Latest revision as of 01:04, 20 December 2010

Gate 1: Project Planning

Work Proposal

Skil 54HD Circular Saw

Intro to Group:

• Faisal Jaffri
  • Faisal has had some experience in CAD. Faisal has taken more courses that relate to our object. Faisal has worked in his dads shop often, which involved working on cars so he has had a lot of experience with different tools. His strengths include the ability to communicate with others effectively as well as a strong background in mechanics. Faisal's weaknesses include his ability to stay focused on the task and occasionally makes grammatical errors. His weaknesses require valuable skills which he should improve.

• Michael Schwab
  • Michael has also had some experience with the CAD program as well as Rhino. Michael has had experience with this specific tool, which may benefit the group as well has having basic knowledge of tools being introduced to many in high school. Michael is not very strong in the public speaking area, which could use improvement; This surly affected our role designation decision. Also, Michael occasionally procrastinates on assignments.

• Kyle Wiedemann
  • Kyle has done some work with the CAD program. Kyle was also pretty familiar with the Autodesk inventor program at his high school. Kyle has the basic knowledge of how tools are suppose to be used and the process of disassembling something. Kyle has had public speaking experience, but has not had to present anything to a large group of people. This is a weakness for the group because Kyle has not had experience with a large group of people, similar to the amount of student in our lecture.

• William Dutcher
  • William has had the same CAD experience as the rest of the group, just introduced to the program. William is able to use tools and able to take things apart, which is important. William has also had experience in a machine shop. William seems to be the best technical writer in the group according to the first few assignments.

• Sherif Omar Azmy
  • Sherif has had some beginner level work in the CAD program just like the rest of our group. Sherif has had experience working with electronic systems. Sherif has also had some experience in modifications to cars. He is not a very strong technical writer which is a weakness, but he is very familiar electronic devices, both hardware and software.

Disassembly/Reassembly Plan:

This part of the project will consist of our group taking apart the saw from the outer components inward. We will write down, take pictures, and diagram every step so that we have a clear and concise record of our actions. We all plan to participate taking the object apart. This will introduce each group member with the equipment so we all have an understanding about taking the object apart should another member be busy. It will also allow the deconstruction process to be much faster. We plan that the necessary tools for the job will be readily available being that it is a home use product and is designed for tools found in an everyday house. However, if we get to a position in which we need a specialized tool our group will discuss it and decide what the options are. For the reassembly of our product we will use our carefully noted directions for disassembly and reverse the process. It will require the same type of tools as disassembly, but used in reverse order. We will then test the product to assure that it is in working condition and properly assembled. Management Proposal:

Project Roles:

Project Manager: Kyle Wiedemann (kylewied@buffalo.edu)

The project managers job includes being the one that gets the group members information and putting it together in a neat and organized way. The project manager has the responsibility of getting information from the others so that transition to the wiki page is easy. The manager helps decide whether meetings take place depending on the amount of work that is done and needed to be done at the time.

Wiki Expert: Michael Schwab (mrschwab@buffalo.edu)

The Wiki Page Manager has a job to become familiar with the usage of the wiki page. This person is responsible for putting the data into the wiki page with a neat format and good usage of tables or charts. This person is in charge of getting photographs, charts or graphs to the wiki report.

Deconstructionist: Sherif Omar Azmy (sheriazm@buffalo.edu)

The Job of the deconstructionist is to be the person who takes apart the Skil saw and becomes familiar with the saw and its components. This person also has the responsibility of putting that product back together all in one piece.

Team Scribe: William Dutcher (wsdutche@buffalo.edu)

The team scribe has the responsibility to write everything down. This is the person who writes down a detailed document of what went on during the project, this is especially important in the dissection of the saw in order to put it back together right. This person should also document when meetings occur, when they start, end, what was covered and who was there.

Time Coordinator: Faisal Jaffri (faisalja@buffalo.edu)

The job of the time keeper is to make sure that project is going to be done on time. This includes a creation of a schedule of dates that show a plan when possible meetings could be. If any part is lagging behind the others, the time keepers job is to help them in any way they can. The time keeper could be considered to be assistant to everyone.

Management Proposal

Schedule Chart:

This Gantt chart is going to act as schedule for our group. We plan to be working on the specified task while there is a red bar present to a corresponding task.

Meetings:

Meetings will take place after every session of class either in the lab or in Capen Library for approximately one hour and the hour before lecture. The idea of having meetings after this class is based on the fact that every member of our group is done with classes after that class so we all know that every other member should be able to attend. At each meeting we will document who is there, and if they are not there we will try to document why they were not there. The goal of the meeting is to make sure everyone is doing their part of the project and to insure that our group will be able to make the given deadline. The decision on whether the group will work together during the meeting will be decided by the group based upon what is all ready done and what is needed to be done.

Group Conflicts:

If there is a conflict in a way to do something, it will be dealt with by allowing the two who have different views to explain their view to the others in the group present. These other people in the group ultimately side with one way or another, majority of votes wins. If there is a conflict that involves one not doing their work sufficiently or not showing up to the meetings then there will be a notation in the report that says what he was assigned and did. This will be followed with a notation of who covered their work, and the possibility of an email to the instructor if the conflict is worth that attention.

Preparation and Initial Assessment

Preparation and Initial Assessment:

This product was intended to be sold in America, Canada, and Puerto Rico. The 54HD Skil saw's design is similar to Michel Electric Hand Saw's first, patented circular saw of 1923. It is intended to be a small yet powerful circular saw that can make precision cuts at different depths and angles with ease. The economic concerns were trying to make a saw that could have enough power and versatility while still selling for a relatively cheap price as well as supporting the product in the warranty honoring countries of America, Canada, and Puerto Rico. A global concern for the developers of this product is where to acquire the materials.

