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 and soft wheat; rye, hull-less oats, spelt, open pollinated corn, and emmer. Last year we grew buckwheat for the first time. 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 mid-spring 2012 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 & Breakfast on the farm) which we have operated since 1992. We are currently farming 195 acres. We own 102 acres and farm another ~73 acres on three separate nearby farms. In 2013, we began transitioning a neighbor farm ( 20 acres of cropland) to organic; we plan to also utilize their pastures (after clearing them).
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 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.
I had the machine fabricated, painted and assembled by June 25th. However, my electrician became unavailable unexpectedly and it has been difficult to find a replacement due to demand in the area. For this project I need someone who specializes in industrial control electronics. Most of the electricians of this type in my area are tied up with long term well-paying projects and are not interested in a small project like mine. I have been told by other electricians that it would cost $5,000 to wire the machine. This electrician told me that it would take at least 2 days to build up the control panel (I built up the control panel in 3 hours and it looks very professional).
I have talked at length with the electrical component suppliers I used for this project and have figured out the proper way to hook up all of the components. I will be finishing the wiring in the New Year and have the variable frequency drive vendor come out and program the drives. I will then proceed to test the dehuller.
I have designed the spelt dehuller in CAD. 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. The fabrication of the machine went very smoothly. Wiring the machine has been a different story. .
It is currently too early to say what the exact economics of the dehuller are. Unfortunately, the electronics cost considerably more than I initially estimated. Two of the dehuller manufacturers (Codema and Heger) use externally mounted variable frequency drives. I am not sure if they have drives that are more impervious to dust or if they figure the drives will last longer than the warranty and then it will be the purchaser’s problem. While I don’t doubt that the machine will have excellent electronics, I am not sure if it isn’t a case of overkill on the part of the two electrical supply houses I used and my original electrician. I think that the electronics are more complicated and complex than they really need to be but in hindsight it was in my electrician’s and the supply house’s interest that I spent as much money as possible.
If I had configured the electronics for the machine as I originally planned with externally mounted drives the wiring would have been pretty simple. There are two things that make the wiring much more complex:
A.) By putting the drives inside a panel you need to have fans with filters to provide cool filtered air for inside the panel. You need a transformer to make the power to run the fans. You need a relay system to turn the fans on and off. Also the wires for the input power, the output power and the controls all need to be segregated from each other by set distances and can only cross each other at 90 degree angles due to possible induction interference. Externally mounted drives would have their controls on their faces but now as the drives are inside an enclosure you need to have a separate “control” panel. If the drives had been externally mounted none of this would have been needed as the drives would be cooled by their own fans. However, with an externally mounted drive there would be a possibility that dust could build up and reduce the ability of the drive to cool itself, it would overheat and be permanently damaged.
B.) Both the supply house and my electrician felt that I needed a dynamic brake. They felt that due to the nature of the machine that electrical demand could surge or quickly diminish due to how much material was in the chamber. The dynamic brake will slow the motor down if there is suddenly less material in the chamber and the rotor starts to overrun. Overrunning can generate power that could damage the drive and is sometimes a problem with hammer mills. I think that the rotating hammers and spelt in the chamber of my dehuller will have much less mass that the motor’s rotor and that the dynamic brake is overkill. No commercial dehullers have a dynamic brake but my electrician and the supply house were very adamant so I acquiesced. The dynamic brake due to the heat it produces needs to be in its own enclosure with its own fan system. I am putting the basic electronics together myself and will have one of the electrical supply houses to help with the final programming of the drives. While the final cost will be less than a purchased dehuller, the mechanical and electrical skills required to put it together are significant.
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 go with 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 pulleys some of the motors rated horsepower will be lost. I upgraded the motor from a 7 ½hp motor to a 10hp motor which use 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.