Group 8 - Skilsaw Circular Saw

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Contents

Background

This page is for Group 8 of the MAE 277 course at SUNY Buffalo. The purpose of this page is to document and organize the data for the project set forth to the group by the course. The project task set forth is for the group to reverse engineer a Skilsaw Circular Saw. The purpose of this project is for the members of the group to learn to work with other people, become better problem solvers and critical thinkers, as well as familiarize the members of the group with the design process. During the course of this project the group will disassemble as well as reassemble the saw. The group will also document all crucial elements of the project as well as the major components of the product. The group will then organize all data collected and and present it, in the form of a Wiki page.

Skilsaw Circular Saw 54HD

Gate 1:Project Planning

Introduction

The purpose of Gate 1 is for the group to become more comfortable with the project. The group will accomplish this by assessing the project, the product, and their very own group members. A work proposal, along with a management proposal and an initial assessment of the product, will be produced during this stage of the project.

Product Overview

The Skilsaw 54HD is a corded handheld circular saw manufactured by Skilsaw Inc. Its design is similar to the first portable electric handsaw, the "Michel Electric Handsaw" patented in 1923 by the predecessor of Skilsaw Inc. The Skilsaw 54HD uses a 12 amp motor to drive the blade which is mounted onto the motors shaft while the orignial portable handsaw uses a worm drive gear arrangement to drive the blade. The saw features an ergnomic grip for control and comfort, a lower blade guard designed not to get caught, a spindle lock for easy blade changing, rear view depth adjustment to quickly adjust cut depth, and a safety guarded trigger to prevent accidental starting.

Work Proposal

The product that’s going to be dissected is a Skilsaw Circular Saw 54HD. This product contains a total of 57 separate components. Most of these components consist of many screws, a few washers, and some bolts. To reverse engineer this product the group began by first planning a work proposal as well as a management proposal. In these proposals the group outlined a basic assessment of what would be needed to reverse engineer the product, dissect it, manage the time as well as manage the duties.


Group Member Capabilities Disabilities
Devpriyan Maniarasu Working with Excel, CAD, Auto Desk Inventor, Editing, Problem Solving Procrastinator, Slow Worker
Ian Connolly Writing, CAD, Auto Desk Inventor, knowledge of Tools, Wiki Procrastinator, Not Good With Calculations
Wren Jacob Varghese CAD, Good with Tools, Good with Tools Computer Programming, Slow Worker
Kevin Shieh CAD, Public Speaking, Good With Groups Programming, Not Great with software(i.e. Excel)
Johanny Roman CAD, Problem Solving, Good Leader, Good With Groups, Experience with Hands-on Projects Slow with Calculations, Procrastinator, Busy Schedule


Reverse Engineering Approach:

  1. A management and work proposal will be outlined.
  2. The product will be disassembled into its basics components.
  3. These components will be analyzed and the system in which they were used will also be analyzed.
  4. The data collected from analyzing the product will be documented in an organized and professional matter.
  5. The product will then be reassembled.
  6. The data will then be reorganized in a presentable and professional manner, and will then be presented.


Proposed Disassembly Approach:

  1. Remove the casing foot, which consists of a Round-Head Bolt, a Wing Nut, a Roller Pin and a Lever.
  2. Remove the set of handles, which consist of 6 Self-Tapping screws.
  3. Remove the guard plate, which consists of a Lever held in by a Screw, Retaining Ring, 2 Supporting Disks and a Hexagon Screw.
  4. Remove the Bearing Flange which is connected to the Pinion Shaft. These components are held together by 3 screws.
  5. Remove the Protective Cover. This consists of a Sintered-Metal Bushing that must be removed, along with a Headless Screw, and a Stop connected by a Spacer Bolt to a Socket Head Screw.
  6. Remove the 120V Armature from the Bearing Sleeve which has a Plain Washer in between.
  7. Remove the 120V Armature from the 120V Field. You must remove 2 Headless Screws, as well as a Washer and a Plain Washer.
  8. The Housing should be separated from the Armature as well as the Field. Now remove the Housing Cover. There will be 2 Screws.
  9. In between the Housing and the Housing Cover there will be a Carbon-Brush set which can also be removed.


Tools Required:

Tool Component to be Removed
Roller Pin Punch A Roller Pin
Phillips Head Screwdriver Screws
Torx Screwdriver Hexagonal Screw
Allen Wrench Headless and Socket-Head Screws


Possible Challenges:

  1. Keeping track of all the components and where they belong.
  2. Damaging certain components.
  3. Losing or misplacing pieces may also be a problem.
  4. Documenting the piece may become trivial as there are many different components.


Time Management:

The following Gantt Chart provides an overview of the overall project.

Gant r 2.jpg


Management Proposal

Group Meetings: The group will meet 3-4 times a week, after class as well as on the weekends. These meetings will be for a few hours at a time and will be announced ahead of time. The meetings will take place on the 10th floor of Furnas Hall unless otherwise noted.

Group E-mail: mae277g8@gmail.com

Group Job Assignments:

  1. Johanny Roman : Project Leader- the job entails ensuring that the job gets done in a timely and organized fashion. Some responsibilities include setting up meetings, organizing the work done, managing the group e-mail and resolving group conflicts.
  2. Devpriyan Maniarasu: Technical Expert- this job entails doing 3D models, of components in programs such as AUTO CAD or AUTO DESK INVENTOR, as well as taking pictures of each component and labeling these pictures for future reference.
  3. Kevin Shieh: Communication Liason/Presenter- writing up certain documents and e-mails as well as speaking publicly. The person with this job should be able to send and receive messages between the group as well as to the professor if needed, in a professional manner.
  4. Wren Jacob Varghese: Product Component Specialist- this job entails disassembling as well as reassembling the product. Through this process this person must also keep track of each component, where they belong, how they will be put back and what tools will be used.
  5. Ian Connolly: Documenter/Organizer- this person will be in charge of documenting all finds made while dissecting the product. They must also organize all this data in a presentable manner in order to make the class presentation more efficient.


Conflict Resolution:

All group conflicts will be resolved at group meetings via peer mediation. In the event that mediation doesn't work the group will then work in smaller sub groups and organize the overall project in an orderly manner.

Initial Assesment

Product Complexity Profile:

How many components are used?

There are approximately 7 or so major parts aside from various screws holding the product together. These major parts consist of the motor, the shaft to the saw, the saw itself, the guard plate, the shoe which makes contact with the surface being cut and the plastic handle. (Reference Figure 1)


Figure 1 - Skilsaw Components http://mdm.boschwebservices.com/MDMCache/English%20[US]//t10/0000000/r00753v-1.pdf

How complex are the individual components?

The individual components themselves are not complex. The outside consists of a basic hard plastic to make up the handle, while there are metal components on the other side of the saw which serve to shield the saw until use, and a foot to keep the saw even with the surface of the object being cut. The internal parts are also simple mostly consisting of gears, screws, and a motor. The motor may be the only component that can be seen as complex which breaks down to components such as a stator and coils which produce a magnetic field when supplied with an alternating current.

How complex are the component interactions?

The overall complexity of the product is not very high. Since the tool is powered by electricity, it is already far more advanced than a manual tool, such as a wrench or a screwdriver, because the Skilsaw circular saw must be able to convert electrical energy into mechanical force though the use of a motor. Motors are somewhat complex as they use coils to produce a magnetic field after being supplied with a current which then provides the force to rotate an internal rotor. The rotor is then attached to various gears transferring the mechanical energy to the saw which enables the user to utilize the product. Aside with interactions with the motor, the product has components that either hold the product in place or are there for user utility such as a plastic handle or a static flat piece of metal that helps the user slide the product across the object being cut.

Product Material Profile:

What materials are clearly visable?

On one side of the product, there is a hard plastic covering in the shape of a handle and is also shaped in a way that seems to house a motor. There is an on/off switch and a saw cover protecting its user. Various screws can be seen along with a piece of metal that is flat on the bottom to allow the user to slide the product across the surface that the user is cutting. There also is a cord to bring an electrical current to the product.


Based on previous answers to the above questions, what materials do you think are not visible but present?

Materials that are present but not currently visible would be the motor and the internal gears which help transfer the mechanical force generated by the motor to the saw allowing the user to cut objects. Electrical wire must also exist inside of the hand saw to bring the electrical energy from the outside cord the motor where it will then be converted to mechanical energy. Clearly, in order for the saw to work would be to have a motor converting the electrical energy from the cord into mechanical energy for the saw. The gears must be present to transfer said energy to the blade allowing it to spin at a rate that could cut most material.

Product Interaction Profile:

How does the user interface with the product(s)?

The user must have his/her measurements ready prior to the cut and also should have the object held tight using clamps (not any part of the body for supporting the object ), before he/she proceeds to use the Skilsaw circular saw. One must then set the depth of the blade by using the depth adjustment lever. Next, the shoe needs to be positioned on the surface on which it has to be cut, aligned with the scale in front of the shoe. Then get a good grip on the saw with both hands positioned and pressing the safety switch, pull the trigger and start to cut.


How intuitive are the interfaces?

The handle of the Skilsaw circular saw with a trigger (Figure 1) is designed like the one of a gun’s which makes it more explicit for use .The measurements on the saw mark the depth of the cut. The guard plate (Figure 2) is used to prevent the blade from coming in contact with other surfaces when not being worked with. It has two levers out of which one is used to adjust the depth and the other (Figure 3) is used while replacing the blades and for protective purposes. There is a safety switch just before the trigger which is used to minimize the risk of inaccuracy and injury. The shoe(Figure 4) is used to position the blade on the surface and there is also a angle adjustment scale held intact using a round head bolt and a wing nut which helps to adjust the angle in which the object is to be cut. The plug is then connected to the electric socket for it to function.


Trigger - Figure1 (Trigger - Figure 1)


Guard Plate - Figure2 (Guard Plate - Figure 2)


Lever - Figure3 (Lever - Figure 3)


The shoe - Figure4 (The shoe - Figure 4)

Is the product easy to use?

The product is easy to use as most of the parts are very intuitive and efficient .One’s safety should always be taken into priority. The weight of the object is not a problem because it is balanced onto the surface in contact.

Is regular maintenance required? If so, how easy is the maintenance?

Regular maintenance is required. It is recommended that tools with gears be re-greased with a special gear lubricant at every brush change. The brushes and commutator in your tool has been engineered for many hours of dependable service. To maintain peak efficiency of the motor, the brushes are recommended to be examined every two to six months. Only genuine Skilsaw replacement brushes specially designed for your tool should be used. After about 300-400 hours of operation, or at every second brush change, the bearings should be replaced at a Skil Factory Service Center or an Authorized Skil Service Station. Bearings which become noisy (due to heavy load or very abrasive material cutting) should be replaced at once to avoid overheating or motor failure.

Product Energy Profile:

What types of energy are used? How is energy imported into the system? How are different types of energy transformed and modified?

The Skilsaw 54HD is powered by electrical energy (delivered in the form of an AC or Alternating Current) coming from an electrical outlet that is located in a residential or professional setting. A power cord delivers the electrical energy from the outlet to an electric motor which then rotates the saw blade and causes the product to perform its function. Through this process, energy is converted from electrical, to mechanical and eventually to thermal. Note that in the conversions to different forms of energy, some energy may be lost due to heat.


Product Usage Profile:

What is the intended use of the product? Is this product for home or professional use? What jobs does the product perform?

The Skilsaw 54HD is a circular saw intended for joinery works, performing quick and fairly accurate straight cuts, and cutting different materials such as wood and plastic(with the use of proper blades for each type of material). The Skilsaw 54HD is designed to be used both at home and in a professional setting. The product can range from performing simple home improvement tasks such as cutting materials for windows, to more professional oriented jobs such as cutting parts for furniture and other products in factories. The product may also be widely used by professionals in machine and carpentry shops to cut materials to desired sizes and shapes. The Skilsaw 54HD is designed to perform a variety of jobs which include cross-cutting, ripping, cutting paneling, making angled cuts, and making miter cuts.


