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

Part 1

Veneering Basics

14 Good Reasons
Vacuum Press Uses
Vacuum Press Options

Questions & Answers
Part 2
Project: EVS Vacuum 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
Part 3
Vacuum Bagging

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

Part 4
Veneering Information

About Veneer
Veneering Glossary
Veneering Myths
Balancing a Panel

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

Part 5
Miscellaneous Info

Vacuum Press FAQ
Veneering FAQ
Veneer Glue FAQ
Copper Veneer FAQ
Vacuum Forming
Vacuum Chucking
Vacuum Clamping Pedal
Vacuum Clamping Jigs
Vacuum Clamp Matrix
DIY Vacuum Manifold
Vacuum Press Gallery 1
Vacuum Press Gallery 2
Downloads (PDF's)


Vacuum Veneering - Tips, Tricks, and More

Method #1: Standard Bag Stem

When used in conjunction with the lock-on connector, the standard bag stem is a great way to create an air-tight connection between the vacuum bag and the vacuum source. This bag stem will work on vinyl and polyurethane vacuum bags as well as a range of other applications.

These bag stems have air channels cut from outward the center hole to direct airflow quickly from the vacuum bag.

The stem consists of the following parts:

  • Zinc plated bag stem (x1)
  • Extra-wide zinc plated washers (x2)
  • Zinc plated stem washer (x1)
  • Zinc plated stem nut (x1)
  • O-ring
  • Medium density foam grommets (x2)

Lock-On Vacuum Connector


Standard Bag Stem

The grommets are attached to the washers with an acrylic adhesive which prevent them from creeping if the vacuum bag stretches. With only a bit more than hand pressure, this combination also prevents elongation of the opening where the stem is placed. No cementing is needed and because of this, a bag stem can be moved from one bag to another if needed.

Attachment Instructions

  1. Cut a 3/8" hole near the top center of the vacuum bag to accept the bag stem body.
  2. To significantly increase the speed of air flow from the vacuum bag, remove the valve core inside the stem with a pair of small tweezers or a dedicated core remover. The valve core is the largest flow restrictor in the system.
  3. Cut a 3/8" hole near the top center of the vacuum bag to accept the bag stem body.
  4. Slide one of the grommet/washers onto the bag stem body with the black side facing up.
  5. Insert this portion of the assembly through the hole in the vacuum bag.
  6. Slide the other grommet/washer onto the bag stem with the black side facing down (against the vinyl).
  7. Attach the washer and tighten the nut with a 9/16" wrench. One complete turn past standard hand/finger tightening will suffice.

See the vacuum connector
lock on and stay on!

Method #2: Flush Mount Bag Stem

Flush Mount Bag StemThe flush-mount bag stem allows you to use the full length of the vacuum bag without worry of project surface imperfections caused by the protrusion of the standard bag stem.

These improved bag stems have a specially designed 2.5" diameter 50 mil flange molded onto the valve body which gets cemented onto your vacuum bag. A sharp-barbed brass insert slides into the valve body and locks into place.

Attachment Instructions

  1. Mark the location on your vacuum bag where you wish to install the bag stem. For convenience, we recommend installing the stem 15” out from the bag opening. The location will not affect the pressure inside the bag.
  2. In the selected area, cut a 3/8" diameter hole in the vacuum bag using scissors or a razor knife.
  3. A small tube of cement is included with your bag stem kit. This cement will
    work with both vinyl and polyurethane materials. Be sure to follow the safety
    instructions included with the cement and wear appropriate eye, skin, and lung protection when using this product.
  4. In a well ventilated area, clean the mating surfaces of the bag stem body and the vacuum bag with acetone. A synthetic abrasive pad will help maximize the effectiveness of the cleaner. When completed, the cleaned areas should look dull and abraded.
  5. Apply the cement to the bottom of the valve body and to the vacuum bag area where the bag stem will be attached. Be sure there is full coverage on both pieces.
  6. For vinyl, allow 3 to 4 minutes for the cement to set up. Then apply the valve
    body directly over the port hole (step 2). Using adequate pressure, smooth out the bag stem flange until any air bubbles are removed. A wood roller is helpful with this process. Allow 1 hour of drying time before using the vacuum bag.
  7. For polyurethane, immediately set the valve body directly over the port hole after application of the cement. Gently massage out any air bubbles but try not to squeeze out too much of the cement. Allow 24 hours of drying time before using the vacuum bag.
  8. Insert the brass barbed valve core that is included with the bag stem. Proceed carefully since the edges of the barbs are sharp. Once inserted, the valve core is not easily removed.

Method #3: Do It Yourself Automotive Valve Stem

The do-it-yourself method is great if you need a quick and cheap solution. You'll need to purchase a pack of threaded "mag" wheel valve stems from a local automotive supplier such as Pep Boys.

Construction and Attachment Instructions

  1. Reinforcement is needed on the vacuum bag where the bag stem is applied. Cut two pieces of vinyl sheeting about 2" x 2" and use acetone or xylene to clean the vinyl where it will be bonded to the vacuum bag. You'll also need to clean the mating areas on the bag itself.
  2. In a well-ventilated area, apply HH-66 cement to one side of each of the 2x2 vinyl pieces. Place one of the vinyl pieces inside the bag at the location where you will be mounting the bag stem. Then place the other vinyl 2x2 on the outside of the bag (directly over the inside vinyl piece). Now place a piece of scrap wood under the inside 2x2. This will prevent the cement from bonding to the inside-bottom of the bag. Press the assembly down with a wood roller. Allow one hour of drying time.
  3. Remove and discard the valve core assembly inside the mag stem by unscrewing it using two small flat head screwdrivers or a pair of tweezers.
  4. Use a Dremel tool or hack saw to cut an "X" on the bottom of the bag stem about 1/8" deep. This will allow air to escape, even if the bottom of the stem is pressed against the flat area on the top of the platen.
  5. With a razor knife, remove the extrusions on the black washers so that the only rubber that is left is a flat washer, similar to the ones in the picture. These washers will seal the bag stem and the port hole on the vacuum bag and give you a reasonably air-tight connection.
  6. Now cut a 3/8" hole in the center of the reinforced of the vacuum bag. You will be cutting through three layers of vinyl (two reinforcement pieces and the bag itself).
  7. Place one of the rubber washers on the stem. Insert the stem up through the port hole in the vacuum bag. Press the other soft rubber washer onto the stem (from the top of the bag). Attach the metal washer and nut and firmly tighten.
  8. To connect the vinyl tube from the vacuum press to the stem, you'll need a lock-on connector designed to attach to the bag stem.


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