Revision as of 13:15, 25 October 2012

Dewalt 4 1/2" Angle Grinder

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.

**Table 1: Categories of Difficulty for the Dissection Steps**
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

**Table 2: Step-by-Step Dissection**
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	One Side Panel Removed Both Side Panels
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	Spring-Brush Connection Brush Components
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