The intended use of this product is to make precision cuts in basic building materials such as wood or light metals. This product given its size and power output would primarily be used for small home type projects although it would have the capability to be used professionally. For example, it can be used by a carpenter for construction of a house. There is only one type of job for this piece of equipment and that is to cut materials. However, it provides some options as far as depth of cuts and the angle at which cuts are made. There is also an option to replace or switch the blade being used.

There are a few types of energy that are used in the Skil saw. The first type of energy that is used is electrical energy. Another form of energy that is used by the Skil Saw is mechanical energy. The saw runs by importing energy through the electrical cord that plugs into the wall. The energy provided through the wall outlet allows the saw to function by getting that energy to other parts of the saw by converting one form of energy to another. The energy travels from the outlet in the wall to the electromagnetic motor. The electromagnetic motor uses magnetism and electric current to generate power that is transmitted through the shaft of the motor into the gear system, which is then transferred to the blade of the saw. This is a transformation of electrical to electromagnetic to mechanical energy.

There are approximately twenty five components to our product. These components are listed in the table below.

Many of the components are fairly simple, such as the screws, stoppers, the blade wrench. A few of the components have a mild complexity such as the housing cover, trigger, blade guard and blade housing since they require dimensions to be pretty accurate and precise in order to give a straight cut while giving the user a good aesthetic feel.

Other parts such as the bearing, the motor and the carbon brush set are very complex. The Carbon Brush set allows the motor to work when positioned right, the motor is made up of coils of wire inside and magnets to transform electrical energy to mechanical energy. The bearing assembly is complex because of the individual ball bearings and the precision required in the manufacturing of the assembly. The component interactions are very complex. For example, the Carbon Brush must be positioned correctly for the motor to work, which is where the transformation from electrical to mechanical energy occurs. The gear system that turns the blade is also very complex because of the gear ratios relationship. This is complex because there was most likely a desired rpm of the blade so it could make clean cuts.

The materials that are clearly visible are plastic, used for the handle and motor cover, and both stainless and galvanized steel (iron, aluminum, or steel coated with a thin zinc layer), used for the metal disc (or blade) and the trim around it. Other materials that are not visible, but are likely to have been used are aluminum, copper for inside the moor, and different kinds of steel.

The Skil saw has a knob on the front designed for a comfortable and firm grip as well as also preventing possible kickback. The trigger handle has a grip on it, increasing control over the tool. The saw appears to be designed for right handed people; otherwise the blade will be between the user and the two handles. The saw also has a line guide, helping the user ensure straight cuts through the material.

The Skil saw is not very intuitive because the user must do everything in order to accomplish the task. A saw that is intuitive would perhaps slightly move through the material itself because it knows the user will have to force the saw forward through the material anyways. The Skil circular saw can be very easy to use, if the user reads and comprehends the owner's manual and is above a desire age determined by the manufacturer. Power tools, such as the circular saw, are very dangerous and the manual should be read by the user to ensure safety as well as ease of use.

There is not a lot of maintenance required the Skil circular saw. One important part is the blade. Working with a dull blade can make cutting difficult and can be dangerous, so any dull blades should be replaced with a new one. Other maintenance required is simply checking components such as the tightening bolt, the screws on the handle, and the blade arbor bolt. Checking these components can greatly reduce the chance of injury. Also, the user should use clean compressed air to remove any foreign materials from the saw. Some parts of the saw may be difficult to replace, such as anything inside the plastic outside covering. Overall, the maintenance for the Skil circular saw that is down by the user is very easy considering the most common parts that would need to be replaced are the trigger (easy to get to) and the blade (tool provided by manufacturer).

There are a plethora of product alternatives to the Skil circular saw. Skil must compete with brand names such as Milwaukee, DeWalt, and Craftsman. Perhaps one of the better brands of circular saws that is a major competitor is Milwaukee. The advantages of a Milwaukee circular saw are the comfort of use, reliable blade guard and brake, quick bevel adjustments, sturdiness, and a five year warranty. The Milwaukee saw does have its disadvantages though. The saw is not designed for left handed users, so it blows sawdust towards the user. Also, the base tends to slip occasionally and the rip fence is extra money, about ten dollars. The Skil circular saw does not really compare to the other saws that are available, but the price is lower. A Milwaukee saw that is the most similar to the Skil 54HD saw is $139, while the Skil 54HD saw is about $55 on the website of a Skil retailer founded on the Skil website. The DeWalt saw can also be found at about $139.

http://www.consumersearch.com/circular-saws/sears-craftsman-10871/specs - Specs for Sears Craftsman 10871

http://www.consumersearch.com/circular-saws/milwaukee-6394-21/specs - Specs for Milwaukee 6394-21

References

"Circular Saw Maintenance Tips." Home Improvement Tips, Tool Reviews, How-To Articles, Cool Products, Free Tools, and DIY Resources, All Delivered Funny. Web. 02 Oct. 2010. <http://homefixated.com/2010/03/11/circular-saw-maintenance-tips/>.

"Circular Saw." Wikipedia, the Free Encyclopedia. Web. 06 Oct. 2010. <http://en.wikipedia.org/wiki/Circular_saw>.

"Hot-dip Galvanizing." Wikipedia, the Free Encyclopedia. Web. 07 Oct. 2010. <http://en.wikipedia.org/wiki/Galvanized_steel>.

"Milwaukee 6394-21 Review." Product Reviews and Reports - ConsumerSearch.com. Web. 06 Oct. 2010. <http://www.consumersearch.com/circular-saws/milwaukee-6394-21>.

