Spring week 6-7

We are excited to have started prototyping our final (for this quarter) design! Our team has been learning how to weld and are going to spend the next week figuring out how to do the following through welding:

1. Bend sheet metal - This will help us form a curved cover for the shredder 
2. Weld sheet metal to sheet metal - so that we can have compartments for our motor, and gear-belt system
3. Weld cutter shafts onto our axel - this is so that we can bolt on the blades to the axel. 

We are also working on sourcing the following items so that we are ready to build once we know how to weld:

1. ​Sheet metal - We are considering galvanised steel because of its durability, low maintenance requirements and ability to withstand outdoor conditions. This is for our curved cover which needs to be durable, protective and light enough that the shredder can still be used by one average person. None of us are materials experts so any other material suggestions are highly welcome
2. Hammer blades - We are just finding small and light blades for now so that we can feasibly attach it to our relatively (to existing farm equipment) small shredder. 
3. Cutter shafts - This is what attaches the blade to the axel. We are trying to source one that matches the hole diameter of the blade and relatively small compared to the axel. 
4. High power drill - We will use what we have available for now. We need to run some tests to determine optimal rpm before finalising the drill, but these are easily available in most hardware stores and any drill can be used with our shredder as long with a shaft and a coupler.
5. Axle - This is the most complicated part of the materials list. We need a shaft that is durable and strong enough to withstand high forces but also light enough and small enough that it can be operated by one person. We will probably buy 3/8'' lawnmower axles for now, but we are still unsure about the optimal axle. 

Alawab and Sree are planning to learn welding by working with welding experts in the PRL and experiment with scrap sheet metal, while we wait for orders/ go to hardware stores to buy materials. There are various large pieces of sheet metal available, so we may start working on the cover if we find a piece that works well. 

Jierui unfortunately has COVID, so she'll be taking a lighter load this week. Jierui will be working on researching available materials and their costs from the list above so that they will be readily available when we put the shredder together.

Isabella will be working on a testing plan for the shredders specifications for the remainder of the quarter. We have some rough experiment ideas to measure different aspects. We have thought of experiments to measure momentum required to knock over the stalk so that we can identify the right motor with the right rpm that will generate this momentum. We will also be testing whether the blades hit at the right angle and the depth at which the blades hit the stalk to understand the effectiveness of the shredder design. 

Here is the link the to testing plan: click here. This doc will be constantly evolving as we update some of our ideas. We would love to hear your thoughts on these tests and if you can think of better experiments to measure these parameters (feel free to leave comments on the doc!).

We would also love any welding experts to help us out with learning and determining which type of welding is suitable for different aspects of the design. 

~Boomitra team

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