The Full Belly Project (FBP), has designed a Universal Nut Sheller (UNS) for distribution throughout West Africa and Haiti. The UNS shells large amounts of nuts in a fraction of the time that it would take a single person.
- Create a smaller version of the UNS to be marketed in the US in order to fund FBP's efforts abroad.
- Find a way to make a UNS out of cheaper, lighter and more sustainable materials for the countries of West Africa.
- Find a way to make molds out of recycled plastic bags for the working parts of the UNS using extremely limited resources in Haiti.
Our team worked on the first of these assignments by redesigning the UNS to be marketable in the United States.
The Full Belly Project asked our team, Shell Shock, to re-design their Universal Nut Sheller (UNS) to be smaller, more portable, and more aesthetically pleasing so that they could have a product marketable within the United States. To accomplish this, we implemented the five phases of the design process. The five phases of the design process are:
- Project Formulation
- Problem Analysis and Literature Review
- Search for Alternative Solutions
- Decision Process
- Specification of Final Solution
Nutsy is the result of this design process. Nutsy is smaller and lighter than the original UNS and has an aesthetically pleasing (i.e. extremely cute) acorn shape. Nutsy is safe and easy to use, and simple to disassemble and clean. We produced a prototype of Nutsy out of plywood and were able to shell a few nuts, however, further refinement is needed to make a fully functioning model.
Keywords: Full Belly Project, Nut, Shell, Universal Nut Sheller
 Problem Analysis and Criteria
Our objective for this project was to design a nut sheller that is marketable in the US to fund and promote the Full Belly Project.
To best meet this objective, we rated our alternative designs on the following criteria:
- The design should have an attractive outer appearance and be appealing to the US market.
- Safety of Use
- The design should be safe for the user to operate.
- The design should withstand five to ten years of regular use.
- Level of Embodied Energy
- The design should contain the lowest level of embodied energy possible. Using recycled and recyclable materials as well as minimizing the energy necessary for manufacture, transport and use will reduce embodied energy.
- Ease of Use/reuse
- The design should be easy to assemble, disassemble, reassemble and clean.
- The design cost should be as low as possible. The final cost is composed of the material and manufacturing costs and should be less than $75 on the US market.
- The design should be able to shell a range of nut sizes ranging from walnuts to pine nuts.
- The design should be able to be transported by one person.
 Final Design Description
The final design solution, Nutsy: The Acorn-Shaped Nut Sheller Funding and Promoting the Full Belly Project, is modeled after the shape of an acorn. Externally Nutsy has a textured top, which mimics that of an acorn, with an upside-down cone-shaped midsection and a hemispherical base. Internally the sheller mimics the design of the UNS, but it is rotated 180 degrees to fit within the external acorn shape. Autocad software was used to create drawings of a workable model shown in Figure 1.
The lid, mid-section and base of Nutsy lock together using a twisting mechanism similar to a food processor. Nutsy's handle is easily detachable using a square drive with a small ball and spring mechanism similar to a rachet and socket. The base includes a small viewing window made of clear plastic. This window allows the user to see the shelled nuts and to view when the sheller is full. The lid includes a small, hinged door that allows nuts to be added without removing the handle and lid.
Internally, this design is an inverted version of the UNS model. Maintaining the cone-within-a-cone design of the UNS allows for versatility in the sizes of nuts that can be shelled. To ensure that the design would still function properly, the internal angles of the original UNS are reversed so that the rotor is is angled at 82˚ from the horizontal and the stator is angled at 66˚ from the horizontal.
To accommodate the necessary adjustment of the height of the rotor, the rotor can freely move along the aluminum shaft. The adjustable rotor is then held in place with a metal ring and thumb screw. The shaft has a line of divots incrementally spaced into which the screw can be tightened. This mechanism is shown in more detail below. The combination of these mechanisms allow the user to adjust the grinding space to accommodate different sized and shaped nuts by sliding the internal cone up and down the shaft of the rotor. The adjustable rotor is pictured in Figure 2.
 Prototype Performance
Though the material recommended for the final design is recycled plastic, in the interest of time and feasibility, the working prototype was constructed out of plywood, an aluminum shaft, and some scraps of metal. Our prototype is pictured in Figures 3 and 4.
The prototype fully meets the design criteria in terms of ease of use/reuse. The handle turns smoothly and leaves enough space for the user to place a hand on the sheller for stability. Nutsy can be quickly opened by removing the handle from the square drive of the shaft and lifting the lid. Shelled nuts are readily accessed by removing the entire body from the base. The sheller can be quickly disassembled for cleaning or repair into six pieces: the handle, top, midsection, rotor, shaft and base. The prototype lacks the locking mechanisms described for the lid, body, and base. This has not been an issue since the wood components generate enough friction that they do not slip when the sheller is being used. The metering plate, viewing window and hinged door were also not included in the prototype.
Nutsy meets most of the other design criteria as well. The prototype is fully portable. The prototype is lightweight and small enough to easily be carried by one person. Using a thumb screw, the rotor can be moved up or down the shaft to shell a wide range of nut sizes, making Nutsy versatile. Nutsy is also extremely aesthetically pleasing.
During functionality tests, Nutsy has been able to shell some hazelnuts. The prototype has been unsuccessful, however, at shelling walnuts and peanuts because the rotor is presently made of a wood that is too smooth to grip the surfaces of most nuts. Most of the nuts gripped against the inside wall of the sheller, but slipped along the smooth rotor.
After failed initial tests, vertical grooves were made in the rotor to add friction. Trials with this adaptation have been slightly more successful. The nuts were gripped by the rotor, but not by the stator, causing an upward movement of the nuts. It may be also be advantageous to add some slight, downward spiraling grooves to the rotor surface so that the nuts being shelled are pushed down into the shelling area. Alternatively, it may be necessary to increase the angle of the rotor.
Nutsy is easy to use and has successfully shelled some nuts, but still requires some refinement before fully meeting the design criteria.
Our cost constraints for the project were that our prototype must cost less than $300 to build and our final design should sell on the US market for less than $75.
Thanks to generous donations of plywood from Almquist Lumber (Arcata, CA) and donations of time and materials from Marty Reed (Equipment Technician at HSU), our prototype was created for free.
We estimate that our final design could be sold for less than $50.
 Next steps
While our design concept is well developed, further work needs to be done to increase its functionality. Currently, there is not enough friction between the rotor and stator to shell hard-shelled nuts. Tests of various materials and textures should be performed. Also, the nuts do not seem to be forced down between the rotor and stator and are able to move upwards to avoid being shelled. This could possibly be fixed by adjusting the angle between the rotor and stator or by adding directional grooves to the rotor and stator.
Once the design is refined, additional work needs to be focused on determining the most cost-effective and environmentally friendly material and manufacturing process to meet the design needs. Additionally, analysis of the market should be performed before attempting to produce Nutsy or a similar product.
United States: Wilmington, NC and Arcata, CA