The Asparagrabber

Clients: Richard Barker & Steve Shoemaker

Course: InterEgr 160: Intro to Engineering Design

Instructor: Katie Kalscheur

Date: December 11th, 2014

Team Members: Andrew Baldys, Erik Kernozek, John Robert Lee V, Josh Le Noble, Bradley

Mergener, Phil Michaelson, Monica Samsin, Will Smithayer, Alex Spicer, Anna Tessling, Trace

Thorp

1

Table of Contents Executive Summary: ................................................................................................................... 3

Introduction ............................................................................................................................... 4

Problem Statement: ................................................................................................................. 4

Background Information: ........................................................................................................ 4

Specifications: ......................................................................................................................... 5

Design Process for Group 2: .................................................................................................... 6

Design Description of Small Group 2: ...................................................................................... 7

Design Description for Group 5: .............................................................................................. 9

Design Process and Description: .............................................................................................10

Design Review: .......................................................................................................................10

Final Design: ..........................................................................................................................11

Project Execution.......................................................................................................................13

Gantt Chart: ..........................................................................................................................13

Workload Allocation: .............................................................................................................16

Testing ......................................................................................................................................18

Calculations and Equations: ...................................................................................................19

Calculations for Current Harvest Rate: ...................................................................................21

Design Limitations .....................................................................................................................23

Conclusion .................................................................................................................................25

Work Cited................................................................................................................................27

Appendix ...................................................................................................................................28

A. Materials: ..........................................................................................................................28

B. Fabrication Instructions: ....................................................................................................28

Parts Guide ............................................................................................................................38

2

Executive Summary:

Richard Barker and Steve Shoemaker of Dancing Oak LLC asked the team to design an

innovative and distinctive method of harvesting asparagus involving a new device for use on their

four-acre farm in New Glarus WI. Dancing Oak LLC proudly produces organic asparagus, so their

method of harvesting the crop is very traditional in that the harvesting is done by hand. The current

method includes much bending over in order to cut the plant near the ground while carrying a

heavy pack on one’s back. This motion repeated over the long work days of roughly 12 hours does

considerable damage to the farmer’s back and hamstrings. The team’s new design will minimize

the strain on the user’s body and increase efficiency which, in turn, will reduce the harvesting time.

The team eventually decided on a device that can be used while standing upright, thus

greatly reducing the strain on the farmer’s back. The design is comprised of a pole containing an

inner drive-shaft connected to a blade at the bottom of the pole near the ground. This blade

mechanism is similar to that of a scissor. The tool is to be used with two hands: one to operate the

handle that turns the drive-shaft, and one to hold onto the device. A forearm brace is included in

order to minimize strain on the wrist. When the handle near the top of the pole turns the drive-

shaft, the drive-shaft transfers the torque to the blade which cuts the asparagus. The asparagus then

falls directly into the basket that is attached at the bottom of the pole, near the ground, on a rail

system. Once this basket is full, holding 15-20 asparagus, it can easily be pulled up the pole on the

rail with a cable. Then, when the basket is within reach of the user, the farmer can simply remove

the harvested asparagus and put them in the knapsack, satchel, or any storage unit currently in use.

After the produce has been removed from the basket, the wire can be released to allow the basket

to ride the rail system back to the bottom of the pole. In this way, the farmer can seamlessly return

to harvesting asparagus.

This device will satisfy all of Richard Barker’s and Steve Shoemaker’s specifications. It

will reduce most, if not all strain on the body of the user. After some practice, this device should

also increase the efficiency of the harvesting process, because one can harvest many asparagus

before unloading the basket. The device is also within the team’s budget of two hundred dollars

with the cost of production being $170.26. Ultimately, this design will minimize the bodily damage

involved with manually harvesting asparagus while also increasing the speed, giving the farmers

of Dancing Oak LLC a viable option for use on their farm.

3

Introduction

Problem Statement: Our clients, Richard Barker and Steve Shoemaker, need a device for harvesting their four

acres of asparagus at their farm, “Dancing Oak,” in New Glarus, Wisconsin. Currently, they use

traditional methods which involve harvesting on foot and by hand. This causes them to repetitively

bend over for 12 hours a day. Additionally, carrying an excessive amount of weight is involved,

placing great strain on a worker’s knees, lower back, and hamstring. Our design needs to increase

harvest worker efficiency, be lightweight, maneuverable between the rows, adjustable for different

heights of the user, and be able to withstand any type of weather. Most importantly, our design

must be safe and reduce the strain placed on the lower back, knees, and hamstrings of a harvest

worker.

Background Information: In order to better understand the problem statement and final design, one must first

understand the process of harvesting asparagus. Asparagus is a seasonal crop. One thing that makes

harvesting it unique is that not all of the plants are ready to harvest at the same rate. An asparagus

can grow as much as six inches in one day,¹ so an asparagus that is too short one day may be just

right the next. Additionally, if the asparagus is allowed to grow too tall, it will have much tougher

skin and be unmarketable.¹ For this reason, asparagus harvesting is usually done manually as a

farmer’s judgment is needed on what plants need to be harvested each day. Furthermore, the

asparagus is usually harvested daily for a 60 - 90 day period in the spring.

During our initially meeting, the clients described the current harvesting methods.

Typically, one of our clients harvests the four acre field by himself for eight to twelve hours a day.

His methods include bending over and cutting each individual asparagus with a serrated knife three

to four inches above the ground. He then stores the asparagus in a satchel that he wears over his

shoulder. It is important that he manually places the asparagus into the satchel as not to damage

the top part of the asparagus, the floret.

Many different mechanisms have been invented over the years for harvesting asparagus.

