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VITA                    TECHNICAL BULLETIN               51025-BK
                        Chain Link Fence Making Machine
This bulletin contains step-by-step procedures for parts manufacture and
assembly of a hand-operated machine for making chain link fencing.   The
machine here is designed to produce fencing up to 244 cm (96") but can be
used to produce fencing of any height.  The size of the openings in the
fencing is controlled by the size of the "bending-head." The machine described
here requires #12 or #14 wire, but the machine could be modified to
take larger wire.
The chain link fence making machine was designed by VITA in response to requests
from South America and Africa.  In Botswana, the machine has become
the basis for a small fence manufacturing business which serves as a source
of employment and produces fencing which is far more affordable locally
than is the imported fencing which was the only material previously available.
Please send testing results, comments, suggestions and requests for further
information to:
                       1600 Wilson Boulevard, Suite 500
                         Arlington, Virginia 22209 USA
                     Tel: 703/276-1800 . Fax: 703/243-1865
                                                         ISBN 0-86619-105-4
                           VITA TECHNICAL BULLETINS
                 This Technical Bulletin is one of a series of
                 publications that offer do-it-yourself technology
                 information on a wide variety of subjects.
                 Technical Bulletins are idea generators, intended
                 not so much to provide a definitive answer as to
                 guide the user's thinking and planning.  Premises
                 are sound and testing results are provided, if
                 Users of the information are asked to send us their
                 evaluations and comments based on their experiences.
                 Results are incorporated into subsequent
                 editions, thus providing additional guidelines for
                 adaptation and use in a greater variety of conditions.
Clamp two halves of crankshaft-bearing block (1A) in vise, drill two 0.6cm (1/4")
diameter holes vertically through both halves and drill 2.5cm (1") diameter hole
horizontally.<see figure 1>

clf1x1.gif (353x353)

Similarly, clamp and drill two 0.6cm (1/4") diameter and one 5.7cm (2 1/4") diameter
holes in bending-head block (1B); also drill 0.6cm (1/4") diameter vertical
hole with 1.3cm (1/2") diameter x 0.6cm (1/4") deep counterbore in top half. <see figure 2>

clf2x1.gif (353x353)

Drill 0.6cm (1/4") diameter hole in bending-head arm (4) and round off corners. <see figure 3>

clf3x1.gif (317x317)

    A          5        2
    B          1          3/8
    C          0.5        3/16
    D         21        8 3/8
    E          3.2      1 1/4
    F          0.5        3/16
    G         16        6 1/4
    H          3.7      1 1/2
    I         11        4 1/4
    J          5        1 7/8
    K         14        5 5/8
    L         13        5 1/4
    M         38        15
1.   Assemble tension-assembly as shown. <fig 14>

clf14x2.gif (309x382)

Assemble tension-assembly sheaves in one way. <fig. 11 & 12>

clf11x20.gif (353x353)

Bearing pipe ODs in Figure 12 may have to be filed slightly so that sheaves

clf12x2.gif (353x353)

are snugly free-turning.
2.   Assemble bending-head assembly. <figure 13>

clf13x3.gif (486x486)

Crankshaft OD may have to be filed slightly so
that handle (1) is snugly free-turning; bending-head
arm (4) width may have to be filed slightly so that it is
snugly free-turning inside pipe.
3.   Fasten machine bed (2) to suitable sturdy legs approximately 90cm (36")
above floor. <see figure 15 and 16>

clf15x3.gif (600x600)

4.   Mount all machine components to bed (2) as shown in top and side views.
<see figure 18>

clf18x4.gif (600x600)

Cross-section assembly view of bending-head mounting; force nut (14) into
counterbored bending-head block (1B), place bending-head brace (8) on top
of block and mount to bed (2) with bolts (13), flat washers, lockwashers
and nuts; thread bolt (14) through nut until end of bolt is flush with
bending-head pipe ID; tighten second nut to prevent loosening.
4.   Bend crankshaft (5), cut slot in end
    indicated, drill 0.6cm (1/4") diameter
    hole through slotted end and
    drill four 0.3cm (1/8") diameter
    holes. <see figure 4>

clf4x5.gif (486x486)