Product Alternative Profile:

What product alternatives exist?

The Makita 5007FK is a good alternative to Skilsaw 54HD circular saw. It is an alternative because it has many of the same capabilities of the Skilsaw 54HD but also has some distinct qualities, different to those from the Skilsaw 54HD.

Makita 5007FK

Advantages:

  • An onboard L.E.D. light with a switch, independent of the trigger, which will help you keep your sight of line.
  • Easy to change blades quickly and efficiently, because the devices flat motor housing design will increase stability.
  • A 15 Amp motor which produces about 5,800 RPM so you can carry on through some tougher jobs.
  • An AC/DC switch allows the user to choose between different power sources.
  • A 0-to 45-degree bevel allows to you make different and more flexible cuts.
  • A heavy base gives the user more stability in making more secure and accurate cuts.
  • Shaft lock allows the user to change blades easier, and safer.

Disadvantages:

  • Price could be a problem, costing almost 3 times more than the Skilsaw 54HD.
  • While providing more power, it may not be suitable for users who are new to working with power tools.
  • Though it has some safety features, the Skilsaw provides more safety precautions.

How does this alternative compare in performance?

One way that these two products differ is that the Skilsaw provides some more safety measures. One of these measures is an Anti-snag lower guard design which, besides from keep the user safe, makes it easier to make more narrow cuts for users new to using these types of power tools. Another difference is the fact that the Makita uses a more powerful motor providing about 1,200 more RPM than the Skilsaw. One major difference is the fact that the Makita has an L.E.D. light which keeps your sight of line easy to see and follow.

Specifications Makita 5007FK Skilsaw 54HD
Amperage: 13.0 12.0
Blade Size: 7-1/4” 7-1/4”
No-load RPM: 5,800 4,600
Depth of cut at 45-degrees: 1-3/4” 1-15/16”
Depth of cut at 90-degrees: 2-3/8” 2-7/16”
Weight: 11.1 Lbs 10.8 Lbs

References

  1. . "Power Tools: Circular Saw." Amateur Woodworker. Web. 29 Sept. 2010. <http://www.am-wood.com/tools/circular.html>.
  2. . Formisano, By Bob. "Circular Saw Tool Profile." Home Repair - Maintaining and Repairing Your House. Web. 29 Sept. 2010. <http://homerepair.about.com/od/toolsmaterialsyouneed/p/prof_circ_saw.htm>.
  3. . Ryan, V. "Hand Held Circular Saws." A Design and Technology Site. Web. 29 Sept. 2010. <http://www.technologystudent.com/pwtol/circsw1.htm>.
  4. . "Makita 5007FK 7-1/4 Inch Circular Saw with L.E.D - Makita Circular Saw." MAKITA Power Tools MAKITA Tools MAKITA Cordless Power Tool LXT Lithium. Web. 24 Sept. 2010. <http://www.makitapowertoolsonline.com/Circular-Saws/Makita-5007FK-Circular-Saw.html>.
  5. . "Circular Saw - Skilsaw - 7 1/4" Saw - Hd5687." Official Skil Power Tools Website. Web. 24 Sept. 2010. <http://www.skiltools.com/en/AllTools/Category/Product/default.html?pid=HD5687-01&cid=45>.
  6. . "Circular Saws." Home. Web. 24 Sept. 2010. <http://hometoolsrus.com/circularsaws.aspx>.


Gate 2:Product Dissection

Purpose

Gate 2 has to main components: the first part was an assessment of the work proposal as well as the management proposal. Another component of Gate 2 was a dissection of the product. The purpose of assessing the work proposal and management proposal was to see how efficient the groups plan's were, as well as helping the group improve previous plans. The purpose of the product dissection was to help the group better understand how the product functions.

Project Management: Preliminary Project Review

Cause for Corrective Action

After the dissection of the product the group had to do a reflection of the work and management proposals. The reverse engineering approach outlined by the group has been accurate thus far. No major obstacles have been met by the group in the outlined reverse engineering approach. The product disassembly approach was accurate for the most part, any changes that were made to the outline are described in the following paragraphs. In step one of the disassembly approach the group had to remove the casing foot which consisted of a lever. This section of the plan was not as easy as anticipated because the bolt holding the lever in was deformed, and removing it with an Allen Wrench was not as easy as expected. Another small obstacle in step one was removing the roller pin. There was not a roller pin punch available so the group had to compensate for this. The group did this by using a hex key and a mallet in order to remove the roller pin punch.

Mallet with Hex Key

Step two was as outlined in the plan. Step three of the plan was slightly more difficult than anticipated because, while removing the hexagon screw, the bearing flange had to be held still by another group member with a wrench. Another change to step three was that in order to remove the guard plate, the protective cover also had to be removed at the same time. This was not anticipated by the group and so steps three and five of the dissection plan had to be done simultaneously. This change did not really affect the overall disassembly approach and was not very difficult to complete.

Guard Plate Protective Cover Pinion Shaft

Step four of the plan was slightly easier than anticipated because there were no screws holding the bearing flange and the pinion shaft together, therefore the two components were removed by hand. Step five of the plan had to be done in unison with step three because the protective cover and the guard plate were held together by 7 screws, and in order to reach the bearing flange and pinion shaft these two components had to be removed in unison. Steps six through nine were performed as outlined in the disassembly approach and were not difficult to complete. The tools which were required were accurate for the most part. One correction that was made to the tools required was that there was not a roller pin punch available. In order to compensate for this the group used a hex key and a mallet in order to remove the roller pin punch. The possible challenges outlined were accurate for the most part, though the group was able to avoid these challenges. The time management for the group has been accurate and easy to follow up to this section of the overall project. Thus far all group meetings have been met as planned, and have run smoothly on a consistent basis. Each group member has met their job assignments and requirements successfully and efficiently.

Product Archaeology: Product Dissection

Parts List

# Quantity Component Name Component Photograph # Quantity Component Name Component Photograph # Quantity Component Name Component Photograph
1 1 Housing Housing 2 1 120V Field Field 3 1 120V Armature Armature
4 1 Trigger Trigger 5 1 Mains Connection Cable Housing 6 1 Nameplate Housing
7 1 Reference Plate Reference Plate 8 1 Bearing Flange Bearing Flange 9 8 Self Tapping Screws Self Tapping Screws
10 1 Protective Cover Protective Cover 11 7 Screw Screw 12 2 Supporting Disk Supporting Disk
13 1 Guard Plate Guard Plate 14 1 Spring Spring 15 1 Lever Supporting Disk
16 1 Wing Nut Wing Nut 17 1 Roller Pin Roller Pin 18 1 Hexagon Screw Hexagon Screw
19 1 Carbon-Brush Set Carbon Brush Set 20 1 Pinion Shaft Pinion Shaft 21 1 Set Of Handles Supporting Disk
22 1 Retaining Ring Carbon Brush Set

Step by Step Dissection Instructions

Step # Description Time Tool Required Difficulty
1 Remove the casing foot, consisting of a lever,wing nut and a roller pin. 20 Minutes Hands, Allen Wrench (11mm), Hex Key, Mallet 4
2 Remove the set of handles, consisting of 6 Self-Tapping screws. 2 Minutes Torx T20 Screwdriver 2
3 Remove the guard plate, the protective cover, and the pinion shaft which consist of 7 screws and a spring. 3 Minutes Torx T20 Screwdriver, Hands 3
4 Remove the pinion shaft from the guard plate which had no screws holding it together. 5 Seconds Hands 1
5 Remove the 120V Armature from the bearing sleeve. 2 Seconds Hands 1
6 Remove the 120V Armature from the 120V Field. 2 Seconds Hands 1
7 Remove the housing cover consisting of 2 screws. 1 Minute 30 Seconds Torx T20 Screwdriver 2
8 Remove the Carbon-Brush set. 1 Minute Hands 1

Total dissection time: 27 Minutes 39 Seconds

Difficulty Scale:

  1. Not difficult: No specific knowledge of tools required, could be taken apart by hand.
  2. Not difficult: Some knowledge of tools required.
  3. Medium Difficulty: Knowledge of tools required(or required tools not available and group had to improvise), able to disassemble in few attempts after some thinking.
  4. Difficult: Knowledge of tools required ( or ability to improvise with the lack of necessary tools), able to disassemble only after multiple attempts and much thinking.

Overall Difficulty of Product Dissection: 3

* Note - Explanation of why certain steps were difficult are outlined in previous Work Proposal/Management Proposal Assesments

Product Dissection Assessment

Based on the product dissection, and the common types of bolts and screws used, you could infer that product was meant to be disassembled. Looking at the difficulty levels of each step we can determine that overall the dissection wasn’t difficult. Only one step was difficult to complete and it wasn’t because of the type of bolt used, but rather the fact that the bolt was deformed. Other than that one step every other step, except step 3, was rated as a 1-2, which means they were not difficult. Step 3 was a little more difficult because it required a smaller amount of thinking. A reason for this could be to make the changing of blades easier as well as replacing components that wear due to the consistent work put in by the motor.

It is also important to look at how the subsystems of the product were connected, to better understand how the product works. The first connection was the trigger to the rest of the system. This connection was connected via cables. The bearing flange is connected pinion shaft physically (the pinion shaft is inserted into the bearing flange). The pinion shaft was connected to the armature physically via a bearing sleeve, a plain washer and a sintered-metal bushing. The armature was connected to 120V field physically via a washer and plain washer. The field was connected to the carbon-brushing set physically.

While looking at how the subsystems of the product, you must also try to understand why they are connected. The first connection was via cables because it was efficient to import energy through cables as opposed to another medium. The pinion shaft inserted into the bearing flange was an efficient way of having the connection because it allowed an efficient way for the pinion shaft to rotate. The pinion shaft was connected to the armature via the bearing sleeve, a plain washer and a sintered-metal bushing because it made an efficient connection which helped to change the RPM and torque in a manner that better well suited for the output wanted by the user. The armature was connected to the 120V field physically via a washer and plain washer because it made for an efficient connection for the field and the armature. Since the armature just needs to be able to rotate, it just needs a type of connection with the field which allows it to rotate enough that it’s efficient.

To help the group better understand why some of these subsystems were connected, looking into some factors that influenced why certain connections were made is also necessary. The economic concerns that effect how the parts are connected are the different costs for the different materials. The manufacturer must have chosen the specific types of connections because they provide the desired performance for the best or preferred price. A global concern that affects this is the types of components which may need to be replaced later in the use of the product. If a certain component fails in the product, the components within the product must be easy to replace in different regions of the world where certain components are not as easy to obtain. This type of consideration must have been taken and influenced the type of connections in product.

Performance is another factor that could influence the connection type, and so looking into how this effects connection type is also necessary. The desired performance influenced the connection type of the trigger because the connection for the trigger could be made with different types of wires of different materials. Some materials had less resistance than others, along with the thickness of the wire. The manufacturer must have chosen this material for a specific reason in order to achieve the desired performance.

The subsystems are arranged as follows:

  1. The trigger with wires
  2. The bearing flange
  3. The Pinion Shaft
  4. The armature
  5. The 120V Field
  6. Carbon-Brushing Set

The group must also try to see if there is a reason for each subsystems placement. Yes, there is a reason for each subsystems placement. The placement of these subsystems makes it possible to import energy, transport the energy and convert it in an efficient manner. Place these subsystems in any other manner would have caused a longer trip for the energy to flow through from one end of the product to the end of the product. If this trip, of the energy being imported and converted was longer than necessary than the chance of energy being lost would also be greater. This would therefore create a less efficient product. No there are not any subsystems which cannot be adjacent. In this product most subsystems are adjacent.