These include carts in which a harvester lies on his/her stomach to harvest,4 others have the

harvester in a sitting position,5 and still others include much more machinery and must be driven.6

Many of these require more than one person to operate, and are made for large scale farms.

4

However, our clients are from a small scale farm, and one of them will be harvesting by himself

most days.

Specifications:

After meeting with our clients, many specifications arose that our design needs to meet.

First, Dancing Oak has a four acre field with a 10” buffer on the ends and about four feet between

each row. However, the rows are not perfectly straight, and the landscape is rough and bumpy with

a slight grade. For these reasons, our design must be sturdy and easily maneuverable. The most

feasible design to meet those specifications would be a lightweight, manual, one person operable,

hand tool. That way it can be easily used in any part of the field.

Secondly, the main operator is one of our clients, Steve Shoemaker, who is 6’2” in height.

Our tool has to be long enough to reduce bending over, but also adjustable in case another worker

would need to use it. Additionally, it has to be built to be ambidextrous. This is because Steve is

left-handed, but other workers may not be.

Third, asparagus must be kept in favorable conditions in order to sell. The marketable

length is seven to nine inches. However, since asparagus do not all mature at the same rate, a

farmer must discern which asparagus in the field are ready to be harvested each day. This is another

reason for making the device a man-powered tool. Additionally, the floret of the asparagus cannot

be damaged at all. For this reason we must take precautions to ensure our device does not handle

the floret too roughly when the asparagus are harvested.

Fourth, the workers at the farm currently spend twelve hours a day seven days a week

harvesting in spring time. Part of our goal includes making it possible for them to reduce their time

to eight hours harvesting (around 8.5 shoots per minute, 780 shoots per hour). They would unload

30-40 pounds, eight to nine times a day. This would drastically improve the efficiency of the

process.

Finally, all of this must be achieved within a $200 budget. To do this we must have strategic

planning and extensive product research. Additionally, our team needs to be resourceful and make

use of leftover materials provided to us by the shop.

5

Design To form our final design we merged two designs that were developed in separate, small

groups. There were initially six small groups in our class, and our final team was formed from

groups two and five. Each small group went through a slightly different process in forming a

general design idea. Each of these general design ideas were then used to create a final design as

a large group.

After being assigned small group teams, the design process began with a lab revolved

around meeting with the client. During this meeting, the client first introduced himself and

described what his plans were in terms of harvesting asparagus. Following a brief presentation

from the clients, Richard Barker and Steve Shoemaker, the students were given a chance to ask a

lot of questions on harvesting asparagus in general and what specifics the clients are looking for

in a product. For example, students asked questions pertaining to where the asparagus must be cut,

what kind of physical strain the current method causes, and the dimensions of the client’s field.

Following the question and answer session with the client, both teams individually

regrouped and formulated a problem statement and specifications. In order to formulate these two

items, the teams defined the problems with the current methods and outlined the specifications

such as the field dimensions and height of the user that the new design needed to meet. Following

this step, the groups started the brainstorming process.

Design Process for Group 2: After the problem statement was firmly established and the client’s needs were made clear,

the team began to brainstorm many different and innovative ideas for harvesting asparagus. At

first, the brainstorming was aimed towards broad ideas, and out of this vast bundle of schemes and

systems, the designs were condensed into two separate categories: for use while standing and for

use while laying down. The next step was for the team to brainstorm specific designs that allowed

for the best strategy of collecting the crop. This included the actual cutting mechanism to the

storage system the design should incorporate. In order to weed out ideas, the team set up a decision

matrix that would separate the good ideas from the great ones. Once the final designs were decided

on, small group presentations were prepared in an attempt to sell our designs to the client. The two

designs presented were the scissor-stick and the laying-cart. Both of these systems were chosen

due to the fact that they scored highest on the decision matrix, and they each were completely

6

different designs and strategies for picking asparagus. This variety allowed for the team to give

the client the greatest opportunity to find the best option for use on his farm. At this point, the team

began brainstorming and deciding on materials to be used in each design. Final, after team two

had presented in front of the client, it was paired with team five because of design similarities.

Figure 1: Group 2 Design Matrix (self-created) - This design matrix shows a comparison

between three different design ideas based on various criteria. The design with the highest

weighted total is the most ideal based on the specifications outlined in the chart.

Weight Poop Scoop Scissor Stick Laying Cart

Safety 2 4 5 4

Ease of Use 9 5 4 4

Accuracy 5 3 4 5

Mobility 6 5 4 3

Strain 20 4 5 4

Efficiency 8 3 4.5 4.5

Fabrication 6 5 3 3

Cost 7 5 4 2.5

Weighted Total:

227 222 198.5

Design Description of Small Group 2: Team two’s original design was comprised of both a handheld device and a cart that would

be pulled along in order to store the asparagus after it was harvested. The handheld device

consisted of a shaft running from the farmer’s elbow to the ground with a scissor mechanism at

the bottom of the shaft. The farmer would squeeze the trigger mechanism in the handle which

would close the scissor, cutting the asparagus near the ground. The farmer could continue to hold

the asparagus with the device by squeezing the trigger. From there the farmer could directly place

the asparagus into the storage cart. The storage cart would be located low to the ground and pushed

7

along near the cutting area. This way the device would not have to be lifted too high, reducing

strain on the body. The cart would be lined with a removable bag for easy removal once the cart

is full.

