JoeWoodworker
JoeWoodworker Veneer
The Official Website of this Non-Professional Woodworker ™

Part 1
Introduction

Welcome
Veneering Basics

14 Good Reasons
Vacuum Press Uses
Vacuum Press Options
Overview

Questions & Answers
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Part 2a (Option 1 of 2)
Project: V2 Venturi Press

About Project: V2
Parts List
Build the Manifold
Build the Reservoirs
Assemble the Venturi
Make the Carrier
Wire the Press
Testing and Adjusting
Mods and Options
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Part 2b (Option 2 of 2)
Project: EVS Pump Press

About Project: EVS
Parts List
Pump Selection
Build the Manifold
Build the Sub-Manifold
Build the Reservoirs
Make the Carrier
Final Assembly
Wire the Press
Testing and Adjusting
Mods and Options
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Part 3
Vacuum Bagging

Vacuum Bag Basics
Polyurethane vs. Vinyl
DIY Vacuum Bags (A)
DIY Vacuum Bags (B)
Connect the Bag
Bag Closures
Platens/Cauls
Breather Mesh
Maintenance
DIY Frame Press

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Part 4
Veneer Information

About Veneer
Veneering Myths
Backer Veneer

Veneer Glues
Veneering Tips
Substrate Materials
Flattening Veneers
A Sharp Veneer Saw
Jointing Veneers
Taping Veneers
Dealing with Defects
Curing Glued Panels
Veneering w/o Vacuum
Hammer Veneering
Iron-On Veneering
Veneer Storage
Amazing Bookmatches
Copper Veneer Guide
Paperbacked Veneer

Edgebanding Guide
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Part 5
Miscellaneous Info

Vacuum Forming
Vacuum Chucking
Vacuum Clamping
Vacuum Clamp Matrix
Vacuum Infusing
DIY Vacuum Manifold
JWW Visitors' Vacs
Veneer Quality
Veneering FAQ
Veneer Glue FAQ
The Vac FAQ
Copper Veneer FAQ
Downloads (PDF's)

VeneerSupplies.com

Vacuum Veneering - Tips, Tricks, and More

Making A Small or Narrow Vacuum Bag

Vacuum Press for GuitarThe process of making an airtight bag had eluded me for many months. Time after time, I would make a decent sized bag and take all the necessary steps to prepare and seal it, only to notice a tiny leak somewhere. It was nothing but pure accident that led me to discover a solution that would seal the leaks on even my oldest bags. The secret? Well...read on.

The vinyl can be purchased at any place that makes boat covers or canvas awnings. Some fabric stores also offer it. If you have a difficult time finding vinyl for the bags, it can be purchasd it at VeneerSupplies.com. There are a few different thicknesses available in vinyl membrane sheeting. The most common are 20 gauge and 30 gauge. Either will work with similar results but the 30 mil will last longer.

Polyurethane bagging material is also available. If you are building your first vacuum bag, consider building it from vinyl. Though the polyurethane will last longer, it is more expensive and can be more difficult to work with when building a custom-size bag. The time involved in building a vacuum bag offsets any savings over buying one pre-made for most people.

The instructions below will work with vinyl or polyurethane.

Dont Forget

  1. The vinyl cement is extremely flammable and will destroy your brain if you use it in a poorly ventilated area.
  2. The vinyl cement is very much like contact cement when used on vinyl sheeting. Once you touch the sides together, there is little hope for removal.
  3. Polyurethane sheeting has a different reaction to HH-66 cement. It takes a full 24 hours to cure.
  4. You will need a heavy duty seam tool for this part.
  5. Any area that is to be cemented should be cleaned first with acetone or xylene. Synthetic steel wool or 'Scotch Brite' pads will help.

Tools and Parts

 

Small or Narrow Vacuum Bags

For this example, we will be making a bag that is an 18" x 54" rectangle. Cut a piece of vinyl that is 36" in length. The standard width on almost all vinyl sheeting is 54".

Bring the two 54" sides together. Remember, the bag should be about 18" by 54" not 36" X 27". The first two ends should come together so that the result forms a large tube. You do not want the shape to resemble a drop of water (see pictures). 

Correct Bonding Pattern
This is the correct bonding pattern.
Other Bonding Pattern
Do not bond the ends like this.

Using acetone or xylene, clean the surfaces where they will overlap (about 3 inches will do). The overlapped area with serve as a reinforcement for the valve stem. While the xylene is drying, mentally prepare yourself for the next steps. Try to envision the area where the two ends will overlap. Three inches of overlap will make a nice joint.

You will want to apply more cement at the inside and outside edge where the overlap stops. You may find it easier to roll the bag inside-out to get to the inside seam flap. For vinyl, let this dry for an hour or so. For polyurethane, wait 24 hours before continuing and use two flat boards and some spring clamps to keep the seam tight while curing.

Next, you need to seal one edge of the two that remain in order to make a bag.  Lay the bag down so that the first seam that you made (already cemented in place) is centered at the bottom of the bag. Clean the surfaces of the mating edges (at one end of the bag) with acetone or xylene, and proceed with cementing as you did for the first seam. Be sure to use the seam tool to firmly press the corners tight. At the bag end, you won't be able to make the "tube" shape so it will more resemble the tear drop shape this time. If you have an extra piece of vinyl, it would be well-suited to reinforce the end seam. Cut a piece 3" wide that is as long as the bag is wide. Clean the strip with xylene, and press it evenly over the end seam so that equal amounts of vinyl are over each side of the bag.

Making the Bag Air-Tight

Set up your bag and attach it to the system. Place the platens in the bag. Clamp the bag shut, and turn on the press. When at least 18” of Hg is achieved, use the HH-66 vinyl cement to "paint" the edges of all previously sealed seams. Like magic, the cement will be pulled into any leaks. You might even hear the seam bubbling, and then just stop within seconds as the cement fills the void. Turn the unit off and let the cement cure over night. A second application of cement may be necessary.


Tips and Tricks
Bag Making Tip from Vacuum Press Builder Edd Fair:

I worked out another method to glue long bag seams.
Lay the bag in its folded final position after cleaning the surface with xylene. Start lifting and applying cement in about 12 inch segments as you lift the edges apart. This takes two people. The front person lifts and glues. The second person squeegees the seam with a seam tool. Move forward at a slow pace to allow cement to kick just enough to get initial bond. After we "wet" glued the seam, we clamped the seam to the bench with a 3 inch wide strip of plywood and let it cure for about ten minutes.

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