Gate 3:Product Analysis

Purpose

Now that the dissection is complete, a detailed analysis of it can now be done. The purpose of this gate is to examine the product at a component level as well as a subsystem level, while gathering detailed information. This information will then be organized in the form a technical report.In order to do this, each component was analyzed; a few design questions were addressed as well as some possible design revisions.

Project Management: Coordination Review

Cause for Corrective Action

As the group continues to move forward toward the coordination review of the Skilsaw 54HD, a reassessment of the work completed thus far as well as the management plan must be done. There were no major issues in gate 2, as well as in gate 3. The management plan is working thus far because of the group’s ability to work well together and work well within the time period’s given in the Gantt Chart. There are no unresolved problems or challenges to be addressed at this time that could hinder the group’s ability to finish the project on time, therefore no further action needed to be taken. The only challenge we’ve encountered was in Gate 1, and we resolved this by brainstorming as a group and using the tools provided in the lab. Any future challenges will be overcome with group meetings, in a timely fashion with brainstorming.

Product Archaeology: Product Evaluation

Component Summary

Housing

Housing

Model number: 2 610 912 983

Number of times used: 1

Component function: The housing protects and keeps the motor along with the 120V field and armature intact.

Functional or cosmetic (or both, explain): Both. The housing must protect the internal components. It must also be aesthetically pleasing to the eye or the consumer may not want to purchase it.

Material Use: It is made out of black thermoplastic material

Reason for material choice: It is considerately light weight and cheap.

Manufacturing process used: Injection molding.

Reason for machine process selection: It is an easy way to mass produce the component as well as being cost efficient.

Purpose of shape: It houses the electrical field which is round, and must be round, therefore the housing’s shape was determined by this.

Part complexity: low


Armature

Armature

Model number: 2 610 341 306

Number of times used: 1

Component function: Carries a current which causes itself to rotate in the magnetic field set up by the stator, provides the torque that rotates the blade.

Functional or cosmetic (or both, explain): Functional. This is what helps because the main function of the product, which is to cut wood, by rotating a blade.

Material Use: Copper wire wound around a steel shaft.

Reason for material choice: Copper because it is conductive and steel because it is strong.

Manufacturing process used: copper wire was coiled applied by guided mechanical winding process.

Reason for machine process selection: This was an time efficient and cost efficient way to manufacture the component.

Purpose of shape: The shape is very important because the coils are wound in order to repel the magnetic field.

Part complexity: High


Mains Connection Cable

Mains Connection Cable

Model number: 2 610 915 148

Number of times used: 1

Component function: The function of the mains connection cable is to import electricity from an outlet or power source into the saw, as well as protecting the user from the current that is passing through the wires in the cable.

Functional or cosmetic (or both, explain): Functional. The mains connection cable is meant to import electricity from the outlet to the system of the saw and is not very aesthetic.

Material Use: Rubber.

Reason for material choice: It was cheap choice as well as being flexible and durable.

Manufacturing process used: Injection Molding.

Reason for machine process selection: A fast, simple and cost efficient way to produce the component.

Purpose of shape: It is common over the globe and fits well in small areas and tight corners.

Part complexity: low


Name Plate

Name Plate

Model number: 2 610 912 985

Number of times used: 1

Component function: It is an informative part of the product which enables buyers to understand some facts about the voltage and power capacity of the machine .This is also to inform people about the dangers and warnings of the machine.

Functional or cosmetic (or both, explain): Both. It’s functional in the sense that it informs the user of some of the products properties. It’s also cosmetic because it says the companies name and promotes it in an aesthetic fashion.

Material Use: Sticker.

Reason for material choice: The easiest way to produce a name plate that will be held against the side of the housing, in a cost efficient way.

Manufacturing process used: Rapid production.

Reason for machine process selection: Easiest way to produce these components.

Purpose of shape: Easiest way to make aesthetically pleasing to the eye.

Part complexity: low


Reference Plate

Reference Plate

Model number: 2 610 912 986

Number of times used: 1

Component function: Aesthetic to the eye and promotes the product one more time.

Functional or cosmetic (or both, explain): Cosmetic.

Material Use: Sticker.

Reason for material choice: The easiest way to produce a reference plate that will be held against the side of the housing, in a cost efficient way.

Manufacturing process used: Rapid production.

Reason for machine process selection: Easiest way to produce these components.

Purpose of shape: Aesthetically appeasing to the eye.

Part complexity: low


Trigger

Trigger

Model number: 2 610 917 325

Number of times used: 1

Component function: Since the circuit is not closed by default, the trigger acts as a switch allowing the user to operate the saw by completing the circuit and electricity to flow through the saw, which can then be converted to rotational mechanical energy.

Functional or cosmetic (or both, explain): Functional, but brightly colored red in contrast to the black for cosmetic reasons to aid in functionality.

Material Use: Injection molded plastic pieces assembled to an electronic switch.

Reason for material choice: Inexpensive and sturdy plastic.

Manufacturing process used: Injection Molding

Reason for machine process selection: A fast and cost efficient way to manufacture the component.

Purpose of shape: Has two buttons that are externally placed on the handle so that the user can comfortably press the safety button and the control signal button simultaneously in order to operate the saw.

Part complexity: low


Bearing Flange

Bearing Flange

Model number: 2 610 341 347

Number of times used:1

Component function: The bearing sleeve serves as the area of contact for the shaft and allows it to move in a constrained rotational motion.

Functional or cosmetic (or both, explain): Functional. The bearing flange helps to reduce friction between the pinion shaft and the protective cover, which helps to reduce the amount of energy lost due to heat, and create a more efficient product.

Material Use: Steel

Reason for material choice: Strength and durability.

Manufacturing process used: Turning.

Reason for machine process selection: A fast and cost efficient way to have the components manufactured.

Purpose of shape: Designed to provide a place for the shaft to rotate inside of it and also it is flanged to keep it attached to the guard plate.

Part complexity: low


Self Tapping Screws

Self Tapping Screws

Model number: 2 610 341 364

Number of times used: 8

Component function: Fasten together the external parts such as the housing and the handle.

Functional or cosmetic (or both, explain): Functional

Material Use: Steel

Reason for material choice: They need to be strong to withstand the stress of the saw.

Manufacturing process used: Made on a screw-cutting lathe.

Reason for machine process selection: Screws are made on a lathe that cuts the threads and tapers the end to a point to allow it to penetrate materials.

Purpose of shape: Screw threads lock with complementary threads

Part complexity: low


Protective Cover

Protective Cover

Model number: 2 610 312 398

Number of times used: 1

Component function: Shields the portion of the blade that is not on the cutting edge of the saw.

Functional or cosmetic (or both, explain): Functional

Material Use: Steel

Reason for material choice: Strong enough not to be destroyed by the blade or materials in case of snags or improper use.

Manufacturing process used: casting

Reason for machine process selection: Efficient, low cost, simple process to shape steel

Purpose of shape: The semi-circular shape accommodates the circular blade.

Part complexity: low


Screw

Screw

Model Number: 2 610 341 365

Number of times used: 4

Component function: Fasten together the external parts such as the housing.

Functional or cosmetic: Functional

Reason for material choice: The screws need to be strong enough to handle the stress of the saw as it functions.

Manufacturing process used: Cold heading and thread rolling

Reason for Machine process selection: The screws are made by cold heading and thread rolling so that the screws can be quickly and cheaply made in high quantities while still maintaining quality.

Part Complexity:low




Supporting Disk

Supporting Disk

Model Number: 2 610 341 361

Number of times used: 2

Component function: It helps prevent fastening loosening due to vibrations.

Functional or cosmetic: Functional

Reason for material choice: The support disks need to be strong enough to not deform when strained under the load of the thread fastener.

Manufacturing process used: Casting

Reason for Machine process selection: Easy and cheap to mass produce and is accurate to specifications.

Part Complexity: low




Guard Plate

Guard Plate

Model Number: 2 610 916 428

Number of times used: 1

Component function: Shields the cutting portion of the blade when the blade is not in use.

Functional or cosmetic: Functional

Reason for Material Choice: Must be strong enough to not allow saw blade to penetrate the material.

Manufacturing Process used: Casting

Reason for machine process selection: casting allows for the creation of complex geometrical shapes at a relatively low cost when producing components at high volume.

Part Complexity: low





Spring

Spring

Model number: 2 610 914 057

Number of times used: 1

Component function: It returns the blade cover to 'safe' position to protect operator from getting hurt.

Functional or cosmetic (or both, explain): Functional.

Material Use: It is made of hardened steel wound from pre-hardened stock or a cylinder

Reason for material choice: Lightweight and inexpensive.

Manufacturing process used: Cold winding.

Reason for machine process selection: Inexpensive and time efficient way to mass produce the component.

Purpose of shape: This helps to fit in the shape casing easier.

Part complexity: low


Lever

Lever

Model Number: 2 610 924 015

Number of times used: 1

Component function: To allow the user to gain proper leverage for easier removal of the guard plate from the saw.

Functional or Cosmetic: Functional and Cosmetic, the lever is useful for user interface but the plastic lever is colored red which matches the overall color scheme of the saw.

Reason for material choice: Had to durable enough to withstand the user pulling back on it and carrying the guard plate.

Manufacturing process used: Milling

Reason for machine process selection: milling allows for the design of the complex shape that the lever consists of and is relatively cheap.

Part Complexity: low





Wing Nut

Wing Nut

Model Number: 2 610 029 562

Number of times used: 1

Component function: Nuts are used opposite of a mating bolt to fasten a stack of parts together.

Functional or Cosmetic: Functional

Reason for material choice: The wing nut must be strong enough to withstand the strain of holding the casing foot in place without moving.

Manufacturing Process used: Casting

Reason for machine process selection: Cheaply and easily allows the mass production of the wing nut.

Part Complexity: low







Roller Pin

Roller Pin

Model Number: 2 610 914 058

Number of time used: 1

Component function: Holds components together through friction

Functional or Cosmetic: Functional

Reason for material choice: The roller pin must be durable enough not to deform after use.

Manufacturing Process used: Casting

Reason for machine process selection: Cheaply and easily allows the mass production of the roller pin.

Part Complexity: low





Hexagon Screw

Hexagon Screw:

Model number: 2 610 346 554

Number of times used: 1

Component function: To hold the 2 supporting disks into the guard plate, as well as keeping the components connected to the bearing flange and armature.

Functional or cosmetic (or both, explain): Functional.

Material Use: Steel

Reason for material choice: This gives the screw the strength and durability needed to perform its function.

Manufacturing process used: First extrusion is used, to achieve the overall shape of the screw. It is then threaded on a lathe, and the head can be forged.

Reason for machine process selection: The extrusion allows for a fast and simple way to achieve the overall shape of the screw. The lathe provides for an efficient way to achieve the threading on the screws.

Purpose of shape: A standardized shape, as well fitting best into the types of supporting disks used for the product.

Part complexity: medium



Carbon-Brush Set

Carbon-Brush Set:

Model number: 2 610 993 156

Number of times used: 1

Component function: To Conduct current between stationary wires and moving parts, in order to complete the electric circuit.

Functional or cosmetic: Functional.

Material Use: Plastic and copper.

Reason for material choice: Plastic was cheap and effective way to hold the copper components in place. The copper was chosen because it’s an efficient conductor which can easily be fit into plastic holder.

Manufacturing process used: The carbon powder is first mixed together and then compacted in a tool consisting of an upper and lower punch and die, on mechanical or hydraulic presses. The copper wire can then be inserted into a hole in the upper punch. It is then sintered and then treated by heat, at a temperature specific to the material used. It is then grounded into the desire shape.

