Poultry shears
Mark Jonathan Freyer
Technischer Entwurf, 2021
Betreut durch Prof. Tom Philipps
In the technical design course, the task was to equip a tool with a mechanism to improve the tool with.
I designed poultry shears, which have a greater power transmission with bevel gears.
concept
In preparation for the course, I came across the mechanism that later became the basis for my design. Fiskars has
installed gears in their „PowerGear X Rollgriff Pruner “, which are multiplying the power transmission when the scissors
are pressed together. I worked a lot in the garden with a Fiskars model and was immediately taken with the concept.
With regard to poultry shears, this extreme power transmission is an huge advantage. This makes it easier to cut through
the skin, flesh and bones of the poultry.
implementation
At the beginning of the course I dealt with a lot of questions. The poultry shears in connection with the mechanism is very complex and many details build on others. Each answer then brought me closer to the design. How wide do the handles have to be? How long should the cutting edges be? Do I need a bone breaker? How many degrees does the lower handle rotate around its own axis when I open the Poultry shears and how much degrees is the angle between the upper and lower handle?
Which spring system is best suited and fits best with the overall design?
Rapid prototyping and its benefits are one of the main components of the course.
That‘s why I wanted to design my poultry shears so that no part has to be screwed. As a result, my scissors consist of 6 parts printed one inside the other and a spring that i have to install.
The normal poultry shears mostly have a horseshoe shape and have a double evolution spring.
On the one hand, the mechanism restricts me in terms of the pivot point and the division of handles and blades, but on the other hand I was able to design the length and angles freely without paying too much attention to maximum power transmission.
The angle of 45 degrees is reflected in many details of the scissors, like the transition from the handle to the cutting edge or gear and handle, the macimal opening of the scissors, the teeth of the bone breaker or many chamfers and cuts in the model.
Despite the high complexity, I wanted the scissors to look simple and elegant.
3D printing and sectional views
Sketches and technical drawing
