Introduction: Building A Vacuum Press
There are only a handful of tools available to the average woodworker that can make an immediate and substantial difference in the quality of a finished project. A good miter saw, a classic router bit, or a fine hand plane; each of these tools can help turn a pile of lumber into a better display of craftsmanship. A vacuum press is no exception. Within this article, you'll learn how to veneer a panel with a vacuum press.
A vacuum press gives you the opportunity to use some of the finest woods available. Many of these species are so rare and valuable that they are unaffordable in solid lumber. In other cases, the wood may be too unstable to use in lumber form. By veneering those types of logs and burls, wood movement is controlled by the adhesive and a substrate like plywood or particle board.
Ultimately, the question is how to get the wood veneer to cure flat on the project panel. A vacuum press does the trick and now it does it easily and affordably.
After a year and a half of serious trial and error, and another year of updating and improving, I offer several free plans for building a vacuum veneer press. Make no mistake... each press is a heavy duty, durable, and reliable piece of equipment. If you follow the instructions carefully, the press will last for as long as you enjoy the art of veneering.
Most of the veneering books and articles I have read are just too complicated and are geared toward proprietary materials and equipment. The construction method found in the JWW vacuum press article uses standardized parts that can be found on the Internet and at your local hardware store.
I wrote these articles to show that you don't need a mega-buck setup to build a durable and reliabel vacuum press. I hope you'll agree. As always, you are welcome to email me suggestions for improvement.
Project: EVS™ Vacuum Press Examples
The Basic Idea
Imagine a giant zip-lock bag with a piece of plywood and an exotic wood veneer inside. To adhere the veneer to the plywood you need two things... glue and clamping pressure. The glue is placed on the plywood and the veneer is set on top. The panel is then placed inside the bag and the air from within the bag is removed with a vacuum system.
Vacuum can be achieved either through the use of an electric vacuum pump (diaphragm, piston, rotary vane, etc.) or with a pneumatic device called a venturi. On the following pages, you learn how the differences between these pumps affect their use in vacuum veneering.
In either case, a pump or venturi is rated by its air flow (CFM or cubic feet per minute) and the maximum achievable vacuum level which is usually referenced as a measurement of "inches of Mercury" or "inches of Hg".
A vacuum press is a very powerful tool that is capable of producing over 1700 pounds per square foot of pressure at full capacity. The actual formula is 1" of Hg equals 70.56 lbs per square foot. Even more impressive is that the vacuum creates this much pressure on every square foot within the vacuum bag. A simple 2' x 4' panel in a vacuum bag has a total of 11,200 lbs of "pressure" spread across the whole project. It's easy to see why vacuum pressing is considered the ideal method to bond wood veneers to most substrates.
Atmospheric pressure is what makes a vacuum veneer press capable of such incredible strength. When vacuum is applied, atmospheric pressure puts down a tremendous amount of force. Not only does this press the veneer onto the substrate, it also compresses the fibers of the materials being glued. As the fibers are compressed, the air inside of the materials is displaced with glue and within an hour, a bond is made.