The Bosch Splinter is a hand-held combi drill/driver attachment for splitting logs, firewood and kindling. It does this with the high torque rotation of the conical threaded brass bit. The thread pulls the cone into the wood and its conical cross-section is then responsible splitting it apart. 
It was designed primary for those who want to split firewood easily, perhaps they are elderly and/or less abled to wield an axe or use a saw, or who simply want to put in less effort.
Three models were made, firstly a functional prototype to test whether the concept is at all feasible, secondly a solid works CAD model, and thirdly an aesthetic and ergonomic prototype. 
Below: Presentation board image of the CAD model.
Below: Footage of the splitting screw in action, making light work of a 100mm piece of apple wood.
It was important to test function first of all to see if the concept was at all possible, a hand drill on a high torque setting proved it to be so, requiring only an initial push into the woods surface (lean into the device/body weight), then the device does the rest of the work. 
A simple functional model was created using simple aluminium frame which stabilised a combi drill.
A CAD model build on solid works, whereby the battery, motor and gear train had to fit into an injection moulded shell and have the external characteristics defined in the project specifications.
 A focus was put onto realistic manufacturing considerations, so draft angles and wall thicknesses had to be considered correctly, along with materials (ABS shell with a T6 aluminium serrated 'log gripper' section).

Below: Early concept sketch, several changes took place between this and the final proposed design.
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