m202 design project

A – Cover Sheet P a g e | 1

MECH 202 – Spring 2015 Group 30 Project 2 – Lander Competition

A – Cover Sheet

Group Number: 30

Group Members Email Addresses

Keisling, Nate [email protected]

Sandhu, Amroz Singh [email protected]

Sawyer, Chris [email protected]

Visocky, Sean [email protected]

Section Page

A - Cover Sheet 1

B - Title Page 2

C - Project Plan 3

D - Specification Development 10

E - Engineering Analysis 19

F - Concept Generation Concept Selection 39

G - Device Description 66

H - Bill of Materials 112

I - Testing 115

J - Reliability and Design Margin Analysis 119

K - Safety Analysis 127

L - Service and Support Plan 130

M -Teamwork Analysis 132

Supplemental Information Location

CERO files Included .ZIP file

Full QFD Excel worksheet Included .ZIP file

Full Final Gantt Table PDF Included .ZIP file

A

B - Title Page P a g e | 2


B - Title Page

B

C - Project Plan P a g e | 3


C - Project Plan

Project Plan:

The project was managed using a Gantt chart. Tasks were created with a start date, end date, and task

owner. The percentage completion was then tracked against the actual date.

The project plan was drafted mostly at the first project meeting, and agreed upon by all members.

Weekly Snapshots of the Gantt Are Shown Below:

C



March 3 - This grid shows that Idea generation is 92% complete, but it was due three days before this

was taken. At this point we are starting to work on the device description, and prepare to manufacture

our first prototype.



April 6 - At this point, we had started manufacturing for our prototype, but we started falling behind

schedule especially with the sliding arm, and the engineering analysis of the winch, and start

mechanism. To fix this we sent out email reminders with specific tasks to accomplish and deadlines for

those tasks.



On April 11, we had fallen behind substantially in the device description, and testing. Our original Gantt

had us testing at this point, and we were not even done with the manufacturing.



On April 15, we had completed our manuf

acturing and had starting testing our device. At this point, we tried to take a dual approach with 2

members focusing on finishing the report, and 2 others to focus and nail down the testing and the

device improvements to make it functional.



Final Gantt chart Snapshots (A full PDF can be found in the included ZIP)



Summary:

Total Hours Spent: 165

Estimated Hours: 100

According to our project plan, we estimated that it would take us 100 hours to draft a project plan,

generate concepts, do engineering analysis of these concepts, and then manufacture a device. This is

65% over what we thought it would take. We were actually very close to our estimate areas in most

cases. The areas that took significantly more time than we thought, were idea generation, device

manufacturing and testing.

Task Name Estimate Hours Actual Hours % Deviation

Idea Generation 26 45 73%

Device Manufacturing 37 74 100%

Testing 10 18 80%

These tasks all took nearly twice as long as was expected, with manufacturing taking exactly twice as

long as expected.

Idea Generation- This took longer than expected because we did not consider how many steps and

different number of approaches we could take in the design. We ended up breaking down each function

in a morphological table and considering ideas of how to accomplish each task. Once we broke it down

to different components this went much faster.

Device Manufacturing- We did not consider all the redesign time when estimating this section. Several

items had to be redone, or even redesigned. This caused the time to increase much more than expected.

Testing- Again in this section we did not consider how many functions would not work, and then go back

find a new solution, and then test again.

D - Specification Development P a g e | 10


D - Specification Development

Note: Please take a look at the included Excell file. Our QFD is rather large!

D



Introduction

This section is quite directly the exact process laid out by Ullman Chapter 6. That being said, however,

there are some changes to note. First, we determined that we would modify the process slightly.

Because we were solving a new and unique problem, there is no competition to directly compare

ourselves to. We realized this would force us to either completely B.S. the entire Now Vs What section

up front or divert it and make use of it elsewhere. Our group decided the best choice would be to leave

out the Now Vs What and determine our specification targets based on our knowledge of the problem.

Then once we had developed and fleshed out our top concepts, the Now Vs What section and an

updated How Much section could serve as very useful metrics for our selection of our final concept. This

is reflected in the QFD at the end of this section, which has no Now Vs What section and a simplified

How Much section. While this may appear initially as an oversight, this is rounded out in Section F where

a complete QFD is one of the metrics used to compare our top concepts and select our final design.

Identifying Customers

We first addressed who our “customers” are. We could certainly pretend we’re developing a product for

production and sale but functionally in this very unique circumstance our customers can be very

effectively described as ourselves. We are designing and developing a device for the use in a competition

and as such, though the functional life of the product, it will interact with competitors and judges above

all else. In this sense we can consider “competitors” and “judges” the two primary target customers of

our device.



Determining Customer Requirements

But what do the customers want? We started with ourselves: What function do we require from our

device in order to compete?

Must be allowed to compete

Must function successfully in the competition

Must be within the realm of what we can design and build

We expanded these broad categories slightly before evaluating their more specific components by

addressing the requirements laid out directly by the project file on pages one through four, including

some additions decided on by the team.

Physical Requirements

o Meets dimensional requirements (18”x11”x3.5”)

o Meets weight requirement (less than 3 pounds)

Administrative Requirements

o Does not affect other devices

o Stays within bounds

o Does not damage fixture

o Does not damage ball

Functional Requirements

o Easy to set up

o Can be set up quickly

o Starts automatically

o Moves ball over wall

o Leaves ball in frame

o Returns to starting side

o Easily reset

o Completes objective quickly

o Is not affected by the environment or other devices

o Functions consistently and repeatedly

o Does not damage itself

Manufacturing Requirements

o Easy to manufacture

o Easy to assemble

o Easy to maintain

o Easy to program

o Inexpensive



Then we considered the needs of the Competition Judges. These judges are far less concerned with the

function of the device and much more concerned with running the competition without any delays,

hazards, or technical violations. As such we determined the primary concerns of the judges were as

follows:

Physical Requirements

o Meets dimensional requirements (18”x11”x3.5”)

o Meets weight requirement (less than 3 pounds)

Safety Requirements

o Does not endanger onlookers

o Does not endanger other devices

o Stays within bounds

o Does not involve large enough forces to damage anything

Balls, fixture, or itself

Functional Requirements

o Set up does not delay competition

o Easily reset

o Is not susceptible to external influence

o Functions consistently as to provide peace of mind

o Does not damage itself

As should be very clear, there is a large amount of overlap between these two because the competition

requirements were laid out to include all of these very directly and deliberately. Some are concerns of

the competitors simply because they wish to be allowed to compete while some are concerns of the

judges simply because they want the competition to move smoothly and safely. These differences are

reflected next in the development of the fixed-sum Who Vs What metric on the QFD.



Who versus What

Our next step was to consider the importance of each requirement relative to each customer.

This was easiest regarding the judges, as they are clearly most concerned with the safety of themselves

and the contestants, the safety of the equipment, and the integrity of the competition, in approximately

that order. Some argument was had over whether or not competition integrity would fall before the

safety of the equipment, but it was decided that teams could always be disqualified and heats could

always be re-run, but you can’t un-damage the unique fixtures.

The debate over the distribution of the priorities of the contestants was more difficult. We started by

selecting our priorities. By a close margin and after significant debate, we decided that our device’s

ability to complete the functional objectives was more important than the device being allowed to

compete in the first place. While these are obviously the top two concerns, we made this distinction

because we wanted the QFD to prioritize the function of the device more heavily than it was going to if

we had focused on the device meeting the physical constraints. While we realize practically that not

allowing a device to compete makes its ability to function moot, we chose instead to break the fourth

wall, as it were, and make this decision based on increasing the effectiveness of the QFD.



Now versus What

To reiterate, given the unique circumstances of this competition, we do not have any competition to

compare until we’ve gone through the concept generation process and selected our top concepts. These

concepts will then be inserted into a complete QFD as a part of our Concept Selection process. To see

the full QFD, complete with the Now versus What section as well as a fully fleshed out How Much

section, please refer to Section F.



Specification Development

The development of our specifications was a slow evolution that grew in time with our understanding of

the problem and the potential solutions. Some things were obvious, like the constraints of the starting

area, the weight constraint, horizontal and vertical distances to be covered, and the time constraint.

Other things were not so easy gleamed directly from the Project Two file and the operational

requirements of the device. Our safety specifications came as a logically inductive expansion of what it

meant to fit the demanded safety expectations. Other specifications, like the “chance to fail”

specifications, came from evaluating the What section and filling in the blanks. This slow process

developed over 40 quantifiable specifications that we feel very deliberately and accurately break down

the problem.



How Much

The How Much section of the QFD was the most difficult. Because this is not only a unique problem, but

a problem with many potential solutions, it was challenging to nail down exactly what our specification

targets and thresholds were. Some thresholds were obvious- the device cannot weight more than 3

pounds and cannot have starting dimensions greater than 11x18x3.5 inches, for example. Others

required an extra leap of logic- the sum of the times require to go up, over, down, back up, and back

over must not be greater than 30 seconds, to state one case. The rest were determined by evaluating

how much force it takes to do certain things, like dent a ping pong ball or jostle a table. Any left overs

were left to the group- all four members gave what they thought were reasonable targets and

thresholds for each remaining specification and that information was averaged to give the information

found in the final QFD. We also considered that some of these may change drastically. As our design

analysis and concept selection continued, we revisited our specifications as seen fit, either by

developing tests or collecting more data from the group.

In order to compare our design to something relevant, we picked two designs that will most likely be in

the competition: catapult and quadcopter drone. These hypothetical competitors were compared to the

real data that we have from out device in order to draw our conclusions.



How vs How

This section was a monster simply because of the number of specifications. Fortunately, because our

specifications were detailed enough, there was an acceptably small amount of overlap and most of it

was in our favor (improving one spec improved others as well).

E - Engineering Analysis P a g e | 19


E - Engineering Analysis

Before we could begin any technical analysis of our problem, we needed to fully understand our

problem. To do this we very carefully read over the project document. The rules were straightforward,

but the dimensions of the fixture were of some issue. With the tolerances we had to work with we

needed to be very specific about how we went about our design. This meant measuring the fixture.

Figure E1: Our fixture measurements

E



After we had a firm understanding of the rules and fixture, we could start the analysis. To see a detailed

explanation of how we generated and selected our concepts to analyze, read on to the next section: “F -

Concept Generation and Selection.” Also, at the end of that section there are tables which summarize

the results and insights gained from our analysis.

The concepts, generated and selected in Section F, to be analyzed:

Cover Horizontal Distance

o 2A – Scissor Lift

o 3A – Folding arm

o 3B – Sliding Arm

Descend with the Ball

o 4A – Gravity Assisted Winch

o 4B – Folding Arm

Release Ball

o 5A – Crane Game Hand

o 5B – Capsule

o 5C – Bucket

Ascend

o 6A – Winch

o 6B – Tendons

Power sources

o 8A – Batteries

o 8B – Stored Mechanical Energy

o 8D – Gravity

Staying on the fixture

o 9A – Suction Cup

By far, the scissor lift mechanism was the most complicated concept to analyze. As such the most

time was spent on that process. We found a paper on the internet by H. M. Spackman, titled

“Mathematical Analysis of Scissor Lifts”, which helped greatly in this endeavor. The work presented

here is our own, but it was good to have a professionally validated sanity check!



Engineering Analysis – 1A – Electrical Contacts

Using electrical contacts touching the bar and completing a circuit to start the machine sounds nice on

the manufacturing end, but the technical end is more complex. Accounting for the bar’s resistance that

we cannot directly measure before the competition is nothing to bank on. This method should be

avoided.

Engineering Analysis – 1B – Spring Loading

Using this method would release our machine very quickly without some sort of limiting system. This is

not a great idea, as the time between when the bar is removed and replaced is both variable and

unknown to us when designing.

What then?

