Group 16 - DeWalt 4 1/2 in Angle Grinder Gate 2
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
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 |  |
Ease of Disassembly
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.
