Thin Air Vacuum Press Tips
You
might think a skateboard company wouldn't have much to say about woodworking.
But the Roarocket Skateboard Company has not only invented a
new way to build a skateboard deck, but they have also taken their
laminating process into the woodshop to make vacuum veneering technology
available at an incredibly affordable price. Vacuum press
veneering is one of the best methods for applying veneer to a substrate and has
been used for years in the boat building and aircraft industry. With the Thin
Air Vacuum Press Kit, this valuable technique is available in an easy to use,
hand operated form that's perfect for small-scale veneering projects.
Besides producing ample force, a vacuum press has features that make it just
about the perfect method for applying veneer. Unlike mechanical clamping
systems, a vacuum press applies even, consistent pressure over the entire
surface of the workpiece, creating "intimate contact" between the
veneer and the substrate. Additionally, a vacuum press actually draws air out of
the cells of the wood, which is replaced by adhesive. According to adhesive
manufacturers, intimate contact and cellular penetration are the two most
important features in creating an optimum bond.
How it Works
A vacuum press consists of nothing more than a vinyl bag with a pump attached to
evacuate the air from the bag. The press relies on atmospheric pressure to press
the veneer against the substrate while it is being glued. Vacuum presses
produce a surprising amount of clamping pressure -- at 25 Hg (inches of mercury)
a vacuum press will exert 1872 lbs. of pressure on a 1 square foot piece of
wood. And for all of the advantages that a vacuum press offers, it's a
fairly easy to use piece of equipment.
Most vacuum presses are operated with an electric air pump, or a Venturi pump
that operates using compressed air and the Venturi principle to create a vacuum
by running air through a small orifice. The Thin Air Vacuum Press instead uses a
very simple hand pump to evacuate air from the veneering bag. One of
the features of the Thin Air pump is that the bag is so well made that it
virtually eliminates leaks, which means that there is no need to keep
pumping air out of the system, as is often the case with larger
systems. The Thin Air bag will hold 24 Hg of vacuum for days - far
longer than you'd ever need in a veneering operation. Bags for the system are
available in 14'' X 47'' and 26'' X 28'' sizes and are perfect for everything
from marquetry projects to making parts for smaller pieces of furniture.
 The
Thin Air Kit comes with everything you need to do a great job of veneering small
project, including easy to follow instructions that cover vacuum veneering onto
a substrate, "freehand" vacuum bending, and vacuum bending using a form. Be
we think this vacuum press is such a great tool, we'd like to add a
few of our own suggestions for getting the most out of the pump.
Thin Air Vacuum Press Tips
Make a platen for the press. It's
important for your work to maintain the correct position and shape while it is
in the press. If you're going to be doing a lot of veneering of flat surfaces, we
recommend making a "platen" for the the press. A platen is a rigid
flat surface that's positioned underneath the work-piece and
helps keeps things flat and lined up while the glue sets. It's also
important for the vacuum press to have a route for air to flow out of
the bag when it's being drawn down to a vacuum. The kit comes with a mesh
bag that covers the glue-up parts and helps give the air in the bag an
"escape route." A vacuum press platen usually has groves cut
into it to give the air in the bag an easy route out of the
press.
A piece of 3/4'' melamine that's a couple of inches smaller than the usable
area of the bag will make a perfect platen. Cut groves 1/4'' deep in
the melamine 2'' apart going in both directions. Remember to ease off
all of the sharp corners of the platen to protect the bag from cuts and
sharp creases when the press in use. The platen will help keep your
flat work flat, and it'll give the air that you want out of the bag an
easy route.
Make sure that you use the right sized cauls when veneering. A
caul is a flat piece of wood laid over the top of the veneer to help evenly
distribute pressure. In most cases, the sheet of veneer you use will
be trimmed to a slightly larger size than the substrate. It is important to make
the caul you use slightly larger than the substrate to avoid breaking the
edges of the veneer during the gluing process. If you use a thin
material, like 1/4'' sheet material, the edges of the caul could be snapped off
by the pressure of the press. Worse, the caulks could bend at the edges and bow
upwards in the middle of the workpiece, causing an area of insufficient pressure
in the center of your project.
To avoid these catastrophes, use 3/4'' material for your cauls. MDF
(medium density fiberboard) surfaced with melamine is an excellent choice
because PVA glues (like yellow wood glue or ordinary wood glue) won't stick
to it. Again, remember to round off the top edges of your cauls to protect
the bag.
Stack cauls on glue-ups of rigid materials. Occasionally,
you may want to laminate two or more fairly rigid materials together using
your Thin Air press. For example, you might need three thicknesses of
3/4'' material glued together as a blank for a decorative bracket for a handsome
new bar you've just built. To make sure that the pieces of
thicker stock are thoroughly drawn together, you can increase the
pressure applied by the press by stacking 3 or 4 caulks of incrementally smaller
size on top of the workpiece. Since these caulks serve in
a supporting role, and don't have to be of any exact size, keep them
around for future projects.
Keep the press clean and out of harm's way. One
of the great things about the Thin Air vacuum press is its capacity for
holding vacuum for a long time. Dirt and dust that's allowed to
get into the valve, or onto the butyl sealing tape, will decrease the
presses' capacity to hold a vacuum. Since the press is the type
that gets pulled down to maximum vacuum once, and has to stay that way
until the glue sets (in other words, doesn't have an electric pump and automatic
switch to turn the vacuum back on as larger systems do) it's especially
important to protect the components from dust and other contaminants that
could interfere with the systems ability to keep a strong vacuum.
We expect you'll get years and years of reliable service out of
your Thin Air Vacuum Press. During that time, you're going to need lots of
veneer related supplies. Be sure to check out Rockler's extensive
stock of
veneer and
veneer
equipment and supplies - you'll find the Thin Air Vacuum Press Kit
and accessories there, too.
As always, happy woodworking.
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