Group 20 - HP Inkjet Printer

Revision as of 23:38, 4 December 2009

Introduction

Hp Deskjet 960c

As part of MAE 277's Reverse Engineering Group Product, Group 20 will dissect and reverse engineer a Hewlett Packard (HP) Deskjet 960c. Five "gates" must be completed over the duration of this project: the Request for Proposal, Preliminary Project Review, Coordination Review, Critical Project Review, and the final step, delivery of the final project.

Executive Summary

Product:
HP Deskjet 960c Printer

Group Members

Andrew Katz- Research Manager, Dissection/Reassembly Team

Andrew Katz is a sophomore at the University at Buffalo majoring in aerospace engineering. He plans to take internships at any available firms in his field, and eventually wants to take a full time job working in the aerospace industry, hopefully for NASA or Lockheed Martin.

Kayla Kisenwether- Communications Liason, Presentation Manager, Dissection/Reassembly Team

Kayla Kisenwether is a sophomore student of Mechanical Engineering at the University at Buffalo. Kayla has worked for Material Innovations, based in Sugarloaf PA, in the capacity of head web designer and has also worked on the construction of their patented Big Bale Mulcher. After graduation, Kayla plans to pursue a career in designing consumer products.

Jonathan Murphy- Dissection Manager, Dissection/Reassembly Team

Jonathan Murphy is going to University at Buffalo to earn his Bachelors Degree in Mechanical Engineering. At the current point in time, he does not have any true relevant work experience, other than dissecting or fixing mechanical products in his spare time. In the future he hopes to obtain an engineering job once he gets his degree and help create an innovative product.

Matt Gregoire- 3-D Model Developer, Dissection/Reassembly Team

Matthew Gregoire is currently in his second year at the University at Buffalo where he is pursuing a B.S. degree in Mechanical Engineering. Even though the engineering program involves a rigorous amount of school work, he feels that engineering is the right fit. At the moment Matthew does not have any relevant work experience but is hopeful he will be able to find an internship for the summer of 2010. Once he graduates he hopes to find a job that is very hands on and he is able to be a part of a design team for some type of large machinery. Matthew one day would like to invent a cutting edge product that will have a positive impact on society.

Tim Habben- Group Leader, Webpage Developer, Dissection/Reassembly Team

Tim Habben is a sophomore Mechanical Engineering student scheduled to graduate in May 2012 with a B.S. He is also interested in obtaining a M.B.A. from the University at Buffalo as well. In the summer of 2009, Tim worked at the Eastman Kodak Company as part of the "Testing Technology" group, which provides service and support to many machines and software around the company. During his time at Kodak, Tim helped create a program to track film processing tests from building to building through scans and tracking screens. After graduation, he hopes to obtain a job designing and implementing new systems at companies, that help not only with the efficiency of the company, but the quality of the company’s products as well.

Request For Proposal

The purpose of the Request For Proposal is to provide the group with a plan for the project as well as provide the group with initial information about the printer. The Work Proposal provides an overview of how the group plans to disassemble and reassemble the printer, while the Management Proposal provides a timeline for the group to follow to complete the project on time. The Management Proposal also details what each group member is resposible for during the project. Also, the Initial Product Assessment helps the group to familiarize itself with the printer by discussion certain aspects about the printer.

To view the Request For Proposal, click the link below

Group 20 Request For Proposal

Preliminary Project Review

The purpose of the Preliminary Project Review is to take a look back at our work and management proposals and see if they are working well, as well as provide a step by step guide for taking apart the HP Printer. The Disassembly Procedure details how the printer was taken apart, the Disassembly Reflection discusses what was found during the dissection, and the Causes For Corrective Action looks back at the intitial plan proposed by the group and makes changes to that plan if necessary.

Disassembly Procedure

The disassembly of our printer took approximately three and a half hours over two seperate days. Day one occured on October 19, 2009, and encompasses steps one through twenty. Day two occured on October 26, 2009, and encompasses the remaining steps twenty one through thirty three. Total time spent on each day was two and a half hours on day one and one hour on day two. Each step required to disassmble the printer is detailed below in Table 2: Disassembly Procedure, and the difficulty was measured using the following table, Table 1: Disassembly Difficulty Levels.

