NASA HUNCH  Program

Schrodinger's Roll Dispenser (SRD)

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Design Process

Problem Statement: The International Space Station wants to switch from packets of tissue paper to rolls of toilet paper so that smaller squares would be used and the amount of trash would decrease. This has led to a need for a toilet paper dispenser made specifically for space. As a result, we are designing an ISS capable toilet paper dispenser that is one handed, keeps the toilet paper roll from unraveling, prevents the toilet paper from being a fire hazard, and is easy to use. 
Research: At the start of the project we researched handheld toilet paper dispensers that work on Earth. All of the ones on earth are made for toilet paper rolls that have cores while the rolls NASA will use are coreless (without the cardboard tube). This created the need for a core that is inserted into the toilet paper and will move with the roll as it is dispensed.
Another issue faced is the use of the dispenser in the micro-gravity environment. The micro-gravity environment is simply a lack of a strong gravitational pull—there is still gravity, only very small amounts. With this in mind we came up with the idea of using springs that put compression on the toilet paper to keep the roll from unraveling within the dispenser.
  

Criteria

  • Has to handle rolls without a core    
  • Has to be compatible with Georgia-Pacific 2-Ply White Coreless Bath Tissue (4” wide x 6” diameter)
  • Easy to replace new rolls
  • Simple  

Constraints

  • Must attach to seat track     
  • Must be one handed use
  • Must cover the paper roll to protect against fire hazard or water droplets
  • Must prevent the roll from spinning freely and unrolling

Initial Prototype: The initial prototype was made using a CD holder as an inspiration. From there, SolidWorks was used for the design work for the next 3D Printed Prototype. Due to the size of the SRD, a quarter scale prototype was printed initially, and then a half scale prototype was printed. This initial prototype was displayed at two design reviews, one at Warren Tech which was primarily just local schools, and then at Wings Over the Rockies, which was a statewide design review. The following critiques were recorded from the design review.

Pros

  • It was a simple design and wasn’t too technical or had too many parts      
  • The twisting mechanism worked good
  • It glowed in the dark, thus making it easy to find during the night
  • We addressed and understood the requirements from NASA

Cons

  • Make sure that the moving parts can withstand years of wear and tear
  • Make sure to design the center post so that it doesn’t break
  • Make a place for the seat track attachment
  • Make sure that the toilet paper tears easily and is held in tension so that it doesn’t unravel while not in use

 

Prototype 2.0: 
A specialized focus was placed on multiple aspects of the design to prepare for the final design review at the Johnson Space Center in Houston. This focus included a main component to cover connection unit, lefty use, clips, possibly machining the core piece, a toilet paper pusher, designing a way to keep toilet paper from unraveling, and creating a connection to allow the SRD to attach to the seat track.

SRD MAIN PART:

-Added channel for seat track attachment block
-Holes for core insert and seat track attachments, so bolt will be inside design
-Sliding channel all the way around 

COVER:

-Handle connects to cover
-Extruded inside circle to receive other end of core insert 

CORE INSERT:
-Final product to be made out of strong material, possibly machined out of metal
-Tapers inward to fit toilet paper roll, and create some friction
-Strengthened by going through main part and seat attachment block 
HANDLE:
-Connects to cover, allows twisting on main part
-Smaller so Astronauts don’t use it to put all their weight on it
ATTACHMENT BLOCK:
-Seat track attachments connect to outer holes
-Core insert goes through middle hole 
TENSIONER:
-Core insert goes through middle hole
-Attached to cover with spring, acts as a brake on toilet paper roll to keep it from unraveling
CLIP:
-Stops Cover from turning too far and coming off
-Will be tethered to main part  
FOOT:
-Keeps SRD from moving on seat track 

 

All Pictures Taken by Austin Zuehlke Unless Otherwise Mentioned

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