Reason for machine process selection: An efficient way to create the carbon brush sets, as well as making efficient carbon sets that fit the use of the product specifically.

Purpose of shape: This shape best fits the housing as well as the overall shape of the product.

Part complexity: high



Pinion Shaft

Pinion Shaft:

Model number: 2 610 997 776

Number of times used: 1

Component function: Transfers torque from armature to bearing flange.

Functional or cosmetic: Functional

Material Use: steel

Reason for material choice: The steel is strong and durable, making it an efficient material for the purposes in which the pinion shaft is being used.

Manufacturing process used: Metal casting.

Reason for machine process selection: It allows production of a high volume of components of this type as well as efficiently taking the type of material used and making it into the desired shape.

Purpose of shape: The shape of teeth at allow the gear on the pinion shaft to transfer the power from the armature efficiently, while also allowing the pinion shaft to connect to the bearing flange, so the power and torque can be transferred to the blade.

Part complexity: medium



Set of Handles

Set of Handles:

Model number: 2 610 915 260

Number of times used: 1

Component function: Gives the user a way to hold and control the product in a way that’s ergonomically satisfying.

Functional or cosmetic: Functional and cosmetic.

Material Use: plastic

Reason for material choice: An efficient material to fulfill the function of the component as well as a cost efficient way to do it.

Manufacturing process used: Injection Molding

Reason for machine process selection: This was a cost efficient process as well as efficient way to rapidly produce this component.

Purpose of shape: It’s pleasing to the eye as well as ergonomically satisfying to the user.

Part complexity: low



Retaining Ring

Retaining Ring:

Model number: 2 610 341 359

Number of times used: 1

Component function: Secures the bearing flange to the protective cover.

Functional or cosmetic: Functional

Material Use: steel

Reason for material choice: It’s strong and durable enough to fulfill the purpose of retaining ring, which was to hold the bearing flange in place on the protective cover.

Manufacturing process used: Cold Winding

Reason for machine process selection: An efficient way to mass produce many of these components.

Purpose of shape: This shape best fits around the bearing flange and in the protective cover a way that keeps the parts loose enough that bearing flange can still move, but won’t slip out of the protective cover.

Part complexity: low




Product Analysis

Bearing Flange:

Bearing Flange

The function of the bearing flange is to reduce the friction between pinion shaft and the inner rim of the protective cover. The bearing flange does help to do multiple functions. Apart from helping to reduce friction, the bearing flange also helps to support radial and axial loads. Another application is to reduce torque, and help the blade reach maximum speed. One flow associated with the bearing flange is the magnitude change. The magnitude change was to lower torque and helps raise RPM, so that the blade could cut material. The component functions in a lubricated environment. This helps to reduce even more friction within the bearing flange and the inner rim of the protective cover. The temperature in this environment is not very hot, but a lot of torque is entering this environment, so the material must be able to support this torque.

The general shape of the bearing flange is a cylinder sitting on top of a sphere with a larger radius than the cylinder sitting on it. Some notable properties of it are that it is axis-symmetric, has rounded edges and can move only in a circular motion, in either direction, left or right. Since the bearing flange moves only in a circular path either left or right, than it is two dimensional. The dimensions of the bearing flange can be separate as such, a .1” thickness with a 1.15” radius for the sphere on the bottom of the part of the bearing flange and a radius of .85” radius and a .5” height and .1” thickness for the cylinder sitting on top of the bottom sphere.

The shape of the bearing flange is coupled to its function in a couple different ways. One way the shape is coupled to its function is in reducing friction. This is done because the best shape in reducing friction is a sphere or circle, because it has no edges. Another way it’s coupled to its function is in the fact that it helps to convert torque, so it must spin, and the shape of a circle accepts torque easier than other shapes. The component weighs about .40 lbs.

The bearing flange is made out of steel. Manufacturing decisions impacted this because bearing flanges need to be produced rapidly. Since bearing flanges need to be produced rapidly, they need to be made cost efficient, and to perform the functions that the bearing flange needs to perform, steel was an obvious choice. There is a specific material property that is needed for it to function and that is strength. If the bearing flange wasn’t strong, it wouldn’t be able to support the torque being transmitted through it.

There are many factors that influence the use of a bearing flange in this product. One factor that influences the use of a bearing flange in this product is societal and economic. If the product was to be used in a developing country where many homes are being built and more expensive forms of rapidly cutting wood isn’t available, then the Skilsaw would be a good product to use. Since a developing country would be building as many homes as possible the country would in turn need a good number of circular saws, at a cheap a price as possible. If the bearing flange was made out of another material, such as titanium, the price of the saw would then be a lot more expensive, and would possibly not be very affordable to this type of society.

Another factor that influenced the design was a global one. If the bearing flange wasn’t made out of steel than it wouldn’t be very resistant to certain climates with high humidity’s, which could mean that the bearing flange would become weaker over time. This could cause many problems with the saw, or ultimately have the saw fail.

The bearing flange does not have many aesthetic components, other than having rounded edges which make the bearing flange seem “cleaner”, in a sense that it looks as if it has a nice surface finish. The component is silver and reflective, which is due to the fact that it’s made of steel and the processes by which it was manufactured caused it to be reflective. The bearing flange has a nice and relatively clean surface finish. This is more for it a functional reason because a nicer surface finish results in less friction, which assists in the purpose of the bearing flange.

There are a few steps which go into the manufacturing of a bearing flange. First you begin with steel tubing of appropriate size and machines similar to lathes cut the basic shape of the race. Those tubing’s are heated, then dipped into an oil bath and tempered. These races are now hard and tough but need to be finished, so that they have a good surface area, this is done with grinding wheels. A very fine abrasive slurry is used to polish these races until they give off a reflective mirror like finish. Next the cage for the balls must be made. To do this a stamping method is used on a fairly thin sheet of metal, and it is then bent into its final shape with a die. To finish the process the balls are inserted into the cage, and the cage is inserted in between the two races and riveted together. Finally the bearing flange can be coated with rust preventive material and the process is complete. The evidence for this is the reflective, almost mirror like surface, smooth finish and fairly accurate dimensions. Material choice impacted this decision greatly because since it’s made from steel the bearing flange process is a little tougher and more time consuming than making one that was to be made from plastic, or almost any other material. Shape also affected this decision because if it wasn’t round than different approaches to removing material could have been used, and polishing the material would have to have been done differently, since a grinding wheel is truly meant to be used on a round component.

There is an economical influence on the decision of this manufacturing process. The process used to manufacture the bearing flange is efficient and can be done to rapidly produce many bearing flanges. This ease of production translates into cheaper production, and if this component is cheaper to produce, than the overall cost of the product is also cheaper, allowing for a bigger consumer base.

In order to decide if the bearing flange is a complex component a meaningful scale must first be defined. A meaningful scale for this type of component must include the component function, the geometry, and the manufacturing process used to make it. These three categories greatly affect complexity of the component. The component function itself is not very influential on the overall complexity of the component. The geometry greatly affects the complexity of the component. Some components have very complex geometry’s which in turn make fitting them into a certain series of other components within the overall product to be very difficult. The manufacturing process used also greatly affects the overall complexity of a component. Some components require very intricate manufacturing processes to produce them. The more intricate of a manufacturing process something is, usually the longer it takes to make the component. A more intricate process also means that someone with a lot of manufacturing processes knowledge must also head that process.


Because of the above listed factors we can define a scale. A scale for complexity of a component would be as follows:

1 – Low – A simple product function, simple geometry, and simple manufacturing process.

2- Slightly Low – A simple product function, basic geometry, and may involve basic or slightly more advanced manufacturing techniques.

3 – Medium – A simple or slightly advanced product function, slightly intricate geometry, and basic or slightly advanced manufacturing techniques.

4 – Medium High – A slightly advanced product function, intricate geometry, and slightly advanced or advanced and intricate manufacturing process.

5- High – Intricate product function, intricate geometry, and involves an advanced and intricate manufacturing process.

Based on this scale the bearing flange can be given a grade of 2. The interactions of this component must be defined upon a scale as well. A meaningful scale for this can be based upon how intricate the geometry of the interacting components is, as well as the functions being performed between them.

1 – Low- Geometry’s are simple and functions being performed are simple.

2- Slightly Low – Geometry’s are simple and functions being performed are slightly more advanced, with knowledge of a specific field required (e.g. electricity).

3- Medium – Geometry’s are slightly intricate and functions being performed are slightly advanced.

4- Medium High – Geometry’s are intricate and functions being performed are advanced.

5- High- Geometry’s are intricate and functions being performed are advanced and intricate.


Pinion Shaft:

Pinion Shaft

The function of the pinion shaft is to transmit torque from the armature to the blade. The pinion shaft does help to perform multiple functions. Other than transmitting torque from the armature to the blade it also helps to complete a magnitude change from high torque and low RPM, to a lower torque and higher RPM. The flow associated with the pinion shaft is the magnitude change, of torque and RPM. The pinion shaft exists in an environment that isn’t relatively hot, but has a lot of torque. In order to keep the system efficiency relatively high there must be a relative low amount of friction in this environment, so it is safe to assume that there is a low amount of friction in this environment.

The overall shape of the product is a circular disk with tips around the edge, like a star, with a rod going through its center. Some notable properties of the pinion shaft are that it’s axis-symmetric, has a good finish and most components have basic geometry. The pinion shaft is primarily two dimensional because of the fact that it only rotates in one direction. The component consists of a rod that is approximately 2.25” long with a 1.5/8” radius and a disk that has a radius of 1 and 1/8”.

The components shape is coupled to its function because a disk is an efficient way to perform the function that the pinion shaft has. For the pinion shaft to efficiently transmit torque from the armature to the blade it needs to rotate with a very efficient speed and a disk is the best choice for this because its moment of inertia tends to be higher than any other shape. The component weighs approximately .50 lbs and the component is made of stainless steel.

The decision of using stainless steel was a manufacturing decision. In order to manufacture this component in a way that it comes out strong and is easy to manipulate. A specific material property is needed for it to function, it needs to be strong. If the pinion shaft is not strong and can’t bear the load of torque than it will fail and saw will in turn fail and perform its function.

There are some factors that influence the decision of using stainless steel as material for the pinion shaft. One factor is a global factor. If the saw is to be used in an environment where there is a high humidity then regular steel would not have been appropriate because it would have eroded faster and wouldn’t have been very efficient over time. Economics also influence the reason for using steel as the material for the pinion shaft. In order to make sure that the pinion shaft is able withstand the load of torque from the armature but at the same time economics need to be taken into consideration. For this reason steel was a great choice because it can accepts the torque and has a proper strength for its function, but is also affordable to produce at a rapid rate and mass produce it. The choice of steel is also affected by an environmental concern. In order for this component to not have to be replaced often it needs to be strong. If the component wasn’t strong and had to be replaced often then more materials are being used to manufacture this component which takes more energy, which is worse for the environment, but since it’s strong and made of steel this shouldn’t be a problem.

The aesthetic property of this component is the fact that it has a good finish and is slightly reflective. The component does have an aesthetic property being that it helps to reduce friction. The reduction in friction translates into less energy lost which creates a more efficient product which is also better for the environment. The component is silver and reflective. This is because of an effective of the manufacturing process. The component has a good and smooth finish, which is mostly done for function. The smooth finish allows for less friction which creates a more efficient product.

The two manufacturing processes used for manufacturing the pinion shaft are turning and casting. The rod was manufactured via turning. Turning is a manufacturing process in which cylindrical parts are made in a lathe. The gear part of the pinion shaft was made via casting. Casting is a manufacturing process in which a liquid material is poured in a mold and allowed to solidify. The finish on the rod can allow you to believe that it was turned because of the light scratch like marks along its sides which follow a single path all the way around the rod. Material choice influenced this decision because if different materials were used, than easier and more cost efficient methods would have been used to produce these components. Shape also greatly influenced the choice of manufacturing process used. Turning was a great choice for the rod because it was the simplest way to achieve the desired shape. Casting was also a choice based on shape because to achieve the shape of the gear would take much longer if done by other processes, so casting in this situation saved a lot of time.

