7.0 Knife Installation/Changing
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A knife can last between 2,000 and 5,000 cuts before it needs to be sharpened. Cutting soft paper
(such as newsprint paper) or paper with high post-consumer recycled content can cause the knife to
need sharpening after only 2,000 to 3,000 cuts. Cutting pure paper, such as bond paper with no
recycled content, or hard paper can allow the knife to be used for as many as 5,000 cuts before it
needs to be sharpened. In all cases, the operator should continually check the quality of the cut to
determine when the knife blade needs to be sharpened. Some characteristics that indicate a blade
needs sharpening are:
•
The knife hesitates or stalls while making a cut.
•
The sheets are not all cut to the same length (usually the top few sheets are longer than the
rest of the sheets - this is sometimes called “draw”).
•
Cut marks appear on the cut face of the paper.
•
The profile of the cut (side view) is not perpendicular to the table.
•
The cut does not appear straight when viewed from the top.
•
The knife makes a “rough” sound as it passes through paper.
•
Nicks are visible on the cutting edge of the knife.
7.3.2 Cutting Stick
A worn cutting stick can affect the cut quality of the bottom sheets. When this happens, the cut stick
can be rotated. Usually, the stick should be rotated one or two times between knife sharpening.
There are 8 possible cut stick positions. The stick can be rotated 4 times, and then turned end to
end, and rotated 4 times again.
7.3.3 Bevel Angle
Challenge recommends that bevel angles for the Spartan 150 knives be 21°.
7.3.4 Helpful Suggestions
•
It may be helpful to own a “set” of knives. A set consists of 3 knives: one in the machine,
one as back up, and one at the grinder.
•
If the machine seems to strain but the cut quality is still good, reduce the pile height. You
may also carefully apply glycerin to the bevel when cutting hard, coated paper. Tie a cloth to
the end of a stick; dip the stick in glycerin, and apply. Never apply by hand! In lieu of
glycerin you may lightly rub white bar soap along the bevel. Lubrication will prolong the life of
your machine and reduce maintenance.
7.3.5 Knife Care
•
To prevent corrosion, knives are coated with light oil. It should be REMOVED WITH CARE.
•
While removing or installing a knife, be careful not to allow the edge to bump against the
machine. Nicks will result.
