Group 16 - DeWalt 4 1/2 in Angle Grinder Gate 2
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===Intent of Disassembly=== | ===Intent of Disassembly=== | ||
| + | *'''Gaurd, Handle, and Axle nuts''' | ||
| + | :-They are intended to be adjusted by the user. The gaurd can be removed or re positioned to accommodate various attachments. Axle nuts slip off. | ||
| + | *'''Gearbox and Backplate''' | ||
| + | :-Backplate removal is essential to routine maintenence (greasing) and inspection. | ||
| + | :-Gearbox must be removed to service other parts of the grinder. In industry, if a gearbox is damaged the whole unit is replaced. | ||
| + | *'''Bottom of Plastic Housing''' | ||
| + | :-This component makes access to routine maintenance sites quick and easy for the user. | ||
| + | *'''Power cord Attachment''' | ||
| + | :-Made so a replacement cord can be replaced easily. In case of electrical fire this unit can be replaced easily as well. | ||
| + | *'''Brushes Assembly (contacts)''' | ||
| + | :-The brushes are a normal wear component in the grinder and must be replaced routinely throughout the tool lifetime. The ease of access is helpful in maintaining a working tool. | ||
| + | *'''Fan Baffle''' | ||
| + | :-This component can be removed for cleaning and for access to the coil. | ||
| + | *'''Switch''' | ||
| + | :-can be removed with some intuition. Must be removable for replacement of broken switches. Its an inexpensive part that is critical to product operation. | ||
| + | *'''Electromagnet (coil)''' | ||
| + | :-usuall not replace during the life of the part, but during maintenance can be easily removed for cleaning. | ||
| + | *'''Gear and bearing on main shaft''' | ||
==Connections of Subsystems== | ==Connections of Subsystems== | ||
Revision as of 13:25, 26 October 2012
Contents |
Gate 2
For this gate our group dissected our product and considered what its assembly revealed about the design factors that went into this product. Before we could do this, our group first had to analyze how our original plans outlined in Gate 1 had gone, and what changes needed to be made in order to make our group perform better. This group assessment is provided under the Project Management section below. We then proceeded to dissect our part, and have provided step-by-step instructions on how to do this. Under the Product Archaeology section we describe our scale of difficulty for disassembling each part and then provide the aforementioned step-by-step instructions, along with a rating of the difficulty of each step. Finally, under Connection of Subsystems our group documents the connections of the subsystems and considers the factors behind these design decisions.
Project Management
Summary
- At the start of the first gate our group had gotten together and divided the work load amongst most of our group. Each individual that was present was given a task to perform so the work load was on every one (we thought). Michael Halloran was appointed our communication liaison and none of us had ever used wiki before. The other group members could not figure out the wiki so we sent email to the communication liaison to put it up on the wiki. He put all of our information together and posted it to our wiki, but Gate 1 was posted to our user page, not the main page, or a specific Gate 1 page.
Cause For Corrective Action
Potential problems
- We didn't know how to use the wiki.
- The communication in the group was limited to in class meetings and email.
- The workload was unevenly distributed.
Proposed solutions
- Our communication liaison went through wiki tutorials and attended office hours in order to learn how to use the wiki well.
- He has showed the group the wiki basics so now we all can post at least basic text to our page.
- The group as a whole had a meeting, and now understands the work needed to be done ahead of time so it could be proofread and reviewed.
- We have discussed and redistributed the work load so that the communication liaison will have an appropriate amount of research and analysis given that he also has to form tables and upload images, which the rest of the group does not.
Product Archaeology
Difficulty Scale
In order to describe the difficulty of each step, we will use the categories outlined in Table 1. When assessing the difficulty of each step, it was important not just to assess the time a step took, but rather the aspects that would make the task challenging for the average user. We therefore considered the tools required for a task, the intuitiveness of the step, and any difficulties that may have arose from inaccessibility of a part or the amount of force that must be applied.
