Group 16 - Black & Decker Drill

Revision as of 17:48, 29 October 2009

Group Members

Leader & Main Contact: Eric Kieffer
Head of Wiki-Page: Jonathan Lottes & Alexis Wong
Head of Product Dissection: Sanket Chavan
Head of Solid Modeling: Kyle Lynch

If there are any questions or concerns please contact Eric Kieffer at kieffer7@buffalo.edu

Gate 1

Work Proposal

Our product for the project is a Black and Decker corded hand drill (Model No. DR202). The drill is a mechanical tool that converts electrical energy into mechanical energy. It is made up of 6 main parts, made of various materials.

1. The Cord
2. Trigger Mechanism
3. Keyless Chuck
4. Gearbox
5. Electric Motor
6. The Housing it is enclosed in.

The tools we would require to disassemble the drill:

1. 3/16 Flathead Screwdriver
2. Small Pick
3. Large Pick
4. Needle Nose Pliers
5. Small Wire Cutters
6. Torx Driver Set
7. Vice
8. Soldering Iron

Approach for Disassembly:

First we will start with taking the housing apart, a 3/16 flathead screw driver (or a #10-#21 torx driver) and pick will be used. There are 9 visible screws on the housing. After the screws are removed the housing can be carefully pried open using the pick and a screwdriver, while doing this we will remove the installed level and disconnect the cord. The cord may be male to female clips or soldered to the trigger switch in which we might have to cut it off with a small pair of wire cutters. Once we finish separating the cord, we will move on to disassembling the main components of the drill. We start off by removing the trigger and the forward/reverse switch using needle nose pliers and a flathead screwdriver. The gearbox, keyless clutch, and electric motor come out as one part and can be assessed further to be broken down into the components. It is assumed that the gearbox, keyless chuck, and electric motor are held together inside the drill by the housing and can be pulled apart, there might be a lock ring or some kind of press fit that could have been used during assembly. This means that we will have to pry the components apart using a screwdriver and possibly a vice.

Since one of the team members has worked on disassembling a drill earlier, it would probably take us around 3-4 hours to disassemble the hand drill. We have discussed the disassembly procedure and feel that we will not have any major hurdles through it. The only problem we face is to make the drill work, as it was given to us in a non-working condition. We first have to identify the fault in the drill and then try and repair it to make it work.

Capabilities of the Group:

There are no present weaknesses in our group’s skills to disassemble the drill. We do have weaknesses and shortcomings as individuals’, but it is balanced out by other members of the team. Everyone is eager and willing to work on the project as a group. Every member is assigned to be in-charge of different parts of the whole project.

Management Proposal

Main Contact for Group 16: Eric Kieffer
Email:kieffer7@buffalo.edu

Motto for this Project: All members are to treat one another with respect and to do their share of the work as described below. Working as a group and helping one another is essential to making this project a success.

Group Members and Responsibilities:

Eric Kieffer- Group Leader and Main Contact
Eric will be in charge of organizing each aspect of the project and distributing the workload of the project in a fair and even manner. The workload will be distributed by Eric with the strengths and interests of each group member in mind. Eric is in charge of outlining when each part of the project begins and will be due to submit to the entire group so it can be put up on the wiki in a timely manner. The meetings will also be set up by Eric by email and text message. Eric will also be helping out every group member in each aspect of the project when help is needed.

Kyle Lynch- Solid Modeling Expert
Kyle will be in charge of the solid modeling aspect of this project. Kyle is the solid modeling expert because he is interested in the topic and has some experience with it. Also, Kyle has access to a solid modeling program which benefits the group greatly. Before the solid modeling aspect of the project begins Kyle will be helping with the workload of the other group members when needed.

Jonathan Lottes and Alexis Wong- Wiki Developers
Jonathan and Alexis have taken on the creating of the wiki as a team because the group feels for in order for the project to look professional and impressive it would be more than a one man job. Both Jonathan and Alexis seemed interested in learning on how to create a wiki which will benefit the group as they both seem very eager to master this task. Together Jonathan and Alexis will be taking reports and various information given to them by the other group members and putting this information on the wiki. It is their responsibility to make sure the wiki looks organized and eye appealing throughout the project. Most of the information will be sent to them via email.