Design Process of Small Group 5:

For small group five, initial brainstorming categories included safety, mobility, frame, and

functionality. Within each of these categories the group thought of ideas that pertained to the

overall category. After the initial brainstorming, the group evaluated the different ideas and

narrowed them down. From there the team formulated four key designs: a cart, a mower, a vacuum,

and a hand-picker. First, the cart idea consisted of a recumbent bike that a harvester could ride and

then harvest from the sitting position. Second, the mower was a mechanical device that would go

over a row of asparagus. Then a button could be pressed to indicate that the harvester wanted to

pick a given asparagus. A large problem with this device was what to do with the asparagus after

they were cut. Next, the vacuum consisted of a backpack type device that would have a tube

coming over a harvester’s shoulder to suck up the asparagus. Finally, the hand picker was a hand

held device that a harvester could walk with and harvest asparagus from a standing position. The

group thought possibly the vacuum picker would work best, but after talking to some of the shop

experts and formulating a decision matrix decided that a hand-picker was the best option. We drew

our idea onto a poster and named it “The Asparagrabber”. From there the group presented it to the

class and gained insightful feedback to work off of. Afterwards, we were joined with group two,

another team who shared a similar hand picker idea.

Figure 2: Group 5 Decision Matrix (self-created) - This design matrix shows a comparison

between four different design ideas based on various criteria. The design with the highest weighted

total is the most ideal based on the specifications outlined in the chart.

Weight Cart Mower Vacuum Hand-picker

Storage 4 5 2 5 4

Feasibility 10 3 4 3 5

Amount of Assistance

6 4 3 4 4

8

Comfort 8 5 4 4 4

Efficiency 9 3 5 4 5

Weighted Total:

141 143 142 167

Design Description for Group 5: As shown in Figure 3 below, the initial hand picker design consisted of one main shaft.

This shaft would be retractable by pressing the button on top. This makes for easy storage of the

device and allows it to be adjustable according to the size of the user. By squeezing the handle, the

single blade perpendicular to the rod is triggered to swing back and forth to cut the asparagus. The

product would then fall into either of the two trays attached to the sides. The team also had the

idea of possibly using a scissor-like design in case the single blade was ineffective. Additionally,

the team included a cart system in their initial design. The farmer would attach a belt connected to

the cart around their waste and roll it behind them. This way, the asparagus could be stored within

dividers as the worker made their way down the rows.

Figure 3: Group 5 Hand-picker Design Sketch (self-created) - This picture shows our original

Asparagrabber design in the center. The right hand corner displays the alternative scissors blade

and the lower left corner shows a better view of the trays. Finally, the lower right hand corner

shows our carrying cart.

9

Integrated Design

Design Process and Description: After the initial small group presentations, groups two and five came together to form one

design. We took two key elements from each group’s hand-picker to formulate one main design.

In our final design we incorporated the wrist support from group two’s design and the asparagus

holding tray from group five’s hand-picker design. Focusing on including these two elements, we

further fleshed out the design for our hand-picker and tried to meet all of the specifications.

The main body of our project was a hollow aluminum pipe. Inside this pipe there was a

solid aluminum drive shaft. At the bottom of this drive shaft, a blade was attached. Several inches

from the bottom, a short metal bar was attached perpendicularly to the drive shaft, sticking through

a slit in the aluminum piping. Several inches from the top there was a similar bar. This allowed for

limited rotation of the drive shaft inside of the piping. As one pulled the bar at the top, the lower

bar and the blade also simultaneously rotated. The blade cut the asparagus as the lower bar hit the

top of the asparagus, knocking it into the basket. The basket was attached at the bottom of the

device such that when the asparagus was cut it will fall into it. The basket had a capacity of 10-15

asparagus. The basket was on a track that went up the length of the piping. The set up consisted

of a pulley system such that one could pull a cord and the basket would travel up the pipe for easy

emptying. At the top of the pipe, another aluminum pipe (approximately the length of an average

forearm) was attached at ~110 degrees. Near the end of this pipe was a velcro strap, and on this

pipe near its intersection with the other pipe was a perpendicular bar. This bar served as a handle

such that when one were to hold onto it, the pipe rests on top of one’s arm, and the velcro strap

strapped to one’s forearm to provide extra support.

Design Review: The next step in the design process was the design review. For this, our group performed a

small presentation on October 20th for our class, our teacher, Dr. Katie Kalscheur, and special guest

biomedical engineer, Dr. Tracy Puccinelli. Our presentation included the following: our problem

statement and specifications; a description, pictures, and an animation of our design; a projected

budget; assigned group member roles; and a Gantt Chart schedule.

10

Additionally, our group voiced a few concerns and questions about our design to our

audience in hopes of gaining some valuable insights. We asked the following: Do you think that

the bolt-action method of cutting the asparagus is the most effective and efficient method? If not,

what cutting mechanism would work better? Do you think that a hand held tool, such as ours,

would work best if it were made to be used with one hand, or two? Why? Can we make this product

ambidextrous? What is the best way to transfer the asparagus from the small basket on the grabber

to the main carrying basket? What is the best way to counterbalance the weight of the basket? One

idea we had was to implement a wheel on the other side. Most people responded that they liked

the bolt action but it seemed complicated. Many said to make the device more simplistic for the

user, only one hand should be used, and that the device probably could not be made ambidextrous.

Additionally, many of the respondents said that they liked our string idea for getting the asparagus

in the basket to the harvester. In terms of the question referring the weight counterbalance, a

popular idea that was given to us was to add a weight to the other side.

Finally, there were a few things that Dr. Puccinelli pointed out to us to be careful of. First,

she reminded us of safety and the potential need of a blade guard. She also cautioned us about

having the asparagus fall into the basket. She said we needed to ensure this fall will not damage

the asparagus. Finally, she emphasized to us how we do not want any bending over or twisting of

the body to be involved in order to reduce strain on the lower back. We wrote down all of the

advice and kept all of it in mind as we finalized our design.

