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Dehuller operations step by step

Topic Type: 

Hi FarmHack,

I just want to make sure I understand the basics of how the machine works.

  • The seeds enter the center of the rotor
  • The rotor rotation sends the seed with high velocity to an outer ring where the shell breaks
  • (Where/How does the machine separate the shell and the seed?)
  • The cyclone filter recuperates the seeds at the bottom

By the way, I will draw everything on Autodesk Inventor before I start building. Any info will help!


dorn's picture

I will try and add more to the the wiki later - but your description is pretty accurate. The vanes in the rotor spin the seeds out where they hit the stator (stationary ring. The hull is knocked off by the impact. In some impact dehullers I have seen, the stator is a stone like material, but the one documented here used a steel ring.

The seed/grotes and hulls are blown/expelled by the air movement caused by the rotation of the fins on the side of the rotor. The cyclone separator is designed to have a vacuum on the top to separate/winnow out the hulls and have the heavier seed drop down for collection. Alternatively the mixture can be collected and run through a fanning mill (which I will be documenting later this spring). A fanning mill screens for over and under size and separates by weight.

To hull barley or spelt more velocity is needed and a higher rotational speed. Hammers/impellers are also added to the rotor and a correctly sized screen is substituted for the stationary ring such that the hulled grain can be expelled, but the unhulled grain is beat up further until it is able to exit through the screens. I do not yet have any drawings of this feature.

It will be great to have this design into autodesk inventor. I hope that the sketchup drawings are helpful as a start. It needs some cleanup but I can save it in another format like 3ds for importing if it would be useful. My hope is that we can post machine files here too if you use a torch table or water jet etc. for cutting any of the pieces.

Tones's picture

Hi Dorn,

Thank you for all the info! It really helps! Now, if I was to install a screen allowing only the hulled seed to get through it, how would I collect the shells and the unhulled grains? And how would I automate the unhulled grain to pass a second time?

On a more technical aspects, what size of motor would you recommend using? What size of vacuum would you recommend using?

Thanks again for your time!

dorn's picture

My understanding is that the screen size is very important so that after the dehulling process both the hull and the grain are able to fall or push through the screen and then are carried by the air flow up and out of the housing to the cyclone separator. There are details about the vacuum setup in the engineering drawings and notes posted. I think it was 2000cf/min and a 2hp suction fan.

My understanding is that even with the large commercial systems the process is fairly manual for re-running unhulled grains - and requires some fine tuning and attention to varying crop conditions. larger capacity seed cleaners and number of screens both prior to and after hulling will help reduce the labor of the process to get a quality finished product and reduce loss. Like with most of this kind of processing sizing and sorting for consistency helps prior to processing. That is why I think the fanning mill is so important.