Sanket Chavan- Dissection and Reassembly Manager
During the dissection and reassembly it will be Sanket’s responsibility to take vigorous notes and to create diagrams when needed for the dissection and reassembly of the drill. Sanket will be responsible for most of the product dissection plan as he will know the most about this process. All aspects of parts and construction details will be the responsibility of the Dissection and Reassembly Mananger. Sanket will also be helping the other group members before his aspect of the project and during when asked to do so.

• All group members will have the responsibility of helping other group members when asked by the Group Leader.
  
  

Meeting Times and Location:

As of 10/6/2009 Group 16 will be meeting weekly on Tuesday nights at 4:30 pm at the Lockwood Library. Other meetings, times, and locations are sure to be needed and will be told to the group by the Main Contact for the group.

Plan to Complete all Necessary Work:

If each group member does their job as specified above then the project will get done in a timely manner that can be seen on the gantt chart below.

Initial Product Assessment

Intended Use
The intended use of the Black and Decker Power Drill is to accept various bits and rotate it with various torques.

Home Vs Professional Use: This product is geared towards home use because it is inexpensive. Professionals would look for a higher end model because reviews say the keyless chuck wears out after extended use and would not tightly hold bits. ₁

Different Functions: The different functions of the Black and Decker Power Drill include rotating bits in clockwise and counter-clockwise directions, and ensuring the drill is level with a spirit level in the back.

How It Works
The product operates by rotating the bit at speeds proportional to the pressure applied to the trigger. The direction of the rotation is determined by a three-way toggle above the trigger. The position of the toggle determines whether there is clockwise rotation, counter-clockwise rotation, or the drill is locked for safety, allowing no rotation. The spirit level works by partially filling a small tube with a liquid, leaving a small amount of less dense gas that will remain at the top of the tube. Small lines are printed on to show where the bubble should be when the drill is level.

Types of Energy: The drill uses electrical energy, mechanical energy, and gravitational energy.

Transformation and Modification of Energy: The drill accepts electrical energy through the power cord as an input, which is converted to mechanical energy by the motor to turn the bit and fan. It also uses gravitational energy so the bubble can be leveled in the spirit level.

Functionality
The product is not currently functioning and it is difficult to tell what is causing the problems currently. The electrical energy is not being properly converted into mechanical energy, suggesting that there might be a detached wire internally.

Complexity
Using a scale from 1 to 10, with 1 being a screwdriver and 10 being a milling machine, the Black and Decker Power Drill falls around a 4. This is because the drill has far fewer components than a milling machine, yet is still clearly more complex than a screwdriver, with the addition of a electricity, a motor, and a chuck for exchangeable bits.

Number of Components: It is estimated that there are around 10 components to the drill. This estimate comes from what is visible on the outside, such as the trigger for operator interaction, chuck to hold a bit, toggle to select safety or direction, bit to apply the work of the drill, cord to deliver electricity, spirit level to ensure the drill is level, and a casing to hold the components together, as well as what is believed to be inside, such as a motor to drive the bit, potentiometer to determine the speed of rotation based on trigger position, and a fan to keep the motor cool.

Complexity of Components: The individual components in the drill are not highly complex. The trigger, toggle, bit, casing, fan, and spirit level are very simple, with very few parts and easy to understand operations. The most complex parts in the drill would be the motor, chuck, and potentiometer. However these parts themselves are not very complex, as none have many parts.

Materials
There are number of different materials used in the drill.

Visible Materials: On the exterior, the case appears to be made of a plastic or polymer. The trigger and toggle are made of plastic. The bit appears to be made of steel. The spirit level looks as if it is made from a glass case partially filled with water. The cord is likely made of copper wiring encased in a rubber insulator. The chuck looks like it is made of steel and plastic.

Interior Materials: The fan is likely to be made of plastic or aluminum, while the motor is likely made of iron and steel. The potentiometer is estimated to be made of iron and graphite.

