Group 29 - Black and Decker Jig Saw

Revision as of 02:51, 10 December 2007

Black and Decker Jig Saw

Executive Summary

Power drills and saws are common tools necessary in any kind of construction. My group fully disassembled a Black & Decker Jigsaw and examined all the different parts it was made up of. We found out what kind of materials were used and how those materials were manufactured. Prior to the disassembly, we thought of it's usage, took an educated guess on how many parts the jigsaw consisted of, and assumed its features and how they work.

Introduction

The Black and Decker Jigsaw is a power tool used to cut sharp turns, with the ability to switch blades very simply. We dissected the jigsaw, named each part and analyzed the saw completely.

Our group equally worked on the project and consisted of the following members:

Mike Fama

Craig Castiglione

John Kresconko

Rex Chan

Ryan Spies

Pre-Disassembly

Purpose of the Jigsaw

The purpose of the Jigsaw is to cut different intricate bends into a piece of thin wood. The Jigsaw has the capability to cut sharp curves and turn at a small radius, where most saws only allow you to cut in straight lines.

Operation

The Jigsaw receives AC power from a wall outlet from which it is supplied to the motor. The motor then creates rotational mechanical energy which is then converted through a series of gears to produce linear motion/energy. This energy allows the blade to move up and down rapidly when the trigger is activated.

Amount of Components

Estimated number of components:

1. Screws
2. Casing
3. Cutting Deck
4. Blade Holder
5. Gel Pad
6. Trigger
7. Wiring
8. Motor
9. Gears

Types of Materials

Estimated types of Materials:

