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.