Table 2: Disassembly Procedure

Step #	Process	Tools Used	Difficulty	Picture
1	*Power on the printer *Open lid so print head assembly comes into view *Disconnect power cable so print head assembly does not move back out of view	None	1
2	*Remove both ink cartridges from print head assembly by lifting up teal clips.	None	1
3	*Remove two Torx 10 screws on top of printer casing.	Torx 10 Screwdriver	1
4	*Turn knob and remove back panel.	None	1
5	*Remove paper tray from front.	None	1
6	*Reach inside from of printer and disengage clips attaching the top cover to the bottom, then do the same for the back. *Slowly pull cover off of printer, as other parts will still be connected to top cover.	None	3
7	*Disconnect panel with buttons from the case by pulling the clips on either side toward each other. *Rotate the panel with the buttons so the panel can fit through the opening in the case, then seperate the panel from the case. *Wires connected to panel can be disconnected by slowly pulling them away from the panel.	None	2
8	*Lift out parallel port and USB port cover.	None	1
9	*Remove two screws holding in silver bar on top of printer. *Lift out the silver bar.	Torx 10 Screwdriver	1
10	*Remove the two screws holding in the large motor on the left side of the printer. *Gently remove the belt and click the motor out from the back.	Torx 10 Screwdriver	2
11	*Remove screw holding on the metal plate near the power adapter.	Torx 10 Screwdriver	2
12	*Remove control board next to left motor by removing the screw holding it in place.	Torx 8 Screwdriver	1
13	*Remove second motor (also on left side) by removing two screws. *Detach the wires from both motors. *Also remove metal clip with rollers next to motor.	Torx 8 Screwdriver	1
14	*Disconnect ribbon cable on both ends (from print head assembly and circuit board).	None	3
15	*Remove screws from silver rod. *Rod and print head assembly can now be lifted out in one piece.	Torx 10 Screwdriver	2
15a	The disassembly of the rod and print head can now occur. *Disconnect thin transparent strip by carefully releasing the strip on each end. *Disconnect the silver rod by popping it out from the frame on each side, and slide the rod out from the print head assembly. *Remove the 6 pink screws from the print head assembly. *Remove the 3 pieces of plastic that were released by the screws. *The wires and circuit boards for the print head assembly can now be removed.	Torx 10 Screwdriver	3
16	*Depress two tabs on the bottom of printer (towards the front) in order to remove plastic tray that guides the insertable paper tray. *Remove paper tray.	None	2
17	*Disengage large spring (covered in black plastic) on left side.	None	2
18	*Carefully pull wire connector out of the circuit board. Remove the circuit board from the printer.	None	1
19	*Remove roller cover that has four springs on it.	None	2
20	*Pull rollers out through the back of the printer.	None	2
21	*Pop out lower right corner plastic guard using a flathead screw driver. *Blue and black wires that are not attached to anything will be exposed- these must be slid back through the small hole into the main part of the printer.	Flat Head Screwdriver	3
22	*Two little white plastic clips holding wires must be detached with needle-nose pliers. *One is on the right, in the front behind the plastic door that was just removed, and the other clip is on the left in the very back, between the internal frame and the plastic back wall (holding blue and white wires).	Needle-nose Pliers	3
23	*Remove two screws on top of black box on the right side of the printer. *Once the top part of the box is removed, the roller, ink assembly, and sponge can be removed as well. *The box itself can then be removed by depressing the two tabs hoding it in- one on the top left side of the box, the other on the right. *After removal, detach the gray wires from the little motor on the side of the black box.	Torx 10 Screwdriver	4
24	*Remove the small motor from side of black box by removing screw and undoing clip. *Remove the two gears.	Torx 10 Screwdriver	1
25	*Disconnect the yellow and green wires from the small tan circuit board.	None	1
26	*Remove the small metal blocks from either side of metal frame by turning them so they fit through the slot on the frame.	None	1
27	*Remove black wing with spring from gray plastic piece jutting out on both sides of the printer by pulling the front of the wing through the plastic frame piece that it is attached to. *Be careful not to bend the springs as the wings are taken out.	None	2
28	*Remove the gray plastic pieces that held the wings by disengaging the two clips on the bottom of each piece and sliding the pieces upwards.	None	4
29	*Slide out the small black bar in the direction of the plastic pieces that were just removed. *Slide out the main rollers (a loose spring will slide off as well).	None	2
30	*Remove the blue and white gears on the left side of the printer.	None	1
31	*There now remains a black strip of plastic in the back of the printer. *Gently pull the strip forward until it pops out.	None	2
32	*Remove black bar with clips that held the black strip of step 31 in place.	None	1
33	*The printer is now disassembled, with only the frame remaining.	None	1

Disassembly Reflection

Challenges to Disassembly

Our group had to overcome a few challenges during our dissection process. One of the main challenges was that the printer was not designed to be taken apart. This is due to the fact that the average user of the printer has no reason to disassemble it. The only parts of the printer that are designed to be easily removed are the ink cartridges (step 2), and the back panel (step 4) in case of a paper jam. A second challenge was the removal of some screws and clips that were in hard to reach places, which we overcame by changing the angle at which we were attempting to remove the screws and clips until we found an angle that allowed us to remove said obstruction. A final challenge was keeping track of the amount of small parts that came out of the printer. This challenge was overcome by organizing all of the small parts in a sectioned box so we knew where they came from.