1. Steel
2. Plastic
3. Rubber
4. Copper
5. Gel

Disassembly

Disassembly Process Table

Parts

Part Table

Part #	Part Name	Quantity	Material and Reason for Choice of Material	Function	Reason for Shape	Manufacturing Process	Image	CAD Crawings
1	Casing Screws	7	Steel which is needed for a sturdy screw	Holds casing and parts inside casing together	A good design to pull two pieces together	Machined
2	Saw Blade Locking Lever	1	Steel because it needs to withstand twisting and direct force.	A bar to keep the rip fence sturdy	To lock in on many points along the bottom	Machined
3	Rip Fence Bolt	1	Steel because bolts need to be strong enough to endure twisting and regular force	To hold the rip fence onto the casing	So it can pull two objects together	Molded then Machined
4	Dust Blower Angle	1	ABS Plastic because it does not take a lot of wear and tear. Also it is cheap and easy to make	To be a pathway for sawdust and air when a vacuum is attached	To turn so the angle can pick up sawdust directly off of what is being cut	Injection Molded
5	Dust Blower	1	ABS Plastic because it does not take a lot of wear and tear. Also it is cheap and easy to make	To be an opening for the pathway which the dust will flow through	To be an opening so it can pick up dust and be pressure fit to the rip fence	Injection Molded
6	Rip Fence	1	Steel because the bottom will be rubbed and hit as it is used quite often	To provide a guide and a base with which to push down on and move the blade	It is flat so it is easy to push and guide the blade along it's path	Injection Molded, Machined
7	Right Side Casing	1	ABS Plastic because it is durable and when it is thick it can deal with a lot of abuse and punishment	To hold all the parts together along with screws	To hold all parts in one area and keep them from moving in ways they aren't supposed to	Injection Molded
8	Left Side Casing	1	ABS Plastic because it is durable and when it is thick it can deal with a lot of abuse and punishment	To hold all the parts together along with screws	To hold all parts in one area and keep them from moving in ways they aren't supposed to	Injection Molded
9	Plastic Blade Guard	1	Plastic because it is a part you look through to see the blade and to protect a persons hand from the blade	To guard the front of the blade so nothing hits the blade that is not supposed to	to cover an area to make it inaccessible to hands and fingers	Injection Molded
10	Gel-max Comfort Grip	1	Gel because it gives and helps absorb the vibrations of the jigsaw	To comfort the hands of user	To cover and area where the users hands would be	Manufactured
11	Shoe Plate Locking Gear	1	Plastic because it is cheap and easy to make and the part does not take much punishment	The person spins it to lock the rip fence in place at a certain angle	It is a gear with teeth to turn another gear locking the rip fence	Injection Molded
12	Shoe Plate Locking Knob	1	Plastic because it is cheap and easy to make and the part does not take much punishment	The person turns the knob with their fingers to lock the rip fence in place	It is a gear and knob with teeth to turn another gear to lock the rip fence in place	Injection Molded
13	Trigger Switch Component	1	Plastic, Copper, Steel, Aluminum because all these are need to get current to flow through it into the motor	To control rate of flow of current to the motor	It is made so there is a constant flow and path of a certain amount of current to the motor	Manufactured
14	Lock on Button	1	Plastic because it is cheap and easy to make and the part does not take much punishment	It locks the trigger so that it cannot turn the engine on	It has two sides so it can be pressed and a small dash in the middle so it can block the trigger	Injection Molded
15	Lock Spring	1	Steel to make a durable and strong spring	It helps make moving the locking trigger easier	It is made in the spring shape to force an object in one direction	Manufactured
16	Plastic Lock Washers	2	Plastic because they do not get much force on them and it is cheap to make	It is to be put on either side of the spring and holding it there	It is made to hold the spring so it will not slip and be wide enough so all the force will be transfered	Injection Molded
17	Switch Breaker	1	Aluminum because it is conductive to metal and will melt breaking the circuit if to much current flows through	A circuit breaker that causes the jigsaw to stop working of too much current starts to flow through it	It is cheap and melts at relatively low temperatures and can handle current going through it	Machined
18	Cord Clamp Screws	2	Steel because they need to be durable and withstand the torque and shear force	To push down on the cord clamp to hold the cord in the casing	It was made to pull the cord clamp against the cord	Machined
19	Cord Clamp	1	Steel because it needs to be strong and is pushed against things	The screws push on it and then it in turn pushes on the cord to keep it in the casing	it was made that way to push evenly on the cord and near flat to save on manufacturing costs	Injection Molded, Machined
20	Red Motor-connecting Wire	1	Rubber and Copper which are great insulating and conducting properties	It conducts electricity from the trigger to the motor	It is made to conduct electricity as efficiently as possible and the rubber to insulate it	Manufactured
21	Black Motor-connecting Wire	1	Rubber and Copper which are great insulating and conducting properties	It conducts electricity from the trigger to the motor	It is made to conduct electricity as efficiently as possible and the rubber to insulate it	Manufactured
22	Spring Loaded Brushes	2	Plastic, Copper, Graphite because they are what is used for a AC to DC motor	It changes electricity from AC to DC	It is made because those materials are needed for the translation of AC to DC	Manufactured
23	Motor Screw	1	Steel because of high stress and torque put on it	It helps hold the motor to the casing	It pulls the motor onto the casing and holds it there	Machined
24	Armature	1	Steel, Copper, ABS Plastic to be durable and cheap	This part is the inside of the motor and a fan to keep the sawdust away	They are all made to do each job as efficiently as possible	Machined
25	Metal Gear	1	Steel for it's durability	It is turned by the motor and spins	It is a gear and helps turn other parts of the jigsaw	Machined
26	1/4 Inch Metal Plate	1	Steel for it's durability	Helps keep everything in place	It was made thick and strong due the vibrations and forces that act upon it	Machined
27	Small Metal Plate	1	Steel for durability	To help hold everything in place	Made thin because it vibrates and is used to protect the large plate from abrasion with a large amount of grease between each of them	Machined
28	Armature Shaft with Rotor	1	Steel, Copper, ABS Plastic, Tape	Part of the motor that alternates to turn the inside causing the rotation	Made to turn electrical energy into mechanical energy	Machined
29	Linear Oscillator	1	Steel for durability	Oscilates up and down moving the blade	In this form it is highly durable and can move easily	Machined
30	Washer off of Gear	1	Steel for durability	Moves inside the hole on the linear oscillator and pushes on it in a vertical direction	It is formed this way to fit in the linear oscillators hole and have the least amount of friction possible	Machined
31	Cylindrical Slider	2	Steel for durability	This is to align the linear oscillator to keep it in line and moving up and down	It is made to be simple and cheap but still strong enough to deal with the friction	Machined
32	Blade Changing Piece	1	Plastic for durability and to keep cost down	It pulls up the springs and the blade holder to allow the old blade to fall out and put the new blade in	It just needs to endure a momentary pull of the finger so it is not thick or strong	Injection Molded
33	Blade Changing Component	1	Steel for durability	It holds the springs and blade changing piece and pushes down on the blade to keep it in place with help of the springs	It is built for the least use of materials and just enough to do what it needs to do.	Cast
34	Blade Changing Spring	2	Steel for durability	It pulls the blade changing component onto the blade holding it in place	It is built to have a large amount of force behind it to endure the fast rate at which the blade is moved	Manufactured
35	Alan Wrench Screw	2	Steel for durability	It holds all of the blade changing components in place	It is built to pull to objects together	Machined
36	Felt Piece	1	Felt for shock absorption	This to absorb any impact the motor may hit linear oscillator wiht	It is minimally built to cover the area's that may be hit	Manufactured