Based upon the scale defined earlier in the bearing flange example it is easy to conclude that complexity of the pinion shaft deserves a grade of 3. The component function, geometry and manufacturing process impact the complexity of the pinion shaft in various ways. Since the function is slightly advanced then the part itself can be inferred to be slightly advanced. The geometry greatly affects the complexity of the pinion shaft because it must fit into two different components at the same time, therefore making the geometry more intricate because of the fact that it must fit into two different components at once. The manufacturing method is also a great indicator as to how complex a component is. In the pinion shaft a fairly basic manufacturing process you could infer that the piece is not overly complex. When looking into those three factors as a whole it’s easy to see why the pinion shaft received the grade it did.

The interactions for the pinion shaft can be graded as a 2, as defined by the scale used in the bearing flange analysis. This scale was based upon how intricate the geometry of the interacting components involved in the analysis of a component are, as well as the functions being performed between them. The pinion shafts interactions include a screw entering at one end, and the gear on the other end interacting with the armature. The interaction with the screw is fairly simple and doesn’t affect this grade very much. The interaction with armature is fairly simple as well and involves the one end of the pinion shaft coming into contact with a sintered metal bushing, which comes into contact with the armature.

Trigger:

Trigger

The function of trigger is to sense user input, so that the saw knows to begin to allow electricity to flow through the system. This component doesn’t perform any other function, other than sensing user input. The flows associated with component are transporting energy as well as being a signal. The component functions in an environment that is on the external part of the product, it is usually has no or low pressures on it, unless being used, and is mostly stationary in equilibrium, unless the product is in use.

The general shape of the component is a red rectangle with a slightly concave center, which is connected to a small black box (which isn’t visible from the outside of the product). Some notable properties that it has are its color, a good finish, and curved edges. This component is primarily one dimensional because when you pull the trigger, it only moves in one direction, and it then returns to its original position afterwards. The component is roughly 3/4” long and 3/8” wide. The components shape is coupled to its function because it’s meant for the user to apply pressure to, mainly with one finger, various times. The concave shape in the center of the rectangle provides an ergonomic factor so that consumer isn’t affected by prolonged use or various uses of the product. The product weighs approximately .05 lbs.

This component is made from plastic. Manufacturing decisions did impact this. Knowing that the trigger doesn’t need to be made of a strong material, because it doesn’t take many loads, and that the triggers must be produced at a high rate as well as cost efficiently, made plastic the obvious choice for the material for the trigger. There is no specific material property needed for the trigger to function properly.

A global factor influenced the decision for the use of the red plastic in the decision of the component form. Using a color like red helps to attract the user’s eye to that certain point. This type of color scheme on a component like this can help the user to infer that this is the trigger that needs to be pulled to have the saw begin its function, regardless of different language barriers. Economics also had an influence on the choice of this material. Since the function of the trigger is fairly simple, and doesn’t need to be very strong, plastic is the obvious choice for this type of component, since it would be cheaper than most other materials. Environmentally this decision was also influenced because it can be recycled and reused easier than most other materials that could have been used.

Some aesthetic properties of the trigger are its ergonomic shape, smooth finish, and color. The ergonomic shape can allow the user to use the product repeatedly without being affected after many uses. The same could be said about the smooth finish of the trigger. The smooth finish of the trigger allows for more comfortable handling of the trigger without irritating the users fingers after various uses. The color is red and that color of the component helps the user to realize that the trigger is how to start the saw after it’s plugged in, even between language barriers.

The manufacturing method used to make this part was injection molding. A clue to this is the material of component. Plastic components are usually made with an injection molding process. Another clue is a seam on the inside of the trigger. The material choice clearly influenced this choice. Injection molding is a very affective, fast, simple and cost efficient way to manufacture components made of plastic. Since the trigger was made of plastic made injection molding an obvious choice as the manufacturing process, for the previously stated reasons. The shape of the component didn’t influence the manufacturing process used, though injection molding was a good choice for this shape desired, since a mold could make decently accurate components.

Economics influenced this decision in a simple way, injection molding was a cheap way to rapidly manufacture and large amount of these components, so again this was an easy choice. This manufacturing process was also influenced environmentally. In injection molding, there is a mold of the component that is going to be created, liquid plastic in this case, is then poured into the mold and allowed to solidify. In this type of process there is a small amount, if any amount, of material that is lost, unused or thrown away, which makes this manufacturing process more environmentally safe. The manufacturing process for this component isn’t influenced very much by global factors.

This component has a low level of complexity. Based on the scale defined in the bearing flange example, the trigger would receive a grade of 1. This is because the function of the trigger is simple, the geometry is simple, and the manufacturing process is also simple. Considering that the function of the trigger is simple, the geometry is simple and the manufacturing process is simple, the overall complexity of the component is also simple. The interactions in the trigger are also very simple. The two interactions that occur are between the user and the trigger, and between the trigger and the mains connection cable. The interaction between the user and trigger is when the user puts in an input so the saw knows to begin to allow electricity to flow. The interaction between the trigger and mains connection cable is to allow electricity to flow so that the rest of the saw may receive electricity, which will be converted to rotational mechanical energy. Based on the scale in the bearing flange analysis, the trigger’s interaction complexity would receive a grade of 1.

Mains Connection Cable:

Mains Connection Cable

The function of the mains connection cable is to import electricity from an outlet or power source into the saw, as well as protecting the user from the current that is passing through the wires in the cable. This component may perform multiple functions as well. One possible alternate function for the mains connection cable is to lower the amount of electricity coming through the wire before it reaches the product, depending on the amount of resistance in the wires of the mains connection cable. A flow associated with the mains connection cable is that it’s

a channel for importing electrical energy into the saw. The environment that the mains connection cable functions in is on the external part of the product. This environment can be different depending on where the product is being used and when it is being used. If the product is being used in an outdoor environment the weather can be different on different occasions, for example temperatures and whether or not it rains on any given day can vary. For these reasons the mains connection cable must be durable and resistant to different elements.

The general shape of component is a long round cable with a plug at the end, that is flexible and can be bent in many angles and in many different directions. Some notable properties of the component are that it is decently thick, and made of a decently durable rubber. The component is primarily one dimensional because it is only plugged in and out of walls, so it is only put in motion in one direction. The mains connection cable is a round cable with a radius of approximately 2/8” with a plug at the end that has dimensions of approximately.7/8” x 6/8” x 1” with two prongs sticking out of it that are approximately 7/16” apart and the total length of the cable is approximately 5’. The general shape of the component is coupled to the function of the component because the function is to import energy into the system from an outlet or power source. Therefore the mains connection cable must be able to reach certain connections in difficult to reach areas, as well as bend and make turns, so the general shape of the component must be able to be varied. The component roughly weighs about .2 lbs.

The component is made out of rubber. Manufacturing decisions did not affect the type of material that would be used for this component because it was one of a very small amount of options for this component, and of all these options they all use the same manufacturing process. A specific material property is needed for this material to work, and this property is that it must be a good insulator in order to keep the user from being electrocuted from the current being passed through the wire. The material also needs to be flexible in order to be to get power from some sources that are harder to reach or tight spaces. The wires inside of the cable must also be good conductors.

There were some factors that influenced the decision of the material choice in this component. Economically the components material choice was influenced by the fact that this component must be produced at a high volume. If a different type

of material was used the price of production of the product could have increased, including the selling the price of the product, which could have lowered the consumer base. This material of the component was also influenced globally. The fact that the material is durable, under most types of weather, indicates that it can be used in many different environments all over the world.

Some aesthetic properties of the mains cable are that it’s axis-symmetric and the color scheme matches with other parts of the saw well. The component does not have an aesthetic purpose. The component is black and that may be attributed to the fact that it matches the color of the handles that it goes into. The mains cable has a smooth finish with ridges along its sides. This is more functional because it helps to give the user a better grip on the mains cable.

The manufacturing method used to make this part was injection molding. The evidence that supports this is a parting line on the head of the plug. The material used for this component also influences this choice because of the fact injection molding is a cost efficient and simple way to manufacture components made of rubber. The shape also slightly influenced the manufacturing type chosen to create this component. Since the shape was basic it was simple to create a mold of and easy to manufacture.

A factor that influenced the manufacturing process used was economics. Injection modeling is both simple, and relatively cheap to do for various components. An environmental factor that influenced the manufacturing process that chosen was that not much material is lost when using injection molding, therefore saving more natural resources, which is better for the environment. A global factor also influenced this decision. Injection molding can be done in various parts of the earth, making it easy to produce this component all over the globe.

The overall complexity of the mains connection cable is not high. Using the scale defined in the bearing flange analysis one can conclude that a grade that could be given to the mains connection cable would be a grade of 1. The component function, geometry and complexity are all very simple for the mains connection cable. The interactions between the mains connection cable are also fairly simple. At one end of the connection you have the plug going into the outlet and at the other connection is between the wires in the connection cable and the trigger.

The interaction between connection cable and the outlet is fairly simple and bring electricity into the system. The other end of the connection cable is connected to the trigger which senses user input.

The Handle:

Set of Handles

The function of the handle is to allow the user to have sufficient control over the skilsaw while it is in use, and thus provide a means of safety. Thus the handle functions to reduce the vibrations caused by the motion of the saw blade, and to reduce slippage while using the machine. The handle is designed to hold the weight of the device by the area which the user holds it. Thus the handle is able to take the load of the main device so that it will not break off from the handle when it is held in different positions (improving safety). Also the handle functions to hold the trigger, which links the user with the device.

Although not in a direct way, the handle helps to perform multiple functions by allowing the user to actually use the device. The handle allows the user to hold the device, and the trigger which it encases enables to power the machine on and off. Thus the function of the handle is a base important function that allows for the performance of other functions of the machine, such as the armature, the blade and etc.

The handle is associated with the energy and signal flows. Electrical energy is input from the electrical outlet, to the power cord which carries the current to the handle and thus to the device (energy flow). Thus the handle serves as an intermediary for energy flow. The user inputs their signal (signal flow) to the device through the trigger (enclosed by the handle) which tells the device to perform the function. The energy and signal inputs are then carried through different sublevel-functions to help perform the overall functions.

The handle functions in the environment in whichever the device is used. This is because the handle is not an interior component but an exterior one, meaning that is not a small piece within the device but is fairly large and located outside the device. Therefore primarily it will serve to function in machine shops, carpentry shops, or places where wood work is done.

The general shape of the handle is similar to a hook when viewing it from a side

view. The components shape is adjusted to fit onto the device. The handle shape is designed for the user to hold it by the U-shape part in the handle. The shape of the handle is designed how it is to encase the trigger, allow the user to have a firm hold on the device, and to be attached to the device.

The device has notable properties in that it is ergonomically designed to for the user to hold it with their hand. The handle has a place where the user could grasp and thus have a comfortable and firm grip on the handle and thus the device. The device is also symmetric it can be divided into two from the vertical axis where the user would grip the handle. The handle can be separated into two by removing the 6 screws holding them together.

The handle could be considered three dimensional in that can move in almost any direction about the point where the user is supposed to hold it. For example from the place that the user holds the device, the user is able to move the handle in any direction that their wrist can move.

Component Dimensions:

Length: 7 inches

Height: 10 inches

Width: 2 inches

The handle’s shape is coupled to the function that it performs. The handle is shaped for the user to be able to hold the device firmly thus providing control and safety. The handle has a space with an altered material (to create friction and thus reduce the risk of the handle slipping out of the users hand), for the user to hold the device by. This part of the handle also is designed so that almost any human hand (of age) will be able to hold the device by it. The handle also functions to hold the trigger. The handle is designed and shaped to be wide enough and to be separated symmetrically to be able to enclose the trigger.