"Milwaukee 6394-21 Specs - Specifications for Circular Saw." Product Reviews and Reports - ConsumerSearch.com. Web. 27 Oct. 2010. <http://www.consumersearch.com/circular-saws/milwaukee-6394-21/specs>.

"Sears Craftsman 10871 Specs - Specifications for Circular Saw." Product Reviews and Reports - ConsumerSearch.com. Web. 27 Oct. 2010. <http://www.consumersearch.com/circular-saws/sears-craftsman-10871/specs>.

"SKIL 7-1/4" Circular Saw 54HD." Fast Specialty Shopping - Toys, Health/Beauty Aids, Office, and Home. Web. 04 Oct. 2010. <http://www.gogoods.com/product/PPI-DS2445/SKIL-7-14-Circular-Saw-54HD.html>.

"Top 7 Cordless Circular Saw Comparison: Makita vs. DeWalt vs. Milwaukee and MORE! | ToolCrib.com Blog." At ToolCrib.com You'll Find Power Tools, Power Tool Reviews and Cordless Power Tools at ToolCrib.com, Your Tool Crib Online. Web. 04 Oct. 2010. <http://www.toolcrib.com/blog/2009/03/17/top-7-cordless-circular-saw-comparison-makita-vs-dewalt-vs-milwaukee-and-more/>.

"View Source - GICLWiki." Redirecting. Web. 01 Oct. 2010. <http://gicl.cs.drexel.edu/wiki-data/index.php?title=Group_3_-_Skil_Circular_Saw&action=edit>.

Gate 2: Product Dissection

Cause for Corrective Action

This is a group assessment of the work that was done during the disassembly of the Skil Saw compared to how our group planned to take the Skil Saw apart. This also includes everything that happened, even any group conflicts.

The Management plan of our group has been working out pretty well. We decided that the best time to meet would be right after class because everyone would be around campus and everyone stated that they should be free during that time. This plan made it convenient to meet after class. The meetings were held on Mondays and Wednesdays and lasted between a half hour and two hours. The group would start the meeting by figuring out whether we were on the right course for getting the gate done in time and exchanging any information for the gate with each other (Especially with the member uploading information to wiki up). If we were on schedule then we would simply assign the tasks needed to be assigned evenly throughout the group and then ended the meeting. This was our meeting routine when we meet, and we were able to complete our task on time with this meeting schedule.

Our group put the dissection plan that we proposed to good use. We followed our plan of just starting from the outside and working inward. The actual dissection of the Skil Saw was done in just one meeting that took place after class one day. The disassembly halted our group for a little while when we first started our disassembly, but after we got ourselves organized the procedure went very smooth. We had two people handing the Skil Saw and removing pieces from it with the tools that were required, one group member did a chart in Excel, another member took pictures to document our progress and the final member made sure that everything was done at the right pace so no one got too far ahead. This was done so that the order the saw was taken apart would be the complete reverse of how we put it together. During the dissection of the Skil Saw we noticed in several places that there was damage done during previous disassemblies. Some of these include the metal sleeve that connect a wire from the trigger system to the outer part of the electric motor, one of the washers for the inner part of the electromagnetic motor was bent terribly and finally the piece that held the blade plane to the body of the saw seemed to be forced back into place.

Taking the saw apart in one meeting shows that our group was able to work together, so it was not surprising that conflicts between group members did not occur. The small problems that took place during the dissection were quickly solved by the group. For example, the member of the group who did the table on Excel claimed he would probably be able to do a better job on the part where a description of how the difficulty of each question was. Someone else in the group wanted to do this part at first, but after hearing the comment from the other group member he quickly made sense of it and understood that the group agreed on this being the best way to approach that particular spot on gate 2.

Subsystem Connections

The motor and field magnet are two components that combined are called the electromagnetic motor. The field magnet is mounted physically on the plastic housing via two screws. The field magnet is connected to two wires, each with two split pieces that connect to the field magnet. Both wires are connected to the trigger subsystem. The field magnet makes the motor turn within the saw housing and a washer piece that is mounted at the other end of the plastic housing. The end of the motor is connected to the saw housing, to create a gear system. These are connected using screws rather than a glue or other adhesive so they are securely fashioned and will not move during use. The motor and field magnet work together with the force created by the magnetic field. The magnetic field force is created by the electrical charge put through it by the wires which then causes the motor to rotate with the right amount of torque. A fan that is placed on the shaft leading to the gears system is designed to help cool the inner system of the Skil Saw. Different materials could probably be used to create the electromagnetic motor system, such as silver instead of copper since it conducts electricity well, but since a desired rpm and performance is required for the saw then the best way to go is to choose the cheapest materials that still give the quality and performance desired by the designers.

The connection of the trigger and the electromagnetic motor with the wire is important, this is another subsystem to subsystem connection. Without the trigger completing the circuit and sending the current through the wire then the saw will not be powered and would not perform its desired function of cutting the specified material. This means that the trigger must be held at all times during the use of the product. The trigger has a total of four wires going through and coming out of it, along with another plastic piece that has been embedded as a safety feature. The two copper wires going through the trigger are white (positive) and black (ground), provide the electrical energy flow coming from the plug plugged into the A/C outlet. They are heavily insulated using rubber. In order for the trigger to bridge the connection between the two wires and thereby completing the circuit requires first pushing the safety feature button, which is operated by a spring mechanism, to either side horizontally (right or left). Once the circuit has been complete, two black copper wires (assuming one is positive and one is ground) are used to deliver the flow of electrical energy to the mechanical motor The motor shaft must be spun at a certain speed and allowed to create a certain amount of torque by the magnetic field force so that it can cut the material properly without any danger. The wires are made from cooper because they conduct electricity well and it is a fairly cheap material, which plays an important role for sales and the price people want to spend for certain products for certain tasks. Using a different material maybe cause a higher rpm or lower rpm for the saw blade, but since a specified rpm is desired for a proper cut changing the gear sizes could adjust the rpm to the desired rpm for proper cuts. So using copper may have the best combination of gear cost compared to other materials costs and their respective gear costs.

