NTATE PLAN' "K J
May 1943 ET-209
United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine
A FAST-MOTION SIFTING MACHINE 1/
By Oscar G. Bacon
Division of Fruit Insect Investigations
The fast-motion sifting machine here described is adapted to
the violent agitation of light-weight samples of infested materials.
It was designed and used for removing insects and their eggs from
approximately 2-pound samples of raisins. The screen was made to
hold a sample of that weight spread 1 raisin deep. Over 1,000 sam-
ple examinations have been made with the machine without need for
repairs or replacements.
As shown in figure 1, the apparatus consisted of an electric
motor, a power-transmission assembly, and a swinging screen and its
Power was furnished by a 1/4-horsepower motor rated at 1,750
r.p.m., and fitted with a 1-1/2" V pulley. It operated the sifter,
loaded or empty, at a speed of 363 round trips per minute, or about
6 per second, with a lateral movement of 4-1/2 inches. Connecting
the motor pulley with the drive-shaft pulley was a V belt 39-3/4"
The transmission unit was made by fitting an 8" V pulley to
the center of a 12-3/4" piece of 1/2" steel shafting. Two face
plates 3-1/2" in diameter were fastened at the ends of the shafting,
which rested in two bronze bearings. The shaft was centered between
the bearings by means of two 1/2" collars. The bearings, of the ad-
justable type, were extended so that the center of the bearing hole
was 3-1/5" from the bottom surface of the metal base. They were
mounted on wooden blocks 3-5/8" high, 1-3/4" wide, and 5-3/8" long.
!/ Other power-driven sifters have been described by R. E.
Campbell and M. W. Stone, Soil sifters for subterranean insects,
Cir. ET-49, 1935; by M. C. Lane and F. H. Shirck, A mobile power
soil sifter, Cir. ET-70, 1936; by Ralph W. Bunn and V. G. McDuffie,
A shaker and modified Berlese funnel for extracting alfalfa weevils
from baled hay, Cir. ET-1OS, 1937; by G. M. Gjullin, A machine for
separating mosquito eggs from soil, Cir. ET-135, 1935; by A. W.
Morrill, Jr., A sturdy but compact soil sifter for field use, Cir.
ET-14I, 1939; and by F. W. Carlson and M. A. Others, A power-driven
soil-sifting machine, Cir. ET-181, 1941.
The blocks were bolted to a I1 x 12" x 225 wooden base. The motor
was bolted to the same bas. so that the power and transmission were
assembled as a unit on one support. Four carriage bolts secured the
base to a heavy supporting stand. U
Eccentrics were made from blocks of oak 1" z 2-3/41 and 4-.3/4-
long, cut to the shape shown in figure 1. The end holding the crank
pin was left a full inch in thickness. One and one-half inches in
from this end a saw out 3/8V deep was a-ie and a piece of that thick-
ness was split out, leaving the remainder of the block 5/8' in thick-
ness to provide clearance for the connecting rods. The eccentrics
were fastened to the face plates by three 1/4" flat-headed stove
bolts 1-1/4' long, countersunk in the wood.
Connecting rods of hard, straight-grained gum wood were made
8-1/4" long and 3/4' square. One end of each rod was fastened to
the oak eccentric by means of a crank pin made of a 5/16" machine
bolt 2-1/80 long, threaded to within 1' of the head. The pins were
screwed into holes bored in the eccentrics 2-1/4' out from the cen-
ter of the face plates. At the other end the connecting rode were
attached to the fraa holding the screen by means of 1' hinges.
With the light loads handled, the wooden connecting-rod bear-
ings gave no trouble from heating or wear. The wood was hard, and
the bearings were kept oiled. Ball bearings and more durable crank
pins would be preferable where more severe conditions are to be met.
A frame from which to suspend the moving sere- was made with
four legs 29" high of 1" x 140 white pine stock, tapered to a width
of 2-1/2" at the bottom. At the corners on the side opposite the
operator, where room for removing the screen was not needed, two of
the legs were doubled, with the members at right angles to one an-
other. At the top the legs were screwed to a frame 21-3/4 z 27-1/2",
using 10-gauge screws 1-1/2" long. The legs were secured to the
supporting stand by iron angles. For added rigidity, the cross mem-
bers of the top frame were set in from the ends of the side members
a distance of 4-3/4" and were braced with triangular wooden corner
A black iron baking or drip rai with the bottom replaced by a
wire cloth of 6 meshes per inch, leaving a narrow edge all around,
was used for the screen. A wire-cloth lid, hinged near the middle,
prevented the raisins from being thrown out. This screen, 17-7/8' z
19" by 2-1/2" deep, was removably set in a wooden frame of 1" x 4N
white pine built to hold it snugly. The frame was suspended by four
strips of oiled oak, 1-1/2" x 1/8" And 17-1/2" long. They were each
fastened rigidly at the top with four round-headed screws, two of
which passed first through a metal plate 1" x 1-1/2" by 1/89 thick
to reinforce the attachment of the oak hangers. The lower ends of
the strips were fastened to the screen frame by 1' hinges which were
attached to the strips by 5/8" stove bolts passed through a metal
plate 1-1/2" x 1', for added strength. The other leaves of the
hinges were screwed to the screen frame.
Beneath the screen, a while enamel developing pan, 20" x 24",
was used to catch the sifting, the pan being raised on guides to
hold it near the bottom of the screen. Referring to the illustra-
tion, there was room for the removal of the screen to the-right,
while the pan was withdrawn on the side opposite the motor. A switch
between the motor and a wall plug was provided for convenient start-
ing and stopping.
The cost of the sifter, not including labor or the cost of the
stand, was about as follows: Lumber, $3.00; shaft, bearings col-
lars, pulleys, face plates, and belt, $7.76; miscellaneous hardware,
$2.29; trash pan, $4.17; motor, $6.45; total $23.67.
Fgure 1.--Fast-motion sifting machine mounted on heavy stand.
UNIVERSITY OF FLORIDA
3 1262 09240 8813