Knekk - Process
The nut cracker for everyone
Knekk - developed as a personal project in my fourth semester - is the nut cracker for everyone.
A design heavily influenced by the parent course User Oriented Design - it is a product of extensive user testing. In short, it is design revolved around and adapted to the end users experience. Thus the product is required to fulfill universal design standards. By including elite users in the design process - persons suffering from arthritis - the user spectrum is substantially widened and the demands for a efficient design increase thereafter.
The things that make life easier for the few, makes life easier for everyone
IDEATION
Early on the process was very free. I wanted to explore all the possible ways of cracking nuts, and so I delved into the array of different products that existed.
There are numerous nut crackers for sale today, and the cracking methods varies from the traditional plier mechanism to the more experimental marble balls crackers. They all have their pros and cons, but some work better than others. This became apparent through user testing.
User testing
The benefits of user testing are many. Observing how existing products are used reveal their shortcomings. A wide range of users will operate the cracker - some have small hands, others reduced strength. These elite users often constitutes a small percentage of the total users, but demand higher performance from the product. For the user testing we chose persons with varying degree of arthritis - from those who have a minimum of strength reduction, to those who cannot properly use normal kitchen tools. We then presented them with a range of existing products, and observed. Using the products and communicating with us provided very valuable insight to their situation.
USER REQUIREMENTS
On the basis of the user testing feedback a requirement specification was formulated. These requirements adressed several key findings from the user testing. The requirements adress both the function of the product, but also the esthetics.
The function of the nut cracker should be as effective as possible, allowing as many as possible to use the cracker. By setting up three tentative users, some with reduced abilities, and actively referring to these users they guided the process in the right direction.
When it comes to esthetics, successful universal products should look as little universal as possible. Unfortunately these universal products have a tendency to inherit an esthetics of their own. This is unfortunate because the elite users do not want identify themselves with these products as they communicate a shortcoming with the user. Users requiring universally design products wish the fact that they use these products. Therefore, the esthetics of the nut cracker is very important.
sketching and 3d cad
While sketching and developing the final shape, a complete 3D model was made with CATIA 3D PLM software, allowing a free forming of the grip shape while running FEM (Finite Element Method) analysis to ensure sufficient dimensioning and structural integrity. A mechanics simulation was performed to confirm the efficiency of the mechanics.
mechanics and manufacturing
The model consists of six parts, all produced in recycled aluminum - providing a light and strong construction.
The two arms pivot around the screws on the upper part of the cracker. They yield power on to the inner clamp, pressing this together. The pressure squeezes the nut together until it breaks. When the user releases the force, the clamp retracts back to its normal position, and the handles follows. The reduction of distance between the points of contact executes the cracking.
BUILDING THE MODEL
Upon completion of final 3D model in CATIA, I sintered a SLS Rapid Prototyping model. The product of SLS machines are a rough porous surface. To achieve the desired visual appearance i proceeded as followed:
• Dry sanding to remove the roughest patches of the nylon model.
• I then applied a layer of two-component putty on the entire surface.
• Then another round of dry sanding with a finer paper (circa 600)
• Then a new thin layer of two-component putty.
• A quick rub with dry paper (circa 600) and then wet sanding with 800 and upwards, depending on the quality of the finish.
• Then I applied a couple of layers with spray putty while wet sanding in between.
• Now the model was ready for paint.
The model was finished of with top coats of metallic grey lacquer and clear coat applied with a moire effect to best imitate an aluminium appearance.
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