SMALL-SCALE PAPER BAG
VITA Volunteer George R. Clark
This process is for the manufacture of small, box-shaped
paper bags (our specific process
turns out one and three quarters kilo bags, but a similar
process is possible for other sizes as
well.) It is
designed to make 500 bags per day with a labor force of 3 to 5 people.
This method uses labor as much as possible, and simple machinery
where necessary to
provide speed. The
machinery is completely hand operated, and consists of a device for
folding the bag tube and simple aids in hand-folding the bag
Please send testing results, comments, suggestions, and
requests for further information to:
1600 Wilson Boulevard, Suite 500
Arlington, Virgnia 22209 USA
Tel: 703/276-1800 * Fax:
[C] VITA, Inc. 1989
VOLUNTEERS IN TECHNICAL ASSISTANCE
VITA Technical Bulletins offer do-it-yourself
technology information on a
wide variety of subjects.
The Bulletins are idea generators
intended not so much to provide a definitive
answer as to guide the user's
thinking and planning.
sound and testing results are provided,
Evaluations and comments based on each
user's experience are requested.
are incorporated into subsequent editions,
thus providing additional guidelines
for adaptation and use in a
greater variety of conditions.
SMALL-SCALE PAPER BAG MANUFACTURING
This simple process for manufacturing paper bags requires
construction of several simple pieces of equipment.
made mostly of wood, with some pieces of spring steel and
or mild steel strips.
Construction requires basic carpentry skill
and simple tools.
TOOLS AND MATERIALS
fine-toothed saw (for cutting small pieces
vise (for bending metal and sawing)
both wood and metal files
small hardened drills
smooth planks, fine grained wood that can
be cut into
very small blocks)
soft spring steel
wood screws, nails, washers
mild steel or iron strips (approximately
1.25cm x .3cm)
a small cutting board or equivalent
a supply of white glue and a dispenser
a supply of paper bag paper in a roll cut
to the proper
HOW TO CONSTRUCT PAPER BAG MAKING EQUIPMENT
The most complex equipment is the BAG FOLDING MACHINE, which
used to convert a roll of paper into a bag-shaped tube by
of a continuous folding process.
Others are a GLUING AID and a
BOTTOM FOLDING AID.
See drawings for details.
Please note: All
dimensions are in centimeters.
not shown in the drawings are optional.
Bag Folding Machine
The base of this mechanism is a long smooth plank,
254 cm in length. A
convenient width is approximately 20cm.
A rack (Component 1) to hold a roll of paper is fastened at
end of the base so that the paper is held with the center of
roll at the beginning of the base.
The rack is made so that the
roll will be exactly centered on the base, and not free to
from side to side.
Further along the base is a shoe (Component 2) that
slopes downward so that it almost touches the base about
from the center of the roll (measured along the base).
is designed to bring the paper down to the base, and to fold
the sides of the paper.
To aid in this folding, guides made of
steel wire on each side of the shoe almost press against the
of the shoe where the shoe comes closest to the plank.
Approximately 15cm from the bottom edge of the shoe is a
(Component 3) made of iron stock.
The main purpose of the guide
is to keep the bottom of the paper as flat as possible
the base. The guide
is the exact width of the distance between
the two first folds that were made by the shoe.
It keeps the
paper from drifting from side to side.
This guide also is fastened
so that it does not quite touch the base.
About 50cm further along the base are two more guides
one on each side of the base.
These are horizontally placed
pieces of metal that extend in from the position of the
fold to the position where the second fold is to be placed.
A block of wood (Component 5) is positioned between these
guides. This block
makes the second two folds by means of a small
piece of iron stock screwed to the bottom of the far end.
block of wood itself tends to keep the paper apart so that
two second folds will not be too close together.
The block is
prevented from moving with the paper by a piece of wood that
About 68cm further along the base are two guides (Component
that hook under the two second folds and hold these flaps of
paper approximately 1cm above the base.
Their purpose is to keep
the flaps from slipping under the next guide, another block
This second block of wood (Component 7) is positioned with a
2.5cm space between it and the previous guides.
This block is
identical to the other in every way except that it has no
of iron. This block
is simply a guiding device, not a folding
device. It is held
down by a piece of spring-steel.