Final Design: After the review session we decided to make several small changes to our design in order

to make it more user friendly and efficient. We changed the the blade from a single flat blade, to a

set of curved blades that come together similar to pruning shears. This allows the cuts to be more

precise and reduces the risk of the asparagus slipping out of the blades during the cut. We changed

the basket slightly to be more rounded so that the asparagus glide smoothly to the laying position,

rather than just falling which may have potentially damaged them. We also decided that just having

one handle position on the handle arm would not very well accommodate the full range of arm

lengths that the users will have. To fix this we played around with ideas of having a handle that

one could take out and put into multiple different positions. However, we eventually decided that

11

it would be both more comfortable and accommodating if the user just gripped the piping of the

arm directly instead of holding on to a perpendicular bar.

We also altered the design of the bar so that the user pulls to cut the asparagus. In our

design before the review session, it was just a simple bar that extended out perpendicular to the

drive shaft and parallel to the ground. After finding that it would actually be more comfortable to

hold a bar that is parallel to the drive shaft and perpendicular to the ground, we added another bar

to the end of the initial bar. This bar is attached at a 90 degree elbow, pointing upwards, to make

an “L” shape. In addition to this, we decided to add a hollow pipe that goes around this bar with

bearings in between. With this design, when one grips the piece of piping and pulls to cut the

asparagus, the pipe rotates around the bar as one pulls so that one doesn’t have to repeatedly twist

his/her wrist. This eliminated possible strain on the wrist from repetitive movements. A bill of

materials, fabrication instructions, and user instructions that illustrate the formation and use of the

design can be found in Appendices A, B, and C, respectively.

Figure 4: 3D Model of Final Design (self-created) - These pictures display various features of

our design in 3D.

12

Project Execution

Gantt Chart: For our large group we created a Gantt Chart to keep us on schedule for meeting deadlines

and completing tasks. The Gantt Chart shows our goals of what we planned to complete during

each lab period and the week following each lab. Each colored box indicates the goals for the

week. A checkmark in the box indicates what was completed. Additionally we created an

individual chart for organizing and completing our fabrication in a timely manner. Using these

two charts we were able to plan out the semester and complete the necessary tasks each week to

meet our deadlines.

Figure 5: Gantt Chart - The Gantt Chart shows the dates for each lab period and what tasks were

planned for that week (shaded, blue box). A checkbox indicates which tasks were completed each

week.

Lab Dates

Tasks 10/6 10/13 10/20 10/27 11/3 11/10 11/17 11/24 12/1

Preliminary sketches

Design review power point

Finalize design

Research materials

Decide on materials

Order materials

Final sketches/ models

Design testing

Fabrication

Write final report

Final product testing

Final presentation practice

13

Figure 6: Fabrication Chart - The Fabrication Chart more specifically breaks down the

fabrication process and the order in which the process was completed.

Part Materials

Needed

How will it be

fabricated?

Who Will

Fabricate it?

Order of

Completion

Main Outer

Shaft

1” Aluminum

Pipe

-Cut to length -Cut and grind slots into it

for pushing arms and clipping grip attachment

-Cut slots for blade

Trace and Brad 1

Main Inner

Shaft

0.5“

Aluminum

Rod

-Cut to length -Drill and tape hole in the end for blade attachment -Drill holes perpendicular

to the shaft for clipping

grip attachment

Brad, Josh,

Andrew

1

Main

Inner/Outer

Shaft

Main Shaft,

Inner Shaft,

75” bearing

(x2)

-Combine inner and outer shafts with bearings

Trace and Brad 1

Pusher Arm

(x2)

0.25 “

Threaded

Rod,

Rubberized

Shrink

Tubing

-Thread the inner rod and screw in pusher arm

Josh 2

Basket

Track

System

Bike Brake

Line, Cable

Housing,

Mounting

Channel,

Bolts

-Cut the slider track and base track to size

-Screw and thread holes into the slider track so the

basket may be attached -Screw and thread holes

into the base track so the

track system as a whole

Erik 2

14

may be screwed into the

main outer shaft

Shears

Integration

Fiskar Shears -Thread the rotating shaft and screw the blade into

the inner shaft -Using Loctite, attach the outer piping to the plastic of the blade so the rotating blade can freely move in correspondence with the

inner rod.

Brad, Andrew,

Trace, and Erik

1

Arm Shaft

Assembly

1.05 “ Aluminum Pipe, Metal

Clip, Velcro, Strap,

Adjustable Elbow Joint

-Cut to length -Drill multiple left hand

grip positons -Cut and size Velcro strap

-Attach clip to rod to attach Velcro strap

-Put on adjustable elbow

Brad 2

Clipping

Grip

0.25“ Threaded Rod

1.05 “ Aluminum

Pipe 0.5”

Aluminum Rod

0.75 Bearing (x2)

Grip Tape

-Cut 0.25 “ treaded rod to size

-Cut 0.5 “ rod -Cut 1.05” pipe -Drill and tap

perpendicular hole in 0.5 “ rod

-Bolt 0.5” rod to threaded rod

-assemble rotating grip form 1.05” pip, 0.5 “ rode,

and 2 bearings -wrap grip with tape

Brad, Andrew,

Trace, Josh, and

Erik

3

Left-Hand

Grip

25” Threaded rod

1.05 “ Aluminum

pipe Grip Tap

-cut 1.05 “ pipe to length -attach with 0.25 “ traded rod so it can be screwed

into the arm shaft -wrap grip with tape

Brad, Andrew,

Trace, Josh, and

Erik

3

Basket Polycarbonate

Sheet Lexan

-Cut polycarbonate to layout shape

-Fold using heat gun -Cement together with

Epoxy

Erik 4

15

Complete

System

Assembly

N/A -Screw clipping grip and pusher arms into main

shaft assembly -Attach basket to

track/cable system -Attach arm shaft elbow to

main shaft -Screw in left hand grip -Screw in pusher arms

-String the wire from the basket through the arm shaft so the basket may freely move up the track

system - Screw in the Track

system in line with the proper drilled holes

All Group Members Involved

4

Workload Allocation: Once our large group was formed, we assigned tasks. Each person was given a task that

aligned with their interests and talents. This chart displays each group member, their position title,

and the tasks associated with each position. Throughout the semester every group member did

his/her part to contribute and make our final product a success.

