Worm
Harvester Basics
A Worm Harvester
is basically just a Trammel Screen, which is a rotating cylinder with a
screen mesh for the sides. There are some Harvesters that work with a vibrating
or shaking flat screen, but the most common types are all trammels. As the
cylinder rotates, the material inside is rolled across the screen as it moves
from the input end to the output end. This forward motion is accomplished by
the angle that the harvester is tilted. As the material is rolling, anything
smaller than the holes in the screen will fall through the screen, and the
rest will continue till it comes out the output end. At the output end, a cone
is installed that can separate most of the worms from the other material
that did not go through the screen. There are
several factors that can affect the efficiency of a Worm Harvester. We will
look at each one of these below. Moisture Level If too much
material is put in at one time, the screening process will not be efficient, as
some of the material will never reach the screen where it could fall
through. The moisture level is important in this, as wet materials tend
to stick together and "ball" up from the rolling action. If you take
castings that have been screened through an 1/8-inch screen, and soak them in
water, very little of it will go back through the same size screen. They will
instead form large balls, and roll out of the harvester. This demonstrates the
need to have your worm bed as dry as possible before harvesting. Worm beds are
all wet to some degree. When this moisture level becomes excessive, less slope
on the Harvester, and less material put in at one time, can increase the
efficiency of the screening process. When the material is dryer, more slope can
be used, and more material can be added at one time. The ability of a Worm
Harvester to be easily adjusted in slope can be an advantage. Most worm
farmers will hit their Harvester's screen with a stick from time to time, to
knock off particles that are stuck on the screen. Finish nails can be taped to
the Jets' rotating hoop where the castors will run over them. This causes the
screen to jump, which can dislodge stuck material, just as in hitting it with a
stick. With the WW-JetHarvesters though, this vibration can be made automatic,
and either used or not. Speed of Rotation There is no
perfect speed, in RPM's (Revolutions per Minute) for a rotating Worm Harvester.
If the Harvester rotates too fast, it will sling worms and material to the side
from centrifugal force. If the speed is too slow, it takes much longer for the
material to move through the Harvester. As the diameter of the rotating screen
increases, the RPM needs to be reduced, to maintain the same speed at the
circumference of the barrel. This is the important speed, the inches per minute
that the screen moves, not necessarily the RPM that the Harvester moves. WW-Jet
Harvesters have the proper speed for both diameters. Slope The slope of a
Worm Harvester will determine how fast the material will move from the input to
the output. A WW-Jet Harvester is designed with the most often used slope
built in, when the legs are adjusted so that the frame is in a level position.
The slope can be easily changed with the adjustable legs, to suit any type of
material. In general you
will increase the slope when the material being screened comes through the
screen easily. This will be drier material, material with few worms, and when
using a larger size screen mesh. The slope is
decreased when most of the material is not going through the screen, but rather
going out the end. This can happen with wet material, material with many worms,
and when using a smaller mesh screen. The other factor
that works in conjunction with slope is the amount of material put in at any one
time. Slowing down on the input quantity is usually needed when decreasing the
slope, or the Harvester will overfill and not screen the material completely.
When using large mesh screens, and a higher slope, usually more material can be
put in at once. Screen Mesh Size WW-Jet stocks three
size screen meshes: 1/8 inch, 1/4 inch, and 1/2 inch. 1/8 Inch screen
mesh is very fine, and your
castings will look the best, but you will get the least amount of volume. Most
of the worm eggs will not go through this size screen. If the material is very
wet, this size screen will do very little without vibration. 1/4 Inch screen
mesh is the most commonly
used. The castings will still look very good, and you will get more. Some eggs
and very small worms can go through. On wet material 1/4 inch mesh screens out
much more than 1/8 inch. 1/2 Inch screen
mesh is mostly only used
when trying to harvest large worms, and as the second or third screen size on a
multi-screen Harvester. Many eggs and small to medium worms can go through, and
this material would be added back to the bed. Wet material will go through much
better than with any smaller size. WW-Jet builds
Harvesters with one, two, or three different screens. This allows for more
different types of screened material at one time. A two screen model, like the
2420 or 3620, can have 1/8" on the top and 1/4" on the
bottom, 1/4" on both, or 1/4" on top and 1/2" on the bottom. A
three screen Harvester, like the 2430, is suited for separating large
worms, as most everything but the largest worms will have gone through one of
the screens before reaching the output. The screens are easily changed with
only a screwdriver on a WW-Jet Harvester, so you can set it up the way that best
suits your beds and needs. You can specify which mesh you prefer installed when
ordering, and order additional sizes if desired. Output Cone and Worm Diverter The Output end
of a Worm Harvester is generally a cone shape. As the material insides the
harvester rolls around, the larger or wetter particles will form into balls,
like making a snowball. When these reach the end of the Harvester and get into
the cone, the increased slope of the sides of the cone cause them to roll out
quickly. The worms tend to stick to the metal of the cone, and do not roll as
easy, and therefore will stay in the cone longer. Since the cone is rotating,
the longer something stays in it, the further over to the side it will come
out. The longer a cone is, with the same slope, the further to the side the
worms will go, and the better the separation you will get. The output cone on a
WW-Jet Harvesters has been designed for optimum worm separation. With the WW-Jet
Diverter shaped like an upside down "V", these two streams are
separated enough that you can have the worms land in one container, and
everything else in another. The Diverter can be adjusted from side to side, to
be able to place it at the right place no matter what the conditions are. Input Cone on WW-Jet Harvesters When material is
put into any other Worm Harvester, some of it will fall back out. This problem
has been addressed with some Harvesters by having the input cylinder be very
long. A solid cylinder is doing no screening, and these only make it take
longer before the worms can get out. Other put a "ring" around the
input cylinder to try to keep material from falling back out. This ring looks
very much like the blade on a meat slicer in reverse and can be dangerous for
the operator. It also is not entirely effective. WW-Jet has taken a
different and unique approach, by putting a reverse cone on the Input end of
all of our Harvesters. The increased slope of this cone pushes the material
forward and onto the screens. The decreased time that your worms spend in the
Harvester is another plus. Cones are considerably more expensive to build than
a cylinder, but WW-Jet is able to offer this advancement for less money than its'
competitions obsolete designs. When you know how they work, and
you know how they are built, the WW-Jet Worm Harvester stands out as not only the
Best designed and built Harvester, but also the Best Value. We came up with our
innovations because we use Harvesters, and the other designs just didn't cut
it. For More Information
Please Contact:
Dan Warco
Kazarie Worm Farm
(352) 463-7823