A similar idea to the electrical contacts would be a switch actuated by the pressure of the bar, not by

direct measurement of the bar’s resistance. How we didn’t realize this as an option when building our

Morphology is a mystery. Regardless, this method would be much more consistent, and how we should

build the first prototype.



Engineering Analysis – 2A – Scissor Lift




Now, for the important part! From the equations derived above, with our physical constants and our

hypothetical springs, we obtained these comparisons of the forces required to move the lift, Figure E2,

and the required strength of the winch holding the system down, figure E3. These figures will be

invaluable during the specific component shopping phase!

Figure E2: Horizontal Force Required vs Delivered (by the springs)

Figure E3: Resistive Vertical Force Required by a Winch (to hold the scissor down)



Engineering Analysis – 3A and 4A – Folding arm



Engineering Analysis – 3B – Sliding Arm



Engineering Analysis – 4A and 6A – Gravity Assisted Winch



Engineering Analysis – 5A – Crane Game

As you can see from this patent figure, a crane game claw would be rather complicated to make and

calibrate. For this reason, it would be a bad choice for this design.

Figure E2: The crane game claw, from Patent US6234487

Engineering Analysis – 5B – Capsule

A capsule involves a cradle around the ball which is mechanically opened after being lowered or fired. It

would be more complicated than a bucket.

Engineering Analysis – 5C – Bucket

A bucket is a capsule with no moving parts or door, but only an opening. We’ve come up with a novel

design which holds the ball in while being lowered, then tips over, releasing the ball, on contact with the

ground. It is covered in greater detail in “Section G - Device Description”.



Engineering Analysis – 6B – Tendons



Engineering Analysis – 8A – Batteries

There are many types of batteries to compare, but it is common knowledge that Lithium Ion based

systems have the best power/weight/voltage output ratios. For our application, since we are only

powering an Arduino microcontroller and possibly only one servo motor, we don’t need high capacity.

This is the lithium technology’s only downside, so this is the best choice.

http://www.watchbatteries-usa.com/faq.html

Figure E3: Volage/Capacity Discharge graphs for several battery types

http://www.watchbatteries-usa.com/faq.html



Engineering Analysis – 8B – Stored Mechanical Energy

Our designs will most likely incorporate springs of some type. Mostly the standard tension type, but

some constant force springs could prove useful. The scissor lift analysis went into detail about where we

would be using them.

http://www.constantforceusa.com/media/images/Products_SpringsandVersa-TrakMain.jpg

Figure E4: Constant force springs

Engineering Analysis – 8D – Gravity

When it is possible, one should use gravity to their advantage. It’s hard to fight and easy to harness. (At

least in one direction!) Whichever ball holding device we chose, it will most likely use gravity to power

the descent. That’s one less component to power and one less mechanism to design.

http://www.constantforceusa.com/media/images/Products_SpringsandVersa-TrakMain.jpg



Engineering Analysis – 9A – Suction Cups

A mechanical suction cup will help our device stay centered where we place it on the fixture. It is easy to

attach to the device base and, other than adding weight, there are little downsides and we should

include it in the design.

http://www.designworldonline.com/keys-to-applying-vacuum-systems/

Figure E5: from Design World, the force diagram for a mechanical suction cup

Conclusion:

While all these equations and figures may seem overkill considering the scope of our problem, they’ve

given us invaluable insight into our potential design concepts. For that they were worth the time put

into the process, and hopefully will result in a better device.

http://www.designworldonline.com/keys-to-applying-vacuum-systems/

F - Concept Generation and Selection P a g e | 39


F - Concept Generation and Selection

A Note:

While this section isn’t particularly important in the context of our report grade, we wanted to come out

of this experience having produced the best device we possibly could have. To that end, we have

dwelled disproportionally long on this section and its contents and paid special attention to the details.

We have done this because to produce our best, we wanted to front-load our thinking and solve

problems before we encountered them. Thoroughly working out the details before we’re committed to

anything is the best way to ensure that we’re not going to need to restart in the middle of the project

and are simply on the correct path to begin with.

F



Concept Generation:

The process that we’ve implemented to generate then aid in the selection our final design concept is

described in detail by “Building a Morphology”, from Ullman’s Mechanical Design Process, Fourth

Edition, Chapter 7.8. To quickly describe the process, it can be dissolved into three main steps:

1. Decompose the Function

2. Develop Concepts for Each Function

3. Combine Concepts

Step one is straightforward in name. The overarching function of the device is separated into sub

functions which are described very abstractly. This allows significant engineering freedom in step two.

This second step involves coming up with several abstract ideas which could fulfill the functions

described in step one. Abstract in this case means “how”, not “what”. We’re not describing mechanisms,

but ideas which may be translated to one or more actual mechanisms. The benefit of this process is

apparent after completion, where one sees that by not in any way committing to one concept early on

many more concepts can be fairly considered. In this way the best method can be found out then

translated into a physical mechanism to actually achieve the stated purpose.

Step three involves constructing a morphological table, whose rows are populated with potential

concepts which are solutions to the sub functions. The sub-functions are the row headers. After the

table is made, then one can go down the columns, selecting one concept from each row, to assemble a

set of concepts which could be easily engineered into a functional machine which fulfills the started

goal. Not all of the combinations result in a cohesive or even possible set, but this method allows for the

generation and selection of many ideas without leaving anything out. The potential combinations are

compared later to end up with the one best idea. In our case, this will be done with a concept selection

matrix.



Morphology Step 1: Decompose the Function

In the case of this project, we didn’t need to put significant thought into the decomposition of the

function of our device because the instructors (partially) did so for us! The following screenshot is from

Project2-Rev2.pdf

[Figure F1: The decomposed function]

From this list, we devised a more complete list of linearly related tasks for the device to complete:

1. Start Autonomously

2. Cover the Vertical Distance

3. Cover the Horizontal Distance

4. Descend with the ball

5. Release Ball

6. Ascend

7. Return to Starting side

8. Define a power source

9. Method of staying on the competition fixture

Steps 8 and 9 are not strictly part of the linear task process, but are important to consider in this phase

of the design. The tasks in figure F1 not mentioned here are not relevant to the active function, but will

be addressed later.



Morphology Step 2: Develop Concepts for Each Function

In order to create the best functioning device that we could, our group generated many, many concepts.

To that end we utilized several methods for concept generation as presented in class. They are

highlighted in blue in Figure F2.

[Figure F2: Methods For Generating Concepts, from class lecture 9]

First, we used a several hour meeting of all four group members as a mass Brainstorming session. The

results of that meeting are reproduced below. In the middle of this session, we consulted a very

reputable outside source for potential input to our problem. We then used the internet as a reference

to quickly validate the ideas we generated there as potential concepts, and in the process picked up a

few new ones. Finally, and while Incorporating the basis of Axiomatic Design, we produced a large

Morphological Table to aid in the concept selection process.



Morphology Step 2: Develop Concepts for Each Function – Brainstorming

This is a cleaned up version of the flowchart that resulted from our group brainstorming session

[Figure F3: Our Brain Storming Flow-Chart, made with www.draw.io]



Morphology Step 2: Develop Concepts for Each Function – Outside Source

In the middle of our Brainstorming meeting, a small, secondary

flowchart was included next to the primary one. It encapsulated a very

good idea. That idea was to seek outside help with our design process.

Who is possibly the single best regarded engineering firm? NASA. The

National Aeronautics and Space Administration. A clear choice.

Contact was made immediately!

[Figure F5: The Message to NASA]

Unfortunately, at the time of writing we have received no response

[Figure F4: Our Great Idea]



Morphology Step 2: Develop Concepts for Each Function – External References

At this point, presenting our exact thought progression is a bit complicated. A bit of research resulted in

a several images found on the internet which provided inspiration and a few good websites containing

handy equations. A selection of the images are presented here and the equations can be found in the

Engineering Analysis section, along with many we’ve derived ourselves!

http://www.northerntool.com/images/product/2000x2000/430/43007_2000x2000.jpg

[Figure F6: A vertical Scissor Lift]

http://www.aliexpress.com/item/Free-Shipping-Stroke-50mm-2-inches-24V-600N-60KG-mini-electric-

linear-actuator-linear-tubular/32252064724.html

[Figure F7: a Linear Actuator]




http://www.forbes.com/sites/markrogowsky/2013/12/03/that-buzz-you-hear-isnt-an-amazon-drone/

[Figure F8: Amazon’s Quadcopter]

http://abcnews.go.com/Technology/amazon-prime-air-delivery-drones-arrive-early-

2015/story?id=21064960

[Figure F9: Amazon’s Quadcopter, a different view]




http://www.joystixamusements.com/photos/TOY%20SOLDIER%20JUMBO%20CRANE.JPG

[Figure F10: A Toy Crane Game]

[Figure F11: The crane game claw, from Patent US6234487]




https://c2.staticflickr.com/2/1045/1087840678_4ff1dbe3b6_b.jpg

[Figure F12: Ping-Pong-Ball cannon]

http://www.robotsnob.com/pictures/turbinebot.jpg

[Figure F13: a magnetic wind turbine climbing robot]




We found a great paper published by the US Marine Corps written by a H. M. Spackman, titled

“Mathematical Analysis of Scissor Lifts”, which was about the mathematics behind scissor lifts. The

details gleamed from this were invaluable for our analysis. The math is incorporated in the above

section, Engineering Analysis. Figure F14 represents a few of the more visually interesting sections:

[Figure F14: Visually Interesting Sections from the Paper]



Morphology Step 2: Develop Concepts for Each Function – Axiomatic Design

First off, what exactly is Axiomatic Design?

From Wikipedia:

[Figure F15: Axiomatic design, as described by http://en.wikipedia.org/wiki/Axiomatic_design]

Now what exactly does this mean? In short, the two axioms can be summarized: A good design keeps

the internal processes as abstract as possible, then after fully understanding the available conceptual

options the actual physical designs are made. In this way the best design or designs can be found

without being caught up on the details of implementation too early on. This requires a high level of

engineering knowledge and a complete understanding of the problem to be solved, but it consistently

produces a good final product.

The actual details of this approach can be very complicated, but there are tools to help keep track of the

ideas used by the methodology. One of these tools is the Morphological Table, which we have been

preparing to make and will finally will use over the next several pages to help explain our process.

Axiomatic design is a systems design methodology using matrix methods to systematically

analyze the transformation of customer needs into functional requirements, design parameters,

and process variables.[1] Specifically, functional requirements (FRs) are related to design

parameters (DPs):

The method gets its name from its use of design principles or design Axioms (i.e., given

without proof) governing the analysis and decision making process in developing high quality

product or system designs. The two axioms used in Axiomatic Design (AD) are:

Axiom 1: The Independence Axiom. Maintain the independence of the functional

requirements (FRs).

Axiom 2: The Information Axiom. Minimize the information content of the design.

http://en.wikipedia.org/wiki/Systems_design

http://en.wikipedia.org/wiki/Methodology

http://en.wikipedia.org/wiki/Matrix_methods

http://en.wikipedia.org/wiki/Axiomatic_design#cite_note-1

http://en.wikipedia.org/wiki/Axioms

http://en.wikipedia.org/wiki/Decision_making_process



Morphology Step 2: Develop Concepts for Each Function – Morphological Table

Over the proceeding pages, we have stepped through the process by which we have generated our

design concepts. These are not specific designs, but ideas which describe a process that a specific design

would later be created to accomplish. Of the three steps in building a morphology, we have done steps

one “Decompose the Function”, and two “Develop Concepts for Each Function.” We have only Step

three, “Combine Concepts” yet to do. To combine our concepts, we needed to finally assemble a table

from the list of concepts that we had just generated. That process resulted in the following figure:

[Figure F16: Our Morphological Table]



Morphology Step 3: Combine Concepts

Before combining our finalized concepts from step two, we need to first prune them with a process

known as “Feasibility Evaluation.” This process is described in section 8.3 of Ullman’s Mechanical Design

Process, Fourth Edition. It has us categorize the generated concepts into three categories.