Product Improvements

Battery Operated

- Cord can be a safety issue

- Hampers mobility

- Limits use to within a certain displacement of an outlet

Insulate Plastic

- Saw runs loud

- Insulating plastic will reduce noise

Laser Guide

- Help provide more accurate cutting

Increase Amount of Gel Max Comfort Grip

- With long use more gel will maintain comfort

Assembly

Assembly Process Table

Post-Assembly

Assembly Review

- Assembly was just as easy as the disassembly with the exception of the trigger component. The trigger's spring loaded technology made it difficult to assemble, and a few parts were lost.

Functionality

- Our Black and Decker Jig Saw does not work now due to lost parts within the trigger assembly.

How it Works

- The electrical cord is plugged into a standard AC outlet

- The outlet provides AC power which is brought in through the electrical cord to the trigger

- When the trigger is pressed the power is converted to DC power which goes to the motor

- The speed at which the motor rotates is dependent on how much the trigger is depressed

- The motor then converts this DC power to rotational mechanical energy in the output shaft

- The output shaft of the motor connects to a gear that converts the rotational mechanical energy to linear energy on the blade holder

- This linear energy is used to cut materials because the blade holder is going up and down at a fast rate

Analysis Tests

- Impact and Shock Test

- Test individual parts for durability, wear, and tear

- Testing of the variable speed motor could be done

Disassembly/Assembly Process

- The disassembly process was the exact opposite of the assembly process which was very convenient - This is because most of the parts went together very simply

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Design Changes

Throughout the disassembly and reassembly our group noticed that the jigsaw was remarkably well designed. The saw works perfectly well with its current design. Some ideas we did come up with for slight improvements were as follows.

-Remove Cord: We found that the cord was a safety hazard. people could trip on it, or end up cutting through it.

-Less Internal Grease The internal components of the jigsaw were coated in an excessive amount of grease. It is unnecessary and messy.

-More Power Although we were unable to actually test the tool out, it would seem that the jigsaw would have a difficult time with larger tasks. If the engine were to be made larger it would give the jigsaw the power needed to do big jobs as well as make small tasks easier.

Recommendations to Company

- Set variables speeds allowing users to choose which speed to use for different hardnesses of materials

- Stronger blade holder on the side

- Less grease on the gears, this would save Black and Decker money

- Make the jigsaw more difficult to take apart, so that consumers cannot get inside and void the warranty

References

Group Members

http://www.blackanddecker.com/productguide/product-details.aspx?productid=10226&toolview=2#details