| Difficulty Category | Description | Example |
|---|---|---|
| Easy | This step involved minimal effort and either the use of no tools or a very simple one such as a screw driver. This step was completely intuitive, and simple to execute. | Unscrewing a wing nut or a Phillips-head screw |
| Moderate | This step required a little time and effort and involved more complex tools such as a wrench or pliers. This step may have required some thinking and observation of the components before it was clear what to do, and was somewhat challenging to execute. | Removing electrical connections with pliers or unscrewing a screw that was partially blocked by other components |
| Difficult | This step required advanced planning and analysis of the product to determine how to do it. While it may have involved the same tools as a moderate step, it was a challenge to use them on the part that was to be removed, or a large amount of force may have been required. Executing these steps was very challenging and may have required multiple attempts or assistance from another person. | Removing a bearing that is shrunk fit onto a shaft |
Dissection Instructions
The instructions given in Table 2 are intended to provide a thorough and complete description of the dissection process such that an individual with no prior knowledge of the product could disassemble it in the same manner our group did. Pictures are provided for clarity and to specify which component of the product is being dealt with at any particular point.
- Before beginning dissection, the following tools will be required:
- Phillips-head Screwdriver
- Torx Drivers: T-5, T-10, T-15
- Needle-nose Pliers
- Channellock Pliers
- 3/8 in Crescent Wrench
| Step | Tools Required | Description | Difficulty | Image |
|---|---|---|---|---|
| 1 | None | Twist the handle to unscrew it from the main components of the angle grinder. Then remove the clamp nut and back flange by similarly unscrewing them from the general assembly. | Easy |  |
| 2 | Phillips-Head screwdriver | Use the screwdriver to remove the screw holding the two halves of the guard ring together, and then slide the guard off the general assembly. | Easy | |
| 3 | T-10 Torx Driver | Use the Torx driver to remove the four screws attaching the gearbox to the main housing. Then pull the gearbox off and the attached drive shaft will come out with it. | Moderate |  |
| 4 | T-15 Torx Driver | Use the Torx driver to unscrew the four screws holding the housing together at the bottom (near plug) of the angle grinder. Separate the two halves and remove them. | Easy |   |
| 5 | Phillips-Head Screwdriver | Locate the red switch inside the now exposed interior, and use the screwdriver to loosen the clamps on the wires leading to the power cord. Now unscrew the two screws holding the power cord's plastic attachment in place, allowing you to pull the power cord out. | Moderate |  |
| 6 | Needle-nose Pliers | Use the needle-nose pliers to grip the wire contacts between the red switch and the carbon brushes. These four contacts will slide right off. It is recommended a marker is used to note which wire went to which contact on the switch, so that it can be reassembled properly. | Moderate | |
| 7 | Needle-nose Pliers, T-5 Torx Driver | Use the needle-nose pliers to grip the brush spring and pull back on it. You can now swing the brush out and release the spring. Repeat for the other side. Now use the Torx Driver to unscrew the screw holding the brush in place. The entire brush assembly can now be removed and taken apart by hand. | Difficult |   |
| 8 | T-5 Torx Driver | Use the Torx driver to remove the four screws that hold the black fan baffle in place, and remove the fan baffle from the body. | Easy |  |
| 9 | Needle-nose Pliers | First, pull the switch off the switch bar until it snaps off. Then use the needle nose pliers to pull the switch bar out of its slot in the main housing. | Moderate |  |
| 10 | None | By banging the remaining housing on the work surface, the electromagnet will eventually be forced out. It is only held in place by a relatively loose press fit. | Easy |  |
| 11 | Channellock Pliers, 3/8 in Crescent Wrench | Take the drive shaft-gearbox assembly and slide the drive shaft out the bottom of the gearbox. First unscrew the nut that is threaded on using the 3/8" crescent wrench. Remove the pinion by gripping it with the channellock pliers and pulling it off the drive shaft. The back ring retainer will then slide off. Next, remove the bearing by also gripping it with the channellock pliers and pulling it off the drive shaft. At this point it will help to have assistance, as the pinion and bearing are shrink fitted on, and will require a large amount of force to remove. | Difficult |  |
| 12 | T-10 Torx Driver | Use the Torx driver to unscrew the screws holding the back of the of the gearbox in place, and then remove the back. | Easy |  |
Intent of Disassembly
- Gaurd, Handle, and Axle nuts
- -They are intended to be adjusted by the user. The gaurd can be removed or re positioned to accommodate various attachments. Axle nuts slip off.