1. It is not feasible

2. It is conditional

3. It is worth considering

The only of these categories not obvious in function is the second, “it is conditional.” This means that it

is possible for this design to work, but it hinges entirely on currently unknown or unobtainable

information. This category is for ideas not outrightly incorrect, but that require either chance or

incalculable parameters be met, and are therefore unreliable.

The following pages reflect this pruning process.



Morphology Step 3: Combine Concepts - Feasibility Evaluation - “It is not feasible”



Morphology Step 3: Combine Concepts - Feasibility Evaluation - “It is not feasible”

Start Autonomously

Item Removed Cell Reason

Visual Sensor 1D Unreliable without significant calibration, something we cannot do

Cover the Vertical Distance


Jumping Spring 2B The spring force required to launch the 3lb mass is too high

Climbs 2E The hanging wire structure will not provide enough rigidity to climb

Inflated Shape 1 2F Fixture geometry does not allow this design to function as the height of the fixture is significantly larger than the width we need to traverse, so no continuously expanding tube geometry could work

Cover the Horizontal Distance


Flop 3E There is too much variability to coordinate this maneuver safely

Inflated Shape 2 3F See “Inflated Shape 1”

Descend with the ball


Fall 4E Falling may damage our machine or the fixture

Inflated Shape 3 4F See “Inflated Shape 1”

Ascend


Delates and Retracts 6F See “Inflated Shape 1”, also the tubing would be damaged getting pulled over the wires so it would only function once. Non ideal.

Climbs Back 6E Re-finding the wire structure to climb would be too complicated

Return to Starting side


Flop Again 7E This may damage the fixture and device

Continue Retracting 7F See “Delates and Retracts”

Define a power source


Compressed Gas 8C This may be dangerous with the scale of pressure needed to be effective

Method of staying on the competition fixture


Weight Alone 9B This is entirely unreliable on a smooth surface like the fixture

Magnets 9D The fixture is not magnetic

Hooks 9E This will damage the fixture



Morphology Step 3: Combine Concepts - Feasibility Evaluation - “It is conditional”



Morphology Step 3: Combine Concepts - Feasibility Evaluation - “It is conditional”

Start Autonomously


Magnetic Release 1C This mechanism would be prone to early triggering without calibration

Cover Vertical Distance


Quadcopter 1 2C Without extremely significant testing and calibration, this method would not be able to reliably function, if at all. This lack of testing time could even prove dangerous to onlookers or the fixture, which needs to be absolutely avoided.

Launch It 1 2D This method would need calibration with a specific ball and lane, something our group cannot attain before the first competition round

Cover Horizontal Distance


Quadcopter 2 3C See “Quadcopter 1”

Launch It 2 3D See “Launch It 1”

Descends with Ball



Ball Descends Alone 4D See “Launch It 1”

Releases Ball


Decaying Bounce 5D See “Launch It 1”

Sphincter 5E Air pressure on the tube would need to be calibrated much too precisely

Ascends



Returns to Starting Side



Stay on the Fixture


Expanding Clamp 9C To center in the fixture we would need to know the exact width of our lane, something we can’t measure until the first completion round



Morphology Step 3: Combine Concepts - Feasibility Evaluation - “It is worth considering”



Morphology Step 3: Combine Concepts - Feasibility Evaluation - “It is worth considering”

The Remaining items on the Morphological table have been deemed to be worth considering for

possible incorporation into our design. To this end, we needed to entirely understand them from a

numerical, engineering-based standpoint. The full extent of this detailed analysis is the focus of the

preceding report section, “Section E – Engineering Analysis.” The results are summarized on the next

section, “Concept Selection”.

Items Worth Considering:

1A – Electrical Contacts

1B – Spring Loading

2A – Scissor Lift

3A – Folding arm

3B – Sliding Arm

4A – Gravity Assisted Winch

4B – Folding Arm

5A – Crane Game

5B – Capsule

5C – Bucket

6A – Winch

6B – Tendons

6D – Device Never Descends

7A – Refold

7B – Un-slide (3B backwards)

7D – Device Never Crosses Wall

8A – Batteries

8B – Stored Mechanical Energy

8D – Gravity

9A – Suction Cups



Concept Selection:

Bas

elin

e

Elec

tric

al C

on

tact

s o

r P

hys

ical

Sw

itch

Spri

ng

Load

ed

Mag

net

ic R

ele

ase

V

isu

al S

enso

r

(1) Autonomous Starting Weights

Detects starting bar 25

Dat

um

1 1 1 0

Allows for variability 15 0 1 1 -1

Reliable 10 0 1 -1 -1

Will not damage itself 10 1 0 1 1

Easy to set up 10 1 0 -1 -1

Compact 15 1 -1 0 1

Lightweight 15 1 -1 0 1

Total 5 1 1 0

Weighted Total 75 20 30 5

For the process of autonomously starting the device, the key issue was what would detect the starting

bar, do so despite variability in placement and differences in the lane, and remain low impact on our

weight and size constraints. It was also worth considering whether or not the design involved forces that

might damage itself or the device as well as whether or not the design was easy to set up.

The electrical contacts/switch concept clearly performed the best. Our team voiced concerns that a

small electrical switch require an advanced mounting solution to allow for variability in the fixture and

not inadvertently be triggered or released early or in the middle of operation. This was solved by

deciding to have a switch that received the bar upon placement in the secondary position as opposed to

being triggered by the removal of the bar from the starting position as well as programming the device

to start and continue with its programming whether or not the state of the switch changed after initial

triggering.



Bas

elin

e

Scis

sor

Lift

Co

pte

r

Lau

nch

It!

C

limb

th

e w

all

(2) Covering the Vertical Distance

Weights

Can easily cover >24” 15

Dat

um

1 1 1 0

Requires minimal energy 10 0 1 1 0

Simple 10 1 -1 1 0

Fast 15 1 1 1 -1

Reliable 9 1 0 -1 0

Safe 8 1 -1 0 1

Easy to set up 8 1 1 0 1

Compact 15 1 1 1 1

Lightweight 15 0 1 1 0

Total 7 4 5 2


For moving the ball upward in preparation to move it then over and back down (the simplest description

of the general solution to the problem) our top for concepts were the Scissor Lift, a quad-copter drone,

simply launching the ball, and climbing the wall with magnetic treads or hooks. We ruled out an inflated

shape and a “jumping” device based on force constraints and the inconsistency of the concepts on an

inherent level.

The criteria were decided on knowing that above anything else, this would be the most complicated part

of the device and would need to, at a base level, cover the vertical distance, do so quickly, meet the

dimensional constraints, and do this process simply and without requiring an excess of energy or force.

We also considered the reliability, safety, and ease of set up. It was in this order we decided on the

importance so they were weighted accordingly.

While the scissor lift received the best score and received no “-1” ratings, the Copter and launching the

ball were close enough to consider in more depth. It was determined, as reflected in the Morphological

Table, that there were too many things that would have to fall in line for the copter and launching

solutions to function given our financial, time, and expertise constraints. The copter was too

technologically advanced to develop from scratch in a way where we could guarantee safety and

consistency and was considered to be too expensive to simply buy and modify. The launching solution

was determined to be clever and the most simple solution, but had too much variability and after briefly

testing several different brands of ping pong balls, we decided there was too much variability in weight

and bouncing behavior to develop this solution consistently enough. The scissor lift was determined as

our only viable option given the constraints and in depth analysis was started immediately.



Bas

elin

e

Fold

ing

Arm

Slid

ing

Arm

Ho

rizo

nta

l Sci

sso

r

La

un

ch/d

rop

it

(3) Horizontal Displacement

Weights

Covers >4.5” 25

Dat

um

1 1 1 1

Starts at the right time 15 1 1 1 0

Reliable 10 1 1 1 -1

Fast 10 0 0 1 1

Easily Retractable 10 0 1 1 1

Smooth 10 -1 1 1 0

Compact 10 1 1 -1 -1

Lightweight 10 0 1 0 0

Total 3 7 5 1


At this point it is important to note that we’ve deviated from the morphological table. This trend will

continue. Because the processes of this device have to happen in sequence and each process has to be

compatible with the processes before and after it, if we determined a clear winner in a previous Concept

Selection Matrix, this will change the designs considered after that point.

For example, much discussion occurred over the previous concept selection matrix which lead to

significant research and even some testing. The delay between the writing of the previous matrix and

this one was about two days. Only after finalizing the decision to use a scissor lift did we continue

developing these matrices. Since we knew that that certain designs had been considered infeasible, it

was not worth further considering their “daughter” designs- parts of those designs that would function

later down the line. As such, we went to comparing designs that could feasibly be attached to the top of

a scissor lift, leaving out unrelated concepts from the morphological table and even introducing some

new designs we hadn’t previously considered, like a horizontal scissor lift.

These concepts were compared on a series of datum, the most important of which were determined to

be covering the horizontal distance and not starting too early, which could jam the device and damage

the fixture. It was also considered whether each concept would be reliable, fast, retractable, smooth,

compact, and lightweight. We decided these held roughly the same weight.

The sliding arm and the horizontal scissor were the top two designs. The folding arm was left out

because it did not leave very many options for a ball-holding solution. Those decisions are reflected in

more detail in the engineering analysis section.



Bas

elin

e

Gra

vity

Ass

iste

d

Win

ch

Bal

l is

Dro

pp

ed

(4) Descent Weights

Precise 25

Dat

um

1 -1

Starts at the right time 15 1 0

Reliable 15 1 -1

Fast 10 0 1

Easily Retractable 15 1 1

Smooth 10 1 0

Compact 10 0 1

Total 5 1

Weighted Total 80 -5

To continue the previous discussion, you can see clearly that the concepts for the actual function of the

device have converged slightly. It has been decided that something will be extending out over the target

and the ball will be allowed to cover the descent from there. This leaves a very narrow range of possible

concepts- either it can be lowered or it can be dropped.

These two ideas were compared on, most importantly, their precision, not starting too early, general

reliability, and the ability for this to be retracted later on. We also considered the speed of the solution,

as well as the smoothness and compactness of the solution.

Actually lowering the ball is the clear winner here. The nature of that process, as this time, had yet to be

determined but was decided on during the engineering analysis portion, which occurred semi-

concurrently with this process.

Important Note: Because this now converges to a single solution, there is no need for concept

selection for ascending and returning to the starting side. These processes will happen via a winch of

some form pulling them back in. The concept selection focus from this point will be the finer details of

the mechanism and will diverge almost completely from the Morphological Table.



Bas

elin

e

Spri

ng

Load

ed

Cla

w

Spri

ng

Load

ed

Cap

sule

Sph

inct

er

O

ccam

s B

uck

et

Holding the Ball Weights

Will not drop the ball 20

Dat

um

0 1 0 1

Mechanically simple 15 -1 0 1 1

Can spin 10 1 1 0 -1

Fast 10 1 1 0 1

Reliable 15 0 1 1 1

Easy to build 5 -1 0 1 1

Compact 10 1 -1 0 1

Accepts variability in balls 15 1 1 -1 1

Total 2 4 2 6


This section is debating what exactly will be on the end of the winch to hold the ball while it’s lowered

and then release the ball in contact with the ground. It was clear that building electronics into this was

infeasible so it has to function mechanically. Our initial designs were a spring loaded claw, a spring

loaded capsule, and a pressure loaded sphincter. We were dismayed at the complexity of each of these

systems before Nate came up with the idea of a box that’s base was tilted and center of gravity offset

such that when it touched the ground it simply tipped over and the ball rolled out. Considering the

simplicity of this solution we dubbed it “Occam’s Bucket” as an homage to Occam’s Razor, the

philosophical version of “Keep It Simple, Stupid.”

