Group 16 - DeWalt 4 1/2 in Angle Grinder Gate 1

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Dewalt 4 1/2" Angle Grinder



Over the course of this project our group will be dissecting, analyzing, and reverse engineering the DeWalt 4 1/2 in Angle Grinder. This product is a commonly used tool in many machine shops for its versatility. Through the use of a motor and drive system along with varying attachments the angle grinder is able to grind, cut, and polish various materials. By analyzing how the angle grinder currently works at various system levels our group hopes to not only gain an understanding of what allows the angle grinder to do its jobs effectively, but also what could be done to improve it.

In this gate our group developed a plan to efficiently dissect our product and analyze its components. Part of developing this plan was first taking into account the qualities and capabilities of each group member, as well as the times they are available. The plan for dissection and group-member analysis can be found under Work Proposal. Once our group had created an initial assessment of each member's capabilities and the jobs that would need to be completed we created a tentative division of labor. Roles and associated expectations were assigned to each member based on what tasks they preferred as well as which tasks they were qualified for. This tentative division of labor can be found under Management Proposal. Finally, our group conducted a thorough evaluation and analysis of our product without first dissecting it. This initial inspection and analysis can both be found under the Product Archaeology section of this gate.

Project Management

In this section our group provides a self-evaluation of each member's capabilities and lays out our plan for completing this project. In addition, we provide the framework for how our group intends to function both through internal interaction and conflict resolution.

Work Proposal

Plan for assembly and disassembly

Our group plans to perform the disassembly October 10 and 12 in the lab. Given the relatively small size of our product, we do not expect the dissection process to take longer than these two three hour sessions. During the disassembly process we will have one member take pictures of the product after each step of the dissection and one member record a written description of each step. This will facilitate the eventual reassembly of the part. Once the product has been fully disassembled and analyzed, we will reassemble the product by putting the parts back together in the same order we took them apart. The same tools used for disassembly should suffice for this part. Our preliminary dates for completing the reassembly are November 19 and in the lab. The remaining jobs such as part analysis and written submissions will as a rule be completed two days before each gate is due. A timeline of our activities is provided in Figure 1 for reference.

Based on an initial assessment of the product's exterior and the fasteners in place, these are the tools we expect to need for reassembly and disassembly:

  • 1/16”-1/8” Phillips Head and Flathead Screwdrivers
  • 5/32”-1/4” Crescent Wrenches or Sockets w/ Socket Driver
  • 4 mm-6 mm Crescent Wrenches or Sockets w/ Socket Driver

In addition, these are the tools our group may or may not need, depending on the nature of the internal components:

  • T-15-T-25 Torx wrenches
  • Needle Nose Pliers
Figure 1: Proposed Timeline of Events for Project

Analysis of Group Members

Ethan George

• Has limited experience with machines

• Has never operated an angle grinder before

• Has limited computer skills: No solid modeling experience or skills

• Is very well organized and is a good writer

• Works well with people

• Readily available to work on the project

Michael Halloran

• Has worked extensively with gas powered machines

• Has limited experience with angle grinders

• Poor computer skills: Some solid modeling experience and skills

• Decent organization

• Decent people skills

• Readily available to work on the project

Zachary Picciano

• Has worked extensively with machines

• Has worked extensively with angle grinders

• Good computer skills: Has good solid modeling experience and skills

• Decent Organization

• Decent people skills

• Very busy schedule

Thakur Phuyel

• Has no experience working with machines

• Has no experience with angle grinders

• Decent computer skills: No solid modeling experience or skills

• Decent organization

• Decent people skills

• Moderately busy schedule

Tharaka Gabadage

• Has experience with machines

• Has no experience with angle grinders

• Decent computer skills: No solid modeling experience or skills

• Decent organization

• Decent people skills

• Very busy schedule

Overall analysis of group

Our group currently possesses all of the skills it will need; however we are overly reliant on certain group members in certain areas. All of our members will need to familiarize themselves with the general function of an angle grinder. Also, those with decent or poor computer skills need to improve these in order to aid in communicating with other members and submitting work. There is no way to “fix” the limited availability of some group members, so we will instead have to work around this by accommodating meetings to their schedules and doing large portions of the work individually. This will also require our group to develop good electronic communication skills so that we do not waste time or fail to cover certain aspects of the project. Lastly, we will need to get at least one other person to learn about solid modeling, as having only one person with those skills will be crippling if he cannot get the work done (it should be noted the one member who currently has these skills has a very busy schedule). By improving in these area, our group will be able to function effectively for the duration of this project.

Management Proposal

Work Distribution

The general rule for distributing work will be to first allow group members to volunteer for any part of a given gate that they feel they could best complete due to their specific skill set or group role. After this initial process, the Project Manager (see below) will assign any remaining tasks in a manner he feels most appropriate, using the same criteria as above, as well as considering how much work each person already has to do on the project.

Contact Information

Our group can be contacted at any time through Communication Liaison (see below) Michael Halloran. He may be emailed at or (both forward to the same address, so there is no preference in which address to email), and will respond promptly with any information you may require, as well as inform the group about any emails he may receive.

