By Allen Dong and Roger J. Edberg, I-Tech, PO
Box 413, Veneta, Oregon, 97487 USA
This invention became public domain on August 9, 1989, a gift to humanity
The two main components of the I-Tech rice huller are a hand mill/ flourmill or grain grinder and a rubber-faced disk made from:
Short grain rice can be hulled at a rate of 200 g/min. The percentage of rice hulled varies from 75 to 99% depending on the rice cultivars, the spacing between the stationary rubber disk and the rotating abrasive disk, and uniformity of spacing between the disks. A tin plated steel burr disk may produce a black gum residue when hulling rice, until the tin is worn off. No black residue was found when using a cast iron disk or stone disk.
The grain huller also hulls millet (Panicum miliaceum), sesame (Sesamum indicum), and spelt wheat (Triticum spelta) as well as remove saponins from quinoa (Chenopodium quinoa). To "wet" hull sesame, soak the seeds in 1% (w: v) lye (sodium hydroxide) solution for 10 seconds to 5 minutes, then rinse with water and 1% solution of acetic acid (Shamanthaka Sastry et al, J. Am. Oil Chem. Soc. 46:592A, 1969; Moharram et al, Lebensmit. Wissen. Tech. 14:137, 1981). A steel burr disk is preferred for wet hulling sesame, while a stone disk is preferred for hulling spelt wheat.
Hand operated rice huller: A) stationary disk, B) rubber disk, C) handle and D) rotating disk with auger. Remove stationary disk and replace with rubber-faced disk.
In the US, the C.S. Bell model 60 (cost ~$325) and the Corona hand mill (cost ~$40) represent two ends of the spectrum of hand mill quality. For serious hulling, the C.S. Bell is the better choice. This mill weighs 54 pounds; its auger shaft is supported by 2 bronze bearings with oilers; the grinding disks self aligns; and the mill can be motorized. The bronze bearing with oilers allow the shaft to rotate at 300 rpm without heating up. (CS Bell, PO Box 291 Tiffin, OH 44883, phone 419-448-0791).
The Corona hand mill weighs 14 pounds; it has no
bearings; the grinding disks do not self-align; and the mill cannot be
motorized. (R&R Mill Co., 45 West First North, Smithfield, UT 84335,
phone 801-563-3333).
By Allen Dong and Roger J. Edberg, I-Tech, P.O.
Box 413, Veneta, Oregon 97487
This invention was declared public domain August 1994, a gift to humanity.
A portable, engine driven thresher can be made by modifying a leaf shredder/wood chipper or a hammer mill. Small shredders/chippers use 5 to 8 horsepower gas engines that rotate at 2800 or 3600 revolutions per minute (rpm). The modification requires:
A 5 horsepower, 2800 rpm "Roto-Hoe model 500" leaf shredder/wood chipper is used (Figure 1). Additional parts include:
4 2-inch C clamps (A),
6 5/8 x 3 inch bolts (B),
6 1/8 x 1 inch cotter pins (C),
1 8 x 10 inch sheet metal or cardboard (E) to block the slotted portion of the leaf shredder/wood chipper exit port.
The "Roto-Hoe" shredder has six sets of three free swinging hammers (F). Convert the six set of hammers into six rasp bars as follows: Cut the 5/8 inch tubing (D) in segments to fit between the free swinging hammers (F). Tie the free swinging hammers (F) together by inserting the 5/8 inch bolt (B) into the hole of the first hammer, followed by a segment of tubing (D) as spacer, then another hammer, followed by a second segment of tubing, followed by the third hammer. Drill a 5/32-inch hole on the threaded portion of the bolt that protrudes from the third hammer. Reassemble the bolt, hammers, and spacers together and lock the bolt in place with the cotter pin (C) installed in the 5/32-inch hole. This assembly constitutes a rasp bar. Repeat the above procedure and tie together the remaining five sets of free-swinging hammers. Manually rotate the rasp bars and check for clearance between the rasp bars and the walls of the threshing chamber. If there is insufficient clearance, adjust the bolt position, grind the bolt head, or cut the bolt length to obtain the necessary clearance between the rasp bars and the walls.
The Roto-Hoe shredder exit port consists of a slotted section and a 3/4-inch diameter punched-hole screen. Use the sheet metal or cardboard (E) and C clamps (A) to block the slotted portion of the exit port (G). The threshed grain exits through the 3/4-inch holes.
Start the engine and spin the rasp bars. Again, check for clearance between the rasp bars and the walls of the threshing chamber. If there is a knocking sound, grind the bolt down to obtain the necessary clearance.
Operation:
Start the engine and spin the rasp bars. Dried plant materials with vines, stems, and leaves are fed in batches through the hopper. After threshing for 1 to 3 seconds, open the top door to eject the longer vines, stems, and leaves that have not been chopped up. Seeds and small bits of plant material exit through the punched holes at the bottom. The mixture of seeds and plant material must be separated after threshing.
The 3/4-inch diameter holes in the exit port are suitable for larger seeds (e.g. beans) and seeds with loosely attached husks (e.g. wheat, bok choy, and amaranth). Small seeds and seeds with tight husk or pods (e.g. barley, clover and radish) require smaller diameter exit holes to retain the larger unthreshed materials while passing the smaller threshed grains. This can be achieved by attaching a screen with smaller openings under the 3/4-inch diameter punched holes.
Larger seeds crack easier than smaller seeds. Reduce the rasp bar speed to decrease the percentage of cracked seeds. Use a larger pulley (H) and/or reduce the engine speed to achieve the desire rasp bar speed:
250-400 rpm for beans and large seeds
400-800 rpm coriander, radish, sunflower
600-1400 rpm wheat, oats, barley, rice and small seeds
Typical threshing rates are:
Seeds Pounds of seeds per hour,
Bok Choy 22 to 30
Oats 94
Pinto bean 117
Soy bean 81 to 127