The most important criteria for these ball holders was that it did not drop the ball prematurely, is

mechanically simple and reliable, and will accept balls of many sizes and weights. It was also considered

that it should be fast, compact, and easy to build. We also determined that we were going to be

dropping the ball close to the edge of the target, so the chosen design should also not spin and release

the ball in the wrong direction.

The clear winner here was Occam’s Bucket, especially after deciding that the winch could be wired with

flat ribbon, discouraging the tipping bucket to spin off target.



Bas

elin

e

Dri

ven

by

com

mo

n

mec

han

ical

pro

cess

Each

pro

cess

is

dri

ven

se

par

ate

ly

Scis

sor

and

Arm

ar

e lin

ked

Arm

an

d D

esce

nt

are

linke

d

Stages of Operation Weights

Intercompatible 25

Dat

um

1 -1 0 1

Intracompatible 15 1 1 0 1

Reliable 15 0 1 1 1

Fast 10 1 -1 0 1

Easily reversed 5 0 1 -1 1

Low energy demand 5 -1 0 1 1

Easily developed 15 1 -1 -1 0

Lightweight 10 1 -1 -1 -1

Total 4 -1 -1 5

Weighted Total 70 -35 -10 60

Next we needed to decide how to run each subsystem (up-over-down-up-back) in order consistently. It

was most important that the process used drive the systems be compatible between each system

(intercompatible) as well as each process driving the system be compatible within each system

(intracompatible). The next most important values are the system’s reliability and it’s ease of

development, which includes programming, machining, and assembly. On top of that we also

considered the speed of the system and how lightweight it would be, as well as the energy demand of

the system and how easily it could adapt to the final steps (-up-back), which are the most functionally

divergent.

It was determined that driving the systems with a common winch that doled out to allow the scissor to

expand and then the arm and then drop the bucket before reversing and pulling it all back in would be

most effective based on the weighted total. However, having a single mechanism handle the scissor and

a second mechanism let out the arm and drop the bucket would be almost equally as functional, losing

out only in weight and the complexity of development.

Our concerns with the latter system were the size and weight constraints of fitting electronics on the top

of the scissor lift and the complexity involved in programming and testing the system. It also

approximately doubled our projected costs on electronics, which was already our highest expected

expenditure. For these reasons we opted for the slightly less reliable but notably simpler design of a

single continuous winch.

G - Device Description P a g e | 66


G - Device Description

Any device needs a name. It can be boring, descriptive even. A great device? That needs an identity. A

device showing once-in-a-lifetime innovation and spirit? That needs a logo. One worthy of equal praise.

We believe that we have achieved this lofty goal.

Figure G1: The Device’s Logo

Why? Because absolutely no one else at this competition will have a scissor lift, and pirates are fun!

Anyway – this is a long section. As such, a summary to guide you through its reading is necessary.

The sub-sections herein:

Engineering drawings of all parts

3D models of the most critical parts of the device

o The models are to scale, and the CREO files are inside of our included ZIP file

Process sheets for manufacturing all parts

A summary of the assembly process

The steps of the process by which our device operates

o A summary of our electronic systems

The critical design elements for the working of our device

Some cleaver ideas that make our device unique

G



Engineering Drawings



Engineering Drawings: Sliding Arm Cover/Sliding Arm



3D models of the most critical parts of the device: Sliding Arm Closed/Sliding Arm Open

Note: there is a ‘key reel” hooked into the slot on the back of the cover, fed through the channel in the

cover and attached to the back of the arm, this is the spring which powers the opening of the arm.



3D models of the most critical parts of the device: The Base



Part Name: Top Base

Quantity: 1

Material: ¼” thick birch ply

Weight: 0.45 pounds (estimated)

Supplies and Tooling:

Table Saw and Band Saw

Drill Press with 1/8” and 1/4" bits

Dremel tool with slot cutter if available

Notes: All dimensions tolerance to ±0.01” unless otherwise stated. The drawing is the best

reference for dimensions.

# Process 1 Set table saw guide to cut 18”.

2 Make 18” cut on birch ply.

3 Set table saw guide to cut 8.5”.

4 Make 8.5” cut so that you are left with an 18x8.5” rectangle.

!!! Now would be a good time to trim the remaining 18” swath of stock into the 18x11” Bottom Base. Please see the Bottom Base process sheet for more information.

5 Carefully mark 5x4” rectangle at top of piece, 1.75” from each corner, such that the 5” dimension lies in the direction of the 8.5” side, as per given drawing.

6 Carefully mark 5x10” rectangle 1.75” from each bottom corner such that the 10” dimension lies in the direction of the 18” side, as per given drawing.

7 Carefully mark 1.5x2” rectangle 6” from the top right corner, along the right side, such that the 2” dimension lies in the direction of the 18” side, as per given drawing.

8 Transfer piece to band saw running skip tooth blade at recommended speed stated on saw.

9 Carefully cut the left 10” dimension of the bottom rectangle. After meeting length requirement guide material backwards a few inches before turning off the saw. Once the saw has stopped, guide blade out of cut.

10 Carefully cut the right 10” dimension. About 4” from end, begin to gently twist piece to guide blade inward, cutting a curve that tapers off tangential to 5” dimension, as per given cut suggestion on drawing. Carry this cut through to the previous cut in corner of rectangle. Stop blade and remove loose material (should be majority of 5x10” rectangle).

11 Spin the piece around and make two final cuts to remove the leftover corner, shown cross-hatched on given drawing.

12 Carefully cut the right 4” dimension of the top rectangle. After meeting length requirement guide material backwards a few inches before turning off the saw. Once the saw has stopped, guide blade out of cut.



13 Carefully cut the left 4” dimension. After about a half inch, begin to gently twist piece to guide blade inward, cutting a curve that tapers off tangential to 5” dimension, as per given cut suggestion on drawing. Carry this cut through to the previous cut in corner of rectangle. Stop blade and remove loose material (should be majority of 5x4” rectangle).

14 Spin the piece around and make two final cuts to remove the leftover corner, shown cross-hatched on given drawing.

15 Carefully cut the bottom 1.5” dimension of the smallest rectangle. After meeting length requirement guide material backwards a few inches before turning off the saw. Once the saw has stopped, guide blade out of cut.

16 Carefully cut the top 1.5” dimension. Immediately twist piece to guide blade downwards, cutting a curve that tapers off tangential to 2” dimension, as per given cut suggestion on drawing. Carry this cut through to the previous cut in corner of rectangle. Stop blade and remove loose material (should be majority of 2x1.5” rectangle).

17 Spin the piece around and make two final cuts to remove the leftover corner, shown cross-hatched on given drawing. Consider breaking this up into smaller triangles if necessary. It is ESPECIALLY important not to over cut in the 2” direction given the locations of the 1/8” holes for attaching constant force springs.

18 Measure out and mark the location and shape of the 0.5x0.25” thru slot as per given drawing.

!!! The key dimensions for this cut are location and perpendicularity. ESPECIALLY perpendicularity. If it wasn’t clear from the assembly drawings, this slot is for an L bracket that guides the main cable down towards the bottom base. If all else fails, cut extra space so the bracket can be glued into place at a proper angle.

19 Place the piece on the small drill press (with 1/4” bit) and clamp it in place.

20 Drill 1/4” thru holes on each end of the rectangle you marked for the slot.

21 Exchange bit for 1/8” bit.

22 Drill the two holes near the smallest rectangle. The critical dimension for these is 0.25”.

23 Acquire Dremel Tool. If a 0.125” notch cutter or cylindrical sanding bit is available, use that. If not, get a fine point sander and be careful.

24 Prop the piece up on scrap wood so that there’s at least 0.25” of space between the piece and the table.

25 Slowly and deliberately grind into the piece to complete the slot.

26 Weigh the piece. If it weighs more than 0.75 pounds, call Nate immediately (719) 648-2291 Also, cry. Probably crying is good. Especially if it weighs more than 1 pound. Because then we’re straight f****d. <3



Part Name: Bottom Base

Quantity: 1

Material: ¼” thick Birch Ply

Weight: 0.55 pounds (estimated)


Table Saw and Band Saw

Drill Press and 1/8” bit

Dremel Set with slot cutter if available



# Process 1 Set table saw guide to cut 18”.

2 Make 18” cut on birch ply.

3 Set table saw guide to cut 11”.

4 Make 11” cut so that you are left with an 18x11” rectangle.

!!! Now would be a good time to trim the remaining 18” swath of stock into the 18x8.5” Top Base. Please see the Top Base process sheet for more information.

5 Carefully mark 2.5x8” rectangle in bottom left corner of piece, such that 8” dimension lies in the direction of the 18” side, as per given drawing.

6 Carefully mark 5x10” rectangle 1.75” from bottom right corner such that the 10” dimension lies in the direction of the 18” side, as per given drawing.

7 Transfer piece to band saw running skip tooth blade at recommended speed stated on saw.

8 Carefully cut out rectangle in bottom left corner by making two perpendicular cuts along drawn lines.

9 Carefully cut the left 10” dimension. After meeting length requirement guide material backwards a few inches before turning off the saw. Once the saw has stopped, guide blade out of cut.

10 Carefully cut the right 10” dimension. About 4” from end, begin to gently twist piece to guide blade inward, cutting a curve that tapers off tangential to 5” dimension, as per given cut suggestion on drawing. Carry this cut through to the previous cut. Stop blade and remove loose material (should be majority of 5x10” rectangle).

11 Spin the piece around and make two final cuts to remove the left over corner, shown cross-hatched on given drawing.

!!! Now might be a good time to make cuts to finalize the cuts for the Top Base. Please see the Top Base process sheet for more information.

12 Don’t be a dick- clean the table saw and band saw before moving on. Keegan puts up with enough.

13 Measure out and mark the location and shape of the 0.5x0.125” thru slot as per given drawing.



!!! At this time, do NOT mark the 0.5x0.75” pocket. Just trust me on that. Method to my madness.

!!! The key dimensions for this cut are location and perpendicularity. ESPECIALLY perpendicularity. If it wasn’t clear from the assembly drawings, this slot and pocket are for an L bracket with a slot milled into it that serves as a pulley for the main cable. If all else fails, cut extra space so the bracket can be glued into place at a proper angle.

14 Place the piece on the small drill press (with 1/8” bit) and clamp it in place.

15 Drill 1/8” thru holes on each end of the rectangle you marked for the slot. If you’ve got balls go ahed and do a third in the center; it’ll save time later, but it may be difficult to make that cut without deflection. You do you. I believe in you.

16 Acquire Dremel Tool. If a 0.125” notch cutter or cylindrical sanding bit is available, use that. If not, get a fine point sander and be careful.

17 Prop the piece up on scrap wood so that there’s at least 0.25” of space between the piece and the table.

18 Slowly and deliberately grind into the piece to complete the slot.

19 Orient piece as shown in drawing.

20 Mentally (or physically) mark the side of the piece facing you as the TOP.

21 Now flip the piece over. This is the BOTTOM.

22 Upside down like this the piece should look all backwards and flip flopped from the drawing.

23 That’s because you’re looking at the BOTTOM. This is good.

24 BOTTOM GOOD. TOP BAD.

25 On the BOTTOM of the piece, mark the dimensions of the 1/16” deep pocket.

26 Using the appropriate Dremel attachment, mill the pocket on the BOTTOM of the piece.

27 If available, test the slot and pocket for fit with the milled L bracket piece.

28 Weigh the piece. If it weighs more than 1 pound, call Nate immediately (719) 648-2291 Also, cry. Probably crying is good. Especially if it weighs more than 1.5 pounds. Because then we’re straight f****d. <3



Part Name: Lift Member

Quantity: 8 Required. Make 12-16.