Fasteners used in the Printer

The printer is filled with many different fasteners, which make parts of the printer tricky to take apart. The fasteners used are Torx 8 and 10 screws, plastic clips on the outside casing and other plastic parts inside the printer, and white plastic clips to keep the wires organized inside. The Torx screws were the least difficult components to unfasten in the printer, followed by the white plastic clips and the general plastic clips on the printer. The Torx screws were used to hold together parts of the printer that were easily accessible to get a screwdriver into on order to undo the parts. The plastic clips, on the other hand, were used to clip parts together that would have been difficult to unscrew because of their position within the printer. Unsnapping these plastic clips on the casing and removing the internal plastic parts that contained clips was an extreme challenge at times. This is due to the fact that the printer is not meant to be taken apart, so many of the clips are in locations that are very hard to get unclipped, but easy to clip back into place during reassembly. The white plastic clips holding some wires in place were also difficult to remove from the printer, again because they were in hard to reach spots. These white plastic clips were used because, without them, wires would have been scattered throughout the printer with the potential to get caught in moving parts.

Special Tools Required

The tools required to disassemble the printer are all fairly common tools. Out of the three tools necessary to disassmble the printer, only the Torx 10 Screwdriver may not be readily available at one's home or office. The needle-nose pliers and flat head screwdriver, however, are both very commonly found. Due to the required tools prevalence, we were able to disassemble our printer out of the lab, which gave our group the benefit of not having to schedule the disassembly during lab hours.

Causes For Corrective Action

Schedule

So far, with one exception, our group has managed to remain on schedule. All three elements of the Request For Proposal were completed on time by each member of the group, and all elements of the Preliminary Project Review are expected to be completed well before the due date in order to assure proper time for the elements to be incorporated into the wiki. We deviated from our schedule only in the product dissection- we had expected to complete dissecting our product on October 19th, but due to unforeseen circumstances (detailed under ”Estimated Duration of Disassembly”) we were not able to finish during our meeting that night and the task was not completed until our next meeting on October 26th.

Though we have been meeting our targets, we plan to re-evaluate our planned schedule of meetings, as attendance at the previous two meetings has been only three members. Our original plan was to meet each Monday at eight PM in Capen Library- we have since decided that it is more convenient for us to meet in a Governors lounge where we have more freedom to work at any noise level we choose.

Estimated Duration of Disassembly

Originally, our group anticipated that our product disassembly would take less than three hours. In the end, the actual length of disassembly was closer to three and a half hours due to many problems, some unexpected and some anticipated. We did not expect the printer to contain nearly as many parts as it did in actuality. There were many small electronic components that we did not expect, and even one more motor that we would have ventured to guess. We were correct in our assumption, however, that as the printer was not intended to be taken apart, there were many screws in “inconvenient or hard to reach locations” and plastic snaps that were difficult to disengage. Many plastic pieces had multiple tabs that had to be pressed at the same time or in a certain order if the piece was to be freed.

Tools

When we began dissection, we used a set of small electronics screwdrivers (Torx 5 through 10) that we had originally intended to use for that purpose. Some of the screws, however, were too tight for the somewhat delicate screwdriver to be effective. We were forced to switch to a much larger screwdriver set which ranged from Torx 10 through 40. Our belief that we had stripped a few screws proved baseless after we began using the tools that better suited our needs.

Group Member Responsibilities

To date, work has been distributed unevenly between group members. Some of this is due to which skills are needed for the current part of the project- for example, our three-dimensional model designer has little to complete for Gate Two but will have much more work than anyone else during Gate Three. While Group 20 acknowledges this problem, we do not plan on addressing it unless the situation worsens as the workload should begin to balance out by the end of the project. Problems were also encountered due to the lackluster attendance at group meetings- those not present could not be assigned wiki content creation (most of which is done separately by group members and not at group meetings) as they did not have the necessary knowledge or information. Our group hopes to resolve this issue by adopting a more convenient meeting time that all group members will be able to attend.

Coordination Review

The main purpose of the Coordination Review is to have the group analyze the components of the printer in order to see what works well, what could be improved, and what further forms of analysis can be completed in order to get a better understanding of the product. The Component Summary lists all of the components of the printer, including what they are made of as well as their manufacturing process, while the Component Summary Reflection further discusses what was found inside the printer. Using these components, Solid Models can be made to show how part of the printer is assembled in sequence, while Design Revisions can be made by the group based on total analysis of the product. Finally, Engineering Analysis can be used in order to show how further testing and analysis can be done on the HP Deskjet 960c Printer.

Component Summary

After disassembly of the printer, 57 components with important functions were found and documented. The full listing of these components can be found below, in Table 3: Components of the Printer.