There is very fundamental connection between the electromagnetic motor system and the gear system. These two systems are connected physically where the gear intertwines with the gear on the end of the shaft of the electromagnetic motor. They interact through rotational energy and motion. This interaction is designed to create a desired rpm that will allow the saw to cut materials properly and create a smooth cut and does not cause safety problems. The material is chosen depending on its properties and its price, which determine the quality and performance of the saw. A saw could use a strong material for the shaft system and a different gear system that results in an increase in performance. Such a saw would cost more and not be as economically viable. Some environmental concerns could be from the material being cut, such as the waste produced during the production of the material being cut. The price of the steel and motor materials were an influence economically, and an overall global factor is customer location and were to get materials from.

There is also an Air flow system that interacts with pretty much everything. Through dissection our group noted that there were clearly places were air was intended to flow out of the system and carried heat away as well as direct sawdust away with help of other systems. These systems include the body system of the saw with the open slits in the body for air to flow out and the blade guard and base plate directing saw dust generally away from the users face, although precautions are highly advised to prevent injury to the eyes. Without a cooling system the inside of the saw could easily overheat and cause problems for the user, which is definitely not a desired outcome.

There is definitely a specific arrangement of the subsystems. For example, the first subsystem that is use by the person using the saw is the cut-adjustment subsystem. This sub system allows the user to be able to set up the dimensions of the desired cut before even giving power to the saw. The next subsystem is the trigger system. This is one of the most important subsystems in the circular Skil saw because it must be held in to complete the circuit at all times during use of the product, others the product, material being cut or the user could suffer damage. The trigger allows the electricity from the cord plugged into the wall to travel into the coils of the electromagnetic motor. This is where the electromagnetic motor changes the electrical energy into the rotational energy of the motor. The energy that comes out of the motor through the shaft goes to the gear subsystem, which changes rotational energy into mechanical energy of the blade cutting the specified material. The gear system could not be in front of the electromagnetic motor cause the user needs electrical to mechanical energy, not mechanical to electrical. Also the gear system could not be next to the trigger system cause the blade cannot use electrical energy directly, it must be converted in order for the blade to spin.

There were many concerns when the Skil saw was being developed, including economic, social, environmental, and global concerns. The economic concerns were material performance and cost, and where the materials came from. Certain areas of the world have real cheap labor, but the quality of the product is not as good. Other areas of the world have more expensive labor, but make a significantly better product. Using a good materials mean the product will last longer. There were many social concerns during production of the Skil saw. The most important is concern is safety. When used properly, as well as the safety guards, the saw can be very safe. Another social concern is noise. Power tools such as the circular saw are very loud, which could bother many people nearby. The last social concern is the kind of job being done. The developers needed to design the saw to handle the conditions that the user is using the saw under. An environmental concern during development of the Skil saw is disposing unused parts, or saws as a whole. Proper disposal is required when throwing away the saw or parts. Finally, there is a global concern, which is the potential buyers market. This product was intended to be sold in the United States, Canada, and Puerto Rico.

We created a scale for our dissection from 1-10. A score of 1 would mean that this step was very easy and required only hand work and could be done in seconds. A score of 10 meant that the step took multiple tools and processes as well as taking a length of time (ex. 30 min). A score of 5 meant that the step took moderate work including tools and a few minutes of time for the disassembly of the part. Our product is designed with an easy disassembly, however not all of the parts are truly designed to be taken apart by a normal user. Parts like the blade guard and housing are very quick to take apart using same size torx screws. A head bolt tool provided and secured in the base of the saw allows for easy removal and switching of different saw blades. The trigger casing and handle made of plastic are intended to be taken apart so if the trigger mechanism breaks it can be replaced easily. Other parts like the internal electromagnetic motor coils, gear, fan, and shaft are not intended to be disassembled. Due to the product cost it is easier for the consumer to just buy another saw. The saw is also built with components for quick adjustments including the options to change the depth and angle of the cut, which can be adjusted by a simple hand of the user.

References

Robert Bosch Tool Corporation. Skil Tools. Robert Bosch Tool Corporation, 2010. Owners Manuals and Parts Lists. 2010. Web. 21 Oct. 2010. <http://www.skiltools.com/rb/Development/NA/POWERTOOLS/SKIL/mcms/Templates/Unique/OwnerManualPartList.aspx?NRMODE=Published&NRNODEGUID={16095CF6-D5BB-47D6-9A1F-C8588D677C03}&NRORIGINALURL=%2fen%2fCustomerService%2fPartsListsOwnerManuals%2f&NRCACHEHINT=Guest>.

Gate 3: Product Analysis

Coordination Review

Our group has been working together pretty well throughout the project, with a few minor bumps along the road. These include the assigning of roles throughout the project. This is the one problem that seems to come up with the beginning of every new gate. The first few times as a group we discussed who would like which role and why. These all ways seemed to work, however the role assignment for gate 3 was a little different. Each individual of the group read over the gate before a meeting, and at the start of the meeting if you knew what you wanted you wrote your name under that section of the gate. There were no problems with this assigning system, but this system is not recommended to avoid any group conflicts, just because it works once doesn’t mean it will work again. Besides these minor setbacks at the beginning of the gates there have not been any conflicts. There are no unresolved challenges in the group, The last one solved was which individual would do the presentation, which was not hard to do since the individual chosen doesn’t mind it at all, especially when that individual didn’t have to work on gate 4, but just work on the presentation.

