Sunday, 14 April 2013

Meet The Press

The blog has been a little quiet lately, I've been keeping busy with the last details of the chair and desk set and should have some final photos ready soon. I've also been getting geared up for the next big project. Which of course necessitates a few smaller prepatory projects. This upcoming project will require a lot of veneer work and panel pressing. Though I do have a couple friends on whom I could lean to borrow their presses I started to do the math on just how many trips to their shops this would be and how much of their time I would really be asking for and decided it best to invest in a press of my own. A vacuum press is a great tool for any wide panel work. What would require many many clamps and weights can be simply put into a large bag which is sealed shut and has the air sucked out of it.

The first step in setting up the press is to get a large flat surface to work on.  I decided to build a torsion box out of plywood and mount it to the wall with hinges.  The torsion box has a 3/4" thick bottom, 3/4" grid of support inside, and a 1/2" thick top.  The grid was made of 3" wide strips of plywood on edge to give the box the rigidity it requires.  The bottom is a little thicker to allow for screws for mounting some light weight storage on the underside. 

Torsion Box Grid
 The box itself went together quite quickly using about 300 screws. 

Finished Working Surface of the Torsion Box
Of course the torsion box is just the first step in getting the vacuum press running.  The box itself was mounted to the wall on some door hinges and a couple of collapsible legs with adjustable height feet were added to keep it level while in use.  On top of the torsion box is where the bag of the press will reside and inside it there needs to be a platen.  The bottom platen was made out of 3/4" melamine laminate.  The board had a series of channels cut into it to allow for the evacuation of air.  When in use any object that goes into the press needs to rest over top of these. 

Melamine Platen Which Goes Inside the Vacuum Bag
When in use there also needs to be a way on top of the workpieces for the air to be evacuated.  Rather than make another platten which would be a little unwieldy we can use a breather mesh which has channels allowing the air to escape.  The Vacuum hose needs to attach above this mesh and the mesh also needs to cover the workpeices.  This will create a series channels allowing the air to escape throughout the bag which is what gives us the even pressure we need for effective pannel assemblies. 

When an effective vacuum has been reached the pump continues to run and a bleeder valve is adjusted to maintain consistent pressure for the duration of the lamination.  The pressure achieved is somewhere in the ball park of 11psi.    

The Press Being Put to Work for the First Time
On the Friday of the weekend when I was to build the press a good friend at work asked what the plans for the weekend were.  She knows that I'm a woodworker and that most of my weekend plans revolve around wood in some way, so I told her about the project.  She then asked if this stuff was like porn for me.  We both got a laugh and I told her no, though in hindsight, maybe it is.  

If there is one thing that keeps me up at night, that I scour the internet for on a regular basis, and have magazines arriving monthly at my house for, it is woodworking.