The handle is relatively light compared to the overall device. It weighs about half a pound. The reason for this is because the handle is primarily hollow to hold the trigger (which is small and does not weigh much). The handle is also light in weight because it is composed of plastic. The reason for the lightness and plastic

composition of the handle could be to reduce the weight of the overall device. The main device and its components such as the blade, and housing are heavy and creating a light handle would help create a lighter and thus more desirable product. Manufacturing decisions could have impacted the use of plastic. It would have been more expensive for the manufacturer to make the handle out of steel than it would have to make it out of plastic. Plastic may have been a good solution to the material of the handle because it can be light and relatively cheap. The manufacturer may have used plastic as mentioned before to reduce the weight of the overall device. The plastic material proved to be able to allow the necessary functions of the handle with the good overall benefits to the manufacturer and thus was chosen. The benefits could include less cost on handles and more sales (due to the lightness of the device).

A specific material property is not needed for the handle to function. For example steel, or aluminum could be used, however plastic may have proved to be able to allow the functions and allow better benefits.

The cost of the handle to be made would vary with different materials. Thus the company would have to consider the regions in which they sell the product because if the device costs more money to make, its sale value will go up. Different regions of the world have different economic statuses, and some regions may not be able to afford the product if it were made of the best possible materials. Thus the regions where the company aimed to sell the Skilsaw 54HD and their economic statuses would have been considered in choosing the materials for the device, in this case the handles.

Societal factors could have influenced the decision of the handle material in the way that a community and society favor their products to be made. A community or society could be in favor of recycling and would probably favor the use of plastic for the handle. Also a community/people/consumer could favor to have sturdy materials and thus would prefer steel.

The economic factors would be similar to the global factors in that the economic statuses of the regions in which the product is considered to be sold should be considered. The material composition of the device and its components would thus be altered according to the regions and their economic statuses. In this case the

material of the plastic would be cheaper for regions of low economic statuses and may be expensive for regions of high economic statuses.

Environmental factors that could have influenced the decision of the handle material could be if the material could be recycled. Some materials can be recycled easier than others, and the company may be able to provide to collect old unwanted products and reuse them to make new products.

The handle has a few aesthetic properties. It has a smooth black finish with smooth edges. The shape of the handle has curved edges instead of straight edges. The handle also has a design that is in the area where the user must grasp the handle. This design serves as an aesthetic property as well as part of the functionality of the handle. The design involves “bumps” which would provide friction against the users hands and thus reduce the risk of the device falling out of the users hold. The handle may serve an aesthetic purpose in that it seems appealing and thus may draw attention from consumers over other circular saws.

The color of the handle is black. The reason the handle is this color is because it differentiates the handle from the rest of the device. For example, the device is mainly silver in color, and if the user were trying to pick up the saw they could pick it up from the blade with a quick glance because the components would be of the same color. With the handle color as black the user can differentiate between the handle and the rest of the device, reducing the risk of getting hurt. The color black also matches better with silver than other colors which may be important to consumers.

The handle has a smooth surface finish throughout except for the place where the user is supposed to grip the handle. The smooth surface could be considered for aesthetical purposes. The “semi-rough” surface with “bumps” has an aesthetical design but also has functional purposes. As mentioned before the “bumps” create friction against the user’s hand and thus reduces the risk of the device slipping out of the users hold.

The handle was most likely made out of an injection mold. The evidence that supports this assumption is that the handle is made out of plastic, it is hollow, and it also has a parting line from the mold. The material choice of plastic did impact this decision because injection molding is typically used for plastics. The shape of the handles also impacted this decision because since it is fairly intricate, it would be difficult to recreate over and over. Injection molds provide the benefit of allowing the manufacturer to reuse the molds for the handles, thus saving time and capital.

Injection molding is a simple manufacturing process that can be implemented in most countries including less developed countries. Thus depending on where the product was intended to be sold, the manufacturer may have chosen injection molding because it could be implemented in most places and because it can be used to make a mass number of components, or handles in this case.

The community/society/consumer that the product is sold to may prefer sturdy or light and strong materials for their handles. If consumers prefer a light-weight handle that can perform its function, the manufacturer may implement plastic as the material through and injection mold. If consumers prefer more sturdy handles the manufacturer may use a different material like steel and thus another manufacturing method. Also consumers may prefer recyclable materials like plastic which can be made with injection molds.

The manufacturer may have chosen the method of injection molding because of multiple products to be created. The molds can be reused, and although the process may have an expensive initial cost it will prove to make up for itself. Overall the process of injection molding for large quantities of products can be cost effective.

The handle was chosen to be made of plastic material. This could be for environmental reasons, or so the company may be able to recycle old devices (which consumers can send in). Thus with plastic being used for the initial product and recycling the plastic for a new product a injection mold would be beneficial to use because, the molds can be reused and because they can be used with plastics.

The handle is slightly complex. It falls within a Level 2 complexity level as described in the scale above.

This is because the handle has the simple product functions of allowing the user to have sufficient control over the Skilsaw while it is in use (providing a means of safety), and holding the trigger. The geometry of the handle is still basic, and the manufacturing technique necessary is injection molding which is fairly simple.

The three categories Component Function, Component Form, and Manufacturing Methods impact complexity proportionally. It can be noticed that as the more intricate the functions, forms, and manufacturing methods of the component the greater its complexity will be. For example, the handle does not have complex functions, form or manufacturing methods and thus has a low component complexity.

The interactions for the handle are not complex and are fairly simple. The handle can be defined as a Level 1 in interaction complexity as given in the scale above. The interaction of the handle to the rest of the device has simple geometry with simple functions being performed. The handle is connected to the rest of the device through screws which function to attach the handle (along with the trigger to the rest of device).


Solid Model Assembly

For the solid Model Assembly we chose the Hexagon Screw, 2 Supporting Discs, the Retaining Ring, the Bearing Flange, and the Pinion Shaft.

The group chose these components because these components are important and transfer the torque from the armature to the blade. Another reason the group chose these components was because the functions and interactions of these components work together to help perform one of the main functions of the device (cutting wood material), by spinning the blade. These components are some of the main components of the device which allow it to perform its overall function of cutting wood material.

For the Solid Model Assembly, we chose Autodesk Inventor 2011, because our group member Devpriyan had experience with the software and had access to it with his laptop. The drawings could be easily edited on the laptop and did not require the travel to Furnas Hall for access to a CAD package.


Hexagonal Screw hexagonalscrew
Supporting Disc Supportingdisc
Retaining Ring retainingring
Bearing Flange bearingflange
Pinion Shaft pinionshaft
Assembly 1 Assembly 1
Assembly 2 Assembly 2


Engineering Analysis

A key component of the product is the pinion shaft. The purpose of the pinion shaft is to transmit torque from the motor to the blade. The pinion shaft is connected to the armature at one end. At this connection the armature transmits a torque that it produces by converting electrical energy to rotational mechanical energy to the pinion shaft. The pinion shaft is then connected to the blade of the saw at the other end with a bolt. At this connection the torque from the armature, which has been transmitted to the pinion shaft, is now transmitted to the blade. In between the connection of the pinion shaft and the blade, there is a bearing flange. The purpose of the bearing flange is keep the amount of friction between the pinion shaft and the inner rim of the protective cover as low as possible, therefore transmitting as much of the torque as possible, in an efficient manner.

Different diameters of blades affect the amount of torque which will be produced by the blade. These different amounts of torques must be able to be supported by the pinion shaft as well. In other words, if the pinion shaft can’t support the amount of torque that is wanted to be transmitted to the blade from the armature, than the system will not function very efficiently. Therefore the amount of the torque that is desired from different blade diameters, will also affect the desired strength, and possibly size of the pinion shaft used.

Engineering analysis can be used during the designing stage of the designing process. One example of how engineering analysis can be used during the design stage of the designing process of the Skilsaw 54HD is in choosing the diameter of a blade the saw should be designed for, in order to perform the desired function, for the desired consumer base. The desired function is to cut wood, and the desired consumer base is regular people who do handy work around their homes.

Problem Statement:

Determine which diameter blade would be most appropriate for the Skilsaw 54HD, if the desired torque output is about 3400 N-m, given that the RPM of the saw will be 4600 RPM, and the mass of the blade will be .36 lbs. There are a number of possible diameter ranges that could be analyzed. The two blade diameters that will be used for this analysis are 7.25” and 5”.

Abstracting the System:

The spinning blade is essentially a rotating disk, with a certain mass M, a certain diameter D, and a certain speed V.

Identify an Appropriate Model:

The blade is going to be modeled as a uniform circular disk.

Figure/Diagram: On right side of page.

Torque Analysis

Statement of Assumptions:

•The diameter of one blade is 7.25”

•The diameter of another blade is 5”

•The maximum speed of either blade is 4600 RPM

•All energy transferred into system with no loss

•Small hole in center of blade doesn’t affect moment of inertia

•Tips of blade don’t effect inertia equation

•Blade will treated as a disk

•The blade is rigid

•Mass is distributed uniformly throughout the blade

•The blade has a mass of .36 lbs

•The blade doesn’t slow down after reaching maximum speed

Governing Equations:

T = Ia

a= aT/r

aT = v^2/r

I= (MR^2)/2

Determine the Parameter Values:

V = (2(pi)r)/60 x RPM

I= (MR^2)/2

R= d/2

Calculations:

T = (I) (a)

T = ((MR^2)/2) ((aT/r))

T = ((MR^2)/2) ((v^2/r^2))

For 7.25” Blade

R = (7.25")/2= 3.625” x (.0254"m) = .092075 m

V = (2 x (pi)(.092075 m))/(60s) x 4600 RPM = 44.35 m/s

T = (((.36lbs x 9.81 m/s^2)(.092075m)^2)/2) x ((44.35m/s)^2/((.092075 m)^2 )) = 3473 N-m

For 5” Blade:

R = 5"/2 = 2.5” x (.0254 m)= .0635 m

V = (2π(.0635 m))/(60 s) x 4600 RPM = 30.59 m/s

T = ((.36lbs x 9.81 m/s^2 )(.0635m)^2)/2) (30.59m/s)^2/((.0635 m)^2 ))= 1652 N-m



Solution Check:

•No mathematical mistakes

•Units are consistent

Discussion of Results:

The 3400 N-m of torque achieved by the 7.25” diameter blade is about an average torque for a regular at home circular saw, which is used to perform regular duties, such as cutting wood. The estimate of the torque given different diameters reveals that at a larger diameter blade you receive a higher amount of torque coming from the blade, given that there is no loss of energy throughout the system. The different diameters can greatly affect the design of the product. This happens because as you can see through the calculations, a greater diameter gives more torque, so if you want to produce a more powerful saw then you will have to design one which can be equipped with a blade that has a larger diameter. You almost take into consideration that this type of saw is meant to be used at home for smaller projects, which means it should be fairly portable, as well as easy to handle for the user. This means that even if you want to have a higher torque, which means a larger blade, you must also consider the fact that the blade can’t be very large, because if it is than the portability of the product will be hindered. With a larger blade the product also becomes more difficult for the user to handle with their hands, which is a main attribute of this product. Something else that must be noted is that with larger diameter blades a higher torque is achieved, so a stronger, sometimes larger, pinion shaft is required in order to transmit this torque from the armature to the pinion shaft. The type of material used for the pinion shaft could be affected because of the desired amount of strength. This would then lead into what could possibly be an overall more expensive product.

