Silphium Sieve

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Malachi DeHaan Turkey Trot Home School Extreme Redesign: Silphium Sieve Dr. David Van Tassel at The Land Institute in Salina, KS faced a significant problem while breeding the plant silphium for greater yield as an oil crop. He needed to accurately weigh seeds to determine the yield of each individual plant, but this required cleaning the seed to remove stems and capitulums. The normal method is to put seed through a sieve, allowing the seed to pass through while leaving junk behind. However, silphium's flat disk-shaped seeds pose a problem since they require larger holes than the stems or capitulums. When placed in a sieve pan, the seeds would lay flat and only go through large holes. I solved this problem by 3D printing a custom sieve that uses slots in the bottom of a V-shaped groove. Traditional sieves use shaking to agitate seed, but my design employs a tumbler to ensure the seed doesn't just sit in the grooves. I experimented with both square and hexagon sieves before settling on an octagon because it spreads out the seed more efficiently and prints easily. To prevent seed from falling out of the drum, I printed a lid with magnets that stick to magnets in the drum. The sieve and lid were printed on my Creality Ender 3 (FDM) using PETG filament on a glass bed. I chose PETG because it is stronger, more UV resistant, and doesn't degrade over time like PLA. This design is easily printable with FDM but could be improved using SLA for its smoother finish and higher print accuracy. An anti-static filament could also enhance the sieve as seeds sometimes become attracted to plastic. However, due to PETG's hygroscopic properties, static hasn't been a significant issue so far. The effectiveness of the sieve remains to be seen until next fall when it will be put to use sieving thousands of seed samples from the next crop. So far, it has worked well in testing, allowing almost no junk through and particularly exceling at removing capitulums which had been a major problem.