The Design Challenge
The problem we are trying to solve is the lack of accessible and affordable crop-processing tools for smallholder farmers in rural Africa. Many farmers must travel long distances to reach grain-grinding and produce-shredding stations, which costs time and money and reduces overall productivity. In addition, these facilities often require a minimum quantity of produce, making them impractical for small-scale farmers. Our design solution is a mobile agricultural shredder and grain grinder that can be easily transported and powered by a motorcycle, bringing processing directly to farmers and improving efficiency, accessibility, and livelihoods.
Summary of Research
After our cardboard prototype, we identified that there would not be any space on the motorbikes wheel to connect the shaft and flywheel to the grinder. After realizing the problem, we decided to run the motorbike on a treadmill like platform, where the energy from the belt/rollers would be connected to spin the inside shaft of the grinder.
Opening the treadmill to remove rollers
We wanted to use the rollers from a treadmill because our idea was sort of similar to the way a human being would walk along the treadmill and that inspired us to connect a pulley to the rollers to maximise how much energy we can produce for the shredder.
After looking at the shredder and having difficulties with the older pulley design, we decided to change the design to the simpler and more readily available one already on the shredder.
After our first attempt 3D printing the pulley, we saw that all the grooves melted into each other, so we decided to fillet the edges in fusion 360 to create a bigger gap in between the grooves and create a higher quality and more accurate product.
Measuring the bike to create mechanism
As displayed in this image carousel, we have a tape measure and are trying to find the dimensions we would need to make sure the bike can actually fit on to our machine before we start creating more permanent measurement figures.
We replicated the pulley on the front roller and designed another one on Fusion360 to fit onto the rear roller in order to make the shredder spin when the motorbikes wheel spins.
Measurements:
Thickness – 22.83mm
Circumfrance – 88.05mm
inner circle circumfrance – 44.34mm
outer ring inside diameter – 20.9mm
grooves – 1.79mm
The image on the right is our shredder which matches up with what is a rough drawing/plan to ensure that everyone in the team understands whats going on and what we are trying to end up with at the end of the project. The flywheel is what is attached to the shredder which will be connected to a belt system along with the other pulley wheels. This rough draft shows no display of an idle pulley which was later added on.
We wanted to add an idle pulley to our mechanism. where we add an extra pulley that can be moved in order to keep the tension even when the belt stretches out
This is how we added the idle pulley onto our table where the belt passes through it and then goes to the shredder. We made sure we can move the pulley from right to left with aroun 10cm of movement. This now means the belt will pass through the 2 rollers and then the idle pulley before connecting to the shredder
This is a test of our concept using Bernard’s(Mr Sudra’s colleague) contraption. In this video we can clearly see that the roller which is spun by the rear wheel of the motorbike, then connected to the shredder does spin and grind things. Some issues we realized with this test however, was that it was
We made the table bigger in size than Bernard’s so that it could properly fit onto the motorbike for transport and so that it can fit a bucket or a bag that the grain will be shredded into. We also made sure to add supports in the middle in order to hold the shredder.
In order to make it easier for the design to be trnasported. We designed a mechanism where the whole table is able to slide up and down, so that it can be shorter when being transported, while still staying the same height when being used. To help with transport, we also made the roller secion removable, so that it is a slimmer design when moving. We aim to have a pocket or a storage compartment in order to store this section while travelling.
As we were now using metal and better materials to construct the table and the design, we also decided to find metal parts for our pulleys and then we cut the tightening square and welded a rod onto it for the idle pulley.
Link to Process Journal & Final Reflection Video
Process Journal: https://sites.google.com/isk.ac.ke/boda-boda-shredder/home