Component Summary

Component and Part Number	Photo	Component's Function	Materials Used	Manufacturing Process	Reason component is made out of specific material	Attributes of Part	Part # in "Saw Explosion" found above
Housing 2 610 912 983		Hold the internal electromagnetic motor in place and keep the shaft and inner components protected.	Plastic	Plastic injected into mold and let to solidify	Plastic is a durable material which is light making it easier on the user. Plastic is also relatively cheap which will keep the product cost down	Hard plastic protects inside and allows flow of air. Also aesthetic shape given to the housing	1
Field Magnet 2 610 341 367		Provide electrical current which causes the inner electromagnetic motor to rotate providing a turning force to the saw blade	Copper and Plastic	The copper wire is drawn providing the small cylindrical shape, the plastic is injected into a mold and let to solidify	Plastic is cheap and a good material for a housing for the copper wires because it is a good insulator for the copper wires which have current put through them. The copper wires are a good conductor of electricity while also being cheap to produce	Wires are spun in a certain coil pattern to provede optimal electromagnetic force used to spin the inner electromagnetic motor	2
Trigger 2 610 917 325		Act as a switch allowing power to motor when operator desires	Plastic	Plastic injected into mold and let to solidify	Part is made out of plastic because it is durable and can take a constant pressing by the user. It is also cheap and will keep parts cost down	Part is made to fit the shape of the human finger which is what interacts with it. Also built with a safety the user must toggle for extra protection	4
Screw 1 2 610 341 364		Holds plastic handle molding of the saw together	Steel	Steel is extruded and then lathed to apply the threading	Part is made from steel because it has to be strong enough to hold the handle together while still being cheap enough to keep total product cost down	(Three) Torx 20 bit screws are used	19
Screw 2 2 610 341 365		Holds the blade housing together with the housing of the saw (shaft, electromagnetic motor, field magnet, etc)	Steel	steel is extruded and then lathed to apply the threading	Part is made from steel because it has to be strong enough to hold the saw blade housing together with the plastic housing of the body of the saw while still being cheap enough to keep total product cost down	(Three) Torx 20 bit screws are used	27
Screw 3 2 610 347 103		Holds the electric field magnet inside of the housing component of the saw	Steel	Steel is extruded and then lathed to apply the threading	Part is made from steel because it has to be strong enough to hold the field magnet in place, while still being cheap enough to keep total product cost down	Torx 20 bit screw	39
Spring 4 2 610 914 057		Pushes the blade guard back to the safe position when the blade is not being used to cut material. Acts as a safety device for both the saw when it is put on the ground and keeping the user safe froma spinning blade	Steel	Extruded steel which is then spun to give it the shape and properties of the spring	Part is made from steel because it is a bendable material to fit into the spring shape and then a reliable material once the spring is finished	Keeps both the user and saw safe. This is stopped by the Rubber Stop inside the blade housing	33
Casing Foot 2 610 913 231		Keep the saw steady on surface and allow precision cuts to be made by using engraved dimensions and leading lines	Galvanized Steel	Steel which gets stamped out and engraved with dimensions	This hardened steel provides a reliable base for the saw that cannot be easily bent or broken and it also is rust resistant	Engraved with dimensions so that operator can mace precision cuts on a steady path	40
Head Bolt 2 610 346 554		Hold the saw blade within the saw blade guard connected to the rotating gear. It also keeps the blade spinning in a smooth circular motion	Steel	Piece is extruded steel. Then threaded using a lathe and forged at the end	Steel provides a strong enough material to overcome the forces acting on the saw and keep it stationary while allowing it to rotate. Also steel is relatively cheap which brings total cost down	Wrench tool attached to saw made to fit this size so as to allow easy switching of blades while on site	52
Wing Nut 2 610 029 562		Allow for quick adjustments while being strong enough to keep them secure one selected	Steel	Steel was forged and then stamped to get desired shape. Then drilled to get the hole for the screw.	Steel is strong enough to keep the part secure once the selection has been made. Also durable in case of impact on the nut	Wing nut feature allows for quicker readjustment when on the job. There is no need for big wrenches or torx kits	42
Rubber Stop 2 610 341 394		Protect the saw blade guard from damaging when released from the position while cutting. Blade guard swings down 180 degrees and the rubber stop is there to protect it	Rubber	Rubber is injected into mold and let to solidify	Rubber is the best material because it is soft enough to cusion an impact however durable enough to last and maintain its same functionality over time	Round shape allows for a cushioned impact from saw blade guard	49
Rubber Stop Screw 2 610 347 100	In photo with Rubber Stop	Secure the Rubber Stop in place	Steel	Steel is extruded and then threaded on a lathe. Then the end is forged	Steel screw is needed because this screw is holding the rubber stop which takes constant impact while on the job	Torx 20 bit screw	51
Blade Angle Screw 2 610 017 262		Keep the saw angle constant once selected and secure	Steel	Steel is extruded and then threaded on a lathe. Then the end is forged	Steel is needed because this part has to keep the saw angle from moving. If the blade moves it could be dangerous for the user as well as making unintended cuts	Allows greater variety of cuts which include angles	41
Blade Wrench 2 610 968 670		Allow the user to quickly remove and install a saw blade	Steel	Steel is stamped out of sheet metal and then bent giving it some shape to fit on the screw nicely	It is made of steel because it is sturdy enough to apply a high force unscrewing the blade, yet cheap enough to keep the total product cost down	Has two different sizes to adjust different size screws	651
