When a path is blocked make a new way

Sri Lanka has been slow to adopt new agriculture practices due to variety of reasons. Most notable reasoning being most of the generations that are currently involved agriculture prefer traditional methods over novelty.

Some are afraid or are very slow to adopt new technologies due to not being aware of the effectiveness of such practices and others are immediately turned down due to needing upfront investment which makes them more risk averse to anything novel fearing that this will lead to no change or even a perhaps a negative change of the outcome. Most importantly most of Sri Lankan can be said are afraid such failure.

Being a Sri Lankan Engineer I was always interested in agriculture mainly because there is a level of satisfaction that comes with seeing the fruit of the labour grow, however, by no means this is easy work as any crop requires dedication and investment.

From my childhood I grew up around cinnamon and the processes surrounding it and I have profound interest in making this traditional crop more sustainable to farm and there by improve product quality. Ceylon cinnamon as its globally known is mostly found in Sri Lanka in fact 90% of global demand is fulfilled by Sri Lankan cultivation. However the industry has seen very minimal improvement during the past 100 years. Although there are certain new adaptations that has improved the cinnamon processing work when it comes to cultivation, still similar traditional methods are used.

The problem

Under sunny conditions cinnamon as a plan will grow as tree that has multiple branches to get the maximum sunlight. In-order to grow the maximum amount of cinnamon plants per unit area it is advised that plant be grown with a 3*4 (feet) gap configuration. During the first 3 years of the plant growth there is a large impact from weeds over growing the small plants and competing for sun light as well as nutrients. Normal practice for such conditions are to use weedicides to control the unnecessary under growth. Although this is effective in the short term a farmer will have to use weedicides 3-4 times a year to control the under growth. Use of such chemicals poses threat to the infant cinnamon plants growth as well as the quality of it. Due to current labour shortages it is not easy to continuously find people help to do such work.

The solution

Mulching has been used in different agriculture practices as effective means to control weeds and undergrowth. Mostly used in food crops these sheets are generally covered with soil as means of holding it to the ground. However for larger plots of land with a wide spread such as cinnamon this is not practical. For such needs it is best to tie the mulch sheet to the ground using a clip. Such clips are not available locally and unfortunately there is no alternative solution present in the market.

Initially I started using conduit tubes, cutting them 15 cm length wise and heat it in the middle and bend it to help hold the sheets once its tied to the ground. Although this seemed to work well at the beginning, conduit pies were very hard to push into the ground requiring further work to dig holes, and they could not hold the mulch sheets very effectively.

As possible alternative I purchased mulch clips from China as this would solve most of the problems, CIF price of the clips was about 250 USD, not much. However once it arrived in Sri Lanka, the customs took a different approach to tax these. Not being bothered to evaluate the use of it I received final tax amount of 2500 USD for the same goods which should not have a tax value equal to its original goods. This was very unfortunate outcome as this put a large damp in my plans.

Not being the person to give up easily I focused on using my 3D printing capability to find a solution for this.

Solution

I designed several mulch clip designs that would do the job and tested them out for manufacturing cost. The clip design had to be simple enough to penetrate hard soil without braking and once inside it needs to hold the mulch sheet firmly without letting it loose easily. Hence strength was very important and I had to design balancing strength and cost. It is easy to design something that would hold but it will cost more to manufacture and I needed over 10000 clips so it was very important for me to be able to manufacture them fast and cheap.

The basic design had to have elements to penetrate the ground easily and needed to stray firmly held in soil without coming out

Design 1

this was the first design that I tested it out, this was printed in both PLA and ABS to test for strength to penetrate hard soil, although this worked well it was too costly to manufacture in bulk.

Design 2

Similar to initial design this did shave off some the manufacturing time but the price was still high due to higher material consumption and timing

Design 3 – Below design reduced the material consumption and print time thereby reducing the over all cost , however it failed to perform up to the task being more fragile it was harder to pin into the ground.

Design 4 – This was the sweet spot, perfect balance of strength and cost. This held strongly even after being printed with PLA material and manage to hold the mulch sheets steadily to the ground even in toughest soil

I printed all of them at 0.28 layer height using 0.4 nozzel on average it takes about 13.2 hours to print 107 pcs at once and it is possible to print close to 330 pcs from a single spool of filament. I tried simulating different configurations using a 0.8 nozzel which managed to cut down time by about 35% but had no effect on material consumption. In terms of power consumption machine was running on very low power as I used super cool PEI print sheet which allowed me to print at 45 C without any print fails.

I am sharing the print file hoping someone else may make use of it.