#1246 Programmable Mobile Controller Student workbook
FinalDesignReport
1. Peanut Butter Jar Opener
Final Design Report
Conor, Mike, Giuseppe, Abdulla
ABSTRACT
Tasked with designing a machine that could open a jar of peanut butter for an
armless individual, our group worked cohesively to create and stick to a strict
schedule, budget out materials and actually constructa working prototypein
order to ensureanybody can open up a jar.
3. 3
Table of Contents
I - Introduction 4
II – Background 4
III - DetailedDesign Description 5
IV – Design DecisionMatrix 6
V - Design Implementation 7
VI - Budget And Materials Table 8
VII - Testing Procedures and Performance 9
VIII - Conclusion 9
IX - References 10
X - Appendices 10
4. 4
I - Introduction (Abdulla)
For all of those handicapped individuals and especially veterans of war, the need for a
machine to accomplish the simple task of opening a jar has become a necessity. Regaining the
ones own independence once they have lost the use of their arms and hands becomes
increasingly difficult. However, with the advent of new and cheaper technologies this
independence can once again be returned to handicapped individuals. With this goal and mission
in the hearts of the project team, a peanut-butter jar opener is designed. The goal of the jar-
opening machine is to accomplish the task of opening a jar, such as a peanut-butter jar, with
minimal human input with the push of a button. Our design needed to be operable by an
individual without arms, cost less than $100, easy to use, and be able to marketable to the public
on a massive scale. This document will present the background information about the project, a
detailed description of the design, the implementation of the design, a conclusion of the
functionality of the design, works cited, and an appendix.
II – Background (Giuseppe)
The Black & Decker Lids Off Jar Opener Jw275, it is sold for $75. It is made with high
quality materials. This product has a 5 star rating on Amazon. After we came up with our design,
we found several products that accomplished the same task. This product’s aesthetics and ease of
use was deeply important to its design. The jar opener operates by using an adjustable lid
grabber. It operates by using motors to have the top of the opener to lock until the top of the jar.
After the jar tightens to the size of the jar, the motors then rotate it so it can open the jar. These
features of this device is reflected a similarity between our own ideas. Showing that the
marketplace already has a competing market for jar openers and each one operates on the same
principle. Also it shows that the companies that make this product all use the similar design
ideas. However, each one of these products was very expensive for a person to spend a large sum
of money on it. By making a cheaper product, one can deeply increase the availability of this
product to those that need it. These types of products are made for people with bad arthritis or
are disabled fitting the goal of our project.
5. 5
III - Detailed Design Description (Mike)
Our final design (see Appendix 1 for Engineering Drawing of final design) is a C-shaped
rigging that has a hinged arm at the top to allow for removal of the lid of the jar. On the bottom
arm there is a fixed plastic disc with rubber bumpers along the inside that acts as a mount for the
peanut butter jar. A ¼” dowel runs through the top, hinged arm. At the bottom of the dowel is a
plate identical to the one attached to the bottom arm. The two come together at the perfect
distance to fit a jar and, once closed, the rubber grips create enough friction to allow the plates,
when spun, to spin the lid of the jar. Since the bottom plate is fixed, it remains motionless and is
only used to prevent the bottom part of the jar from rotating with the lid. At the top of the dowel,
a gear holds it in place. Two motors, one 24-volt and one 12-volt, spin simultaneously, as
opposed to only one. This is to increase the torque. The motors are connected to two 9-volt
batteries each, and both circuits have switches to turn the machine on and off. As the motors spin
the dowel, the plate at the bottom of the dowel (the one connected to the top of the jar) rotates as
well. Once the lid is spun off the threads of the jar and free, the hinged arm is lifted up, thus
removing the lid entirely and leaving an opened jar of peanut butter at the users disposal.
