The team's goal was to create a 3D printed turtle with fins that rotate using a single motor. They designed multiple prototypes, starting with gears that had issues. Their final design used a closed timing belt system to connect the motor to a dowel rotating the fins. Challenges included waterproofing, unstable bodies, and motor mounts. Lessons learned included being open to new ideas, having backup systems, and how weight and placement impact function. The final prototype was able to swim across the tub using one motor to power the rotating fins.

2. The Shell Shwimmer
IDEAS 170
Gone Fishin’
Amara Leazer, Annabelle Miller, Elana
Abrams, Ford McDill
Sheldon Donashello

3. Team Design Goal
Our team design goal is to
make a turtle that includes a
3D printed fin feature with a
rotational mechanism that
utilizes a singular motor.

4. Design Process
- Began with the large sheet: Fish with legs,
seahorse, duck, etc were all the first ideas
- Boat like creature with fins = sea turtle
- Ordered a small turtle and took it apart to
see how it worked
- Body displace enough water to float and be
balanced
- Fins moving in same or opposite direction
- To gear or not to gear? Deciding gear motor
system or a closed belt timing system
- Water proofing

5. Challenges and Solutions
- Torque issues, worsened by the weight of the water against the fins
- Gears were unstable and imprecise in the body
- 1st body unstable in water
Waterproofing efforts
- Drilled holes and o rings
- Enclosing the turtle with a top cover
- Encased the battery pack in balloons
Motor Issues
- The motor mount inside broke, so we drilled two screws in opposite directions
to fix the motor moving.
- The motor mount connecting to the metal dowel was the largest problem.
- Fixed by placing tape over the exposed motor and super gluing the dowel into
the motor connection piece.

6. Materials and Equipment Used
- Plexiglass
- Acrylic
- Super
Glue
- TPU
- *Foam
- Balloons
- Metal
dowels
- Nuts and
bolts
- O Rings
- Petroleum
Jelly
- Timing Belt
System/ Belt
and Sprocket
System
- Epoxy
- Superglue
- Battery pack
- Motor
- Screws
- Foam Forming
- Vacuum Sealing
- 3D Printing
- Scroll saw
- Vacuum sealer
- 3D Printer
- Laser Cutter
- Conduit cutter

7. Decision Making & Project Management
Differing opinions
- Disagreements or Multiple Ideas: try
them all, see what works and what
doesn’t
- based on time, efficiency, probability of it
working, it actually working (testing), etc.
- Chaotic, but at least we have Fun.
Together.
(Amara Waterproofing Batteries)

8. Individual Project Contributions of Each Team Member
Amara - Fins/3D printed, helped build the body, obtained and assembles
motor closed belt system, always provided alternative ideas
Annabelle - built the body, helped design fins, and assembled motor,
and organized the chaos
Elana - Designed motor mount/3D Printed, assembled motor, and kept
up morale
Ford - Designed gears, gear mounts, assembled motor, healthy dose of
practical cynicism

9. 1st Prototype
Our original design would've required an open top, leaving it exposed to water.
Further, we were having a lot of torque issues, that would’ve only been worsened
by the weight of the water against the fins.
This design was also a bit unstable, which is why we decided to scrap it.
The first build: 3 gear system held
by a housing unit.
- The motor connected to a
dowel that ran through a
gear which turned the other
gears, eventually turning the
rod that the fins were
attached to.

10. 1st Motor Mechanism
- Two gear system
- Motor connected to a larger gear which
spun a smaller gear attached to the fins
Problems though:
- Motor was not bolted in and moved too much
- The MDF gears had too much friction and
would rarely spin
- Since the platform the big gear was on could
move, the distance between the two gears
would change which would stop the system
from turning :(
- Eventually, we decided to scrap this idea
and use a gear and sprocket system

11. 1st Body
- 3 layers of foam shaved down in a
dome-like shape
- Problems with balance
- Vacuumed sealed for water
proofing
- Foam was left in and cut out for
specific parts unnecessarily

12. Fins
- Designed with the
spline tool
- Used flex to create the
128 degree bend
- Moderate infill to be
strong enough to
move water while still
being light
2nd Prototype: too
big/curved
1st Prototype: too
heavy/not curved
enough
3rd Prototype: curve, infill, size
adjust properly

14. Mount
- Hear ye, Hear ye, this is a slide
about the mount!
- We decided to print this on acrylic
so we could attach it to the body
- Also, we chose to drill holes after
we printed it so we could make
them exact
- It has worked excellently! (so far)

15. Limitations and Future Improvements
- Gears got stuck, were unbalance due to the gear mount, and did not
provide enough torque
- The dowel attached to the fins did not move each time
- Fins were too loose and didn’t rotate
- Body was uneven in water
- MDF wasn’t strong enough
- The motor mount wasn’t rotating with both the motor and metal
dowel
- The foam didn’t allow room for the motor or the battery pack
- Focus on aesthetics in the future

20. 2nd Motor Mechanism
- Closed timing belt system
- Attached to the dowel and motor
using a 3D printed part
- Issues with the motor and dowel
moving together
- Super glued the together to solve
the issue
- Motor turns moving the large gear
attached to a belt. The belt moves
the smaller gear fixed on the
dowel that holds the fins.
- Fins move in same
direction/circular motion
- Motor was held in with resin

21. Motor Adapter

23. 2nd Body
- 3 layers of foam carved out
- Bottom two are equal 8”x 6”x 4”
- Top layer is larger by an inch
- More stable in the water
- Removing the foam didn’t do
much weight wise b/c of the
volume of water displaced by the
body
Waterproofing
- Instead of being housed on the top of the turtle, we drilled
holes and o rings and lowered the motor
- Enclosed the turtle with a plastic wrap/battery pack in
balloons

24. And Finally… the Head
The finishing touch to add to the biological
inspired design

25. Results of Product
(did you accomplish your goal?)
- The swimmer swims
- It takes about three strokes
to get across the tub
- It biologically looks like a
turtle
- It only requires one motor
to move
- And it moves fast!
(Ford celebrating with a whipped cream shot)

26. Injuries
MVP

27. Elana Leaves Class For the
First Time on Time on a
Tuesday… before disaster
struck and the whole motor
system broke

28. Insights Gained From the Project
- Be open to alternative design ideas: there is always more than one
way to do something
- It is beneficial to work on multiple systems/mechanisms at once
since they will not all work
- Even if parts of a system are functional that does not mean they will
work together
- Weight and placement matters always!
- Use new tools and became better at Solidworks
- Group projects are fun and effective - we all learned from each other