Figure 7: Task Chart - The task chart displays each person’s name, job title, and the tasks each

group member was responsible for completing.

Name Title Tasks

Trace Thorp Materials/ Fabrication Team - ordered and comparing products to order

- all fabrication that required a green pass

Alex Spicer Lead Editor/ Scheduling - planned - wrote parts of final report

- edited final report

Monica Samsin Writing/ Final Project Prep - took notes during all meetings/ reviews

- worked on final report

16

Robbie Lee 3D Virtual Model Maker - created 3D virtual models and incorporated them into

the final presentation - helped in final presentation

-worked on final report

Erik Kernozek Fabrication/ Design Team - finalized design and created ideas

- fabricated basket and various shaft components

Andrew Baldys Materials/ Fabrication Team - compared and ordered products

- supervised fabrication and recorded steps

Josh LeNoble Materials/ Fabrication Team/ Writing/ Final Presentation

- wrote out fabrication instructions

- made materials chart - added to final report

- final presentation - final product presenter

Will Smithsayer Writing/ Design Team - wrote in final report - assisted in the design

process

Phil Michaelson Writing/ Design Team/ Prototype Tester

- provided demos for testing - assisted in design process

- wrote in final report

Anna Tessling Manager - scheduled/ assigned task roles

- final report/ presentation prep/ testing

- final product presenter

Bradley Mergener 3D/2D design/ Fabrication/ Materials Team

- created dimensions for construction - fabricated

- ordered materials

17

Testing To ensure the reliability of the device, multiple tests were performed including: cutting

force of the shears, maximum capacity of the basket, harvesting efficiency, and quantitatively

testing for body strain. First, the shears needed to be able to cut materials of higher density than

asparagus. Next, we needed to determine the greatest number of asparagus based on size and

weight that the basket could hold. Additionally, the design had to prove more efficient in

harvesting than previous methods. Finally, the general level of strain placed on various parts of

the body, mainly the back and wrist, had to be evaluated to ensure our design was lowering the

level of stress placed on these body parts.

To begin, we tested the force of the shears. We did this by first determining the density of

an average asparagus. We measured the mass and volume of 10 asparagus. We used a balance to

obtain the asparagus weight. Then we estimated the volume of each asparagus by measuring the

height and radius and calculating the volume assuming an asparagus is approximately cylindrically

shaped. From there we averaged these values, converted units, and calculated the average density.

We found the average density to be 35.77g/L. We then looked up the value for the average density

of asparagus and found it to be 35.40 g/L.² Next, we did some research to determine common

materials that are more dense than asparagus and found that cardboard has a higher density (density

is 700g/L).3 Afterwards, we tested to see if the shears could cut cardboard and were successful.

Knowing that the shears can cut cardboard, it is safe to guarantee the ability of the shears to cut

the asparagus.

Figure 8: Testing Chart 1 ~ Density of Asparagus Calculations (self- created) - This table

outlines the data recorded and used to calculate the average density of an asparagus for testing the

strength of the shears.

Mass (g) Height (in) Radius (in) Volume (in3) πr2h

1 1.0 9.125 .25 1.79

2 0.6 8 .25 1.57

3 0.9 9.5 .25 1.86

18

4 0.8 9.25 .1875 1.02

5 0.8 9.625 .1875 1.06

6 0.9 9.625 .1875 1.06

7 0.6 9.125 .1875 1.01

8 1.2 10 .25 1.96

9 0.8 9.625 .1875 1.06

10 0.8 9.875 .25 1.94

Average: 0.84 1.433

Calculations and Equations: ● Density = mass (grams)/volume (liters)

● 1.433 in3*(2.54cm/ 1in)^3 * 1mL/1cm3 * 1L/1000mL = 35.77g/L (experimental)

*Note: We also cut multiple stalks of asparagus with our device to test its ability to cut asparagus.

The above test proves that the device is capable of cutting materials that are denser than asparagus.

This ensures that even the densest stalks of asparagus can be cut.

Figure 9: Testing Cardboard to Determine Strength of Sheers - This picture shows one of our

team members testing the cutting strength of the shears on cardboard to see if it could handle a

denser material than asparagus.

19

Next, we completed tests to determine the maximum capacity of the basket. Asparagus

were placed in the basket until the basket could not hold anymore. We determined the maximum

capacity of the basket to be 55 asparagus weighing 1.75 lbs. In this way we proved that the basket

will easily be able to hold approximately 20 asparagus which is the ideal number in terms of added

weight.

Figure 10: Testing the Capacity of Basket - This picture displays our basket holding the

maximum amount of asparagus possible.

In continuation, we tested the efficiency of harvesting using our device as compared to

previous methods. To determine the average harvesting rate using current methods, calculations

based on information given by the client in the initial meeting were performed. The average

number of asparagus per minute was determined to be 10-11 shoots per minute. We then obtained

a rough estimate of the harvesting rate using our device. Unfortunately there are not real asparagus

fields to test our design. For this reason we simulated harvesting using rows of pre-harvested

asparagus on a flattened, cardboard box. We timed how many stalks could be harvested in one

minute, then averaged the data from each trial to determine an average harvesting rate with our

device to show that it improves efficiency.