User Feedback
It is difficult to say whether one would be happy with this product, as the drill does not currently function, and the circumstances involved with the lack of functioning are unclear.

Comfort: The product is comfortable to use, with an ergonomically designed grip.

Ease of Use: The drill is easy to use, with only two simple mechanisms (trigger and toggle) for the user to operate.

Maintenece: The drill should not require regular maintenance. The difficulty in servicing the drill ranges depending on what the problem is, such as a loose wire, or a burned out motor.

Alternatives
There are many alternatives to the Black and Decker Power Drill, ranging in price and function. Some such alternatives include a simple screwdriver, a drill press, or competing power drills.

Screwdriver: A simple screwdriver would cost far less than the drill, but would require the torque to be provided by the user, which would likely be lower than that of the power drill. It also would not likely have exchangeable bits. However, as the screwdriver does not require electricity, it is more mobile and would not require any maintenance.

Drill Press: A drill press would cost significantly more than a power drill. It would offer more power than that of the power drill, and provide very straight plunges. However, the drill press cannot be manipulated as easily as a power drill, and is less mobile.

Competing Drills: Competing power drills would have varying advantages and disadvantages when compared to the Black and Decker Power Drill. These would like include the quality of the parts used, which would be closely related to the price of the drills. Other drills may or may not have the keyless chuck and spirit level.

Sources

1. http://www.amazon.com/Black-Decker-DR202-8-Inch-Keyless/product-reviews/B0000C6DX3/ref=cm_cr_dp_all_summary?ie=UTF8&showViewpoints=1&sortBy=bySubmissionDateDescending

Gate 2

Causes for Corrective Action

The work and management plans have been followed perfectly by the entire team. Following these plans has made the project very manageable for everyone in the group, as all of the work has been split up evenly and fairly.

In the work assessment, all work required for each stage was intended to be completed a few days early to avoid last minute stress. Everything has been accomplished in the designated time frames with time to spare

Each member has followed the management proposal and everyone has fulfilled the duties that their respective position entails. Every member has embraced their responsibilities and is ready for the challenge of the workload ahead.

In order for the team to continue to work as effectively and efficiently as it has thus far, there are a few essential things the group must continue to do. The group must stick to the management and work proposals diligently. The group must also continue to maintain strong communication with one another, keeping up to date with the individual sections being worked on.

Everyone in the group plans on sticking to the management and work proposals for the upcoming parts of the project, and each will strive for it to go as smoothly as the previous stage has gone.

Product Dissection Plan

Overview

The Black and Decker hand drill is a sturdy tool. It has been built to ensure that all parts in the product remain in place and do not cause a safety hazard. Although built to last, it is fairly easy to disassemble. To rate the difficulty of disassembly, a scale from ‘1’ to ‘5’, with ‘1’ being the easiest and ‘5’ being the hardest, is used. To give meaning to the scale, a ‘1’ is defined as a simple disassembly, requiring few tools and little time, while a ‘5’ would be a complex process, requiring multiple tools, numerous attempts, and a large amount of time. The disassembly of the Black and Decker hand drill is around a ‘2’ on the scale. Disassembly is not very difficult, as it may become necessary to repair or replace broken and faulty parts.

During pre-disassembly, it was assumed the following would be needed:

1.  3/16 flathead screwdriver
2.  Small pick
3.  Large pick
4.  Needle nose pliers
5.  Small wire cutter
6.  Torx driver set
7.  Vice
8.  Soldering iron

During disassembly, it was found that the following was required:

1.  #12 Torx screwdriver
1.  Needle nose pliers
3.  Allen key

Step-by-step Process

Each step will be rated in terms of difficulty on a scale from ‘1’ to ‘5’. This is with a ‘1’ being a simple task such as unscrewing something and a ‘5’ being taking apart a piece that is breakable and not easy to get at without care.

