Design Process - Mellinger

After doing research on the 5-bar slotted slider mechanism, I discovered a fascinating design for a quick return mechanism. The symmetry and minimalism of the design were appealing, but the kinematic complexity was still high. The mechanism output slider (yellow) was restrained to translate horizontally, but the contact point between the output bar (yellow) and intermediary bar (green) was also a sliding joint. Not only this, but the input (blue) to intermediary bar (green) were joined by a slider too.

I also decided to pivot the purpose of the mechanism. Originally the machine was supposed to clean burned residue off pots and pans, but after making pasta one night, I decided I wanted to make a cheese grating robot. Cheese graters, much like saw blades, have angled teeth which shave the cheese in one direction. The Whitworth Quick-Return Mechanism is ideal for this application because it drives the grater in one direction slowly with high mechanical advantage and returns quickly to start the next grating stroke.

The link lengths of the robot were tuned in the MATLAB simulation to achieve a maximum output/input mechanical advantage of 5:1[1]. Furthermore electric motors, similar, to the Nema 17 stepper used in this project have been applied successfully in cheese grating machines as in U.S. Pat. No. 5,364,037. Additional discussion regarding, the joint design can be found in the manufacturing and assembly section.

[1] See Future Work for more discussion regarding the selection of this ratio and suggestions for improvements.