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Manual
Hay Baler Revisited
January 2006
Brian Webb, John Sarge,
and Dick Roosenberg
An update of TILLERS' TechGuide, Manual Hay Baler, 1992
A group
in Peru recently ordered a manual hay baler as a model for their craftspeople
to use in manufacturing balers for local farmers. Although we urged
that the group save money to work simply with our plans and build
the model baler in Peru, they wanted the artisans to have a concrete
example in front of them.
We first
designed the baler in 1990 with Walter Muro of Arusha, Tanzania.
We have been demonstrating that prototype since then and sharing
plans with groups around the world. Only a couple of modest reinforcements
had been made.
Repeating
the construction process after several years proved to be a worthwhile
exercise. With new people looking at the old prototype and at the
1992 plans, we found a few things that could be improved. We are
pleased with the action of the newly built baler in brief tests, and will revise the plans to reflect the changes. We're waiting for
reactions from Peru to add to the thought process before we print
revised plans.
One of the
things that we have noticed is a stickiness in the lever and plunger.
It is occasionally difficult to start the movement of
the plunger from its back resting position. In reviewing this problem,
Brian noted that the geometry of the forces would be better
if we pulled back the push point of the lever on the plunger from
its face a couple more inches. He also noticed that the back brace
legs of the compound lever slide toward the center at times, further
causing a jerking action. Placing a tube around the bar between the
two legs as a spacer eliminated that problem. Finally, we added a
stop to the return of the plunger so
the angle of the lever and the brace legs would not become too acute
to be easily pushed open. (For the stop we left the bottom tails of
the back brace legs hang down below the pivot far enough to stop
the return of the plunger.)
These three minor adjustments significantly improved the glide of
the plunger. The person working the lever should be able to work
more rapidly and not have to attend to irregularities.
The divider
boards that separate the bales and provide the grooves for threading
the twine are not symmetrical top and bottom. The assistants have
always had to pause and inspect the boards to determine which end
should be at the top. We decided the clearest way to eliminate the
ambiguity woud be to place a hand grip at the top of the divider board
to assure that it is always picked up correctly without delay. A few
extra minutes in construction will be rewarded over years of simplified use (see
Figure 4)
The
needle used to thread the twine through the divider boards needs
to be ready at hand for the persons tying off the bales. We redesigned
the handle of the needle as a hook to attach quickly to the baler between
uses.
Since this
is a manually powered baler, it is not intended to compress
hay as tightly as an engine-powered baler. However, we found
that in normal use we usually had to tighten the tensioning bolts to their design maximum of 2 inches to close the
exit. We decided to add side-to-side
compression as well as top-to-bottom compression (see Figure 4.) To
to this we added blocks to the center side board to hold it inward
against the tensioning bar. The test of the effectiveness of this
block will need to occur in the field, but we expect the added
compression and resistance to permit the tensioning bolts to be
backed off some. This will give the machine a wider range
of adjustment. Adding the blocking required about a 1/2 inch cut
out on each side of the divider boards to assure that they would
continue to pass through the narrowed exit.
With the
added compression potential and our use of straight grained boards,
we were concerned with the possibility of splitting out the board
behind the lever anchor point. We added metal plates to keep the
pivot pin of the compound lever from breaking out of the back of
the side boards (see Figure 3.)
To improve
the operation of the baler we also wanted to stop the rocking that
occurred with the first prototype as the lever was pushed to compress
large batches. We made several changes to improve the seating by:
• Adding a cleat on the bottom at the lever end.
• Insetting the bottom ends of the center tie bolt and the
exit tensioning bolts.
A further improvement may be possible by adding an inch
of thickness to the cleat under the exit end. This would throttle
the bottom floor as well as the top to better assist in compressing
bales
We have
found that this small baler needs to be moved frequently. In looking at means to facilitate its being lifted and carried, we realized that carrying the lever end was most difficult. We added cut outs in
the top side boards at the lever end to serve as ready hand grips.
While we
needed to ship this new baler immediately upon completion, we did
test it by re-baling a couple of broken bales. It
worked well, and we look forward to hearing field tests
of how it is working. Each of these improvements was modest, and
nearly without cost. We hope they will combine to make using the
Tillers-Themi baler significantly more productive.
At a
future date, we hope to build another model to test extensively
here and in the tropics. We need support in time and money for such
an investment. We feel that this simple machine has great potential
for increasing the use of fodder in many of the new zero-grazing
cattle projects.
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