Evaluative Design

The team planned and constructed a simple drum seeder (Figure 50 and Figure 51), utilizing bamboo, PVC pipe, bicycle wheels and the dosing plate designed by D11. The participants led the design and build process and utilized local techniques such as cutting strips of bamboo, notching the bamboo, rope knots and heating and stretching the pipe. D5, D8 and D11 all assisted with some of the more technical elements of the build, such as attaching the wheel to the axle. Once constructed, the prototype was tested with a range of participants to ensure it was universally usable (Figure 52). A limitation of the testing was that it was done on hard dry ground, not the tilled, wet ground that would most likely be present during use. However, the testing did highlight the need for a more rigid connection between the main axle and the dosing unit as it was bending under the weight of the seeds. This was improved, and a second prototype was constructed. The prototyping activity was good at engaging all participants in either construction or testing.

Figure 51 - Participants discussing improvements for rice seeding prototype version 1

Figure 52 - Participant testing the rice seeding prototype version 2

The testing of this prototype marked the end of Workshop 3. Based on lessons learnt from Workshop 3, D11 designed another iteration of the rice seeding prototype. This incorporated the dimensions and components developed by the community but aimed to improve engineering feasibility of the frame, and wheel hubs (Figure 53).

Figure 53 - Engineering design of rice seeder for case 1

The doser plate was also modified based on feedback during Workshop 3 that the seeds were falling out and bouncing off the main axle. This created a less accurate position once the seeds hit the ground. To mitigate this issue the holes were drilled on a 30 degree angle. This improvement is illustrated in Figure 54.

Figure 54 - Original and improved doser plate design

The change in doser plate design increased the complexity of the fabrication process as holes now needed to be drilled in a difficult direction. The design change also meant that rice seeder needed to be pulled in a certain direction, as the opposite direction would result in the seeds not being picked up correctly by the dosing hole. It was decided that these added complexities were required as the accuracy of the seed dropping was critical to the function of the product. To assist with this, a small metal jig was created to allow the community to drill the angle dosing holes accurately and safely. To communicate the design to the community effectively during Workshop 4, multiple instructional images were created. These aimed to show step-by-step assembly instructions for the new design

(Figure 55). This could be used to communicate the intended design and allow for the community to provide feedback and modify it as required.

Figure 55 - Step-by-step assembly instructions for Team 1

When the participants and design team reconvened for Workshop 4, one of the participants arrived with a homemade version of the rice seeder (Figure 56). This design was stronger than the prototype made in Workshop 2 and had four wooden stakes placed in front of the seeding units to plough a small groove in the dirt for the seed to drop into.

This independent creation was surprising, but very helpful, as it allowed the team to focus on a physical prototype and discuss ways that it could be refined and improved. The design made by D11 was also presented to the team. It was democratically decided that both designs should be continued with and that half the team could work on each design. From there, all team members worked for rest of Workshop 4 planning, building and testing the two designs. The community design (Figure 57 and Figure 58) utilized a heavy wooden frame and a simple dosing mechanism involving an old paint bucket with holes drilled in it. The frame was strong and created a rigid, durable product. However, the dosing mechanism did not work effectively as it relied on the user pulling the product at a particular speed to achieve correct dosing. The addition of 4 metal spikes to plough the ground in front of the dosing unit was considered novel and effective, but also added complexity to the design as they needed to be adjusted to a particular height depending on the user. During an exit interview, one participant stated “we should measure width between each rake’s teeth. We shouldn’t use metal rake because it’s too small. We should use wood the size of a toe”. The same participant also stated:

“We haven’t finished it yet. This is an experience. Technical experience. But, it is not properly made. First, we missed the back. Second, the rake’s teeth aren’t correctly placed. They are too small. So, we haven’t practiced it. Also, it is the wrong season. It’s dry season”

Figure 58 - Testing of community designed rice seeder

The construction of the D11 designed rice seeder went well with all participants working together to construct the unit. However, there were multiple changes to the intended design due to material limitations and community decisions. These are presented in Table 34.

Table 34 - Table of design changes for rice seeder Original design

decision Change to design decision Rationale Associated design issues Dosing plate to be

202mm in diameter Dosing plate end up being 180mm in diameter

Limited sizes of buckets available. This meant the design needed to work with a smaller bucket

Dosing plates needed to be hand cut smaller, this resulted in a less accurate fit with bucket

4 dosing units spaced 250mm apart on the main shaft. Overall width of unit 1200mm

5 dosing units spaced 250mm apart on the main shaft. Overall width of unit 1500mm

The participants wanted more dosing units to allow for more efficient rice seeding

A wider overall unit meant it was more difficult to

manoeuvre Handle of frame length

1060mm Handle length increased to 1600mm Allows user to stand more upright than previous design

A longer handle meant it was more difficult to

manoeuvre and more loading was placed on the frame during turning Tubing for frame

22.2mm x 1.2mm mild steel

Tubing for frame 22.2mm x 1.2mm aluminium

Decided by partner organisation as it was cheaper and easier to source

Frame much weaker than originally intended

Figure 59 - Construction of D11 designed rice seeder

Figure 60 - Testing of D11 designed rice seeder

Unfortunately, it was difficult to test these prototypes in their actual use environment (muddy, ploughed fields) as field preparation and sowing does not occur until May (Workshop 4 was conducted in November). Some basic testing was conducted using local rice seed. This worked to some extent but seed dosing was not as reliable as it was during lab testing by D11. This was partly due to the less accurate construction and partly due to the rice seed that was used being slightly wet and sticky (in reality it would be hard and dry).