Carbon Brush Set 2 610 993 156		Helps deliver the current from the outlet to the electromagnetic motor after the trigger has been initiated by the user	Plastic, steel, and copper	Plastic injected into mold and let to solidify, the copper contact sheet is stamped out from sheet metal, and the spring is extruded steel which is then spun to be a spring	Plastic because it is easily molded, the spring is made of steel which is reliable and sturdy, and copper because it is a good conductor and this piece is part of the electromagnetic motor	Small in size but a key component in the electricity transfer	810
Set Handles 2 610 915 260		Insulate the saws inner components and allow the user to maintain good control of the saw at all times	Plastic	Plastic injected into mold and let to solidify	Plastic is used because it is a lightweight material which makes the saw easier on the user, yet it is sturdy enough to withstand all of the forces put on it by both the user and the material being cut. Plastic is easy to mold into a shape that fits nicely in an operators hand and absorb any impact distributed through it	Designed with aesthetics in mind because this is the part of the saw the user interacts with most, houses wiring and trigger system, made with grip so the user has optimal control of the saw at all times	837
Blade Housing 2 610 312 398		Intended to protect the user from a spinning blade as well as protecting the blade when the saw is put on the ground	Aluminum	Cast used to create the piece then shaped to create necessary dimensions to house the blade, cover the upper half of the blade guard. Cutting and drilling used to create an exit for debris, ventilation behind blade, and the holes for screws to keep it in place.	Aluminum is cheaper and a better option for the larger components of the saw. It is lightweight and still durable enough for the function it plays	Given designs to look aesthetically pleasing while still performing its job	24
Blade Guard 2 610 916 428		Intended to protect the user from a spinning blade as well as protecting the blade when the saw is put on the ground	Aluminum	Cast used to create the piece then shaped to create necessary dimensions to house the blade, cover the upper half of the blade. Cutting and drilling used to create an exit for debris, ventilation behind blade, and the holes for screws to keep it in place.	Aluminum is cheaper and a better option for the larger components of the saw. It is lightweight and still durable enough for the function it plays	Given designs to look aesthetically pleasing while still performing its job	32
Bearing 2 610 341 347		Allows the pinion shaft to go through both the blade housing and blade guard and attach to the saw blade providing the rotational energy	Steel	Steel was cast and then bored out to give desired dimensions	Steel is needed for this part because there is a lot of rotational force acting on the piece	Well lubricated to prevent wear over time	26
Motor 2 610 341 306		Provide the electromagnetic force which is turned into rotational mechanical energy when the motor shaft meets the pinion shaft. Fan prevents motor from getting too hot	Shaft is made from steel, Wires are made from copper	Steel was lathed down to desired size and then machined at the end giving it the teeth. Wires were drawn providing small cylindrical shape. Fan was made from steel stamped out of sheet metal	Steel is a strong material and this piece has a lot of turning force acting on it. The copper wires are a great conductor of electricity without a high cost	Inner Electromagnetic coil sits on shaft and this is where the turning force begins	3
Pinion Shaft 2 610 997 776		Turns the rotational energy provided by the electromagnetic motor and transfers it using a gear to force the saw blade to spin	Steel	Steel is extruded and then given the teeth. Both ends are forged to provide more strength	Steel is needed for this part because it is relatively cheap and this function requires a part that is stronger than plastic because there is a strong turning force that plastic could not handle	Sits in a well lubricated socket to allow easiest rotation without friction to wear it down	825
Supporting Disc 2 610 341 361		Holds the blade onto the blade housing while allowing it to spin freely in a uniform circular motion	Steel	Cast steel and then bored out to allow the screw to fit through	Steel is needed for this part because this part holds the saw in place and can undergo a lot of force	There are two supporting discs, one for the outside of the saw blade and one for inside of the saw blade. These are also well lubricated to allow as little resistance as possible and protect from wear over time	28
Housing Cover (vent) 2 610 916 204		Allows air flow out of saw which keeps the saw from over heating. Also, it is made without sharp corners so it will not injure the user.	Plastic	Plastic injected into mold and let to solidify	Plastic is durable in case this piece takes impact and still lightweight. It is easiest and most cost efficient to make the vents that allow air flow through the saw out of a plastic material	Rounded shape and nice venting design are both aesthetically pleasing as well as functionally sound. This part is important to keep the saw from overheating and get rid of and debris that might have found its way into the internal part of the saw.	29
Lever 2 610 924 015		Allow the blade to meet the material when pulled back. This lever, attached to the blade guard spring is part of a safety system to protect the operator from a spinning blade	Plastic	Plastic injected into mold and let to solidify	Plastic is a durable enough material to fulfill the function of this piece, as there are only minimal forces put on it by the operator and it will keep the product cost down	Designed with some aesthetics to make the saw a little more appealing while still being functional	34
Bearing Sleeve 2 610 356 680	(found using McMaster)	Keeps the shaft in alignment and stable when it meets with the gear. This allows the saw to work over time without damaging itself	Phosphoric Bronze	Piece is cast out of phosphoric bronze and then bored out to the appropriate diameter	Phosphoric bronze is a durable smooth material which is needed for this part which undergoes thousands of RPM's when in use	Simple part that has an important role in the saw	14