- Gearbox and Backplate
- -Backplate removal is essential to routine maintenence (greasing) and inspection.
- -Gearbox must be removed to service other parts of the grinder. In industry, if a gearbox is damaged the whole unit is replaced.
- Bottom of Plastic Housing
- -This component makes access to routine maintenance sites quick and easy for the user.
- Power cord Attachment
- -Made so a replacement cord can be replaced easily. In case of electrical fire this unit can be replaced easily as well.
- Brushes Assembly (contacts)
- -The brushes are a normal wear component in the grinder and must be replaced routinely throughout the tool lifetime. The ease of access is helpful in maintaining a working tool.
- Fan Baffle
- -This component can be removed for cleaning and for access to the coil.
- Switch
- -can be removed with some intuition. Must be removable for replacement of broken switches. Its an inexpensive part that is critical to product operation.
- Electromagnet (coil)
- -usuall not replace during the life of the part, but during maintenance can be easily removed for cleaning.
- Gear and bearing on main shaft
Connections of Subsystems
The overall function of the DeWalt 4 1/2 in Angle Grinder is to grind materials by converting electrical energy into rotational mechanical energy. This occurs through a series of subsystems.
First Level of Subfunctions
Second Level of Subfunctions
How the Subsystems are Connected
Physically
To achieve the overall function, the subsystems must be physically connected. The power switch is connected to a plastic bar that slides back and forth and allows electricity into the electric motor. The electric motor is connected to the drive shaft. When the electric motor spins, the drive shaft rotates. The drive shaft then connects to the gearbox and to the gears inside. The rotation of the drive shaft causes the gears to turn. The gears are connected to the head, causing it to rotate and thus giving the operator the ability to grind materials.
Signals
For the angle grinder to run, the operator must send a signal to it. This is done using the power switch. The power switch can signal the angle grinder to turn on or shut off, depending on what the operator wants. The power switch is connected to a plastic bar that slides back and forth. When the operator turns the switch on, the bar slides sending a signal to allow electricity into the electric motor, thus activating the angle grinder. When the operator turns the switch off, the bar slides back into its original position sending a signal to stop sending electricity to the electric motor, thus deactivating the angle grinder.
Mass
There is no mass flowing through the angle grinder.
Energy
Electrical energy from an outlet enters the angle grinder through a cord. The electrical energy is then sent to the electric motor. The electric motor spins, converting the electrical energy into mechanical energy. The mechanical energy is then sent to the drive shaft where it becomes rotational mechanical energy. The drive shaft channels the rotational mechanical energy to the gear box and into the gears. The gears take this rotational mechanical energy to the head where it can be used to grind materials.
Why They are Connected
The subsystems must be connected in order for the angle grinder to work properly. The power switch is connected to the plastic bar in order for the on/off signal to be received. The power switch is not located at the bottom of the angle grinder where the electricity comes in so the plastic bar is used to send the on/off signal to the correct location. Once the signal is received, the electric motor can beginning converting electrical energy into mechanical energy. The drive shaft connects the electric motor to the gear box. The drive shaft must be connected to the electric motor to be able to rotate, allowing the rotational mechanical energy to be channeled to the gearbox and the gears. The gears must be connected to the drive shaft so they can turn, otherwise the gears won't do anything. The gears then take the rotational mechanical energy to the head, thus allowing the operator to grind materials.