Table 3: Components of the Printer

Part #	Part Name	Quantity	Function	Material	Manufacturing Process	Image
1	3/4" Torx 10 Screw	2	Hold top casing on printer	Steel	Machining
2	Outer Casing	1	House internal components of printer; protect printer from dust	Plastic	Injection Molding
3	Power Cable	1	Provide power to the printer	Plastic outside, copper inside	Injection Molding, Insertion of wire into cord
4	Ink Cartridges	2	Provide ink to be used for printing	Plastic	Injection Molding
5	Back Panel	1	Allow access to back of printer in case of a paper jam	Plastic	Injection Molding
6	Paper Guide	1	Guide paper out of printer as documents are printing	Plastic	Injection Molding
7	LED and Button Assembly	1	Allow user to turn printer on and off, cancel a print job, and show when ink in printer is low	Plastic, Silicon for buttons	Injection Molding
8	Parallel Port and USB Cover	1	Protect the main circuit board from outside damage from connecting cables	Plastic	Injection Molding
9	Thin Silver Bar	1	Pulls print head assembly into a vertical position	Steel	Die Casting
10	1/8" Round Head Torx 10 Screw with Ridge	2	Hold thin silver bar in place on top on printer	Steel	Machining
11	Large Motor	1	Provides power necessary to move ink cartridges back and forth across print head assembly	Steel	Machining
12	3/16" Flat Topped Torx 10 Screw	2	Hold large motor in place	Steel	Machining
13	Power Port and Circuit Board	1	Takes power from the power cable and uses it to run the motors in the printer	Epoxy Resin, Solder, Polytetrafluoroethylene	Board is molded; Individual components attached to board
14	Power Port and Circuit Board Case	1	Houses power port and circuit board	Plastic	Injection Molding
15	3/16" Flat Topped Torx 10 Screw	1	Hold power port and circuit board in place	Steel	Machining
16	Small Circuit Board	1	Send information to small motor located near the rollers	Epoxy Resin, Solder, Polytetrafluoroethylene	Board is molded; Individual components attached to board
17	Black Plastic Clip	1	Protect small circuit board near small motor from moving parts	Plastic	Injection Molding
18	3/16" Round Edge Torx 8 Screw	1	Hold small circuit board in place	Steel	Machining
19	Small Motor	1	Provides power necessary to move rollers	Steel	Machining
20	3/16" Round Edge Torx 8 Screw	2	Hold small motor in place	Steel	Machining
21	Ribbon Cable	1	Sends information between main circuit board and print head assembly	Copper, Plastic	Molding
22	Heavy Silver Bar	1	Provides sturdy track for ink cartridges to move on	Steel	Die Casting
23	1/2" Torx 10 Screw	2	Hold heavy silver bar in place	Steel	Machining
24	Transparent Band	1	Provides additional support for ink cartridges to move on	Plastic	Injection Molding
25	Ink Cartridge Carriage	4 pieces	Holds ink cartridges and circuit board in place	Plastic	Injection Molding
26	Ink Cartridge Circuit Board	1	Provides information that tells print head assembly what to do	Epoxy Resin, Solder, Polytetrafluoroethylene	Board is molded; Individual components attached to board
27	Pink Torx 10 Screw	6	Hold ink cartridge carriage together	Steel	Machining
28	Print Head Assembly Belt	1	Moves ink cartridges along print head assembly	Rubber	Molded into shape with pressure
29	Print Head Assembly Frame	1	Holds print head assembly together	Steel	Die Casting
30	Paper Tray	1	Stores paper for printing	Plastic	Injection Molding
31	Plastic Covered Spring	1	Pull rollers and print head assembly closer together	Steel	Coiling
32	Main Circuit Board	1	Sends information to all parts of the printer with instructions for printing	Epoxy Resin, Solder, Polytetrafluoroethylene	Board is molded; Individual components attached to board
33	Wire Harness	1	Transfers information from circuit board to all parts of the printer with instructions for printing	Copper	Individual wires braided together
34	Roller Cover (1)	1	Protects rollers from accidental ink spills from cartridges, guides paper	Plastic, Steel	Injection Molding, Die Casting
35	Rollers (1)	1	Pulls paper through printer	Plastic, Steel	Injection Molding, Die Casting
36	Small cover for front right of printer	1	Houses wires	Plastic	Injection Molding
37	Spittoon	1	Catches excess ink from cartridges	Plastic	Injection Molding
38	Spittoon Cover	1	Ensures ink stays inside spittoon, unless a massive ink spill occurs	Plastic	Injection Molding
39	Spittoon Roller	1	Slides print head cleaner along the bottom of the ink cartridges	Plastic	Injection Molding
40	Print Head Cleaner	1	Cleans excess ink off of the bottom of the cartridges after printing	Plastic, Steel	Injection Molding, Investment Casting
41	Spittoon Sponge	1	Soaks up excess ink	Plastic Polymers	Materials mixed in a mold
42	Spittoon Motor	1	Powers print head cleaner	Steel	Machining
43	Small Gear from Spittoon	1	Transfer movement from motor to Spittoon	Plastic	Injection Molding
44	Large Gear from Spittoon	1	Transfer movement from motor to Spittoon	Plastic	Injection Molding
45	Pink Torx 10 Screw	3	Hold Spittoon together	Steel	Machining
46	Small Metal Block	2	Provide a spot for screws from the print head assembly to securely attach to	Steel	Die Casting
47	Wings	2	Guide paper as it leaves the printer	Plastic	Injection Molding
48	Small Spring	2	Allow slight movement of black plastic wings as paper goes through printer	Steel	Coiling
49	Wing Holders	2	Support Wings as paper goes through printer	Plastic	Injection Molding
50	Rollers (2)	1	Pulls paper through printer	Plastic, Steel	Injection Molding, Die Casting
51	Roller Cover (2)	1	Protects rollers form accidental ink spillage	Plastic	Injection Molding
52	Medium Spring	1	Allow slight movement of gears and plastic pieces so pieces do not snap under pressure	Steel	Coiling
53	Large Blue Gear	1	Transfer energy from roller motor to rollers	Plastic	Injection Molding
54	Large White Gear	1	Transfer energy from roller motor to rollers	Plastic	Injection Molding
55	Black Plastic Cover	1	Protect thin moving plastic pieces from breaking	Plastic	Injection Molding
56	Paper Lifter	1	Lifts paper from tray so rollers can make contact with paper	Plastic	Injection Molding
57	Frame	1	Provides a base for all of the printer parts to be placed in	Steel, Plastic	Die Casting, Investment Casting, Injection Molding