5.   Cut 0.5cm (3/16") wide
    spiral slot in bending-head
    pipe (7); to mark
    spiral, cut strip of
    heavy paper 8cm (3 1/8")
    wide and wrap around
    pipe.  Drill 0.6cm
    (1/4") diameter hole
    in top of pipe. <see figure 5>

clf5x5.gif (393x393)

Smoothing the spiral groove.
It is necessary to smooth the spiral groove with a small file so that the wire
will move freely through the bending-head.
Strengthening the bending-head.
To make the bending-head stronger, start with a piece of pipe 2" (5cm) longer
than required.  Cut the spiral groove as described in the instructions leaving
the 2" uncut portion at the end near the crank.  Made in this way the pipe will
hold its original shape much better and the uncut part will not interfere with
the operation of the machine.
Alternate method of crank construction.
The crank can be made from 1/2" diameter pipe and fittings, if available.
Alternate method of constructing tension-assembly.
A very simple and suitable tension-assembly can be made with wooden pegs
mounted in a board as shown below.  The wire is passed around as many of the
pegs as necessary to provide the proper tension.  As wear begins to show on
the pegs they can be driven into the board until the area of wear disappears.
After some time it will be necessary to replace the pegs.
The positioning of the wooden peg tension-assembly will depend on the general
construction of the machine.  If it is built with wooden legs, the pegs can
be placed in the leg nearest the bending-head to form the tensioning device.
Otherwise, the tension-assembly must be constructed as a separate piece and
attached to the machine bed in the appropriate position.
6   Drill three 0.6cm (1/4") diameter holes in bending-head brace (8). <see figure 6>
7   Form hooks (11). <see figure 7>
8   Drill three 1.3cm (1/2") diameter and three 0.6cm (1/4") diameter holes in
   tension-assembly base (6). <see figure 8>
9   There are two methods of fabricating the tension-assembly sheaves (9A & 9B,
   or 10) and their axles (26A or 26B):
   a.  Preferred method, if use of lathe is possible, Figure 9 cross-section
       view: fabricate sheaves (10) as shown.
   b.  Alternate method, if use of lathe is not possible, Figure 10 cross-section
       view: assemble sheaves (2-9A & 1-9B) each) with bearings (9C)
       as shown; file bearing (9C) lengths so that assembled sheaves will
       revolve sungly; 9A and 9B may each be built up of series of thin
       washers, if necessary.
Making the spiral groove in the pipe.
The width of the paper used for marking the spiral groove is:
     2 5/8" (6.7cm) wide for 1 1/2" (3.8cm) pipe
     3 1/8" (8cm) wide for 2" (5cm) pipe
The paper is wrapped spirally around the pipe with just enough space between
the edges of the paper to mark with a pencil.
Using a hacksaw, cut along this line, rotating the pipe so that the blade just
goes through the metal.  Too deep a cut will cause the hacksaw blade to bind.
A second cut is made near the first so that the resulting groove is 3/16"
(0.5cm) wide.
1.   Feed #12 or #14 wire from wire feed roll over nearest tension-sheave;
under middle tension-sheave and over last tension-sheave into spiral slot
in bending-head pipe.
2.   Figure 17:  Clockwise rotation of crankshaft handle will produce properly
formed wire at output end of bending head; continue rotating crankshaft handle
until formed wire is of sufficient length for desired fence height.
3.   Figure 17:  Cut wire and rotate handle so that a second strand is formed
which will interlock with first strand.
4.   Figure 17:  Continue the above procedure until fence length reaches end
of machine-bed; hook hooks (11) to last formed strand to support fence and
continue as above.  As each strand is completed, move hooks to that strand.
5.   5cm (2") ID bending-head pipe used with 5cm (2") wide bending-head arm
will make fencing with 10cm (4") mesh, while 3.8cm (1 1/2") ID pipe and
3.8cm (1 1/2") wide arm will make 7.6cm (3") mesh.
6.   Lubricate both bending-head assembly and tension-assembly occasionally.
Soap makes the best lubricant for the bending-head because it does not leave
the fence dirty as does oil or grease.  The soap can be applied as a thick
soap and water solution to the bending-head itself or by allowing the wire
to pass over a dry bar of soap just before it enters the bending-head--after
passing through the tension assembly.
  The parts are assembled by bolting the blocks "C" and
"D" to a sturdy, narrow table or work bench, as shown
above. If such a work bench is not available, it may be
constructed for this purpose. The top of the bench should
be made of a plank 1 foot wide, 10 feet long, and 1-1/2