Material: 21” Paint Stir Sticks (1/4” thick)

Weight: 0.05 pounds each (estimated)


Band Saw

Pick your favorite wood-friendly sander

Milling Machine – Jacobs Chuck, edge-finder, and 3/16” Two Fluted End Mill in 3/8”

collet

Special mounting hardware

A friend



# Process 1 Begin by carefully drawing the outline of the member on the clean side of the paint stick. One side of

the member should align with one side of the pain stick. Consider using a ½” diameter rod of some kind to trace the curves on the end. It’s not ideal to freehand those.

!!! It is possible to produce two members from one paint stick, but these paint sticks are free. If you feel it’s faster or more accurate one way or the other, do that.

2 Load a rake tooth blade in the band saw and make sure the speed is set to about 1500 fpm (rpm?)

!!! Yes, rake tooth. It doesn’t eat through the wood as fast as the skip tooth so it’s more accurate.

3 Very slowly, carefully, and deliberately cut the length of the member. Try to cut straight and if you have to, air on the side of not cutting off enough, rather than too much.

5 Cut off the extra material by the handle of the stir stick.

6 Repeat 1-5 ad-freaking-nausea until you have 12 to 16 member blanks.

7 Slowly, over at least 3 passes, sand the rounded ends of the member.

8 Check overall length of member- 17.5 - 0.1”. No longer than 17.5”.

9 Check overall width of member- 0.5 ± 0.05”. Check in at least three places, especially towards the end and right in the middle. If too large, sand down. If too small anywhere, break it. Throw it away. I hate to be a hardass about that but 1) the materials are free 2) if these break, bend, or crack the device will not function as expected.

10 If it clears QA, pass off to someone on the mill (in a perfect world).

11 Repeat 7-10 with the blanks until all blanks are ready (or passed off to someone) for milling.

!!! Why are we drilling holes with a milling machine and an end mill? ACCURACY. Every 3/16” drill bit I could find was bent and there’s no easy way shift the piece accurately



on a drill press. Try to grab one of the mills with digital readout. The following steps will reflect the need for accuracy. The SUPER CRITICAL dimension here is the distance between each hole and their alignment to the central axis.

12 On a milling machine with digital readout, load a Jacobs chuck and an edge-finder. Find the left edge of the vise and zero the X readout. Now find the inside edge of the FIXED jaw of the vise and zero the Y readout. DO NOT FORGET TO ACCOUNT FOR THE WIDTH OF THE EDGE-FINDER.

13 Using a clamp, clamp a parallel or similar to the end of the vise to serve as a stop to preserve the datum we just established. Avoid using a 1-2-3 block for this because of the holes.

14 Develop a clever combination of thin parallels and other mounting hardware that allows us to clamp the members about ¾ of the way down their length for rigidity. There are too many variables here to establish a fixed method. Critical think and have fun. The height doesn’t have to be perfect- just as close as you can manage without it clearly being sloped.

!!! “Wow Nate this is all a huge pain in the ass” Yes. Yes it is. But you’re about to do ~14 of these damn things and they need to be IDENTICAL. You’ll thank me later.

15 Place blank in your shiny, fancy new fixture. Make sure you can drill the holes all the way through without hitting any of the mounting hardware. That would be bad.

16 Move 0.2500” in from both the Y zero and the X zero. You should be centered on the end of the member ready to drop the first hole.

17 At about 1500 rpm, drop the first hole. It should be visually obvious if it’s centered.

18 If it looks good, lock the CRAP out of the Y and zero the X on the position of the first hole.

19 Slide down 8.5000” and drop the second hole.

20 Slide down another 8.5000” (should read 17.0000”) and drop the final hole.

21 Remove the piece and check the distance between the end of the piece and the inside edge of the holes. The distance between the edge of the hole and the edge of the piece should be 0.155 ± 0.01”. If the first and second holes are off, something is wrong with the fixture. If the third hole is off, Player One didn’t do their job. Yell at them. If the reference dimension for the third hole is too large, it can be sanded down. If it is too small, this is a critical error and the part should not be used.

22 If part is acceptable, load another and repeat steps 17-21 until you’ve acquired at least 10 parts in spec.

!!! It might be nice to have someone separate doing QA on each part so the mill operator can just keep going.

23 If necessary, repeat all if too many parts are being scrapped.



Part Name: Static Axle Mount

Quantity: 4, consider making an extra

Material: Aluminum L stock

Weight: 0.1 ounces each (estimated)


Horizontal band saw

Plyers

Milling Machine with thin parallel and 3/16” end mill in 3/8” collet

Jacobs chuck with edge finder

Buffing wheel (over by the turret lathe)

Notes: All dimensions ±0.05” unless otherwise stated.

# Process

1 Carefully mark the outer corner of the stock in 9/16” intervals.

2 Place stock corner-up in the horizontal band saw and align the saw with the first mark.

!!! Make 2-3 more marks and cuts than you think you need because these are the same dimensions as for the Lower Cable Guide and the Upper Cable Guide.

3 Grip the very edge of the stock with the plyers so you don’t lose the piece about to be cut.

4 Make the cut.

5 Reposition the stock and repeat.

6 Take parts over to the buffing sander and remove burs from all edges.

7 Place a single 1/16” thin 1¼” tall parallel in the mill vise and the jacobs chuck with edge finder.

8 Place a single piece in on the parallel and against the left end of the vise, finger aligned, with the longer side in the vise with the shorter side ready to be milled.

9 Find the edges of the part and establish them as zeros, accounting for the width of the edge finder.

10 Move in ¼” from each datum to the center of the part.

11 Drop the quill to cut a single hole.

12 Remove part and replace it with a blank, finger aligning it to the edge of the mill.

13 Repeat the cut until all mounts are cut.

!!! The mill is currently set up to make the cuts for the following parts: -Moving Axle Channel -Lower Cable Guide Consider making these cuts now. Please reference their individual Process Sheets.

14 Remove all burs with the buffing wheel.



Part Name: Sliding Axle Guide





Horizontal band saw

Milling Machine with single thin parallel and 3/16” end mill in 3/8” collet




# Process

1 Carefully mark the outer corner of the stock in 9” intervals.



4 Make the cut.

5 Reposition the stock and repeat until quantity is met.



8 Place a single piece in on the parallel and against the left end of the vise, finger aligned, with the shorter side in the vise with the longer side ready to be milled.


10 Move 3/8” in the Y direction and 1/16” in the X direction from the respective datums.

11 Lock the Y.

12 Drop the quill to cut a through hole. Be careful not to drop so low that you damage the vise.

14 Lock the quill.

15 Slowly feed the X no more than 8.875” from the starting point to create the slot for the moving axle.

16 Return to the position established in step (10).

17 Remove the part and replace it with a blank.

18 Repeat 15-17 until quantity is met.

!!! The mill is currently set up to make the cuts for the following parts: -Lower Cable Guide -Static Axle Mount Consider making these cuts now. Please reference their individual Process Sheets.

19 Remove all burs from the milling process with the buffing wheel.



Part Name: Spring Axle

Quantity: 1

Material: ¼” Aluminum Round Stock

Weight: 2 ounces (estimated)


Bandsaw

Lathe that allows for at least 4” of stock to sit safely inside the chuck + lathe tool

1/8” wide cut off tool

3/16” UNF external thread cutting dye and Jacobs Chuck in the Tailstock + thread oil

Notes: This is the most complicated part and should be developed by the team member most

comfortable with the Lathe and threading processes. If you have any insecurities with working

with the Lathe do NOT select this part for manufacture. All dimensions ±0.01” unless otherwise

stated.

# Process

1 Cut a piece of round stock about .25 inches longer than the 8” mark.

2 Insert stock into the lathe with as little material sticking out of the chuck as possible (no less than 2”).

3 With the general purpose tool, face both ends of the rod to 8”, checking length often.

4 Move in 0.5” with the general purpose tool and face the last 0.5” of the rod down to 0.1875±0.0005”.

5 Flip the piece around and repeat step (4).

6 Drop your RPM and apply thread cutting oil and install the thread cutting dye in the tailstock.

!!! Be certain the tailstock is unlocked and the RPM is slow enough.

7 Make the thread cut. You’ll notice that the last 3-ish threads are not complete enough.

8 Flip the dye around so the full threads are on the outside.

9 Make a final pass. Do not force the dye over the piece- it should thread on its own.

10 Flip the piece around and return the dye to its original configuration.

11 Repeat steps 7-9 on the fresh side.

12 Check the threads with a 3/16” nut. If they are unsatisfactory, scrap the part and start over.

13 Switch to the 1/8” cut off tool.

14 Cut the two end notches as described by the drawing. The tolerance on the positions of these notches is ±0.01” with the critical dimension being the distance between the notches. The tolerance on the diameter of these notches is 0.2-0.05”.

15 Measure and mark the middle notch. Position tolerance ±0.1”.

16 With the marked position no more than 3” out of the chuck, turn the center notch. Same diameter tol’.

17 Flip the piece around and repeat step (13) on the other side.



Part Name: Fixed Spring Mount

Quantity: 2

Material: 1/16” thick Aluminum L stock

Weight: 1 ounce (estimated)


Horizontal Band Saw

Milling Machine

¼” two-flute end mill in appropriate collet

1/16” thick, 1¾” tall thin parallel

Jacobs Chuck and edge finder

Notes:

Let tolerances be ±0.01” unless otherwise stated.

# Process 1 Mark two 7.75” lengths of L stock on the outside corner.

2 Cut these lengths with the horizontal band saw.

3 Eliminate burs with the method of your choice.

4 Place with long side resting on parallel in the vise of the milling machine with the short side up with the end aligned with the edge of the vise.

5 Use the edge finder to create datums at the end of the vise and the edge of the piece. Don’t forget to account for the diameter of the edge finder.

6 Switch out the Jacobs Chuck for the ¼” Two Fluted end mill.

7 Move ¼” in to the centerline of the piece. Lock the Y.

8 Move ¼” along the centerline to the first hole. Mill it out.

9 Continue to move along the centerline cutting each hole.

10 Remove part and eliminate burs with method of your choice.



Part Name: Spring Rod

Quantity: 2

Material: 1/8” Aluminum Round Stock

Weight: 0.5 ounce (estimated)


Band Saw

Sander

Notes:

Let tolerances be ±0.1” unless otherwise stated.

# Process 1 Mark two 7.75” lengths on the round stock.

2 Cut these lengths with the band saw. Mind your blade and cutting speed.

3 Eliminate burs with the method of your choice.

4 Congrats that’s it.



Part Name: Lower Cable Guide





Horizontal band saw

Plyers

Milling Machine with thin parallel and 3/16” end mill in 3/8” collet




# Process

1 Carefully mark the outer corner of the stock in 9/16” intervals.


!!! Make 5-7 more marks and cuts than you think you need because these are the same dimensions as for the Static Axle Mount and the Upper Cable Guide.


4 Make the cut.




8 Place a single piece in on the parallel and against the left end of the vise, finger aligned, with the longer side in the vise with the shorter side ready to be milled.


10 Move in ¼” from each datum to the center of the part.

11 Drop the quill to cut a through hole. Be careful not to drop so low that you damage the vise.

12 Lock the quill.

13 Unlock the X direction.

14 Slowly feed the X no more than 0.094” in each direction from the starting point to create a slot no wider than 3/8”.

!!! The mill is currently set up to make the cuts for the following parts: -Moving Axle Channel -Static Axle Mount Consider making these cuts now. Please reference their individual Process Sheets.

15 Remove all burs from the milling process with the buffing wheel.



Part Name: Upper Cable Guide

Quantity: 1




Horizontal band saw

Plyers


Notes:

All dimensions ±0.05” unless otherwise stated.

# Process 1 Carefully mark the outer corner of the stock in 9/16” intervals.


!!! Make 5-7 more marks and cuts than you think you need because these are the same dimensions as for the Static Axle Mount and the Lower Cable Guide.