Component Summary Reflection

Materials used in the Printer

Many of the components inside of the printer, as well as the printer housing, were made out of plastic. Plastic was chosen because it is cheap, lightweight and easy to form. Pieces like the small gears, spittoon, and roller covers did not need to be strong; they needed to be small, light and durable- roles which plastics fill easily. The frame of the printer, however, needed to be strong enough to support all of the components without major deformation, so it was made out of metal, as were the rod and back board supporting the print head assembly. The service station absorber was made out of a fibrous spongy material because its job is to hold as much as possible of excess ink cleaned from the print head.

Forces Applied to the Components

Few components in the printer are meant to handle strong forces. The notable exceptions to this observation are the two larger springs and the frame. Two tiny springs on the wings exert very small forces, not more than an ounce, but the two larger springs exert larger forces. We would estimate the the smaller spring exerts 0.5 pounds of force and the large plastic covered spring exerts 1 pound of force. The frame of the printer is subjected to the force of the weight of the printer’s many components- all told, probably about five to ten pounds of force.

Affects of the Material Choice on the Manufacturing Process

The prevalence of plastic materials in the printer makes the manufacturing process much easier. There were quite a few screws in the printer, but there were also many places in which pieces snapped into place. This is much easier to accomplish with plastic components than it is with metal and made assembly much quicker, and saved money as the cost was not driven up by more screws, as well as the cost of machining holes for the screws.

Affects of the Shape of the Components on the Manufacturing Process

Certain processes must be used for pieces with complicated shapes or thin pieces such as die casting or machining. Investment casting is used for very intricate metal pieces, injection casting for intricate plastic pieces. Injection molding was used for all of the plastic components, such as the gears, wings, and the smaller roller cover because of their complicated shapes. Die casting was used to create the precise configuration of the print head assembly frame and the thin silver bar that pulls the print head into a vertical position.

Reasons why each Manufacturing Process was used

• Injection Molding- Cheap to produce, ideal for producing large quantities of one part, low labor cost, and little wasted material.
  

• Die Casting- Produces smooth surfaces; thinner surfaces can be cast than by sand or permanent casting.
  

• Machining- High precision for metal pieces; can produce complicated shapes and edges.
  

• Coiling- Best way to produce springs.
  

• Investment Casting- Good surface finish, high dimensional accuracy, intricate small parts possible.
  

Particular Shapes of Certain Components

Many of the printer’s components have a distinct shape that allows them to fulfill their purpose. The rollers that draw paper up into the printer are round, some of the screws have flat tops so that they do not get in the way of other components while other screws have rounded tops to make them easier to remove, and the paper tray is exactly the right size to hold 8.5” by 11” paper.

Purpose of the Components- Functional, Cosmetic, or Both

Very few components in the printer serve a cosmetic purpose. The outside casing, and a few pieces such as the back panel that allows paper jams to be easily accessed and fixed, and the paper guide which holds printed sheets until they are dry serve both a cosmetic and a functional purpose. All other components inside of the printer are there because they fulfill a needed function. These functions include transferring data from one part of the printer to another, holding parts of the printer together, or moving parts of the printer.

Component Complexity

All of the components of the printer can be ranked on a complexity scale of 1 to 5, with each of the values outlined below.

• 1. Component is solid, consists of one piece, composed of one material and has a simple shape.
  

• Examples of Components with a complexity of 1 are the gears, spittoon casing, wings, print head assembly belt, the heavy silver bar of the print head assembly, springs, and the spittoon sponge.
  

• 2. Component consists of one piece, is composed of one material and has a complex shape.
  

• Examples of Components with a complexity of 2 are the wing holders, paper lifter, screws, wires, ribbon cable, top casing, and the back panel of the printer.
  

• 3. Component consists of three or less pieces, may be made of different materials.
  

• Examples of Components with a complexity of 3 are the print head cleaner, and the print head assembly frame.
  

• 4. Component consists of four or more pieces made of different materials.
  

• Examples of Components with a complexity of 4 are the rollers and the frame of the printer.
  