Engineering analysis can also be used in the testing stage of the design process as well. When testing a product you may want to test a specific component of the product. One component of the Skilsaw 54HD that is important to test is the pinion shaft. An example of an engineering analysis during the testing stage of the design process would be for this type of component to be test for efficiency. In a perfect system efficiency would equal 100%, but in the real world this is not true. Things such as thermal energy dissipated and friction cause situations like this to be false.

Problem Statement:

Determine the efficiency of the pinion shaft in the Skilsaw 54HD at max speed, given that the saw operates at a max speed 4600 RPM, the mass of pinion shaft is .25lbs, the pinion shaft has a radius of .875” and 15% of the work produced by armature on the pinion shaft is lost due to thermal energy before being transferred to the blade.

Figure/Diagram: On right side of page.

Efficiency Analysis

Statement of Assumptions:

•The maximum speed of the pinion shaft is 4600 RPM

•The radius of the pinion shaft is .875”

•15% of the work out is lost

•The pinion shaft is rigid

•The pinion shaft has a mass of .25 lbs

•The pinion shaft doesn’t slow down after reaching max speed

•The pinion shaft transfers the rest of work to the blade

•The shape of the pinion shaft doesn’t affect the moment of inertia


Governing Equations:

Wout/Win x 100=Efficiency

Wout = (1/2 Iω^2)-(.15 x 1/2 Iω^2)

Win = 1/2 Iω^2

Calculations:

= ((1/2 Iω^2)-(.15 x 1/2 Iω^2))/( (1/2 Iω^2)) x 100 = 85%

Solution Check:

•No mathematical mistakes

•Units are consistent

•Answer makes sense


Discussions of Solution:

The given solution makes sense and is reasonable. These types of analysis during the design process can greatly affect the design or make of the overall product. One way this can affect the over make of the product is if the engineers want a better efficiency out of the pinion shaft. If the engineers want to have an efficiency of 90% they would then need to make a change to the product in order to lower the amount of energy lost due to thermal energy. This could mean more lubrication between certain connections like the bearing flange and pinion shaft in order to reduce friction. This could also mean that perhaps instead of reducing the amount of friction, they could completely change the types of connections within the product itself. This could then affect the production and manufacturing price of the product as well as the sale price, which could affect the sales.


Design Revisions

Throughout the course of analyzing the Skilsaw 54HD the group was able to notice some areas where it determined that the saw was weak or could have improvements. At these points the group decided to make design revisions that could improve the product as a whole.

1. Increase the RPM of the armature.

One distinct issue with the Skilsaw 54HD is that it has a low RPM relative to most circular hand saws on the market today. The average RPM for a 7.25” circular hand saw now a days is around 5800 RPM, while the RPM for the Skilsaw 54HD is only around 4600 RPM at max speed. This revision can be achieved by having a smaller number of turns of copper wire around the armature. This could the armature to be lighter, so that it’s easier for it to spin faster. Another reason is because more current is now flowing which creates a bigger magnetic field flux, and causes the armature to react against the magnet, or electric field, more causing it to spin faster and faster. This faster spinning of the armature will cause the blade to spin faster, allowing the saw to cut through more material. This will also translate to lots of torque which can also help to cut more material.

This change addresses an environmental concern. Now the saw can produce a faster RPM while still taking in the same amount of energy from the outlet or power source that it’s being supplied from. Since a different motor was not implemented it should greatly affect the amount energy being consumed by the motor. This change improves the performance of the saw by improving the RPM. This change is also cost efficient, and can possibly even save you money because less material is being used to create a component of the product.

2. Remove rough surface of handles, and replace with a rubber grip that is more ergonomically pleasing to the user’s hand.

One design change for the Skilsaw 54 HD at the component level is to change the handle. The current handle serves to complete its function as the handle, but can be improved. The material is made of plastic and in some cases may be dangerous for the user to use. For example, if the user is excessively working and he or she builds up sweaty palms they may choose to use the Skilsaw for a specific job. When the user uses the saw, their sweaty palms along with the plastic may cause slippage and thus result in the saw to fall out of the users hold with its blade still in motion. The current design includes a rough surface finish at the location where the user is supposed to grasp the handle. However, this design may not be sufficient enough to avoid slippage under the previously stated conditions.

The design change proposed involves removing the rough surface finish or “bumps” placed on the handles at the location where the user would grasp the handle. The design change would introduce a rubber grip that would go on the handle in place of the rough surface finish or “bumps”. Furthermore the design would introduce a more ergonomic design that would include grooves for the user’s fingers to slip in place. This would provide a firmer grip than that of the current handle. This change would be made by changing the design of the mold, to exclude the rough surface finishes and introduce the grooves for handles. This change will not be difficult to implement because it just involves changing the design of the mold for the injection molding process which can be reused multiple times. The manufacturer would produce the rubber through compression molding. If this process is not possible to be done by the manufacturer, the rubber grip can be produce at another plant and sent to the manufacturer. This change would promote performance by allowing the user to have a better and more secure grasp over the device and leave less room for error in their specific cutting job. Also this change would improve serviceability by reducing less damage to the device. With the device being more securely held by the user, it will be less likely for the product to be damaged from slipping out of the users hold. Thus it could help

reduce servicing for the device, and benefit the manufacturer by reducing costs for servicing. To implement this design it would cost the manufacturer more capital. The design change may also reduce the possibility of law suits due to safety issues. The design change is meant to make the product safer with the rubber and ergonomic hand grooves. However the ease in serviceability, reduction in necessary servicing, and increase in safety that the design change would bring about would probably outweigh that cost. The removal of the rough surfaces and the placement of the rubber grip along with hand grooves may be expensive at first to implement because it would involve creating a new injection molding, but eventually would pay itself off. Thus the actual price of the product will only go up slightly and will still be able to be offered to the initial target audiences. This design change would address societal concerns mainly by improving safety. As mentioned previously, the introduction of the rubber handle grips and ergonomic hand groove design would allow the user to have a better and more secure grasp on the handle and thus the device. This would reduce the risk of the Skilsaw falling out of the hands of the user thereby avoiding dangerous circumstances. The society, community, and consumers would feel safer with this design change.

3. Add a rechargeable battery to the saw.

One issue with the saw is that the length of power cord isn’t very long. Considering that the saw is meant to be very portable a short cord may cause problems with being able to use the saw. A regular household with one circular saw that is used for handy work could be used at all different sections of house, and could be needed in more than one place at a time. Having to unplug the saw each time and plugging it in somewhere can cause the user a hassle. A rechargeable battery would give the user more mobility to reach areas that were harder to reach before.

A rechargeable battery could be designed to be placed on the bottom part of the handles. This placing will help to prevent from obstructing the user’s hands or vision of the cutting line. With the cord now gone, the saw is also more free for movement in different directions. Along with this the chance of the cord getting caught in the blade is now also gone, so the chance of the power source of the saw being cut isn’t ruined.

This change to the saw would have an environmental affect as well. By having a battery that charges, the saw only takes electricity in from outlet for a small amount of time, as opposed to it being connected for an extended amount of time while it’s in use. It also can affect the amount of energy being consumed by the saw. Varying rechargeable batteries have different amounts of voltage. These varying voltages have varying amounts of power that the saw will use, and the amount of energy consumed will also differ. This change can improve performance when using a high voltage battery, by providing power and energy to the saw, allow it to cut more lumber in less time. The price of the saw shouldn’t be affected very much by this type of a change, and could greatly improve its sales.



References

  1. "SKIL Circular Saw 5400." Web. 26 Oct. 2010. <http://mdm.boschwebservices.com/MDMCache/English%20%5BUS%5D//t10/0000000/r00753v-1.pdf>.
  1. Klenck, Tom. "Circular Saw Reviews - Best Circular Saws - Popular Mechanics." Automotive Care, Home Improvement, Tools, DIY Tips - Popular Mechanics. Web. 17 Nov. 2010. <http://www.popularmechanics.com/home/reviews/4205480>.
  1. "HowStuffWorks "How Electric Motors Work"" HowStuffWorks - Learn How Everything Works! Web. 17 Nov. 2010. <http://www.howstuffworks.com/motor.htm>.

Gate 4:Product Explanation

Purpose

Now that a detailed analysis of the dissection is complete, the product must be reassembled and final conclusions made. The purpose of this gate is to analyze all the information gathered thus far, organize it, and make detailed conclusions about the product. In order to do this, a step by step process of the reassembly complete with pictures was documented, some questions were answered, and three design revisions were recommended.

Project Management: Coordination Review

Cause for Corrective Action

As the group continues to move forward toward the critical project review of the Skilsaw 54HD, a reassessment of the work completed thus far as well as the management plan must be done. In gate 2 many corrections had to be made. Many unanswered questions cost the group a variety of points on this gate of the project. Many questions from the table within gate 2 were not answered sufficiently nor were they answered specifically. These portions of the project will be corrected by going back and reassessing these questions and answering them more specifically. Removing the roller pin during the gate 2 dissection was rather tedious and involved some thinking. For that the group had to improvise because the proper tools were not in the lab. To do this the group used a hex key and a mallet and used this to hit the roller pin out of place. Other than this, no other corrections need to be made to gate 2.

In gate 3 some minor revisions need to be made. The cause for corrective action of gate 3 must be reassessed and specific issues had to be explained more carefully. In order to do this, the group will go back and reassess this part of gate 3. During the analysis section and the design revisions section of this gate the group needed to be slightly more specific and answer some other questions to help better analyze the product. The group also needed to use imagery in these sections to help better visualize this section of the gate. The group will address these issues by going back and inserting images and reassessing and answering questions.

In gate 4 problems had to be assessed in the reassembly of the product. Initially for the reassembly the group had decided on assembling the product backwards from the disassembly approach. As the group began to reassemble the product it was evident that this could not be done. In order to reassemble the product in a more efficient manner the group decided to put the product back together in different sections and then join the product together in the end. Another problem faced by the group was the constant slipping out of the armature from the carbon-brushing set’s holding. The carbon-brushed set had 2 surfaces which held the armature via springs, but if the armature were pulled out slightly or slipped out the spring loaded ends of the carbon-brush sets would not allow the armature back into place. To overcome this, the group put that section of the product together and a group member held it in a manner that it wouldn’t slip out. Another problem was when the group would reassemble certain pieces and they would interfere with the placement of other pieces which also had to be put on later on. This happened with the placing of the handles. The handles were placed in between the protective cover and the housing cover and the group didn’t account for this. Because of this the group then had to unscrew the protective cover and guard plate from the housing cover and place the handles in first. No other issues had to be addressed in this gate. The management plan is working thus far because of the group’s ability to work well together and work well within the time period’s given in the Gantt Chart. There are no unresolved problems or challenges to be addressed at this time that could hinder the group’s ability to finish the project on time, therefore no further action needed to be taken. No challenges within the management plan have been met yet, except for the group being able to meet as regularly as scheduled. To make up for this the group has met occasionally on weekends in meetings set up after class. Any future challenges will be overcome with group meetings, in a timely fashion with brainstorming.

Product Archaeology: Product Explanation

Product Reassembly

Below is a step by step guide on how to reassemble the Skilsaw 54 HD.