Implementation of Connections
The connections between the different sub-systems of the angle grinder were each affected by global, environmental, economic, and societal factors. The connection between the power system and the motor system are very economical. The biggest concerns when designing a product and determining the connection of subsystems are cost and safety, or the economic and societal factors. Companies are constantly trying to design products with the same level of quality but for a low price. The DeWalt 4 1/2 in Angle Grinder was designed with the intention of providing a product of high quality and performance at a low price for consumers. To achieve this, the connections used over the entire product and within specific systems are simple and uniform. As a result, the parts and systems are mainly connected together by same types of screws which saves time with assembly and repairing. This is a cheap yet durable way to connect the parts together. The system that has the greatest effect on keeping the cost of the product down is the cutting head. This part is designed to be cheap, degradable, and easily replaceable. Rather than using more expensive materials or manufacturing processes to make the heads last longer, they are made to be replaced regularly, but at a low cost to the consumer. The steel guard around the grinder wheel is connected to the gear rod and is in a position that protects the operator from the high rotating speed of the grinder wheel and from getting hit by any other objects that go through the spinning line. The product also has a side handle perpendicular to the body of the grinder which gives proper grip to make it easier and more convenient to hold and causes less strain on the user. This is a societal concern, as the primary users of this product will probably be using it for prolonged periods of time. The use of plastic for the outer casing and grip also reduces the effect of the vibration that is caused by the engine, which keeps the operator from getting tired. Using plastic for these different systems makes the DeWalt Angle Grinder lighter in weight thus easier to hold. Since the grinder runs on electricity it has no emissions into the air making it very environmentally friendly. Also, the different systems are all made of plastic and metal, which can be recycled and reused. Since the connections between the systems are simple, a single part or system can be replaced without having to replace the entire product, saving0 money , time, and materials. Utilizing non-permanent joints also greatly contributes to the simplicity of replacing parts - since the parts are screwed together and not soldered together; a broken part or system can simply be unscrewed from the surrounding parts and be replaced. For example, the gear box and the motor can be purchased as different units, and are connected simply by the metal head cover and four screws .
They are joined by two wires which is black and white, to deliver the electrical energy to the motor. This type of connection is inexpensive. It is also a safe connection because of the plastic housing the wire is inside of. Environmentally, the wires and the plastic casing can be recycled and wires can be used again in another product to reduce pollution. The wires were also influenced by global factors in that the power cord is one of the first parts that can be removed. This allows the quick changing of wires for sale in Europe or China where AC electricity has a different frequency. The connection between the angle gearbox and the drive shaft is made completely of metal, which provides strength and durability both at the grinding surface and motor. This makes the product reliable, which satisfies the societal demand for a strong, reliable product. Environmentally, this metal can be recycled, meaning the connection between these two systems can be reused in a different system, reducing the end of life pollution of this product. Economically, the raw materials are relatively cheap for this connection, while the shape allows casting of these parts, meaning they can be manufactured cheaply and rapidly. The gears that connect the systems are cheap to make, but are also safe because of the way they are situated inside the grinder metal housing. This safety is a major societal factor when working with a product that could severely injure someone due to the high speeds parts are moving at. The steel used to make the gears can also be recycled to be used on other projects, and are easily made by an unskilled labor force. This is a global concern, as the making of these parts can be done cheaply in any part of the world. All of these connections are designed to allow the high transfer of energy from part to part with minimal loss. While the housing may be plastic, the connections between all major subsystems are made of steel so that the angle grinder will hold up, even when subjected to large forces. Because angle grinders do not have any one particular function, but instead will face many odd orientations and uses over their lifetime, this kind of universal strength and utility is an absolute essential for an angle grinder to have.
Reasons for Subsystem Arrangement
The subsystems are arranged in a way to have the system function properly, so the small angled grinder is intended to be smooth to get work done. Our above pictures show how different subsystems are assembled together to make this grinder.
- The placement of the subsystems is reasonable in this small angled grinder. For instance:
- The electric cord enters at the end, which is the energy source for the grinder. The placement of cord at the end is for the better starting input, as our final output is at grinder. Also, the power cord must lead directly into both the magnet and drive shaft.
- The power switched is located at the top part (near the handle), this allows workers to power the machine on or off at the same time they are doing the work. (Without moving their hands from working position).
- The drive shaft is, and must be placed within the motor, as it is the induced magnetic field along with the current through the drive shaft that allows the shaft to rotate.
- The drive shaft leads to the gear box and grinder head, which is located a safe distance from the general housing so that the user will not be hurt by the grinder.
Subsystems that Cannot be Adjacent
- The subsystems that cannot be adjacent would be grinder and motor. That is because; electric motor converts the electric energy to mechanical energy. Then the drive shaft must be connected in between electric motor and gear box in order to rotate the grinder. If this step did not happen and the grinder head was right on the motor, it wouldn’t make the 90 degree turn, which would remove much of the convenience of angle grinding.
- The grinder head cannot be located near the control system (switch) because the operator would be in danger of being hit with debris when trying to turn the grinder off.
