Silphium Sieve

Last crawled date: 1 year, 11 months ago

Malachi DeHaan
Turkey Trot Home School
Extreme Redesign: Silphium Sieve

Not having the right tools for a job is bad, but the tool not existing is much worse. Dr. David Van Tassel at The Land Institute in Salina, KS, encountered this problem while breeding the plant silphium for greater yield so it could be used as an oil crop. Breeding plants for higher yield requires being able to accurately weigh seed to determine the yield of each individual plant. In order to obtain accurate results the seed must first be cleaned to remove stems, and capitulums (the part of the flower the seeds attach to). The normal method is to put seed through a sieve, allowing the seed to pass through and leaving the junk behind. Silphium’s flat disk-shaped seeds required a larger hole 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 sieve that used slots in the bottom of a V-shaped groove. Of course slotted sieves have already been made, but in order for the seed to pass through the slot, it must land on its edge. The V-shaped grooves cause the seed to stand up and easily slide through the slots.
Traditional sieves usually use shaking to agitate the seed. For my design I used a tumbler to ensure that the seed didn’t just sit in the bottom of the grooves. After printing both a square and hexagon sieve, I settled on an octagon because it spread out the seed more than a square and printed more easily than a hexagon. To prevent seed from falling out the end of the drum I printed a lid with magnets in it that sticks to magnets in the drum.
I printed the sieve and lid on my Creality Ender 3 (FDM) with PETG on a glass bed. I used PETG because it is stronger and more UV resistant than PLA, and doesn’t degrade over time like PLA. PETG is also printable with the stock Ender 3 hot end as opposed to nylon, and doesn’t require a fume removal system like ABS would. This design is easily printable with FDM but could be improved using SLA because of its smoother finish and higher print accuracy. An anti-static filament could also improve the sieve as the seeds sometimes become attracted to plastic, but due to the hygroscopic properties of PETG, static hasn’t been much of an issue.
We won’t be able to tell how effective the sieve is until next fall when it will be put to use sieving thousands of seed samples from the next crop. So far the sieve has worked well when tested, letting through almost no junk. It was especially successful at removing capitulums which had been a major problem.