Meeting Plan

Our group will generally meet every Wednesday and Thursday at 6:00 in the Furnas lab. It should be noted that these times are subject to change based on what work remains to be done, whether an extra meeting is required, and any temporary conflicts that may arise for given group members. During these meetings we will do any work that requires interaction with the product. Other work such as write-ups and research will be done individually outside of meetings and then sent electronically to other group members.

Group Role

Project Manager (Ethan George)- The project manager will be responsible for assigning work to other group members as well as laying out a timeline for meetings. In addition to taking some tasks for himself, he will contact other group members regularly to make sure they are moving at a proper pace and try to prevent parts of the project from being overlooked. In addition, he will make the final decision on issues such as requirement interpretation, group conflicts, changes of schedule, and whether work submitted by other members is of high enough quality or not.

Communication Liaison (Michael Halloran)- The communication liaison will be responsible for being a reliable point of contact with the professors, as well as organizing and posting the group’s work through the wiki page. He will disseminate any information or feedback the professors provide and ask any questions the group has. Below, the contact information for the communication liaison is listed again:

Technical Expert (Zachary Picciano)- The Technical Expert will be responsible for having an in depth understanding of the product’s function, structure, and components. He will through research and prior experience gain an in-depth understanding of these aspects so that he can lead the dissection and reassembly. On these parts of the project, the Technical Expert and NOT the Project Manager will have full authority as he will have the greatest knowledge of what needs to be done and how to do it safely. In addition, the Technical Expert will do any solid modeling of the product, although he will be working with the other members in describing what exactly must be drawn or designed.

Research Expert (Takur Phuyel)- The research expert will be responsible for doing any research not already covered by the technical expert. In addition to completing tasks that are specifically research oriented, he will also look into any other questions that may arise over the course of the project. He will then be responsible for informing the group about his findings so that the entire group will have a clearer understanding of the project.

Product Archaeology

Development Profile

When was the product developed?

The first angle grinder was developed by Flex Company in the late 1920s. The DeWalt Heavy Duty Angle Grinder family of products was developed in the early 2000s.

What were the key economic and global concerns at the time of the development?

Global: The DeWalt angle grinder was developed for countries with developed economies. The tasks angle grinders are intended to do, such as finishing wood, polishing doors, and removing weld seams, are not usually done in developing nations. In addition, a lack of reliable power grid would make the electric angle grinder inferior to those with other power sources.

Economic: The DeWalt angle grinder reduced cost by using less cast iron than traditional angle grinders and replacing many auxiliary parts with plastic. It also uses less power than other similar angle grinders in order to reduce electrical costs for the user.

In what countries or regions is the product intended to be sold?

Our angle grinder is only intended for sale in North America, primarily the U.S. and Canada. This is because the product must undergo special testing for certification to be sold in Europe, and “DeWalt Europe” a similar but different version of this product for sale there.

What was the intended impact on the consumer and the society in which it is used?

The angle grinder was designed to make many household tasks easier. This product furthers that goal of the original angle grinders by making the angle grinder lighter weight and easier to use, which is ideal for household use.

Usage Profile

What is the intended use of the product?

The intended use of the angle grinder is grinding various materials. In addition to grinding, multiple attachments can be fitted allowing the angle grinder to cut, sand, and polish, making this a very useful tool.

Is this product for home or professional use?

Angle grinders can be used for both home and professional uses, however the smaller angle grinder our group has is intended primarily for home use.

What jobs does the product perform?

• The main job an angle grinder performs is grinding metal weld seams to make them smooth.

• Grinding and cutting metal, concrete and stone can be done by attaching a cut-off disk (usually with a diamond blade).

• Sanding disks allow the user to sand wood quicker than with sand paper.

• Polishing disks and wire brush disks allow the user to polish metal and remove corrosion, rust, and paint from metal.

Energy Profile

What types of energy are used?

The product uses AC electrical energy and rotational kinetic energy, which changes direction at the grinder head.

How is energy imported into the system?

Electricity is the only energy imported into the system, which is done by connecting the plug to any standard U.S. AC outlet.

How are different types of energy transformed and modified?

The electrical energy imported into the system is transformed into rotational kinetic energy by an AC motor in the bottom of the tool. This motor drives the main shaft which in turn rotates a gear. This gear redirects the rotational kinetic energy by turning the axis of rotation 90º at the head of the grinder, which in turn delivers its rotational kinetic energy to the grinder’s disk and the object the tool is being used on.

Complexity Profile

How many components are used?

The components our group has observed and theorized are present include:

• Power cord

• Electric Motor

• Main shaft

• Gear box

• Action Surface

• Handle

• Power Switch

• Housing

How complex are the individual components?

Out of the components listed, only the electric motor and gear box are complex. The electric motor will contain magnets, a wire coil, an armature, and carbon brushes designed to transform the AC electricity into high rpm rotational kinetic energy.

The gearbox will contain at least two gears and a bearing that will take the rotational energy from the main shaft and redirect it with minimal kinetic energy loss.

All of the other components are simple, consisting of only a few, easily assembled parts.

How complex are component interactions?

