Publication Date

Fall 2021

Document Type

Final Report

Embargo Date


Problem Statement

The Lost Grains Thresher project aims to design and implement a device that can successfully separate the seed and chaff from various grains that are native to the greater St. Louis area. This project is designed for Dr. Natalie Mueller at Washington University in St. Louis to replace her current method of separating plant seeds from chaff by hand. This project focused on three main performance goals: 1) the device should work on a minimum of two types of seeds and thresh them to an acceptable quality, 2) the device should be easily cleaned and reset within three minutes, and 3) the device should require no more than 1/10th of the mechanical work needed to thresh the seeds by hand.

After working through numerous prototypes, our design group came up with a working design that achieves all three of these design goals. While threshing seeds to an ”acceptable” quality is a qualitative measurement, our device is proven to thresh two types of seeds used by Dr. Mueller at a near-perfect rate. Additionally, the device can be easily cleaned and reset in less than a minute. To accomplish this, the user must simply dump the threshed seeds and chaff out of a kitchen mixing bowl and mesh strainer and return the bowl and strainer to their regular positions. Lastly, the only mechanical work required to operate the thresher is the work that it takes to turn on a kitchen mixer and set it to the appropriate speed. It should also be noted that it takes significantly less time to thresh the seeds in our device than it does by hand. Start-to-finish the Lost Grains Thresher takes less than 10 minutes to thresh a liter of seeds.

Author's School

McKelvey School of Engineering

Author's Department

Mechanical Engineering and Materials Science

Class Name

Mechanical Engineering Design Project (MEMS 411)