The next guide (Component 8), positioned directly in front
this block of wood, prevents the block from being pulled
with the paper. This
guide is similar to the one positioned after
the shoe. It is the
width of the bag, and it sits on top of the
two folds, but under the top layer of paper, which is about
folded down. The
guide serves the purposes of keeping the paper
flat against the base, and of making sure that the top two
which are about to be made are not too close together.
Centered about 2.5cm from the center of this guide are two
horizontally placed metal guides (Component 4B) whose
is to make the final two folds, and to assure that these
are not too far apart.
These guides are the same as Component 4A
except that they do not extend inward quite as far.
This device consists of a foot square wood base, to which
position guides (for the paper bag) are fastened.
base, a template arm is fastened by a hinge mechanism, so
can swing down to place the template on the center of the
be glued together.
Another hinged arm, with a weight, is fastened to the base
opposite to the first arm.
The weight is positioned so
that it will come down on the glued seam in the center of
Make gluing aid weight and template pivot arms of wood as
Fasten with small nails or screws and glue.
Cut glue template out of sheet metal.
Fasten to template pivot arm with
small headed nails.
Bottom Folding Aid
The third device is the bottom folding aid.
This device consists
of a wood base with an aligning block along one side and a
metal spring to hold the bag in place.
<BOTTOM FOLDING AID>
HOW TO OPERATE
The first step in the operation is to place the properly cut
of paper in the machine so that the paper will come off the
bottom of the roll.
The paper should be correctly folded for a
couple of feet (as if it had come out of the machine) so that
paper can be fed into the machine.
The paper should be fed over
and under the guides as appropriate.
To feed the paper under the
spring-loaded blocks, lift the blocks to put less friction
Paper bag lengths of paper are made by standing at the end
machine, grasping the end of the paper, pulling to the
length, and cutting the length off with the cutting edges.
The tube is then placed in the tube gluing aid so that the
can be glued. One
flap of the paper is raised, and the other
left flat. The
temperate arm is lowered, and the glue is applied
in the template slot by
the glue dispenser. The template
raised, the raised flap of paper is dropped, and the
arm lowered to press the glued seam.
The glue will set in about
15 seconds or less.
The glued tube is then placed in the bottom folding aid with
glued seam facing downward.
The tube is placed under the metal
strip with one end placed against the guide line.
The tube is
then folded up on both sides of the metal strip so that
will be two crisp, straight, parallel creases.
Bag Folding Sequence
Folds in a bag tube:
Parallel folds to begin making bottom.
with seam down. Both folds are upward.)
The bag is left flat on a table, except for everything right
the inner fold, which is bent left.
The bag is opened up, and formed into a box shape.
The four 2.5cm-deep cuts are made here:
The sides, top, and bottom are folded in.
Flaps are folded along dotted line (which already exists as
fold), outer flap first, then inner flap.
The bag is then pressed
under a weight. The
bag is now complete.
The bag can now be
Alternate Gluing Methods
An alternative to the tube gluing aid is to glue the tube
by section as it is pulled out of the tubing machine and cut
to the proper length.
The template on the mechanism may have a
tendency to clog, making it somewhat difficult to apply glue
the bag by this means.
There are other simple ways to apply glue to paper besides
a dispenser. A brush
can be used that is manually dipped in a
pot of glue and spread on the paper.
The advantage to this system
is that it is neater, and the glue can be applied evenly and
thinly. The main
disadvantage is that the brush tends to dry out
and may be difficult to clean.
HOW TO ADJUST AND MAINTAIN
The only mechanism that needs careful maintenance is the
Some possible problems:
1) The guides must
not touch the base where the paper is to slip
If they do, the paper will bind and perhaps
2) The spring must
apply enough pressure so that the blocks of
wood will stay in
position, and not be pushed up when the
paper is drawn
through the machine. But the spring
too tight, or the
friction on the paper will be too great.
3) All guides that
keep the paper from moving from side to
side or which
cause the paper to be folded must be the proper
perfectly aligned. Otherwise, the folds
4) There must be no
sharp edges rubbing on the paper (except on
edges). The paper will tear if these
Other than the above, the tolerances are not critical, and
problems can be easily corrected by simple adjustments.
<![if !supportEmptyParas]> <![endif]>