The components interact with each other in very simple ways, often only relating to only one or two other parts. The exception is the main shaft, gear box, and action surface. These components have several parts that all work towards the same goal of redirecting the rotational kinetic energy without failing under a load as well as horizontal forces the user may be applying. We do not know exactly how these components will interact yet, but it will probably require additional parts in the gearbox we are unaware of.

Material Profile

What materials are clearly visible?

• Rubber (cord)

• Copper (cord)

• Steel (guard and wheel nut/screw)

• Plastic (housing and power switch)

What materials are not visible, but present?

• Magnetic iron (electric motor)

User Interaction Profile

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

The two primary user interfaces are the power switch and the wheel nut.

• The power switch allows the user to cut power to the motor, apply power to the motor, and lock the grinder in an on position where power will be applied until removed.

• The wheel nut allows the user to place different attachments on the angle grinder’s drive head and then secure them to prevent the disk from falling off.

How intuitive are the interfaces?

• Both interfaces are very intuitive. The power switch has an O and and I marking power on and off respectively, with a small picture of a lock at the position where the power will lock on.

• The wheel nut is a standard nut as it must be turned counter-clockwise to remove it, and turned clockwise to secure it and whatever head may have been placed on the angle grinder. Placing the head is also very intuitive, as it slides right over the screw the wheel nut came off of.

How easy is the product to use?

The product requires minimal knowledge to use, as one can literally “flick the switch and go.” However, there are certain safety measures the user must first familiarize himself with. While they are not all intuitive (such as allowing the machine to fully accelerate before applying to the material, or fully decelerate before unplugging) they are quite simple, and require minimal user effort once the safety measures are known. In addition, specific materials and jobs come with their own safety measures, but just like the general safety tips, these are not a challenge once known.

Is regular maintenance required?

The primary form of maintenance the user will face is replacing the attachable heads, which is simply a matter of unscrewing the wheel nut, removing the old disk, putting the new one in, and replacing the wheel nut.

The only other forms of ordinary maintenance are replacing the brushes and main shaft bearing. Both of these are slightly more complicated.

• The brushes can be replaced by removing the cover plates located to the rear of the motor (near the bottom of the tool). There is a screw that must be removed, but once it is and the cover plates are off, the brushes can be extracted, replaced, and the cover plates can be put back on.

• The main shaft bearing is replaced by removing the guard, removing four screws in the grinder housing where the guard was clamped, and then removing the housing and bearing. The new bearing is then inserted, and the other parts are replaced.

Alternative Product Profile

What product alternatives exist?

Alternative 1: Milwaukee 11 Amp 5 in AC small angle Grinder with Trigger Grip

What are the advantages?

• 5 years limited warranty, comparing to DeWalt's 3 year limited warranty

• Variable speed available

• Bigger size of wheel: 5 in comparing to 4.5 in

• CSA listed ( meaning product complies with national and international standards)

• 1400 MWO motor that powers through tougher jobs

What are the disadvantages?

• It is heavier than DeWalt (6.88lb and 4.6 lb)

• Uses more electricity (11 A vs. 10 A)

• 10 dollars more expensive than DeWalt

How does this alternative compare?

• Both with maximum speed of 11000 rpm

• Both are 90 days returnable

• Both have an AC motor designed for maximum performance

• The DeWalt uses less electricity during operation

• The DeWalt does not have as much power as the Milwaukee

• The DeWalt does not allow for speed adjustments

What are the differences in the cost?

• DeWalt costs about $89, which is $10 cheaper than Milwaukee's angle grinder ($99).

Alternative 2: Black & Decker G950 4-1/2-Inch Small Angle Grinder

What are the advantages of this product?

• 3-position side extended handle and contoured body with rubber grip for added comfort and control in a variety of applications.

• Metal gear case for added durability and extended life.

• Trigger switch allows for ease of use, even when wearing gloves.

• Spindle Size: 5/8 to 11 inches

• Two year limited warranty

• Spindle lock which provides easy accessory changes

• Included with angle grinder: metal grinding wheel, spanner wrench, and side hand.

What are the disadvantages of this product?

• 2.4 lb heavier than DeWalts (DeWalt's 4.6 lb vs. 7.0 lb)

• After sale service is one year less than DeWalt’s.

• Limited warranty is one year less than DeWalt’s.

• 1,000 RPM less than DeWalt’s.

• No Dust Ejection System.

• No auto-off brushes system which avoid tool damage.

Similarities of the products

• Both are 90 days returnable

• Quick-Change system, allows tool free wheel removal without need for a wrench.

• Equal Spindle Size ( 5/8 to 11 inches)

• Side rubber handle for better control


11 Amp 5 In. AC/DC Small Angle Grinder with Trigger Grip-6121-31A at The Home Depot. N.p., n.d. Web. 06 Oct. 2012. <>.

"4 1/2" Small Angle Grinder." N.p., n.d. Web. 06 Oct. 2012. <>.

"History of the Angle Grinder." FLEX. N.p., n.d. Web. 06 Oct. 2012. <>.

"Sign Up Today!" Grinder Buying Guide. N.p., n.d. Web. 06 Oct. 2012. <>.

Links to Other Gates


Gate 2

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