Paper Supply; Hengstler Paper Roll Holders; Designing Your Own Paper Roll Holder - Hengstler eXtendo X-56 Operating Manual

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eXtendo Thermal Printer Family
Please note that the shell of the USB connector automatically makes the ground
connection that is made via the pigtail in the serial version.

6.5. Paper Supply

6.5.1. Hengstler Paper Roll Holders

Hengstler offers two paper roll holders for use with the eXtendo
printers. One is a small holder intended to position 100 mm rolls of thermal paper in
various positions behind or below the printer. The second paper roll holder is
intended for paper rolls up to 150 mm diameter, and otherwise has similar
characteristics to the 100 mm version. Both paper roll holders will accept paper pre-
end sensors.

6.5.2. Designing Your Own Paper Roll Holder

It is sometimes desirable for customers to design their own paper roll holder in order
to fit in the available space, or to tailor performance to their specific needs. Based on
our extensive experience in designing printers, we would urge you to consider the
following topics and implement your design with care.
Large Diameter Rolls: When using paper rolls over 100 mm in diameter, a "dancer
bar" should be considered. This usually takes the form of a spring-loaded arm under
which the paper is placed before feeding it into the printer. As the printer starts to
print, slack is taken up from the paper roll. This starts to lift the arm against the
spring, which puts force on the paper roll and starts it moving slowly. As more
printing takes place the roll gradually accelerates until it's up to printing speed.
Without the dancer bar, slack paper would be taken up until it was suddenly no longer
slack. Now the printer must accelerate a large, heavy paper roll from zero speed to
full print speed in essentially no time. This usually causes the paper advance motor
to stall or the paper to slip against the platen, causing shortened characters until the
paper roll is up to speed.
Spindle Friction: Another important consideration is spindle friction. As a paper roll
rotates, it slides against the spindle that holds it, assuming a fixed spindle. This
friction will tend to impede the paper roll's free motion, and is dependent upon the
weight of the roll, the smoothness and material of the spindle, and the smoothness
and material of the paper core. When possible, especially with paper rolls over 100
mm in diameter, design the spindle so that it can rotate, greatly decreasing friction
and drag.
Catch Points: More paper jams and transport problems are caused by catch points
than any other issue. Make sure that the paper path is free of anything that can
interfere with free paper flow, especially any sharp edges or "pinch points" into which
the paper may stray and become caught.
Alignment: Any paper roll holder design must hold the paper square to the printer in
all planes. If the paper is angled in any way, it will enter the printer at an angle and
will be more likely to cause paper jams.
Rigidity: It is important that the paper roll holder support the paper firmly and not
move. This is especially true in high-speed printing applications and in large diameter
paper roll applications. Many paper roll holders are made from metal too thin to
support the heavy paper rolls they are expected to handle. This results in twisting
and warpage while printing, which binds the paper and causes paper jams. Vibration
during printing may also cause undesired movement of the paper roll.
Part No. D 684 124 Mod. No. 4 080812 LEV
HENGSTLER
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family of thermal
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