20

Figure 11: Mock-up of an asparagus field – This image shows how we tested our prototype

ability to harvest the crop.

Calculations for Current Harvest Rate: ● 250 lbs/day * 25 shoots/lb * 1 day/10 hours * 1 hr/60 min = 10.416 (approximately 10-11

shoots per minute)

Figure 12: Testing Chart 2 ~ Harvest Rate - This table shows the results of testing the efficiency

of our device.

Trial Number Harvested per Minute

1 15

2 19

3 17

Average: 17

Finally, we tested the biomechanics behind harvesting asparagus. A major concern for the

client was the great deal of stress traditional harvesting methods puts on the body, specifically the

back and knees. These problems come from improper technique in lifting, bending, and constant

repetition of a specific motion with excessive weight on the body. To test if our product decreases

21

the pain, two participants cut pre-harvested asparagus for five minutes with a weighted backpack

on. One used the device to cut, while the other did the traditional bending method. Then both

assessed where stress occurred on their bodies. Compared to the old method of harvesting by hand,

the device caused no back pain and very minimal arm strain for the user.

22

Design Limitations

Although our design meets all of the requirements laid out in our problem statement and

specifications, there are some limitations. If given more time and a larger budget, these are areas

of the design that we would expand and try to improve on. Our design limitations include: weight,

storage, maintenance, and cost.

Considering weight, which is a crucial aspect of design, the Asparagrabber will weigh

~6.75 lbs which is relatively heavy. Combined with the weight of the over-the shoulder-satchel

that the user will be wearing, he/she will be carrying ~30 lbs which is much heavier than the total

load would be ideally. The design does alleviate most of the stress the user encountered using

previous methods, but he/she still needs to carry a heavy load. If more time and money were

allocated the team would have reorder pipes of smaller diameter. The outer pipe would have been

decreased from 1.05” to .95” diameter and the inner shaft would have been a pipe instead of a rod

with a .5” diameter and the inside diameter of 0.3”. These changes would have decreased the entire

weight by 14.91 oz, which is close to an entire pound.

Maintenance is also an issue. Although our device will be very hardy, it will inevitably

encounter problems with repeated use. For example, if a piece breaks, it will be difficult to replace.

This is because some of the components are unique to our design and would need to be fabricated

again. Although we created an instructions manual and a replacement piece can be created based

on this, fabrication takes time and resources. For this reason, our device cannot be easily replicated

and/or repaired.

The third limitation of the design is storage. The basket can only hold (~15-20) asparagus

before it needs to be emptied. This will require it to need to be emptied quite frequently.

Consequently the asparagus will need to be stored in an alternate bin that our design does not

include.

Finally, cost was a major constraint. We were limited to a $200 budget. With this budget

we were able to accomplish our design goals. However, because of our monetary constraints, our

design needed cutbacks, and we were not able to purchase top quality materials. If we were

working with a bigger budget, we could have purchased and tested different materials before

actually using them in the design. Additionally, we could have improved the design cosmetically.

Lastly, the most important process we could have improved on with a larger budget is testing. With

more money we could test without fear of damaging materials we otherwise could not afford to

23

fix. Therefore we managed to stay within the $200, but if we had more money we could have

improved our design more.

Therefore, our design meets the key requirements we formulated from our meeting with

the client. However, the weight, maintenance, storage, and cost are limitations for our design. If

allowed more time and a larger budget, we would attempt to improve on these aspects.

24

Conclusion

In summary, our design needed to meet all of the requirements defined in our problem

statement and specifications. The main problems we needed to address were reducing bending

over and eliminating strain on individual parts of the body, allowing for the device to meet

harvesting needs, increasing efficiency, and staying within our budget. With these goals in mind

we formulated, revised, and finalized our design and then fabricated, tested, and finished our final

product.

Our product is designed around minimizing strain on individual body parts, mainly back

pain stemming from excessive time spent bent over in the fields with current harvesting methods.

Our product cuts the asparagus with the operator in the standing position. Additionally, the basket

at the base of our product that collects the asparagus can be elevated to the harvester for collection

and storage in a carrying device without any bending involved. Our device also has a wrist strap

to help maintain good form and reduce possible strain on the wrist from operation. With all of

these design features, strain on the body during the harvesting process should be minimal.

Next, the Asparagrabber meets all the conditions to be used by our clients Richard Barker

and Steve Shoemaker at their Dancing Oak farm. Because the device is a portable, hand-held

device, it can easily be maneuvered in between rows and around the ends. It allows for the operator

to select which asparagus to harvest each day. Our rounded basket design also allows for the

asparagus to roll gently after being cut reducing the risk of damaging the floret. In addition, our

design is mostly formed from aluminum which is very weather resistant and does not rust. Finally,

our device is adjustable. It is ambidextrous and the height of the device can easily be altered to

meet the needs of the user. These features are important as one of our clients is very tall and left

handed. This way our device can be used by him and anyone else. For these reasons it can be seen

that our design can easily be used at the Dancing Oak farm.

Additionally, our device increases efficiency by speeding up the rate of the harvesting

process compared to previous methods. As illustrated in our testing, it allows a worker to harvest

15-20 stalks at a time before needing to unload and place the asparagus in a carrying cart. For this

reason, the efficiency is improved.

Lastly, we stayed within our $200 budget throughout the course of the semester. Our group

meticulously worked to find low price items. During the brainstorming and design process we also

put much thought into what was absolutely necessary in the design and cut out non-crucial parts.

25

With the cutbacks and careful watching of item prices, we were able to fabricate, from scratch, a

device that meets all of our design requirements while spending no more than $200.

In conclusion, our design eliminates bending over and the pain associated with that motion.

