachment method is applied to a jigsaw rather than a drill, as specified by the revision, the light should be connected to the body in a similar manner.(4)

Citations

(1) Black and decker js660 type 1 jigsaw parts. (2011). Retrieved from http://www.ereplacementparts.com/black-and-decker-js660-type-jigsaw-parts-c-4167_4262_31814.html


(2) Scotch yoke. (2011). Retrieved from http://www.mekanizmalar.com/scotch_yoke.html


(3) Diaz, K. (n.d.). Wearing mechanisms, "wear" are they going?. Retrieved from http://grove.ufl.edu/~wgsawyer/Laboratory/Wear/Mechanisms.HTML


(4) Flashlight with bracket device for cordless drill. (2011). Retrieved from http://www.freepatentsonline.com/6729743.html