Spring Week 3-4

Putting it together

After problems sourcing materials last week, we finally found the gears, motor and belt we need. Our team took a trip to Grainger in San Jose to buy the gears in person. After spending time comparing many different gears and constantly converting from millimeters to inches (and vice versa), we finally bought the following materials. 

Before diving into the teams progress for this week, we wanted to discuss our prototype plan. Our prototype is focused on achieving the following user requirements:

1. Low cost
2. Simple to assemble and repair
3. Can be used by an average human

Inspired by electrical tillers and other farm mechanisms, we settled on a simple motor belt system that turns an axel with blades attached on it. See similar designs here : https://www.johnnyseeds.com/tools-supplies/bed-preparation-tools/tilther/tilther-9286.html.

​Our design utilises a simple motor or a drill, which is easily available from most hardware shops. Our goal is to build a simply motor driven circuit that drives a small gear which then drives a larger gear through the belt. The larger gear drives the axel which has blades attached on it. The small gear drives the big gear results in a lower rotational speed of the axel but a larger torque. The larger torque is required to cut/break the sturdy cotton stalk. 

To build our first iteration of the prototype we acquired the following materials. 

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After testing the motor, we realised the rotational speed of the axel is too slow. We iterated the prototype with an electrical screwdriver which delivered much better rpm. We had success with the rotation of the gear system! Here is what the rough prototype looks like:

Our next steps for this week are:

• 3D print axel and blades
• Attach axel- blade system to the larger gear 
• assess rotation of the axel-blade system 
• Laser cut wood to create a sturdier holder for the mechanism

Looking forward to sharing our finished rapid prototype in the next blog!

​- Boomitra team