It provides a solution for the possible new strain created by using our device through the use of a

wrist support. Furthermore, our clients will have no problem using this at their asparagus farm as

it meets all of the specifications for their specific field and harvesting operations. Finally, our

device increases the harvesting rate thus reducing the number of hours a harvester has to spend in

the field each day. We did all of this while staying with our $200 budget with the final cost being

$170.26.

26

Work Cited

1. "Asparagus Lover." Growing Asparagus - Everything You Need to Know. 1 Jan. 2011.

Web. 1 Sept. 2014. <http://www.asparagus-lover.com/growing-asparagus.html>.

2. "Food & Non-food Substances." Common Substances, Materials, Foods and Gravels.

Web. 10 Nov. 2014.

3. "Food & Non-food Substances." Common Substances, Materials, Foods and Gravels.

Conversions and Calculations: Aqua- Calc, 2014. Web. 03 Nov. 2014.

4. "Solids Densities or Weights." Densities of Miscellaneous Solids. The Engineering

ToolBox, n.d. Web. 16 Nov. 2014.

<http://www.engineeringtoolbox.com/density-solids-d_1265.html>.

5. Benny, Tony. "Lying down on the Job." NZFarmer.co.nz. Stuff.co.nz, 2014. Web. 01 Dec.

2014. <http://www.stuff.co.nz/business/farming/cropping/9325099/Farms-pickers-get-to-

lie-down-on-the-job>.

6. "Vegetable Harvesting." VHS. Web Design Lincolnshire, 2007. Web. 01 Dec. 2014.

<http://www.vhsharvesting.co.uk/>.

7. "Several Types of Machines For Harvesting Asparagus." Mechanical Asparagus

Harvesters. Geiger-Lund Harvesters, 2013. Web. 01 Dec. 2014.

<http://www.asparagusharvester.com/Asparagus-pickers.htm>.

27

Appendix

A. Materials:

Item/description Dimensions Quantity Price Location

Aluminum 6061-T6 Pipe Schedule 40 for Outer Piping

Outer Diameter: 1.05" Inner Diameter: .742"

Length: 72"

1 $26.32 Amazon

6061 Aluminum Round Rod, Unpolished (Mill) Finish, T6

Temper, ASTM

Diameter: 1/2" Length: 72"

1 $30.48 Amazon

Needle Roller Bearing Inner Diameter: 1/2" Outer Diameter: 3/4"

4 $28.64 Amazon

Fiskars Professional Bypass Pruning Shears

N/A 1 $18.75 Amazon

XLC Brake Cable 1650 mm 1 $3.59 Amazon

Polycarbonate Clear Plastic Sheet - Lexan

12" x 24" x 0.125" 1 $10.74 Amazon

Aluminum Miter T-Track with Miter T-Bar

Length: 32" 1 $31.98 Amazon

Futuro Sport Tennis Elbow Support

N/A 1 $11.07 Amazon

Franklin Sports Bat Tape Length: 30’ 1 $8.69 Amazon

Total: $170.26

B. Fabrication Instructions: 1. Cutting the inner rod and outer piping for the primary shaft

● Using a drop-saw, first cut the outer piping at 42” and leave the remaining metals

for the handle

● Repeat the same step for the inner rod, leaving the remaining metal for the handle

as well

28

2. Drilling the hole in the bottom of the inner rod

● Using a complicated clamping system as shown in figure 12, attach the inner rod to

the drill press machine, enabling the 42” inner rod to hang over the side of the

machine’s platform.

Figure 13: Clamp System for Drilling into the Inner Rod – This picture displays how to set up

the clamp for drilling.

● After determining the necessary thread of the hole, create a marking at center of the

bottom of the inner rod using a center punch.

● Using the correct drill bit, drill a hole of a diameter of 0.5 inches into the bottom of

the inner rod at the marking made by the center punch

● Using the tap corresponding with the thread, use the tap handle to tap the hole in

the bottom of the inner rod with a series of twists

3. Cutting the handles of the shear

● Using the steal-enabled band saw, make two cuts for each handle

● Ensure the cuts are made so that the spring remain intact with the blades as

shown in figure 14

● Discard the handles

29

Figure 14: Cuts made to the Shears – This figure displays how the shears must be cut.

● After making primary cuts to the shear, round off the cut edges using the disc sander

4. Machining the joint piece.

• Acquire scrap aluminum big enough for the joint

o Dimensions of the joint piece are as follows in figure 15

Figure 15: Joint Dimensions - This image outlines the dimensions of the joint needed to hold

the two pipes together.

• Use a band saw to cut out basic shape of the joint piece. See Figure 16

30

Figure 16: Joint Piece Shape - This is the basic shape of the joint. We used a band saw for the

cuts.

• Afterwards, several holes need to be milled: one through the middle, one through

the bottom, and one through the peninsula piece. The dimensions of the holes

should be one inch in diameter and the other two should be 0.25 inches in diameter,

respectively.

Figure 17: Joint Holes - This shows where the holes need to be made in the joint.

o After the holes have been milled, the bottom hole needs to be tapped with

¼”-20 tap bit.

• This process needs to be repeated to create a second identical joint piece.

31

o These two joint pieces will be connected with a screw through the top at the

peninsula. Use a wing nut to secure the screw.

• The finished rotating joint. See Figure 18.

Figure 18: Finished Joint Piece - This is what the finished product should look like. They are

connected at the top with a screw and a wing nut.