Product Analysis

Housing

There are no flows associated with the housing; It's primary function is to hold the electromagnetic motor in place. The environment of the housing is the environment where the user is operating the saw. The housing is three dimensional, measuring 6 in x 4 in x 4 in. The shape of the housing allows the motor to fit comfortable and also allows the motor to spin. The housing weighs about a half pound. The color of the housing is black because it is a very appropriate color for a power tool and a very common color for plastic. The part is very simple. Plastic can easily be molded into nearly any shape. On a complexity scale of 1-10, 10 being the most complex, the housing would be a 2.

Field Magnet

The flows of the field magnet are a human signal and electrical energy going in and electromagnetic energy going out. The function of the field magnet is carried out in the housing. The shape of the field magnet is round, with a radius wide enough to allow the motor to fit inside it and rotate. The size of the field magnet is 3.5 in x 3.5 in x 2.75 in. This component weights approximately four pounds. There are no aesthetic properties because the field magnet is not meant to be taken out of the housing, thus is not really seen. The field magnet is very complex. The series of copper wires around the perimeter of the component is very complex. It is one of the most complex components of the saw, getting a rating of 8.

Trigger

The trigger requires human signal to perform its function. The trigger is a switch that completes the circuit allowing electrical energy to flow through the saw to the electromagnetic motor. Human signal and electrical energy is required for the input and output of the function.

Solid Modeling

The decision on which CAD/Solid modeling program to use was very easy to make. This decision was easy for the group to make because Kyle was the individual doing the solid modeling part of Gate 3. The group allowed Kyle to choose any program that he wanted as long as the solid modeling would be done before the deadline. Kyle went with the Autodesk Inventor program for the solid modeling. This program was chosen because he had all ready had experience with this program in his high school, only it was a previous version. The program was very similar to the previous Autodesk Inventor programs so there was some adjusting time to the new format and setup. The choice of the individual and the program was done well because it allowed that part of the project to be done smoothly, not causing any stresses or conflicts on the group because the solid modeling part was able to be done ahead of schedule.

Assembly Drawing

Bearing Sleeve

Blade Fastening Bolt

Blade Guard

Pinion Shaft

Saw Wrench

Engineering Analysis

Although there are several key components of the circular saw, the most vital is the electric motor. The motor is what converts the electrical energy provided into mechanical rotational energy. The main concern with the electric motor during manufacturing was whether the motor was providing enough power to spin the pinion shaft at the desired rpm, which then drives the blade to cut through the desired material efficiently and smoothly, avoiding any jamming or struggling. In order to answer such a question, an analysis process must be applied.

Firstly, in the analysis processes the problem must be identified and stated. In this case, as stated before, the question asked is whether or not the electric motor is providing enough power to spin the pinion shaft, which then drives the blade, to cut through the desired material both efficiently and smoothly, avoiding any strain, jamming, or struggling in general.

Secondly, a diagram of the electric motor must be drawn, labeling all known and unknown forces. In this case, the only forces going in and coming out of the motor are work.

Thirdly, a statement of assumption must be made, listing all factors both taken and not taken into account when it comes to your calculations. Such assumptions should range from assuming that the power being supplied is constant and uninterrupted, the saw blade is rotating at a constant rate, the diameter of the saw blade, the presence of friction, and the force being applied on the saw by the user. In this case, the assumptions are:

• Energy is supplied at a constant rate

• Saw blade rotates at a constant angular velocity

• Neglect external forces acting on saw (From user/normal force of material)

Fourthly, a list of governing equations should be present. Such governing equations should cover and include every aspect mentioned in the statement of assumption. In this case the following equations should be used:

• Conservation of Energy: ∑Win=∑Wout

• Force Equilibrium: ∑Ma = 0

• Torque: T=r x F= rF sin⁡θ

• Angular Velocity: ω = (|v|*sin⁡θ)/(|r|)

• Frictional Force: Ffs=μsN, Ffk=μkN

Fifthly, using the governing equations mentioned before, all necessary calculations should be made, taking all forces/ factors into account that were not specifically stated as being neglected in the assumptions part of the analysis.

Sixthly, a revision of all calculations made should be performed, making sure that all forces were taken into account, avoiding possible math errors, and that the proper units were applied and cancelled throughout the entire process to give the correct units that the answer should be in.

Lastly, a discussion of results should be made as to whether the answer received makes sense and complies with everything taken into account. This is perhaps the most important part of the analysis. This is where the answers physical meaning is discussed, where decisions are made whether the answer is the desired answer that the company wished for or if there a design revisions that need to be made.

Design Revisions

Design Change 1: Plastic Levers

The two red levers are made of plastic because it is cheap and can be easily molded into any shape and is not subjected to high forces. The depth adjustment lever is used to tighten an inner bolt so that the height of the saw blade can be adjusted to users’ desire. The lower guard lift lever is permanently fastened on to the blade guard and is for the user to lift the guard in order to perform maintenance duties.

Both levers should be changed from plastic to a light weight metal. This design change will give both levers a lower chance of breaking. Either lever can be easily broken if the skill saw user unknowingly places too much pressure on the lever. The levers would have less of a chance breaking if the saw fell onto a hard surface.

Economic: This change would cost the skill saw company more because the cost of forming metal is greater than forming the plastic parts. The price increase in the product wouldn’t be extreme, but it would increase the costs of the product. Societal: Giving both of the levers the advantage of not breaking so quickly. The user of the skill saw would have an easier way to lift guard and adjusting the height of the cut, not worrying about breaking the part. If one of the plastic levers did break, it would be greater hassle to the user to tighten the inner nut with a broken lever, or unsafely opening the blade guard. This design would give a safer option of using saw throughout its use in time.