• 5. The component is electronic in nature, such as a circuit board.
  

• Examples of Components with a complexity of 5 are the 4 circuit boards of the printer and the 3 motors..
  

Solid Model Assembly

Our group chose to model the Spittoon portion of the printer for a couple a reasons. First, no one in our group had extensive knowledge of solid modeling, so we decided to model a relatively simple portion of the printer. Second, while the Spittoon itself is simple, the same important processes are used in all three sections of the printer that require a motor (Spittoon, Rollers, and Print Head Assembly). Thus, while we are modeling a simple part of the printer, the more complicated systems use the same basic components to complete their tasks. These basic components include a motor, gears or a belt to transfer the energy, and the final component that uses the energy (the rollers, ink carriage, or print head cleaner). Without any of these basic components, none of the three systems would work correctly, and the functionality of the printer would be greatly compromised. Due to the reasons outlined above, our group felt that modeling a portion of the Spittoon would be very beneficial to our understanding of the printer and its more complicated systems. As for the CAD package, our group decided to use Autodesk Inventor because the program was easily available to students on the Autodesk website, and because no one in our group had a 3D Cad package already available on their personal computer.

• The parts of the Spittoon that we modeled are shown below in Table 4: Solid Model Figures
  

• Solid Model Figure 1 is the Spittoon itself
  
• Solid Model Figure 2 is the inner Spittoon gear that moves the Print Head Cleaner
  
• Solid Model Figure 3 is the Spittoon Motor, which provides the power necessary to run the inner Spittoon Gear and in turn the Print Head Cleaner
  
  

Table 4: Solid Model Figures

Spittoon	Solid Model Figure 1: Spittoon
Spittoon Gear	Solid Model Figure 2: Spittoon Gear
Spittoon Motor	Solid Model Figure 3: Spittoon Motor

The Spittoon works by using energy provided by the Spittoon Motor (Solid Model Figure 3), which arrives at the motor from the power port. The motor then turns three gears, two on the outside of the Spittoon, and one on the inside of the Spittoon (Solid Model Figure 2). The final gear is connected to the Print Head Cleaner, which slides back and forth inside the Spittoon and cleans excess ink off of the ink cartridges after each use. The exploded assembly of the Spittoon can be seen by clicking the link below.

View Exploded Assembly of Spittoon

Design Revisions

While the HP Deskjet 960c Printer is very well put together, the group has come up with 4 design changes that we feel would improve the printer a great deal.

• To ease the maintenance and to increase the reliability of the printer, a new compartment should be made in the case. This compartment should be placed in a location that would allow the end user of the printer to remove the spittoon. If the sponge inside the spittoon was to overfill, the ink could leak out of the box, potentially ruining the printer. Currently the entire printer has to be disassembled to remove the spittoon. If a compartment was made to allow the direct removal of the spittoon then the owner would be able to clean it occasionally, prolonging the life of the printer.
  

• Along the same lines as the previous revision, a spill proof spittoon could have been used in the printer since there is no easy way to clean it. A spill resistant spittoon has higher walls, preventing the ink from spilling when the printer is moved. This would allow the printer to be transported by the owner without fear of spillage. This revision would also be relatively cheap because the spittoon is made of plastic.
  

• A third revision involves the overall weight of the printer. The material used for the frame of the printer is very heavy for what it is. Being constructed of a heavy metal may help the printer’s durability; however, many of the outer components of the printer are made of plastic. The plastic is not very durable in comparison to the metal, so a lighter material could be used, making the printer substantially lighter. This would be beneficial not only for the end user, but also for shipping the printer out to stores. Depending on the chosen material the cost to manufacture the printer could also be cheaper.
  

• The fourth revision that the group has come up with has to do with the fasteners used in the printer. While only screws and molded plastic clips are used, there are two different sizes of screws used in the printer- Torx 8 and Torx 10 Screws. If only one size screw was used, the need to have a second screwdriver would be eliminated, as well as the hassle of switching tools throughout the disassembly and the reassembly of the printer. Since the majority of the screws are of the Torx 10 variety, it would make sense that all of the Torx 8 screws be replaced by Torx 10 screws. While this revision reduces stress for the user taking apart the printer, it would also make manufacturing less expensive, because only one type of screw size would have to be produced instead of two.
  

Engineering Analysis

A key functional part of the printer is the sychronization of the rollers and the print head assembly. Without this synchronization, the printer would produce incorrect print outs, which would severly limit the functionality of the printer. To prevent this problem from happening, tests could be done during the design phase of the printer to ensure that the rollers and print head assembly move at the correct speeds in order to produce proper print outs. To calculate the correct speeds that these parts need to move at, an engineerging analysis problem such as the one below could be performed.

Problem Statement

• What speed, in passes per second, does the print-head assembly of the HP Deskjet 960c need to move at for a proper print out of a black and white text document?
  

Diagram

• Both Eng. Analysis Figure 1: Rollers, and Eng. Analysis Figure 2: Print Head Assembly, which are seen below in Table 5: Engineering Analysis Figures, must be moving in synchronization to produce proper print outs.
  