5. Lathing the Outer Piping and Handle

• Using the right handed cutting tool, touch off on the outer shaft and find your edges

• Apply cutting fluid to the outer shaft

• Begin turning down the outer shaft, 0.310” for a length of 6”

o When turning down do not take off more than 0.030” on each pass

o This will allow for the joint piece to fit over the outer shaft and handle

• Repeat the above steps when lathing the handle, however, only take off 0.310” at a length

of 3” this time

6. Fabricating the Basket

● The dimensions of the basket were laid out on the .125” polycarbonate plastic sheet

32

Figure 19: Basket layout - This is a picture of the basket layout before it was cut on a flat sheet

of cardboard. Later the dimensions and sketch would be transferred to the polycarbonate

● Using a band saw and a belt sander the polycarbonate sheet was refined to its exact shape.

● Then the polycarbonate basket cut out was folded into its three dimensional shape using a

heat gun to soften the plastic to mold it using a little bit of force and a vice.

● Finally, the edges were de-burred and acrylic cement was used to join the touching edges.

7. Fabricating the Rail System

• The Outer Rail

o The Outer Rail is bought at 32”.

o Then drill #7 hole at 0.44”, 1.00”, 16.00”, 27.00”, and 31.00” through.

o Once drilled, countersink holes 1.00”, 16.00”, and 31.00” to the depth of the screw

head on the top side of the outer rail. Top in reference to the orientation of Figure

21.

o Countersink the other holes to the depth of the screw head on the bottom side of the

outer rail. Bottom in reference to the orientation of Figure 21.

• The Inner Rail

o Cut the Inner Rail to 6.00” in length

o Then drill #7 holes at .70” and 4.00” through.

o 1/4-20 tap both holes.

33

Figure 20: Drilling the holes in the Inner Rail -The picture shows the inner rail holes being

drilled. The orientation up refers to the C shape of the rail with the opening up.

8. Machining the slots on the Outer Piping

• Clamped and zeroed the Outer Shaft on a mill.

o Drill #7 holes at 1.25”, 16.25”, and 31.25” through to next surface.

o ¼”-20 tap all holes.

• Rotate the Outer Shaft 120 degrees clockwise.

o Drill #7 holes at .75” and 1.25” through to next surface.

o ¼” -20 tap both holes.

• Rotate the Outer Shaft 135 degrees counter-clockwise

o Drill one .266” slot at 33.00” to a depth of .225

• Rotate the Outer Shaft 60 degrees counter-clockwise

o Drill two .266” slots at 1.25” and 6.00” to a depth of .225

9. Clipping handle Fabrication

• Cut the outer piping to $$$ inches, and the inner rod to $$$ inches.

• Using the same clamp set up from Section B2, drill a $$$$ hole in the end of the inner rod.

• Mark a perpendicular hole in the inner rod ⅛ in down from the end of the outer rod when

the inner is inside of the outer using a ¼ in transfer punch.

• Drill and tap the hole for ¼”-20 thread.

10. Fabricating the Holding Arm

• The Outer shaft pipe is used for the holding arm, cut to a length of 14”

34

• ¾” from the top of the holding arm pipe, a ¼” 20 holes were drilled and taped through one

side of the pipe.

• On the other end of the pipe where it was lathed down to fit the joint piece 5 larger sized

holes to fit the 5 inch bolt used for the handle must be drilled through both sides of the pipe

so that the handle can be threaded into any of the 5 holes each 1 inch farther up the pipe

from the end that goes in the joint.

11. Assembly of Final product.

• Epoxy the shears into the inner rod

o Align the shears to the orientation of the pusher arm at the back side of the

sharpened blade.

o For added support use the existing hole and an “L” joint to make it secure shown

in figure 22.

• Slide a bearing down the length of the inner shaft.

• Insert the inner shaft in the bottom of the outer shaft.

• Insert a bearing at the top of the outer pipe.

• Screw on the side outer rail with the inner rail assembled with it with a quantity of 5 1/4-

20 x .25 Phillips Flat Countersunk Head Machine Screws.

• Screw in the Pusher arms (1/4-20 threads).

• Screw in the Handle extension with the handle attached.

o Use thread lock to ensure zero rotation about the handle extensions axis.

• Assemble joint.

o Thread a screw through the hole on the tab of both joint pieces. And thread a wing

nut on the end of the screw.

• Slide the one of the 1” hole in the joint down the outer shaft, and the Holding arm in the

other as pictured in Figure 23.

• Attach the handle wrapped in bat tape into one of the holes of the Holding arm

• Attach the brake wire to the inner rail and run it up to the handle.

• Screw 1/4-20 x .75 Phillips Round Head Machine Screws in the top hole of the basket and

1/4-20 x 1.00 Phillips Round Head Machine Screws using lock nuts to space the basket

accordingly of the shears so that there is no interference.

35

Figure 21: Solidworks Model of Bottom - The image is of the bottom of the product with the

shears being absent. Showing the use of the “L” joints to secure the Shears.

Figure 22: Solidworks Model of Top - The CAD drawing of the top shows the proper

orientation of the Handle, the Holding Arm, and the joint.

36

C. How to use the Asparagrabber:

1) Hold the Asparagrabber with left hand on non-moving handle and strap it in place on upper left forearm.

2) Place asparagus between cutters at the base of the Asparagrabber and pull the clipping

handle with right hand so that the asparagus is cut and pushed into the basket. Repeat this

process until the basket is full.

3) When the basket is full (~15-20 asparagus), raise it to waist level by pulling on the cable

attached to the non-moving handle and sliding the basket up the track.

4) Hold the cable against the outer pole with left thumb and use the opposite hand to remove

the asparagus from the basket to place them into a secondary storage unit (i.e. over the

shoulder basket).

5) Repeat steps 1-4 moving down each row.

*Opposite hand positioning may be used depending on preference.

37

Parts Guide 1. Inner Rail

38

2. Inner Shaft

39

3. Lever Handle Inside

40

4. Lever Handle Outside:

41

5. Outer Rail

42

6. Outer Shaft

43