Farmer Built Spelt Dehuller
The goal of my project is to design a spelt dehuller that could be built and used by any small farmer. The spelt dehuller will use a rotary screen with a grating/ peeling/ sizing action common to the German style dehullers but scaled down for the smaller farmer. The unit will also feature a simple aspirator to remove the free hulls.
Weatherbury Farm is a diversified small farm. Since 1986 we have had a cow-calf and lamb operation which we transformed in 2006 into a grass-fed beef and lamb operation where everything is sold directly to the consumer. In 2008 we started growing certified organic grains, largely so we could use the straw to bed the animals in the winter. We grow hard wheat, soft wheat, rye, hull-less oats, spelt, open pollinated corn, buckwheat and emmer. Currently our grain production is sold as milling grade grain and used to feed our chickens. In 2011 we purchased a stone mill with plans to sell whole grains, flour, and rolled products directly to the consumer. By early spring 2013 we should have all of our permits in place which will allow us to mill our grains and sell them directly to customers. Our farm also has a Farm Vacation (bed and breakfast on the farm) which we have operated since 1992.
We are currently farming 175 acres. We own 102 acres and farm another ~73 acres on three separate nearby farms.
I have been working with Dr. Elizabeth Dyck of the Organic Growers’ Research and Information Sharing Network (who is my advisor on this project), formerly with the NOFA-NY Northeast Organic Wheat Project. For the past two years she has been doing field trials of emmer on our farm. When I am finished with this project, she will also help to disseminate information about the spelt dehuller through the many workshops she puts on.
In 2011 she connected me with a group of engineering students at Cornell who were looking at building a spelt dehuller as a senior engineering project. I have provided information to that group and have also shown one of the Cornell staff members working with the students the preliminary drawings of my spelt dehuller.
Elizabeth Dyck also connected me with Brian Baker an economist from Cornell who is doing an economic evaluation of the cost of small scale spelt and emmer dehulling. Since I have done a lot of research into different dehulling systems, Elizabeth felt I could provide a lot of insight to Brian Baker.
A number of people have shown interest in my project.
I designed the spelt dehuller in AutoCAD on one design page so that I could quickly check the fit between parts. I have completed the design of the dehuller but might make minor changes to the plans as I am building the machine. I have tried to keep it a clean design with a minimum of parts. I have also designed the dehuller so that I can build different interchangeable attachments at a later date.
I have modified the drive system slightly from my original proposal. Instead of a jack shaft and pulleys to transfer the motors drive into the hulling chamber I have decided to use a direct drive motor and a variable speed drive. The hammers in the hulling chamber will be mounted on a hub that is directly on the motors drive shaft. This setup greatly reduces the number of parts in the dehuller and also eliminates a belt which could potentially slip.
Since I will be slowing the motor down with the variable speed drive instead of using pulleys, some of the motors rated horsepower will be lost. I upgraded the motor from a 7 1/2hp motor to a 10hp motor which uses the same bolt pattern and drive shaft size. When the dehuller is operational, I will be able to measure the amperage draw of the motor to determine if a 7 1/2hp motor could also be used with the same design. I felt it was better to have a little extra power than not enough.
Two sections of this project have gone over budget — screens and electronics.
Screens: Originally I planned to use commercially available wire cloth for the machine’s screens. That material appears to be significantly different from the screens used in the German machines I am using as a pattern. I, therefore, had two different sizes of screens (for spelt and emmer) custom woven that are similar to the screens used in the German machines. I am also having the same company form a screen out of the commercially available wire cloth. By comparing the hulling efficiency of the different screens I will be able to see if the custom screens make a big difference. I will also have the custom made screens available for sale for other people who are building a dehuller. (They are quite costly to have custom made individually but the price goes down substantially when made in lots.)
Electronics: Originally I planned to mount the variable frequency drives directly on the machine. I found out that in dusty environments the drives are required to be mounted in a NEMA rated enclosure with ventilation fans on the enclosure. Also I discovered that the dehuller and fan motors should have a dynamic brake (a big resistor) to stop them after they are turned off. The dynamic brake resistor stops the motor and keeps the motor from building up electrical charge while it free wheels that could damage the drives. The dynamic brake resistor needs to be in its own ventilated enclosure. The enclosures, ventilation fans and associated equipment will be about twice as expensive as all the other electronics in the project (and were budgeted for).
I have begun fabrication of the dehuller. Once the dehuller is built I will debug and experiment with different screen sizes and operational settings to optimize the dehuller’s operation.