Disassembly Instructions
Step Number Step Instructions Tools Used Time Consumption Difficulty of Step Picture of Step
1 Insert the Pinion shaft into Guard plate by hand, with the screw of the Pinion shaft coming out of the Guard plate Hands 2 seconds 1
step 1
2 Insert the other the end of the Pinion Shaft along with the Guard plate into the Protective Cover Hands 2 seconds 1
step 2
3 Insert the two hexagonal disks onto the pinion shaft end, coming out of the guard plate by hand. Hands 2 seconds 1
step 3
4 Insert hexagonal screw with washer into the connected hexagonal disks pinion shaft and guard plates. Tighten the screw with the wrench provided with circular saw. Hands, Wrench (Provided with Saw) 1 Minute 2
step 4
5 Insert the Armature into the back of the housing by hand, by removing the back of the housing and carbon-brush set. Then put the carbon-brush set back as they were, holding the armature in place. Hands, Torx T30 Screwdriver 2 Minutes 30 Seconds 3
step 5
step 5
6 Insert trigger into handle by inserting the respective parts of the cord and trigger to their respective places made in the handle. Hands 30 seconds 2
step 6
7 Put the two parts of the handle together by hand. Hands 3 seconds 1
step 8
8 Slide handle onto the space provided on the fixture on the housing by hand. Hands 3 seconds 1
step 8
9 Screw the 6 screws into the handle using Torx T20 screwdriver to hold the two parts of the handle and its contents in place. Hands, Torx T20 Screwdriver 3 Minutes 2
step 9
10 Insert the casing foot around its respective fitting around the housing. Connect the two parts with the roller pin. This step required improvising because we did not have a roller pin punch, and we used a mallet instead Hands, Hex Key, Rubber Mallet 2 Minutes 3
step 10
step 10
11 Insert wing nut onto casing foot by hand, to connect the casing foot to the housing. Hands 10 seconds 1
step 11
12 Connect the armature along with the housing to the back of the protective cover, by hand, aligning all holes for screws properly. Hands 5 seconds 1
step 12
13 Securely connect the armature with housing to the back of the cover with the 4 long screws and 3 short screws using Torx screw driver. The 3 short screws were screwed on top of the bearing flange (The flat straight edge of the bearing flange must be aligned with the straight edge of the protective cover.) Hands, Torx T20 Screwdriver 5 Minutes 3
step 13
step 13
14 Insert Spring with hook, to connect the guard plate and protective cover. Hands 1 Minute 1
step 14
15 Insert screw with the rubber stopper into the protective cover with Torx screw driver. Hands, Torx T20 Screwdriver 30 seconds 2
step 15
16 Insert the red lever with screw into the guard plate and tighten with Torx T20. Hands, Torx T20 Screwdriver 30 seconds 2
step 16
17 Screw on the lever onto the screw coming out of the protective cover on the side of the front red lever with Torx screwdriver. Hands, Torx T20 Screwdriver 30 seconds 2
step 17

All challenges and difficulties, and how they were overcome, are outlined in the cause for corrective action.

Ease of Assembley:

Now that the assembly of the product has been completed, an assessment of the difficulty of assembly is necessary. The difficultly of each step is outlined in the table of steps taken to reassemble the product.

A meaningful scale can be defined for the assembly based upon a few factors. The amount of thinking which it takes to assemble the step, the tools it requires and how time consuming the step was. A scale is defined below:

Difficulty Scale:

  1. This step is very easy and simple. It can be done very quickly, does not require much thinking, and can be done by hand.
  2. This step is still fairly simple. It can be done fairly quickly, may require some knowledge of and use of tools, and a little thinking.
  3. This step is a little more complex. It may require the knowledge of tools, and the ability to improvise with the lack of required tools. It can be completed after some thinking on how to approach.
  4. This step is at the hardest level. It may require the knowledge of tools, and the ability to improvise with the lack of required tools. It can be completed after some thinking and multiple different approaches to complete the step.

The Skilsaw 54 HD was most likely put together in some form of an assembly line. The various components of the product shown in the parts list were most likely already manufactured and delivered to a specific location or plant for assembly. These components would have been made by different manufacturing processes at different locations by the manufacturer or bought by the manufacturer. Eventually all the components for the saw would be shipped (the amount necessary to assemble the desired number of products) to a location for assembly. The products components were most likely put together as different physical subsystems. This may have been completed with the use of automated machines, which assemble specific physical subsystems repeatedly or by human factory workers who put the subsystems together with specific tools and by hand. In this way the manufacturer assembles different physical subsystems and then brings the subsystems together to finish the overall assembly. This overall final assembly may be performed by either an automated machine or by a human worker.

The assembly of the product is similar as the disassembly of the product, but not the same. The main difference between the disassembly of the product and the assembly of the product is that they can’t be done in the same order. The logical idea for the group was to attempt to assemble the product in the reverse order that it was disassembled. The group attempted to do this, but that plan didn’t work, as some components would get in the way of others. In order to deal with this problem the group began to assemble the larger components of the saw together and was going to connect these larger components together in the end. One problem with this was the fact that the armature kept slipping out of place, and the group also didn’t notice that the handles had to be put in place in between the guard plate and protective housing. In order to deal with problems like this, the group would continue putting components together, and when components would interfere, the group would remove the last component which got in the way and then would insert the correct component, and continue putting the saw together in this trial and error method. Another difference between the assembly of the product and disassembly of the product is that when disassembling the product not much consideration has to be taken into which order to take the saw apart, so there are various ways to disassemble the product. When putting the saw back together, the order in which it is assembled is not as varied, though there are still different orders in which the saw can be reassembled, it is much less varied than the amount of ways in which it can be disassembled. The reason for this is the fact that when putting the saw back together many components may interfere with the placement of others if they’re not put back together in a specific order.

Design Revisions:

1. Add a vacuum and dust collector.

One design change at the system level that is recommended is the addition of a dust port to the Skisaw. This revision would introduce a port for the user to connect a vacuum to the Skilsaw to collect the sawdust created by operating the circular saw. The dust port would be placed in front of the Skilsaw (because the dust may be collected at the source, See Figure- 1-Dust Port Placement and Figure2- Dust Collection). It would be beneficial to place the dust port here instead of the back of the saw because the dust has less distance to travel and thus less dust will fall to the ground traveling a shorter distance(See Figure 2-Dust Collection). The addition of the dust port may provide an initial cost to the company because the current Skilsaw 54 HD model must be modified, and a dust port must be designed and manufactured. However, the company would benefit from the revision relatively quickly because it would be unique from other circular saws and thus increase sales. The additional material cost for the dust port may be balanced with the reduced cost in the amount of material for the protective cover. This would be possible because a portion of the protective cover material must be removed in order to place the dust port (Figure 3- Material Replacement). The dust port would improve performance by removing dust from the material being cut and the saw blade, thus allowing for better cutting. It will improve serviceability by preventing dust to be collected within parts of the Skilsaw and thus increase the lifespan of the product. An increase in the products lifespan, would lead to less servicing for the product. Also it would make it easier for the product to be fixed, with less dust in the way between different parts of the saw. The product would still stay in the same cost range of 100-150 dollars, and would still have the same target audience with a small but beneficial change. This revision would address a societal concern by reducing the amount of sawdust spread out in the vicinity of the Skilsaw while it is being operated. The current design of the circular saw produces a large amount of saw dust like other similar circular saws. This revision would also address the societal concern of safety. With the dust port and the user’s connection of a vacuum cleaner, the dust port would aid in reducing the number of wood chips and saw dust circulating in the air while the saw is being used. It would reduce the risk of the user being hurt by flying wood chips and/ or breathing in saw dust. The design revision with a dust port would also address environmental concerns, by reducing the amount of saw dust circulating in the environment. For example, when construction workers or the users have to operate the Skilsaw outdoors for a task they can connect a vacuum pipe to the dust port to reduce the amount of saw dust released into the air.

Revision Photos:

Dust Collection

Point 1 is where the saw dust is created.

Point 2 is where the dust will be collected. This is a short distance from the source and allows the vacuum to collect the dust right away after the saw dust is being produced.

If the Dust Port is located at position 3, the dust will travel around the blade and be collected. However some of the dust will be lost within the time of the sawdust reaching point 3.

Dust Port Placement


Material Replacement

2. Add a L.E.D. lamp to the front of the saw.

Adding a light to the front of the saw affects the operation of the saw on a system level. This helps to improve the use of the saw because it can be used in an outdoor environment at the end of a day, or when it’s dark outside. This improves serviceability because it lengthens the amount of time per day that a person can use the saw to a limitless amount of time.

This affects the use of the saw globally because it can be used more often in different areas of the world now. For example if the saw was to be used in a place Alaska where most of the day is dark, then the saw could be used more often than what it usually is, making it more efficient.

This also affects the use of the saw in a societal sense because it allows for a longer work day. In many societies working days are much longer than in other areas. If these workers are working in an outdoor area the addition of a light can help the workers to work later into the evening; so the extension of the time during the day in which the saw can be used, also goes hand in the hand with the length of the work day of the worker.

This addition can also affect the saw in an economic factor. Though it would cost slightly more to produce these saws with lights they would be pay off in the long run. This is because the saws could be used for a longer period of time per day, which means they’re being used more often and to more of their full potential.

The addition of this light also has an environmental affect. Since the saw has a light then the use of an external light bulb is not necessary. The use of an L.E.D. in place of a regular household light bulb uses less energy which in turn is better for the environment and more efficient.

For the previously stated reasons, the addition of an L.E.D. light at the end of the saw would make it a more efficient saw as well as more serviceable. It will become more efficient because the saw will be able to be used for a longer time of the day as opposed to being restricted to just day time outdoor use. It’s also more serviceable because it can now be used more easily in different countries with short times of daylight, for a longer amount of time than it would if it didn’t have an L.E.D. light.

Revision Photos:

Placement of Saw L.E.D. lamp. The arrow and number 1 number indicate where the L.E.D. light will placed, on the housing cover of the circular saw. The red beam of light is the laser cutting guide used by this partucular type of saw. Note that the laser is built in, meaning the manufacturing process of the blade cover required major changes.


3. Add a cutting guide utilizing light

Installing a cutting guide that uses light is a simple way to improve the usefulness of the product by helping the user cut in a straight path. The guide could also be helpful if the desired path is not straight because it allows the user to visualize the instantaneous direction of the cutting path.

Possible methods to accomplish this would to use a laser or L.E.D’s as the light source. The most economical source would be an array of L.E.D’s from which the light is diffused in an enclosure and emitted through a slit resulting in a strip of light. A laser would result in a stronger beam of light but it would also be significantly more expensive.

The L.E.D enclosure can be mounted to the top blade cover and calibrated as an extension of the manufacturing process without any need to make major changes to its production. It doesn’t change the process significantly to add the L.E.D because it can be done manually by a factory worker as opposed to changing the process of making the blade cover to include a built in enclosure. By increasing the utility of the saw while maintaining its low price could offer the general public a higher quality option when purchasing an affordable saw.

From an economic standpoint, manufacturers should ideally attempt to offer the highest quality and lowest price in order to compete with other manufacturers. If a potential customer is choosing between two similar affordable saws and one option gives you the bare minimum while another saw gives as many possible and affordable perks usually reserved for higher end models, it is likely to make the difference in the customers choice.

References

  1. "Craftsman 7-1/4 Circular Saw with Laser Trac and LED Worklight." Sears.com. Web. 9 Dec. 2010. <http://www.sears.com/shc/s/p_10153_12605_00910870000P?sid=IDx20100622x00003d&srccode=cii_16079562&cpncode=19-55469192-2>.
  2. "Skil Circular Saw 5400." Skil Circular Saw 5400. Skil. Web. 9 Dec. 2010. <http://mdm.boschwebservices.com/MDMCache/English%20%5BUS%5D//t10/0000000/r00753v-1.pdf>.
  3. "Light-emitting Diode." Wikipedia, the Free Encyclopedia. Web. 09 Dec. 2010. <http://en.wikipedia.org/wiki/Light-emitting_diode>.
  4. "LightEmittingDiodes.org Chapter 5." Electrical, Computer, & Systems Engineering @ Rensselaer. Web. 09 Dec. 2010. <http://www.ecse.rpi.edu/~schubert/Light-Emitting-Diodes-dot-org/chap05/chap05.htm>.
  5. "Laser Diode." Wikipedia, the Free Encyclopedia. Web. 09 Dec. 2010. <http://en.wikipedia.org/wiki/Laser_diode>.