Make your Own Vacuum Bag Pt. 1

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Marc Spagnuolo: Welcome to Episode 17 of the Wood Whisperer video broadcast. I am your host Marc J. Spagnuolo and today I am going to show you how to make your own vacuum bag for your veneer press.

Now last time, I showed you how to cut your own veneer, and when you make big wide sheets of veneer like this, you need an effective way to get even clamping pressure along the entire surface. The best way to do this by far is with the vacuum press.

Now in its most basic form, a vacuum press consists of a sealable plastic bag, a board with grooves cut in it so that the air can escape and a pump which sucks out all of the air from the inside of the bag.

And you simply place your veneer in a glue sandwich inside of the bag. You seal it up and then turn on the pump.

Now by removing all the air, we are actually creating a vacuum and this means that atmosphere pressure is not applying 14.7 pounds per square inch. That is a lot of pressure and it is more than enough for the purposes of veneering.

Now there is one resource that I can count on time and time again when it comes to vacuum press veneering and that is JoeWoodWorker.com. You could buy everything there; pumps, pre-made bags, bag material, and even full kit.

But perhaps the coolest part of all is that if you are the DIY type, Joe provides all the information and the materials that you need to build your own system from start to finish. And since I am a DIY kind of guy and I am cheap, I am going to make my own bag using the tutorial on Joe site.

Now, there are two primary materials that you could choose form when shopping for bag material. There is Polyurethane and vinyl.

Now, you could read more about the differences between these two materials on Joe site, but I will only make it simple for you.

Polyurethane is more durable and flexible but it is also more expensive. Vinyl on the other hand is a bit less durable but it costs less. And my first bag here was made from vinyl and it is still in perfect condition after three years.

But since the prices of polyurethane have come down significantly, I will be using polyurethane for my new bag.

Now I want my bag to be roughly four foot wide by six foot long, so I bought a roll of poly that is about 4 yards and 41/2 feet wide.

This way when I fold it in half, I have a rough size of 4 x 6. So before we jump in, let us review the tools we need:

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You will need a:

Marker
Vinyl cement
Abrasive pad
Seam roller
Utility knife
Long steel rule
Acetone

I started the process by completely unfolding the sheet of poly on my assembly table.

And then fold the sheet in half.

It is important to make sure that the sides line up perfectly.

I need a little extra room to work, so I move the whole sheet back a bit but I need to use quick clamps to stop the poly falling off from the table.

Now I need to draw a line 4 inches from the edge. The easiest way to do this is to use two metal rolls. Each one is 2 inches wide, so there is no measuring involved.

Using a line and a steel rule as guides, I cut through both layers of poly using a utility knife. Notice that I am using a piece of scrap ply as a backer that I do not cut into my table top.

When it is all set and done, you should be left with a very long 4-inch strip.

Next, I cut the 4-inch strip exactly in half. Now we can use one strip to seal up each side of the bag. But that is a few steps ahead.

Now I marked a line 2 inches in from the folded edge of the bag.

I then flip the handover and draw a line on the same spot on the other side.

Now when I unfold the bag again, I have two lines representing the area where I need to spread the glue.

Whenever gluing a joint, we will use the same exact process. It starts with the light acetone scrub using our abrasive pad.

This removes the surface oils and scratches the surface a bit giving the glue something to grab on to. Be sure to use a respirator, eye protection, and gloves, throughout this entire gluing process.

The glue is a clear liquid that spreads easily. I just brush on the nice even layer trying to stay within the lines.

With the help of a friend, carefully fold the bag in half.

Use the lines as a guide and once your lines match up, you can press the pieces together.

And then use a seam roller to ensure a good bond.


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