Our design meets the necessary requirements. It is functional, meaning that when the
switches are flipped, the motors spin the dowel and the plate rotates. However, we do need to
attach a stronger, more powerful motor that will give a higher torque output to fully unscrew the
lid. Besides that minor flaw, once the lid is unscrewed it is still easily removed and the jar is left
open. The design requires minimal human interaction: placing the jar down, lowering the hinged
arm, flipping the switches (on and then off), and then raising the arm. No intense or physically
demanding efforts of any means are necessary in order to complete the task. The machine does
all of the real work, as it should. Our product also only cost us around $30, which is over twice
as cheap as related products we found. We did not paint our design or add any unnecessary
detailing. The creativeness and intricacies of the design lend to its aesthetics. We were proud of
our product and felt no need hide anything. However, while nothing need be hidden, our design
does fit in a locker or cabinet, so storage is simple. It can even be left out on the counter and take
up as much, or possibly less, space as the average coffee machine. Our design is safe, unique and
requires minimal human interaction. It is the perfect solution to the problem.
6. 6
One trade-off we had to make was ditching our original claw idea. This idea was to have
four retractable arms on the plates that would converge and tighten on the lid and jar. This design
proved to be a little ambitious as far as material and time were concerned, so we sacrificed
intricate for a little simpler and more functional. Another trade-off included sacrificing our dual
rotating approach, where both the top and bottom plates would spin independent of each other.
Again, this involved too many moving parts and just meant that more could go wrong with the
design.
Ending up with the final design was through a series of trial and error testing. The initial
“final” design seemed to be the most promising of our three concepts. Though the most
ambitious, it seemed to provide the most torque and, therefore, would be the best design. We also
felt it would be the most impressive of the three. The three concepts were all pretty similar, so it
just came down to torque and function. As far as decisions made during the design and build
process, refer to the previous paragraph on trade-offs we needed to make. A decision matrix of
our three concepts can be seen below.
IV – Design Decision Matrix
Design1 Design2 Design3
Criteria Weights
(%)
Rating
Factor
Rating
Factor*
Weights
Rating
Factor
Rating
Factor*
Weights
rating
factor
rating
factor*
weights
Size 20 6 120 7 140 7 140
Cost 15 8 120 6 90 6 90
Safety 25 6 150 8 200 5 125
Aesthetics 15 8 120 5 75 5 75
Ease of
use
25 3 75 9 225 7 175
Total 100 585 730 605
7. 7
V - Design Implementation
Left – the closed rig perfectly fits to
the average sized peanut butter jar;
rubber fingers used for grip
Right – demonstrating the hinged
arm that allows easy removal and
replacement of lid without the
need for hands
9. 9
VII - Testing Procedures and Performance (Conor)
When we tested our design, our two main concerns were friction and torque. Our design
was changed in a matter of time for testing. For the first step we set both motors to their highest
potential, this testing was done without the Jar at first, to observe the rotations of the gears. We
were happy with how the gears spun quickly due to the power from the motors. Our second
testing was with the Jar placed in the lower and upper dish for final testing. When we flipped the
switch on, the motors could only move a couple of the teeth in the gears and the jar lid wouldn’t
rotate enough to come off. Overall, we think that if we had a bigger and more powerful motor,
the higher torque of the motor would actually make the gears rotate to open the jar lid.
VIII - Conclusion
When it was all said and done, our project turned out pretty well. We built a prototype
that had a wooden frame and two motors on it with the purposes of opening a jar for an armless
man, using the materials we were provided. The final outcome was a prototype that fell just short
of working properly, and needed just a little more torque from the motors to fully open the given
jar. If an actual product were to be built based on our model, it would need to be built with
lighter, less expensive materials. The wooden frame would be changed into a plastic or polymer
frame, and the motors of our prototype would have to be upgraded. If we had been given more
time to complete our project, the first thing we would do is get a stronger motor for our design.
The only major flaw with our prototype was that it lacked the torque to open the jar, and a
stronger motor would solve this problem and make it ready for production. Overall, however,
this was a great experience and we learned a lot as a group. One thing we learned was that
putting together a theoretical design is not easy, and it takes time and a lot of proper planning to
get a project done on time. We learned how important it is to fully plan out a project as a team.
We also learned to think on our feet, for we had to change our design rather suddenly before the
end of the project. Overall, this experience has given us insight as to how a team engineering
project should be conducted if the team members want to experience a successful endeavor.