4 Make the cut.



7 Buff the outer surface of the L to smooth the surface.

8 Be especially aggressive along the centerline and on the center of the corner to create a slight channel for the cable. Also create slight radius on each outer edge to avoid having a running cable strip or cut.



Part Name: Occam’s Bucket

Quantity: Need one, make 2-3

Material: Cardstock paper or thin cardboard

Weight: 0.5 ounces (estimated)


Razor, preferably of the Occam variety.

Printer and fine-point Sharpie™

Heavy cardstock paper or thin cardboard

Gaffer’s Tape (preferred)

Duct or Electrical Tape (acceptable)

Notes:

We should probably make a couple out of both cardstock and thin cardboard. All dimensions

±0.05”.

# Process

1 Print off the template, either onto cardstock or onto regular paper.

2 Check the reference dimensions in both directions.

3 If necessary, scale and re-print the template, checking the dimensions again.

4 Cut out the template with a razor or box cutter. Cut the slot for the cable.

5 Appreciate my joke about Occam’s Razor.

6 Appreciate the simplicity of this capsule solution.

7 Gain new appreciation for the depth of my joke about Occam’s Razor.

8 Go look up Occam’s Razor if you’re not familiar. (tl;dr – It’s the philosophical version of K.I.S.S.)

9 Along the dotted fold lines, place a machinist’s ruler or something else thin and rigid to act as a folding guide.

10 Carefully fold the bottom flaps marked 1 and 2 and tape the very bottom edge in place along the red line.

!!! The flap marked with cross hatching is an internal surface for supporting the ball. It should NOT close off the box and it should NOT be folded all the way down to meet the bottom of the box. It should be folded to meet the RED reference line on the inside of the box.

11 Confirm step 10 by next folding the sides (3 and 4) in. Their tapered edges should align with the bottom of the structure

12 Tape 3 and 4 in place along the bottom.

13 Fold and tape the top in place.

14 Fold and tape the cable attachment. Double tape this area for rigidity.



The Assembly Process

Screw servo head to the reel

Bolt the two parts of the servo mount together and more bolts to attach servo to the mount



Use epoxy to attach brackets, spring, and servo mount to base and top base



Use bolts and epoxy to attach the mechanical suction cup to the base

Thread sliding rod though bracket channels, with nuts, washers, tension springs, constant force springs,

and cross-members in their places like such, then screw down the constant force springs

Thread the retaining rod and snap in the spacers



Attach other side of bottom cross members and middle member bolts

Add second level of scissor members on both sides, meshing with the first



Bolt the scissor members to the top base brackets and bracket channels, with 1/16”gap leeway to make

up for imperfect rail alignment.



Sliding arm assembly

Attach the constant force spring to the mounting bracket on top of the cover

Screw the end of the spring to the back of the sliding arm, glue carbon fiber sheet on top base

Attach the bolts to the cover and bolt the sliding arm assembly to the top base



Thread the cable though the whole system



Securely tape bucket to end of cable

Tape the spring spacer to the bottom of the top base



Glue together the activation switch mount and epoxy to the top of the servo.

NOTE: Do not get glue in the switch! This may competition-day-morning RadioShack runs, where the

shop will be closed, and you may end up having only a few hours to redesign this activation mechanism.

Carefully mount the electronics hardware on the baseboard, so it looks nice



Congrats! You’ve assembled the whole device!! Have a nice overview of the mechanics:



Movement steps and sequence

One of the goals of our design was control simplicity. There is one moving actuator, the servo, and it

controls the entire device’s function, guiding it through all the functions required.

There is a single cable running from the servo, up though the middle of the scissor lift, around to the

back of the top, through the sliding arm, and attached to the bucket so it can be lowered. This is

achieved by having both the arm and scissor mechanism spring loaded, and having gravity release the

bucket. Until reeling the bucket and arm back over the wall, the servo is only allowing the system to

extend itself, only providing resistance to release in a controlled manor.

Figure: The cable path



The servo spins, unreeling the cable. This releases the scissor mechanism upwards.

Now that the scissor lift is at the top, the sliding arm is free to slide out



After the arm fully extends, the bucket is free to descend.

After the bucket hits the table, it tips over, releasing the ball



The ball is released, the servo switches direction and the bucket is reeled back up



After the bucket reaches the top, the arm slides back in, completing all of the tasks.

The machine is fully retracted as designed. (The scissor can be pulled down, but it’s hard on the servo

and not part of the competition, so we don’t bother)



Our electronic system

Our electronics consist of an Arduino Micro, a switch for selecting running mode, a button to start the

device, and a servo to move the device.



Picking though long strings of code is tedious, so here is a summary of our Arduino program:

Note: all of the actions in the green circles are achieved by reeling out, or reeling out and then back in,

respectively, the servo motor.



Critical Design Elements

All of these concepts were mentioned previously, so they will not be explained again, they’re just here

as a neat summary.

Scissor lift with assist spring

Sliding arm

No-mechanical-parts tipping bucket

The simple control mechanism with a single servo motor and single cable

The mechanical suction cup mounted on the bottom of the device to keep it secured to the

table

Cleaver and Possibly Unique ideas

We feel that the suction cup is probably going to be unique. It does a wonderful job of keeping our

device were we intend to put it and requires very little time to attach. It was a good and simple addition

to the design.

The tipping bucket also seems an idea worth noting. It works well and we haven’t seen any other groups

using even a similar concept. They all have buckets that are dumped, which requires moving parts and is

less precise.

H - Bill of Materials P a g e | 112


H - Bill of Materials

Stock #

Description Material Where Purchased Quantity Used Cost Each ($)

Used Cost($)

Cost Total

Item# Item Name Item Quantity Item Description

1 #10 Washers Steel HOME DEPOT 50 32 0.035 1.12 1.75

2 #10-24 UNC

machine screws Steel HOME DEPOT 20 10 0.105 1.05 2.1

3 #10-24 UNC

bolts Steel HOME DEPOT 40 20 0.052 1.4 2.08

4 LOCTITE Epoxy,

0.47 oz Epoxy HOME DEPOT 2 1 5.12 10.24 10.24

5 #10-24 UNC

threaded rod Steel HOME DEPOT 1 1 3.19 3.19 3.19

6 1/16” x36” L

Stock AL HOME DEPOT 3 3 4.57 13.71 13.71

5-1 Bracket 1 1 Holds cable down near base of machine after unspooling from servo and before interfacing

with Bracket 2.

5-2 Bracket 2 1 Guides the cable to the top towards the

Bracket-3

5-3 Bracket-3 1 Holds the cable at the bottom of top base and lead it towards the Bracket 4

5-4 Bracket-4 1 Moves the cable to the top of the base and guides it towards the sliding arm eventually leading it to the bucket.

5-4 Arm

channels 8

Provides bound region for the sliding half of the scissor members to travel through

7 21x2x0.25” paint

sticks Wood HOME DEPOT 6 6 0 0 0

8 2’x4’x0.25” birch BirchPly HOME DEPOT 1 1 10.91 10.91 10.91

8-1 BirchPly-1 Home Depot Used to make the base of device

8.2 BirchPly-2 Home Depot Used to make the top of the device

H



9 5.5” by 2.06” compression

spring Spring Steel

CenturySpring.com, part #5089

1 1 7.13 7.13 7.13

10 4.94” by 0.219”

extension springs

Music wire CenturySpring.com,

part #1839 4 4 3.15 12.6 12.6

11 0.5” by 24”

constant force spring

Music Wire CenturySpring.com,

part #CF148 1 1 2.21 2.21 2.21

12 Ardino Micro Silicon and

magic Adafruit.com 1 1 24.95 24.95 24.95

13 Retractable Dog

Leash Fabric/ABS Petco 1 1 19.99 19.99 19.99

14 22 gauge wire Copper RadioShack 1 1 9.49 9.49 9.49

15 Mini Roller

Switch ABS/AL RadioShack 1 1 3.49 3.49 3.49

16 2xAA Battery

Holder ABS RadioShack 1 1 1.99 1.99 1.99

17 Mini Leaver

Switch ABS/AL RadioShack 1 1 3.49 3.49 3.49

18 10K Resistors Silicon RadioShack 10 1 1.49 0.149 14.9

19 Solderless

Breadboard ABS/AL RadioShack 1 1 9.99 9.99 9.99

20 Heat Shrink Tube Plastic RadioShack 100 10 15.99 1.599 15.99

21 11x14x0.093”

Sheet Acrylic Home Depot 2 1 12.99 12.99 25.98

21-1 Sliding Arm 1

Moves out of the scissor lift and covers the

horizontal distance with bucket hanging

21.2 Arm Cover 1 Defines the path for and secures arm

22 Section Cup ABS/Rubber Ebay 1 1 9.99 9.99 9.99

23 Key Return ABS Ebay 1 0 3.99 0 3.99

24 6X1/2” Screws Steel Home Depot 50 16 1.94 1.94 1.94

25 Basic Sponge Sponge Home Depot 1 1 1.00 1.00 1.00

26 Extension

Springs Steel Home Depot 4 4 3.15 3.15 12.60

27 0.5”X24Constant

Force Springs Spring Steel Home Depot 4 4 2.21 8.84 8.84

28 Aluminum Sheet Aluminum EMECH Bins 2 2 0 0 0



29 Ping-pong ball Plastic Walmart 1 1 0.50 0.50 0.50

TOTALS 176.388 235.04

Calculated from the above table, money spent on…

Total:$235.04

Cost of used material: $176.39

Spares: $12.99

Parts we didn't end up using:$ 3.99

Things that broke: $0

Things we already had: $0 (by definition!)

Figure H1: The Arduino arrived almost broken, but we were able to bend the pins back!

I - Testing P a g e | 115


I - Testing

Test Plan Document

Scope: To test each subsystem of the device, and the entire functionality of the device. Testing will allow

our group to identify design faults that need to be fixed. Each test will incorporate specifications from

the QFD in order to gage how close we are to a value.

Features to be tested:

1. Scissor Lift 2. Extending Arm 3. Servo 4. Arduino 5. Bucket 6. Suction Cup

Device Dimensions: Our device is maxing out all dimensions at 11” deep x 18” wide x 3.5” tall Weight: 2.95 lbs.

Scissor Lift Extension Test

Systems Tested: Scissor Lift, Servo, Arduino Switch

Test Description: The device was collapsed with all the parts assembled on the device and the ball was

put into the bucket. The device was then activated when the Arduino activated the servo to extend line.

The initial height, final height, time to cover distance, and wobble at the top were all recorded. It was

then collapsed down and repeated.

Materials Needed: Tape Measure, Stopwatch

Date of Test: April 15, 2015

Target Test 1

Test 2

Test 3

Test 4

Test 5

Test 6

Test 7

Test 8

Test 9

Test 10 Reliability

Standard Deviation

Starting Height (in) < 3.5 3.063 3.25 3.75 3.5 3.5 3.5 3.75 3.5 3.5 3.5 80% 0.2042

Time Vertical Distance(s) <10 7 6.2 6.5 7.2 7.46 6.87 6.5 6.87 6.3 6.5 100% 0.4068

Height Extension (in)

>24 <32 29 29.25 29.5 29.75 28.25 29.5 29.5 29.5 29.5 29.5 100% 0.4257

Wobble at top base extended (in) 2 2.25 2.5 2.25 2 4 2.5 2.5 2 2 2.5 90% 0.5869

I



Summary: The scissor lift extension test showed that the device ascends every single time to a correct

final height when triggered by hand. The only downfall to this test is that the autonomous start switch

has not been completed yet. Once this is manufactured, the entire reliability of getting the device to

ascend on the actual test fixture can be tested.

Autonomous Start Test

Systems Tested: Arduino Switch, Arduino Switch Mount

Test Description: The device will be placed in the starting zone in 20 seconds by a group member. The bar will then be lifted up and back to the second zone which will then trigger the circuit.