Table 5: Engineering Analysis Figures

Rollers	Eng. Analysis Figure 1: Rollers
Print Head Assembly	Eng. Analysis Figure 2: Print Head Assembly

Assumptions

• Black and white print speed of the printer is 15 pages per minute ^[1]
  
• Rollers move paper at print speed; therefore print-head assembly must keep up with rollers
  
• Printed document is single spaced
  
• Printed document has 48 lines of text with size 11 Calibri font
  
• One pass of the print-head assembly is equal to one cross of the page, or 10 inches
  
• One pass of the print-head assembly covers 5 lines with ink
  
• Page must be completed on a whole pass, not a partial pass
  

Governing Equations

• Seconds to print a page = ((1 minute)/(Pages per minute))*(60 seconds/1 minute)
  
• Passes required to cover page with ink = (Lines of text)/(Lines covered per pass of the print-head assembly)
  
• Passes required per second for proper print out = (Passes required/Seconds to print one page)
  

Calculations

• Seconds to print a page
  

seconds/page= ((1 minute)/(15 pages/minute))*(60 seconds)/(1 minute)=4seconds/page

• Passes required to cover page with ink
  

Passes= (48 lines)/(5 lines/pass)=9.6 passes=10 passes

• Passes required per second
  

Passes/second=(10 passes)/(4 seconds)=2.5passes/second

• Passes per second = 2.5
  

Solution Check

• The above answer of 2.5 passes per second is a reasonable answer to this problem, as a print-head assembly can generally be heard moving at a pretty quick pace to print out a document when using a home printer. Also, all calculations check with units, showing that the answer of 2.5 is indeed in the correct units.
  

Discuss and Interpret

• After calculations, it is found that 2.5 passes per second are required to properly print out a black and white text document based on the assumptions that were made. This means that every second, the print-head assembly passes over the document 2.5 times, all the while putting ink on the page. By associating the manufacturer’s specification of 15 pages per minute print speed with one specific part of the printer, (the rollers), the other main part of the printer used to print a document, (the print-head assembly), can be isolated and the speed required of this particular part can be calculated. While black and white text documents are by no means the only types of documents that are printed, they are very common, and a nice benchmark to calculate data for that can be used in most cases. By using these assumptions, the required speed of the print-head assembly can be calculated.
  

Critical Project Review

The purpose of the Critical Project Review is to provide a final review of the printer and its components before submission of the project, as well as provide a step by step guide for reassembling the HP Printer. The Product Reassembly Plan details how the printer was put back together, while the Reassembly Reflection discusses the differences between the disassembly and reassembly, how well the product works after reassembly, as well as any additional suggestions that the group may have regarding the printer.

Product Reassembly Plan

The reassembly of our printer took approximately two and a half hours over two seperate days. Day one occured on November 9, 2009, and encompasses steps one through fourteen. Day two occured on November 16, 2009, and encompasses the remaining steps fifteen through thirty eight. Total time spent on each day was one hour on day one and one and a half hours on day two. Each step required to reassemble the printer is detailed below in Table 7: Reassembly Procedure, and the difficulty of each step was measured using the following table, Table 6: Reassembly Difficulty Levels.

