Head thickness determines the life span of a cutting tool in much the
same way as the head shape. The cutter life is directly proportional to the
thickness of the head.
High precision cutters are finished so that they meet exactly at the
point of the head. If you hold a good pair of diagonal cutters up to the
light you should see an increasing amount of light toward the back of the
cutters. Since most cutting is done at the tip, this increases the cutter
life by allowing the tips to continue to meet after some wear. Larger
cutters (over 5" in length) may meet along the entire blade as less tip
cutting is typically performed with larger cutters.
A pair of cutting pliers is a lever with the fulcrum point at the
center of the joint. The mechanical advantage of the lever is expressed as a
ratio by dividing length A into length B. Cutters with the largest
mechanical advantage will generally last the longest.
COST PER DOLLAR
Plastic cutting pliers have one purpose, to cut plastic. Proper
selection of cutters ensures that the tools you purchase will cut the
plastic you need to cut, where you need to cut it and most importantly, will
give you the maximum number of cuts per dollar spent. Once the physical size
and shape of the desired cutter is determined by the mechanical aspects of
the cutting problem, the economic justification and selection should be
based on the number of cuts per dollar.
The costliest mistake most often made in selecting cutters
is to buy too small. It is easy for a craftsman to be attracted to tiny
precision cutters under 4" in length. The number of cuts obtainable
from a cutter is directly proportional to the square of the weight of the
cutting head. Allowing economical considerations to put a 4" cutter
where a 5" cutter would do the job, reduces the number of expected cuts
by nearly half. Since 4" cutters typically cost more, the cuts per
dollar spent increases substantially. The rule of thumb is always the
largest cutter than can be used, should be used for the job at hand.
ANGLE OF THE
Most manufacturers offer various cutting blades described
as semi-flush, full flush, regular, etc. This refers to the angle of the
blade while looking straight at the end of the cutter. Flush cutters are
designed to reduce the amount of pinch left on the plastic. Flush
cutters should be specified where necessary. A good rule of thumb is the
greater the angle. the more cuts available from the tool.
Often, pointed or narrow cutters are chosen for the same
reasons that small cutters are popular, A pointed head, however, greatly
reduces the expected life span of the tool. With cutters of the same size
are compared, a round head will outlast a pointed head almost two to one.
Pointed head cutters should be used only where necessary. This is typically
when use of a rounded head cutter is impossible due to access tot he work.
The more material behind the cutting blade, the greater the number of cuts
that can be expected.
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