Material Needed: Device, Stopwatch

Date of Test: April 16, 2015

Summary: The autonomous start switch functions 80% of the time when placed on the test fixture. The

switch was not activated 100% of the time due to the large amount of wobble experienced by the

mount. To address this issue, we are going to look at the failure mode, and determine a potential

redesign of the switch mount.

Autonomous Start Switch Test

Testing Criteria Target

Test 1

Test 2

Test 3

Test 4

Test 5

Test 6

Test 7

Test 8

Test 9

Test 10 Reliability

Standard Deviation

Time to Place Device

20 38 31 35 29 26 25 22 26 21 22 100% 5.72

Device Activated

Y Y Y Y Y Y Y N Y N Y 80% N/A

Mount Wobble

<0.25” .16 .20 .21 .23 .27 .25 .28 .24 .30 .29 60% .045



Starting Height Test

Systems Tested: Scissor Lift, Bucket fit while collapsed

Test Description: With the device fully extended, the switch is then activated, and the lift is manually

guided down by hand.

Material Needed: Device, Tape Measure

Target Test 1

Test 2

Test 3

Test 4

Test 5

Test 6

Test 7

Test 8

Test 9

Test 10 Reliability

Standard Deviation


Summary: The starting height was variable on the procedure used while the device was being collapsed.

If the sliding arm was extended at all, then the bucket would not fit properly in the device, and would

cause it to have a higher starting height.

Sliding Arm Test

Systems Tested: Sliding Arm, Scissor Lift, Servo

Test Description: The scissor lift was extended to full height, the sliding arm was activated, and the

resulting distance traveled and time to reach distance was recorded.

Materials Needed: Device, Stopwatch, Tape Measure

Summary: The sliding arm was activated 100% of the time, but the horizontal distance covered by the

device was never enough to allow it to reach the license plate holder. In order to fix this, we will look the

FMEA, and draft ideas.


Test

1

Test

2

Test

3

Test

4

Test

5

Test

6

Test

7

Test

8

Test

9

Test

10 Pass/Fail Reliabilty

Standard

Deviation

Sliding Arm

Activation Y Y Y Y Y Y Y Y Y Y Y Pass 100% N/A

Distance traveled by

horizontal arm (in)

>5

< 93.2 2.7 3.1 3.2 2.9 2.8 3.2 3.1 3.1 3 Fail 0% 0.177

Time to reach final

distance (s)<3 1.2 1.1 1 1.1 1.1 1 1 1.2 0.9 0.8 Pass 100% 0.126

Sliding Arm Test



Suction Cup Test

Systems Tested: Device, Suction Cup, Scissor Lift

Test Description: With the device placed in the starting position on the board, the suction cup is

activated, and the scissor lift is extended. The device is then manually displaced by applying pressure at

the top of the lift to determine the rigidity of the device.

Materials Needed: Device, Tape Measure

Summary: The suction cup was determined to work very well, as the structure has no movement while

ascending, and had very little wobble at full extension.

Not entirely relevant, but funny nonetheless

cvcv

v

“Special Tooling” used to build our foam scissor prototype

That prototype was invaluable for finding the weak spots in the members

Target

Test

1

Test

2

Test

3

Test

4

Test

5

Test

6

Test

7

Test

8

Test

9

Test

10

Pass/

Fail

Average

Deviation

Wobble at full

extension<3 2.2 2.5 2.3 2.2 2.4 2.4 2.1 2.2 2.2 2.1 Pass 0.135

Device Moves

while extending N N N N N N N N N N N Pass N/A

Suction Cup Test

J - Reliability and Design Margin Analysis P a g e | 119


J - Reliability and Design Margin Analysis

Reliability and Design Margin Analysis: Variability and Reliability Analysis of Scissor Lift

Scope: To find areas of variability we analyzed our test results, and created a failure mode and effects

analysis diagram to identify the most important areas that could affect device functionality.

Starting Height Analysis

Target Test 1

Test 2

Test 3

Test 4

Test 5

Test 6

Test 7

Test 8

Test 9

Test 10 Reliability

Standard Deviation


According to our tests, the starting height was at or below the maximum allowable 80% of the time. The

standard deviation between heights was 0.2042 which is fairly low.

Variability: After analysis it was identified that the bucket would not fit correctly if the sliding arm did

not fully retract while the device was descending. This caused the bucket to get caught on a member

arm of the lift and this would cause the device to have a higher starting height.

After running the test several important factors affecting variability were found.

1. The starting height would vary based on the position of the bucket.

If the bucket gets caught in the members, the starting height will be above the allowed

height.

Solution: Make sure the sliding arm is fully retracted and the winch line has no slack.

2. The line to the servo switch came off after running the last test.

Solution: Ensure all electrical lines are secured

Overall Reliability of Scissor Lift: 72%.

This can be maximized by ensuring our solutions to variability are maintained.

The scissor lift would collapse to below 3.5” 80% of the time.

Performance Effect: The starting height does have a potential to disqualify our device, if it measures

too high.

Solution Improvement: Manually retract the sliding arm while the device is descending, and make sure

bucket does not get caught on the lift member. We ensured each member of the team practiced

lowering the device, and making sure they could successfully collapse the lift.

J



Height of Extension

Target

Test 1

Test 2

Test 3

Test 4

Test 5

Test 6

Test 7

Test 8

Test 9

Test 10

Reliability Standard Deviation

Height of Extension (in)

>24 <30

29 29.25 29.5 29.75 28.25 29.5 29.5 29.5 29.5 29.5 100% 0.4257

Variability: After testing the device 10 times, the scissor lift ascended every time, but did have differing

maximum heights. The standard deviation between the heights was 0.4257” which is fairly significant.

The maximum height achieved by the device, however has no significant impact on device performance,

so no steps need to be taken to solve the variability here.

Reliability: 100%

The scissor lift would ascend 100% of the time, with the ascent being controlled by the servo.

Sliding Arm Extension Test

Variability: The sliding arm has a reliability rating of 0%. When the lift reaches the max height, the

sliding arm does not extend fully. The variability in the distance travelled by the arm is shown in the

standard deviation of 0.177”. This number is not concerning, because the sliding arm does not extend

fully.

Reliability: 0%

Solution Improvement: In order to get the sliding arm to work, a failure mode analysis needs to be

done to determine how to fix the problem.

-Reliability of Entire Scissor Lift: 72%

-Reliability of Sliding Arm: 0%

-Reliability of Entire Device: 0%


Test

1

Test

2

Test

3

Test

4

Test

5

Test

6

Test

7

Test

8

Test

9

Test

10 Pass/Fail Reliabilty

Standard

Deviation

Sliding Arm

Activation Y Y Y Y Y Y Y Y Y Y Y Pass 100% N/A

Distance traveled by

horizontal arm (in)

>5

< 93.2 2.7 3.1 3.2 2.9 2.8 3.2 3.1 3.1 3 Fail 0% 0.177

Time to reach final

distance (s)<3 1.2 1.1 1 1.1 1.1 1 1 1.2 0.9 0.8 Pass 100% 0.126

Sliding Arm Test



Failure Mode Effects Analysis

FMEA Sliding Bucket

Failure Explanation: After testing, it was determined that the sliding bucket would not fully extend. To

determine how to correct this failure, we analyzed our failure and effects analysis sheet. The sheet is

included below.

Cause of Failure: According to the failure mode and effects analysis the potential problems of the sliding

arm are dependent on the tension of the winch line, or too much friction on the arm. The actual result

was very similar with too much friction on the arm causing it to stop when it was halfway out.

Risk Priority Numbers: 18 and 28

Looking at the risk priority numbers the two least risky areas are associated with the tension applied by

the winch tension at 18,28. Since the sliding arm is dependent on this force to keep it sliding out, ideally

this force would be constant. However, the tension in the winch line is greatest at the bottom and

decreases linearly as the device ascends.

Fix #1: To account for this, we reduced the spring force which pulled the sliding arm out when the spring

force became greater than the tension in the cable.

Result: The spring did not activate until the device reached the top of its extension, but it only extended

about half of the needed distance.

Solution #2: The next possible solution to this problem addresses a redesign of the system. This

however, is the risk priority number of our device at 240. This is the highest number because it is

dependent on several other functions, has a high severity rating, occurs frequently, and is hard to

measure. To fix these we instead drafted a redesign which allowed for a smaller height, two springs, and

a channel. This allowed the device to extend fully while at the top of travel.

Process

StepFunction Failure Mode Failure Effect

Se

ve

rit

y

CPotential Failure

Cause

Oc

cu

rre

nc

e

Preventive Action Detection Action

De

tec

tio

n(1

-

10

)

RP

N

Servo Allow for Constant

Lift VelocityLift spings up

To much acceleration

and force9

Servo motor

damage, broken line2

Reduce assisted

spring force

Time how long to

travel upwards1 18

Reels back sliding

arm

Not enough

tension on line

Sliding arm extends

while lift is going up7

Too much force in

spring2

Reduce spring force or

increase tension in

line

Test device 2 28

Sliding Arm not

fully extended

Too much

friction on armdoes not fully extend 5

Misalignment of

parts6

Measure and recut

parts4 120

8 Poor design 6 Redesign Test 5 240



FMEA Sliding Axle

Failure Description: When trying to machine the sliding axle, the lathe would not successfully thread the

part. Instead it would warp and become unthreadable. The original design called for a complex rod with

threading on both ends and slots in the middle. It was determined later on that we could not turn such a

complex piece on the lathes. The part was too small and kept deflecting when we tried to cut it, and the

threading was not working and very inconsistent.

Risk Priority Numbers: 30-70

The risk priority numbers associated with the sliding axle were all in the moderate range

A high severity but easy detection made it easy for us to identify what went wrong, and create a

solution to the problem relatively quickly.

Cause of Failure: Complex Design, Inappropriate Tooling, Lack of experience

Solution: Design Change

We opted instead for threaded rod in the correct diameter and threading them through the various

parts and springs in order. This decision is backed in part by the failure mode effects analysis. According

to this, the failure mode for the sliding axle is the lift not going up, with the effects being not proper

threading, poor fit in guide rod, and too much friction. The failure cause was creating a very complex

design that had to be threaded in the machine shop using a lathe. While threading the part, we were

getting a thread warp age to the point you could not screw on a nut. Another problem with this design

was that the lathes were too big and the lathe tool used was not precise enough to machine it properly.

Function Failure Mode Failure Effect

Se

ve

rity

CPotential Failure

Cause

Oc

cu

rre

nc

e


De

tec

tio

n(1

-

10

)

RP

N

Allows for Device

Ascension

Lift does not

go upThreading not proper 9 Poor material, 4 Tram Machine Measure travel of slot 2 72

Does not fit in guide

rod9

Incorrectly mounted

tooling2 Use correct tooling Measure travel of slot 2 36

Large amount of

friction7

Too much contact

force5

Add second sliding

mountTest device ascention 1 35



FMEA Suction Cup

Failure Description: The suction cup did not have any suction after it was mounted on the board.

Cause of Failure: The mount hole for the suction cup was too small, and the rim of the cup was not

making proper contact with the table when placed down. Also the failure mode and effects analysis

shows that a potential failure cause is not having the suction cup centered in the hole.

Risk Priority Number: The suction cup has a low risk number due to the low severity and low occurrence

of the device.

Solution: We expanded the hole where the suction cup was placed in so the lip of the suction cup

would only contact the table the device sits on. We also changed the mount, so it would center the

suction cup in the mount hole.