Table 7: Reassembly Procedure

Step #	Process	Tools Used	Difficulty	Picture
1	*Put small silver clip back in on the bottom of the frame.	None	1
2	*Insert paper lifter into clips and through the left side of the frame.	None	1
3	*The Black Plastic Cover must be popped back in by sticking it in the two slots in bottom of printer, and popping in the back clips.	None	1
4	*Put matching blue and white gears back in on the left side of the printer.	None	1
5	*Slide the Rollers (2) into slots on both sides of the frame.	None	2
6	*The rollers must mesh with the gears that have already been inserted, and the medium spring must be placed over the white peg before it is snapped into its slot.	None	3
7	*Black clip must be fitted into the rollers while the white external clip with the spring must be connected to the blue gear.	None	3
8	*Snap the gray wing holders back into place on each side.	None	1
9	*Put the Wings and their small springs back into place on each side.	None	2
10	*Place the Small Metal Blocks back into the slots on either side	None	1
11	*The Rollers (1) must now be inserted into a slot on one side and popped into the slot on the other in the back of the printer.	None	2
12	*Put Roller Cover (2) back onto the printer.	None	1
13	*Put Roller Cover (1) back onto the printer	None	1
14	*Put large Spring back into printer. (See picture for connections)	None	2
15	Reassemble Spittoon *Place long gear back into Spittoon, followed by the Print Head Cleaner. *Replace two small gears on outside of Spittoon, followed by Spittoon motor, which is attached using a pink Torx 10 Screw. *Snap Spittoon Cover back into place.	Torx 10 Screwdriver	2
16	*Pop Spittoon back into place and secure with two pink Torx 10 Screws.	Torx 10 Screwdriver	3
17	Reassemble Print Head Assembly *Replace print head assembly circuit board, and secure it with the three casing pieces using 6 pink Torx 10 Screws. *Slide the Ink Carriage back onto the large silver bar, and reconnect this back onto the print head assembly frame. *Reconnect the transparent band. *Reinsert the ink cartridges.	Torx 10 Screwdriver	3
18	*Reconnect the Print Head Assembly to the printer using the two long screws.	Torx 10 Screwdriver	1
19	*Slide in main circuit board behind the print head assembly frame, and use two flat 3/16" Torx 10 Screws to secure the board.	Torx 10 Screwdriver	1
20	*Reconnect the Ribbon Cable to both the circuit board and the print head assembly.	None	2
21	*Reattach the black plastic clip to the small circuit board using 1 Torx 8 Screw and carefully insert it into the front left of the printer. *The metal plate also needs to be reinserted into the left side of the printer.	Torx 8 Screwdriver	2
22	*Reattach the small motor to the plate using two Torx 8 Screws.	Torx 8 Screwdriver	2
23	*Reconnect the green and yellow wires to the small circuit board, and reconnect the blue and white wires to the small motor.	None	1
24	*Insert the large motor into the print head assembly frame, and attach it using two flat topped Torx 10 screws.	Torx 10 Screwdriver	1
25	*Stretch the print head belt over the large motor.	None	4
26	*Thread the remaining wires through the hole in the frame, then reattach the breadboard to the main circuit board.	None	2
27	*Put the power box back into the printer and attach it using two 1/2" Torx 10 Screws. *The power box must be lifted over the pegs prior to being screwed into place. *Reattach the red and green wires to the circuit board in the power box.	Torx 10 Screwdriver	2
28	*Reconnect the green wires to the small green circuit board and screw it in near the power box using a flat topped Torx 10 screw.	Torx 10 Screwdriver	2
29	*Press wires into clip that holds them in place near power box.	None	1
30	*Push blue and black wires back through hole in front right of printer, then pop in small cover.	None	2
31	*Reattach gray wires to Spittoon motor.	None	1
32	*Slide in the paper tray and the paper guide.	None	1
33	*Replace silver bar on top of the print head assembly frame using two 1/8" Torx 10 Screws.	Torx 10 Screwdriver	1
34	*Snap white wires into LEDs, and insert the LED panel into the printer housing.	None	1
35	*Press housing down onto the printer until all four clips snap into place.	None	2
36	*USe two 1/2" long Torx 10 Screws to attach the housing to the printer.	Torx 10 Screwdriver	1
37	*Reinsert back panel into the printer and turn the knob, locking it in place.	None	1
38	*The HP Deskjet 960c is now reassembled.	None	1

Reassembly Reflection

Differences Between Disassembly and Reassembly Processes

The majority of the printer was reassembled using the reverse steps from the disassembly procedure. The only differences occured when parts on opposite sides of the printer from eachother were reassembled in a different order than what had occured during disassembly. However, this did not affect the overall reassembly of the printer, because as long as an entire layer of components were replaced before the next layer of components, the printer would still be rather straightforward to reassemble. Additionally, the entire Spittoon was put back together before being reinserted into the printer, where as during disassembly, the cover, print head cleaner, and internal gear were taken out before the Spittoon itself was removed from the printer. Besides these minor differences, the disassembly and reassembly processes of the printer occured in the reverse order of eachother.

Just as the reassembly and diassembly processes were similar, so were the tools necessary for both procedures. During disassembly, Torx 8 and Torx 10 Screwdrivers, a Flat Head Screwdriver (used as a pry tool), and hands were the only tools needed to complete the procedure. The same was true for the reassembly, as the exact same tools were necessary, and no additional tools were required.

By using detailed notes and pictures as a guide, the entire printer was able to be reassembled in the same way that the printer was prior to disassembly.

Product Functionality After Reassembly

Before disassembly, the printer was tested to see how well it functioned. After the intital assessment, the printer was able to power on, with multiple functions occuring. First, the LEDs on the button panel lit up, signifying that the printer was indeed on. Second, the motors could be heard rotating inside the printer every time the printer was turned on. Third, when the cover was opened on the printer, the Print Head Assembly started to function, bringing the Ink Carriage into view for the user. Closing the cover returned the carriage back to its initial position. After reassembly, the printer was tested and was found to work in the same way that it did prior to disassembly. Unfortunately, without a USB cable to hook the printer up to a computer, it is unknown whether or not the printer could acutally print a document if prompted to.

Final Thoughts About Printer

After completing the reassembly of the printer and testing its functionality, no additional revisions are believed to be necessary to the printer. Overall, the HP Deskjet 960c Printer is very well put together and performs its tasks extremely well. Naturally, new technology eventually led to better printers being produced, with increased capabilities and increased functionality. However, prior to its discontinuation, the HP Deskjet 960c Printer was a very respectable model in the home printing market, as its functions, seen with each print out, suited the needs of the people perfectly.

References

^[1] Epinions.com