Design Change 2: Screw

A variety of screws are used to hold many components of the skill saw together. They are in varying lengths based on what they are used to fasten. The screws are designed to be fastened by one of two different torx sizes. The screw designs should be made to be tightened by a Philips screw driver rather than designed to be tightened by a torx set or a flat head screw driver. This will give the individual doing the disassembly an easier way to take apart the saw since a Philips head screw driver is more popular to have than both a torx and flathead screw driver. Also, with Philips screwdriver, the person doing the disassembly will only have to use one type of Philips screw driver to open all the screws. Societal: The person taking saw apart will be able to take apart skill saw quicker and easier without using a varying torx wrenches and being able to use a more common screw driver. Someone will most likely have a Philips screwdriver if they have a torx set. A screw driver is a lot more convenient to use, and any maintenance of the saw could be done by more people, meaning more people would be able to identify what tool to use (if Philips was used). Economic: The component would be easier to make because creating intrusion of the torx is more difficult to create rather than intrusion of Philips screw driver. This is because a torx screw driver somewhat resembles a six pointed start, while a Philips head is just a cross. Making the cross compared to a six point star on the same size of material is easier because there are not as many features that would need to be put into the part.

Design Change 3: Housing Cover

The housing cover is held in place by two screws and is attached to the housing. This part is very significant of the saw. It is used to cover the inner components and used to ventilate the dust and heat out of the housing. The housing cover should have larger ventilation strips. Giving the saw a better way to discharge the saw dust, heat or other unwanted filaments from the inside of the housing. This would allow the inner part of the saw to stay clean, which could reduce unwanted internal reactions (overheating). Societal: This will decrease the chance of creating an electrical fire within the saw and there for will make it safer for the user and the place where skill saw is being used. Environmental Factors: This will increase the amount of debris blow out of the saw into the work area, so the working area may be slightly polluted depending on what materials are being cut.

Design Change 4: Longer/Retractable Cord

The cord of the saw can be very annoying for the user at times. Sometimes the cord is just lying around the ground while it is in use and can get in the way of the user. If there was a retractable cord built into the saw, Then there would not be so much cord lying on the ground and getting in the way. The user of the saw may not be near an outlet while using the saw. So adding a few more feet to the cord would allow a greater distance from an outlet for the saw to be used. This would allow the user to be able work in a larger area. Economic: The retractable cord and adding length to the cord would cause an increase of price because of the increase in function and material need for the saw. Even with a price increase, the saw would still be affordable because the increase in price would not be significant compared to the overall price of the saw. Environmental: An environmental concern is that the longer cord would increase the total resistance before being used by the saw. This would increase power loss through the cord, which would waste energy by using the saw over time. Societal: The user of the saw would be less likely to trip over the cord, adding another safety feature to the saw. The user would also avoid the inconvenience of having to wrap up the cord themselves and being able to let the retractable cord do that job itself with just the push of a button from the user.

Gate 4: Product Explanation

Project Management: Critical Project Review

Cause for Corrective Action

Throughout the project there have been very few conflicts within the group. These conflicts were, in general from disputes on what member should get what part for a certain gate of the project. These disputes were very easy to solve because the whole group was able to talk over the part selection and we always solved the problems with no problems. The other conflict in deciding gate work was the “lottery” way, where a member just picked what they wanted and signed up for it after a certain time passed to let everyone else see what they wanted. This didn’t cause any direct conflicts, but it did help lead to a problem later on near the end of gate 3. This problem was a problem in getting the wiki page completely up in time. This conflict has been resolved within the group. The group has put that behind them and has been dedicated to not let anything like that happen again by getting the required work done a little bit ahead of schedule if possible. There are no conflicts in the group at this point of the project, which is the way we want it to be since the group is in the closing stages of the project.

Product Archaeology: Product Explanation

Product Reassembly

The reassembly process for us was very similar to the disassembly process. There were no major problems that our group encountered. We used the same difficulty scale as the disassembly process as well. We created a scale for our dissection from 1-10. A score of 1 would mean that this step was very easy and required only hand work and could be done in seconds. A score of 10 meant that the step took multiple tools and processes as well as taking a length of time (ex. 30 min). A score of 5 meant that the step took moderate work including tools and a approximately 15 minutes of time for the disassembly of the part. By disassembling and reassembling the saw our group gained knowledge of the manufacturing processes that were used as well as the assembly of mechanical consumer products.

Design Revisions

The three design revisions that were made to the circular saw on the system level were based mainly on economic, societal, and global concerns. In specific, certain factors that were taken into consideration when making the design revisions were comfort, safety, ease of use, and most variability.

The first design revision made was placing a rubber grip on the plastic handle used to hold the circular saw. Doing so would help increase the comfort of use, reduce user fatigue, and increase the factor of safety by eliminating the chances of the user’s hands slipping due to sweaty palms. This increases the safety factor of the saw, so it looks more appealing to the consumers, although it may cause a slight price change.

The second design revision made was adding variable speeds at which the blade spins at. Doing so would give the user the option of setting the desired amount of torque and angular velocity needed to cut the desired material. Incorporating such a feature would help in using a lower torque and slower angular velocity when using the saw to cut through material such as wood, lowering the strain places on the electric motor, which in turn would lower the amount of required maintenance. This feature would also give the user the capability of opting for a higher torque and faster angular velocity when needed to cut through material such as sheet metal. This would increase the price of the saw, but the Skil saw is cheaper and lower in performance, so the Skil saw could increase its rpms to get the same performance of its competitors for possibly a lower price. This would increase the weight of the saw though, and make it have a bulkier body since extra parts would be needed to add this feature.

Finally, the third design revision made was the addition of a laser cutting guide. This added feature would increase precision and help in decreasing the amount of time required to cut certain material by making the cutting line of the material very easy to see. The advantage of the laser is that material falling onto the wood wouldn’t cover up the cutting line. In other words, the laser guide would help eliminate the user from having to constantly squint and stop to make sure that the material was being cut with reasonable precision. Such a factor may also be a great improvement in helping users who wear glasses have a an easier time guiding the saw along a straight path.

Gate 5: Delivery