inches in thickness.
  As the wire feeds off the supply roll, it goes first
through the pulley assembly. It goes over the first pulley,
under the second, and over the third. The end of the wire
is then inserted in the slot in the pipe "A". When the
crank is turned (clockwise) the wire winds around the
steel plate or "bending arm", follows the spiral slot, and
is forced out the other end in the form of a flat spiral.
When the spiral strand reaches the desired length, it is
cut off with wire-cutting pliers. The first strand is held in
place while the next strand winds itself around the first.
  A narrow board (1 inch x 4 inches x 103 inches) is
fastened to one side of the work bench, as shown above.
Wire hooks are arranged along the edge of this board, and
are used to hold the finished section of wire in place,
while each succeeding strand is being made. This arrangement
holds the fencing up off the table, so that the spiral
has room to turn.
  As each strand is cut off, the two ends are twisted together
with the ends of the preceding strand.
  Finished fencing accumulates on a roll on the floor beside
the work bench. For continuous production, a rack
may be prepared, with an axle-and-crank arrangement, on
which the finished wire may be rolled up as it accumulates.
  Also, for continuous production, it is best always to
leave a short section of fencing in line on the machine,
since the first few strands are always somewhat difficult
to hold in line. To separate two sections of fencing, it is
not necessary to cut the wire; simply loosen the two ends
of one of the strands and turn the spiral backwards out of
the fencing.
     An abstract of the fence-making machine as it appeared in "World Neighbors
     in Action." <see figure>
A. The size of this pipe determines the size of the openings
   in the mesh. A 2-inch pipe will make fencing with
   4-inch openings. To mark the spiral, cut a strip of
   heavy paper 3-1/8 inches wide and wrap it around the
   pipe. To cut the spiral slot, a hacksaw is used. The
   slot should be 3/16 inches wide. A 1/4-inch hole is
   drilled in the top of the pipe, for holding it in place.
B. This "blade" may be made from steel or strap iron. It
   must be tough enough so that it will not tend to twist
   out of shape with use. The edges should be filed off
   so that it fits snugly but turns freely inside the pipe.
C. Two blocks are clamped together and a 1-inch hole
   bored between them horizontally, as shown. Two 1/4-inch
   holes are also drilled vertically, for fastening the
   blocks to the work bench.
D. In the same way, the two blocks are clamped together.
   A hole 2-1/4 inches in diameter is bored horizontally,
   and three 1/4-inch holes are drilled vertically, as
   shown. The top center hold also requires a 1/2-inch
   counterbore, (1/4-inch deep) in the top block, to admit
   a locknut. A 6-inch strap iron is also drilled with three
   1/4-inch holes to match the holes in the blocks. (See
   Figure 3 on page 5).
E. The crank may be made from a 1-inch rod, 31 inches in
   length. A 3/16-inch slot is cut in the end, so that it
   will fit over the "blade", or bending arm. Holes are
   drilled as indicated, to hold the crank in place. A 5-inch
   length of pipe is fitted over the handle, so the
   crank will turn easily in the hand.
F. The size of the pulley sheaves is not especially important.
   A 1-1/2 or 2-inch diameter is a good size to
                              [C] VITA, Inc. 1978
                                      IN TECHNICAL
                                  ABOUT VITA
                 Volunteers in Technical Assistance (VITA) is
                 a private, nonprofit, international development
                 organization.   Started in 1959 by a
                 group of concerned scientists and engineers,
                 VITA maintains an extensive documentation
                 center and worldwide roster of volunteer
                 technical experts.   VITA makes available to
                 individuals and groups in developing countries
                 a variety of information and technical
                 resources aimed at fostering self-sufficiency--needs
                 assessment and program development
                 support; by-mail and on-site consulting
                 services; information systems training.  It
                 also publishes a quarterly newsletter and a
                 variety of technical manuals and bulletins.
                       1600 Wilson Boulevard, Suite 500
                         Arlington, Virginia 22209 USA
                     Tel: 703/276-1800 . Fax: 703/243-1865