03 - Whetstone Knife Sharpening Mechanism

Summary

Our project was to design a mechanism that mirrored the human motion of sharpening a knife with a whetstone. Using a whetstone to sharpen a knife is a very intuition-driven process of maintaining specific angles of the blade relative to the whetstone, and it follows a complex human path that is difficult to reproduce with mechanisms. This brings us to the challenge of the project, which is to create a linkage mechanism with one input driver that can mimic the motion of the sharpening. The model for the design was to create a linked oscillating four-bar and slider-crank system that moves both the whetstone and the knife to evenly sharpen the knife along its entire profile, from hilt to tip.

Our final prototype ended up being a simplified version of what we had originally designed. Instead of the linked system, in order to simplify the system and better match the exact profile of the knife, we decided to go with a slider-crank and a cam follower that would move the whetstone along the profile of the knife and then cause the knife to rotate as the linear slide comes into contact with the cam. This prototype was designed to be a model of how the system would be housed with a simpler mechanism, as the simulation was conducted using the original, more complex mechanism. These combined were a proof of concept for the whetstone knife sharpening mechanism where, given time to improve and refine the design, we could use a similar housing geometry with the actual linkage mechanism.

03 - Project Proposal

03 - Initial Concepts

03 - Kinematic Analysis

03 - Lessons Learned