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Ski Press
Overview
A ski is made by using a ski press. A ski press provides high, uniform
pressure to squeeze the ski materials together to form a ski. The basic
concept of pressing materials together to form a ski is depicted below in Figure
1. Pressure is exerted on the top and bottom of the materials until the epoxy between the layers of the materials
cures. The shape of a ski, that is, the camber and the curvature of the
tip (and tail), is created by pressing the materials up against a mold as shown
below.
Figure 1. The basic concept of pressing materials
together to form a ski.
Types of Ski Presses There are three main types of ski presses: (1) clamp press
(2) vacuum press, and (3) pneumatic press.
1. Clamp presses consist of a top and bottom mold as
shown in Figure 2.
The ski materials are placed between the two molds, and the
materials are sandwiched together by clamping the two molds together. Some techniques
to clamp the molds together include bolts, ratchet tie-down
straps, and hydraulic car jacks. Whatever the clamping method, the
objective is to achieve as uniform of clamping pressure on the ski materials as possible.
One major drawback of
using a clamp press is difficulty ensuring that uniform pressure is applied
along the entire length of the ski. Additionally, it is challenging to measure
accurately the pressure being applied. Although a clamp press is the most affordable
to built of all three types, the quality of skis that it produces may not be the
best.
Figure 2. A clamp press.
2. Vacuum presses work on the principle of vacuum
(or negative) pressure. Basically, a “bag” encloses a ski mold and the
ski materials. Uniform pressure to squeeze the ski materials
together is created by using a vacuum pump to suck out the air. Figure 3
depicts a simple diagram for a vacuum press. Ski materials are placed on a
bottom mold, then plastic film is placed over the materials and secured to the
edges of the mold creating a sealed cavity. Finally, a vacuum pump sucks out the air to produce the needed pressure
to squeeze the materials together.
For the most part, vacuum presses are versatile, relatively
easy to build and provide uniform pressure. However, the drawbacks are
limited pressure (often low) and problems associated with wrinkles and bubbles in
the vacuum film.
Figure 3. A
vacuum
press.
3. Pneumatic ski presses are common in the ski and snowboard
industry. Because of their ability to produce
extremely high pressure, these presses provide the best results.
A diagram of a pneumatic ski press is shown in Figure 4. In the figure, the
press consists of a very
stiff frame, a mold and a flexible bladder (or a large flexible hose capable
of sustaining high air pressure). The bladder is placed between the
molds as shown. Ski materials are placed between the bladder and
mold, and by inflating the
bladder, uniform pressure is created which squeezes the ski materials against
the mold. Note that the bladder pushes against the frame and mold.
Figure 4. A
pneumatic press.
The design and construction of a pneumatic press is more
difficult compared to the other two types. However, a pneumatic ski press
produces higher quality skis because of high, uniform pressure.
We use pneumatic presses exclusively and therefore only
discuss how to build these presses. The first step in building a press is
to build the frame. Afterwards, the press components such as the molds and
the bladder are constructed to fit the press. The following links
discuss each topic:
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