1. Place the drill on the table, check that it is unplugged and the drill is flat and steady with the Black and Decker label side down.
Difficulty: 1

2. Remove the 9 screws that keep the housing intact using a #12 Torx screwdriver.
Difficulty: 1

3. Remove the top shell of the housing by hand and set it aside.
Difficulty: 1

4. Remove the level cap and rubber drill bit from the inside of the housing. This may require force.
Difficulty: 1

5. Remove the level from the top right corner and the bit holder from the upper middle area. Both components are black in color making them easy to identify against the red shell.
Difficulty: 1

6. Remove the two screws holding the cord clamp using a #12 Torx screwdriver. This clamp is in the central region of the handle. The clamp easily comes off once the screws are taken off.
Difficulty: 1

7. There are two wires connected to the reverse ring on the top right corner. These wires connect the directional switch to the external 120V power supply. The main cord is fastened by compression from the housing at the bottom of the handle. Remove the cord from the slots at the bottom of the handle and remove the two cables inside the housing. Note: Removing the cable is simple, but care must be taken while removing the wires from the reverse ring.
Difficulty: 2

8. Remove the trigger from the shell. Take note of the assembly of the reverse ring and its positioning with the toggle switch and trigger.
Difficulty: 1

9. Remove the directional switch. Be sure to take the left end of the switch out of the lower side of the reverse ring. Once the switch is out, there are no parts held by compression from the housing.
Difficulty: 2

10. Carefully take out the entire arrangement of the reverse ring, motor, fan, gearbox assembly, and keyless chuck from the housing together. As the assembly is held in place by built-in slots in the housing, the assembly should be lifted straight out applying equal force across the each member of the assembly. Note: Perform this step slowly and carefully to ensure the brushes do not fall out or break.
Difficulty: 4

11. Place the assembly on the table and separate the gearbox from the motor; it will pull out with ease.
Difficulty: 2

12. Separate the reverse ring from the end on the motor. It is held on by plastic clamps and snaps off easily; care must be taken as the brushes are held in place by the ring with a spring mechanism that pushes them against the motor. Remove the ring and take out the brushes and set them aside.
Difficulty: 3

13. The reverse ring bracket is fastened to the motor by two long screws. Use a #12 Torx screwdriver to remove the screws. The bracket pulls out.
Difficulty: 2

14. The gearbox assembly is made up of four parts: the rear bearing plate, the gear and pinion, front bearing plate, and the spindle attached to the keyless chuck. The four components come off once the gearbox assembly is twisted. This requires little force. After twisting just pull the assembly apart.
Difficulty: 4

15. After step 14 the disassembly is complete. Be sure to take notes on all the parts and label the direction of insertion for the parts. It is suggested to put all small parts such as the screws and the brushes in a bag.

Total Time: 45 minutes

Analysis

If you faced challenges during dissection outline those challenges and describe how they were overcome.

There were very few problems during the disassembly. The following challenges were faced:

1. The chuck could not be taken apart from the spindle. In the attempt to remove the chuck, the chuck was clamped down while an Allen key was inserted and twisted with as much torque as could be produced. After numerous attempts, the chuck could not be successfully removed.
2. The drill was in a non-working condition when handed over to the group. The group believes it has successfully identified the problem in the drill. It was not working due to the broken reverse ring. The group tried to fix it temporarily using insulating tape to hold the two pieces of the reverse ring together. The insulating tape did not work; as soon as it was put back in the assembly, the two pieces broke off again. This problem will try to be resolved in the future by using duct tape or a better option if available. Until then the drill is still in non-working condition.

Is the product intended to be taken apart easily?

As mentioned earlier, the drill is supposed to have a very sturdy build but, as it is a power tool, it is made to be disassembled. Even with the sturdiness it can be disassembled fairly easily which makes repairing/replacing the parts convenient.

What fasteners are used and why?

Fasteners used:

1.  9 Screws for the housing.
2.  2 screws and a clamp for the cable inside the handle.
3.  The whole housing is designed with grooves and slots such that the internal mechanical assembly is secured and in place once the two shells of the housing are screwed together.

Are special tools required?

The only special tools that are needed to disassemble the drill were the #12 torx screwdriver and the allen key.

Parts List

Sources

DeWalt Service Net - http://www.dewaltservicenet.com/Products/DocumentViewPDF.aspx?productid=33258&typeId=8795&documentId=21976