Process


Se

ve

rit

y

CPotential Failure

Cause

Oc

cu

rre

nc

e


De

tec

tio

n(1

-

10

)

RP

N

Suction

CupMaintain Stability

Device does

not stick

The device is not

stabalized6

Suction Cup not

centered in hole2 Center Suction Cup Test 1 12



Entire Failure Mode and Effects Analysis Sheet

Process


Se

ve

rity

CPotential Failure

Cause

Oc

cu

rre

nc

e


De

tec

tio

n(1

-

10

)

RP

N

Cutting

BasesSupport

Not cut to

Spec

Device Dimensions to

large6

Measurements are

off2

Double check

measurementsMeasure after cutting 1 12

2Did not account for

saw blade kurf5

Indicate which side of

making to cutMeasure after cutting 1 10

Lift

MembersDevice Ascention

Member

Breaks

Scissor Lift will not

ascend9

Member not thick

enough2 Use thicker material

Stressing member

until failure 4 72

7Member not wide

enough2

Make Larger Width

Dimension

Stressing member

until failure 1 14

9Member is made

from weak material4

Use stronger material

for members

Stressing member

until failure 4 144

Sliding

Axle

Allows for Device

Ascension

Lift does not

go upThreading not proper 9 Poor material, 4 Tram Machine Measure travel of slot 2 72

Does not fit in guide

rod9

Incorrectly mounted

tooling2 Use correct tooling Measure travel of slot 2 36

Large amount of

friction7

Too much contact

force5

Add second sliding

mountTest device ascention 1 35

Spring

Rod

Holds springs in

place

Lift Does not

go up

Rod does not fit in

groove7 Incorrectly sized rod 2

Face rod down, or buy

new rodInstallation 1 14

Rod incorrectly

threaded 9 Bought wrong rod 2 Buy new rod Thread nuts on rod 1 18

Cable

Guide

Allows for scissor

lift ascention

Lift does not

go up9

Sliding slot not

milled correctly2 Remeasure and remill

Measure slot and

tram machine3 54

Servo Controls Lift

AscentionLift spings up

To much acceleration

and force9

Servo motor

damage, broken line2

Reduce assisted

spring force

Time how long to

travel upwards1 18

Lift does not

go upBatteries are low 3

Did not charge

batteries2

Get full chage on

batteries before the

competition

None 10 60

Reels back sliding

arm

Not enough

tension on line

Sliding arm extends

while lift is going up7

Too much force in

spring2

Reduce spring force or

increase tension in

line

Test device 2 28

Sliding Arm not

fully extended

Too much

friction on armdoes not fully extend 5

Misalignment of

parts6

Measure and recut

parts4 120

8 Poor design 6 Redesign Test 5 240

Allows for bucket

descent

Bucket does

not descend

Too much friction and

not enough weight7

Large line, sharp

corners, high friction6

Cut down line, sand

corners, increase

bucket weight

Test 3 126

Suction

CupMaintain Stability

Device does

not stick

The device is not

stabalized6

Suction Cup not

centered in hole2 Center Suction Cup Test 1 12

Process FMEA

Process: Device Manufacturing and Electrical Functions Responsibility:

Product: Scissor Lift Bottom and Top Prepared by: Sean Visocky



As a result of this analysis, we have:

Modified the arm several times to reduce friction and increase spring force



Redesigned the bucket 3 times

`

Whereas previously, we had only made a real model of the scissor mechanism out of foam bard. This

greatly helped us flesh out exactly what we needed to do otherwise.

K - Safety Analysis P a g e | 127


K - Safety Analysis

Components which can pose risk in our device

1. Pinch from the scissor lift.

2. Wood sticks should be handled safely as wood splinters may cause injury.

3. Edges of aluminum components

4. Overheating of motor.

The product was made safe by:

1. Using suction cup in order to stabilize the device.

2. Most of the wiring was done with extreme care.

3. No sharp edges.

4. No exposed wires.

5. Operated the devise at reasonable speed.

The risks while machining the device:

1. Operating band saw, table saw and other cutters could dangerous.

2. Operating lathe machine could be imperiling.

3. Drill presses and Vertical mill machines could cause injury.

4. Electrocution could be possible while wiring.

K



The machining risks were avoided by:

. 1. Using safely glasses all the time while manufacturing.

2. All the machines were operated with caution.

3. Vises were used while using files and sand papers.

4. Tried not paying attention to the distractions.

5. Always followed “Two People” rule while machining.

Additional device safety was performed by:

1. Using a timed circuit to turn of the motor.

2. Switch is present to turn off device in worst case scenario.

3. Device was designed to operate within its own lane to avoid any casualties.

Issues Hazard-Description Category Likeliness to occur

Spring failure Critical II Improbable

(<0.001-0.1%)

Motor overheating Marginal III Occasional

(0.1%-1%)

Failure of suction cup Marginal III Remote

(0.001-0.1%)

Battery Leakage Negligible IV Occasional

(0.1%-1%)

Arduino Failure Catastrophic I Improbable

(<0.001-0.1%)



Hazard-risk Index Criterion

Spring Failure 15 Acceptable With review

Motor Overheating 11 Acceptable With Review

Failure of Suction Cup 14 Acceptable With Review

Battery Leakage 18 Acceptable Without Review

Arduino Failure 12 Acceptable With Review

Mishap-assessment matrix table 8.4 from The Mechanical Design Process Fourth Ed MCGRAWHILL

From all of the above analysis, machining our parts poses the greatest risk. The table saw, band saw

were the most risky machines used in the project. Proper care was taken while working on the saw.

Additional parts such as push sticks were used in order to increase the safety. All the instruction-

manuals were read while using the machines. All the machines were run according to the acceptable

speeds. Overall from the whole project there is “level 3” threat to the humans. “Level 2” threat to the

environment as lithium batteries were used which can pollute the environment. This is acceptable in

our context.

L - Service and Support Plan P a g e | 130


L - Service and Support Plan

In order to make everything run smoothly we have laid out the following tasks with this Who vs what

chart for responsibilities on competition day:

Group Member Responsibilities

Nate Keisling Scissor lift, Suction cup

Chris Sawyer Arduino, Sliding arm, All electrical parts

Sean Visocky Fixture Setup

Amroz Sandhu Bucket and other mechanical components

Problem solving chart:

Problems that can occur Probability Cause Troubleshooting

Scissor lift getting stuck <5% Friction Use of lubricants

Arduino Failure <5% Improper wiring Fixing the wires and power

Sliding arm Failure 10-20% Improper positioning, getting

stuck in middle on top surface

Proper alignment and use

of lubricant

Motor Failure <1% Power issues Re-plug, Change plugs

Bottom Spring Failure 1-10% Positioning Align it straight

Bucket not dropping ball <5% Orientation Re-orient

L

L - Service and Support Plan P a g e | 131


Spare parts and extra supplies chart:-

Parts Failure Probability Quantity

Super Glue 10-20% 3

Epoxy 1-10% 2

Duct tape 10-20% 2

Batteries 10-20% 2

Wires <5% 1 roll

Electrical tape N.A 2

Bolts, Nuts, Washers N.A` ~30

Other supplies and equipment:-

1. Extra Acrylic

2. Hand Drill

3. Chargers

4. Wire Strippers

5. Pliers

6. Screw-driver

7. Extra Cable

8. Ping-Pong ball

9. Extra Cardboard for Bucket

10. Band-Aids

M -Teamwork Analysis P a g e | 132


M -Teamwork Analysis

We used facebook to keep track of things. Often.

M



Unfortunately the original was lost, and this scan was all we had left. This was much more ridged than

the Project 1 version, and we followed it much better.



3/12/2015 team health assessments



Project wrap up team health assessments



Final thoughts:

Amroz:

This was very big project which needed the amazing skills of design and engineering understanding. All

team members did the job satisfactorily but some people did way more work than others which was not

fair until some point but in the end team tried hard and in the last week everybody tried to help each

other and got everything that was needed to be done. If, we win the competition it will be a great

achievement as it is really hard to win a competition won when almost 90 people compete. Hopefully

we’ll win it.

Chris:

During these last few days of the competition, things have gotten little hectic. No animosity has come up

between the group members, but the strain of making sure all the loose ends of the project are nipped

before the turn in date has affected our sanity a little. This project has been quite the time commitment.

We’re working together quite hard and I feel strongly that we should have a legitimate chance at the

competition and at the very minimum a good grade on the report score. If anything, the deadline

pressure has helped us work more smoothly. I have no real problems to report.



Sean:

Our group functioned well, but there was definitely a feeling of them and us in the group. The

time and effort level committed by each member to the project was substantially different across

the board. As project manager, I should have tried to get a more even distribution of effort, but

some members of the group needed more structure, and motivation than others. If I was in lead

of a similar project, I would have set clear expectations up front, and made all group members

agree upon it. In addition to this, I personally would have sent out more structured tasks with

deadlines. As there were different motivation levels in the group, one member would take off

with an idea and write several pages and create a prototype while another would do the bare

minimum. Toward the end of the project, this effort level was getting to the point where it

needed to be addressed, and we resolved the difference face to face. From then on out, he gave

more effort and time commitment that was needed to complete the project. Overall our

functionality as a team suffered due to the culture that was established in the first project that not

meeting deadlines was fine. I tried to enforce this in this project more, but we already had the

bad habit and it was hard to break. However by constant pressure deadlines were usually kept

within a few days of the originally assigned day. Other than these issues, we were a diverse team

that utilized each member’s strengths fairly well, and came up with a great design.



Team health assessment by Nate Keisling.

This is going to be a doozy. On the Health Assessment Matrix I noted that I would “Disagree” that the

“team environment was characterized by honesty, trust, mutual respect, and teamwork.” This was

largely for the very last statement- teamwork. The burden of effort was not distributed very evenly. I

wish I could say that this was because one member slacked off but instead I believe the fault lies with

everyone. There were members of the team disinclined to jump forward and show initiative and

effort on a large scale. Normally this would be okay with some gentle pushing to help even out the

workload. Part of the problem is that this did not happen. This ties in to “trust” and the lack of “trust”

was very much a personal failure. I did not trust my group members to contribute to the successful

design of the device. As such I took upon myself the burden of about 60% of the analysis work, 90% of

the design work, and 75% of the manufacturing work. I put such a disproportionate amount of time

into the development of the device that I failed a class this semester because I did not possess enough

hours in the day to succeed at everything. The only thing I did not design was the horizontal arm and

the specifics of the programming. Everything else, including most of the problem solving and

redesigning, was developed by myself and, for the most part, also manufactured and assembled by

myself.

But let me be clear- this was a personal failure. Above anything else this failure to distribute

teamwork was a failure of my own pride and distrust of my teammates, and while this lead to a very

cohesive device that was designed from the ground up to work together, it also meant that many

things were overlooked- something having multiple people working on design would have solved. I

firmly believe that if I had chosen and trusted a partner for analysis and design we would have

developed a product on time that would have demolished the competition. This all falls back on my

comment that I was “Neutral” about the team treating every member as having potential value and

let me be clear- that is 100% a criticism of myself. I failed to treat all group members as having

potential value, despite the fact that, retrospectively, all of my group members are extremely skilled

and respectable. My pride got the better of me and this has been a significant learning experience for

me.

But when it comes to the development of the document, another concerning problem does appear to

fall on the shoulders of group members disinclined to pull their own weight. The development of the

final document fell far too greatly on Chris, and I feel deeply for the stress this caused him. There were

certainly delays incurred by me, by myself, doing most of the analysis and design. But at the same

time, there are countless other parts of the document that were assigned to other members who did

not pull their weight, either producing sub-par content or not producing anything at all.

All in all, our greatest flaw as a team was collectively believing that our process was copacetic and not

doing enough to carefully distribute work to maximize efficiency and effectiveness. This is a flaw that

falls on the shoulders of everyone- on me for not being willing to trust my partners to do good work

and on some group members for not showing that they were either not capable of high quality work

or that they were not willing to put in the time for high quality work.And let me emphasize again:

These failures experienced fall largely on my shoulders and the sub-ideal quality of the project is

primarily my fault. My pride in my own skills and my unwillingness to ask for help and demand quality

and equivalent effort from my partners lead us to be far less successful than we were capable of

being.

m202 design project

Documents