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)
DIY Vacuum Bags (C)
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

Choosing a Vacuum Press Model
This page references the vacuum systems offered at VeneerSupplies.com.

Vacuum Press VideoVenturi System: A venturi model (Project: V2) cycles on and off using compressed air through an electro-mechanical valve and vacuum generator. This type of system is automatically controlled by a vacuum switch which measures the pressure inside of the system and keeps that level of pressure reasonably constant. A video clip of the press is now available.

Cycling Electric Pump: Also available are pump driven vacuum press systems (Project: EVS) that cycle on and off but achieve vacuum via an electric vacuum pump. Again, this type of system is automatically controlled by a vacuum switch which measures the pressure inside of the system and keeps that level of pressure reasonably constant. Here's quick video clip of the vacuum press in action.

Continuous-Run Electric Pump: A continuously running vacuum system uses an electric pump but does not cycle on and off. Instead, it is allowed to run continuously. Most pumps are rated for continuous duty and can last a very long time even with very little air flowing through the pump chamber. These systems are commonly sold by retailers because they are least expensive and easiest to assemble. The Project: CRS kit sold at VeneerSupplies.com has a unique feature that allows the user to dial in the exact vacuum level needed with a bleeder valve.

Portability
Though the EVS system is portable in the sense that electricity is easily obtainable, the system weighs a good 30 lbs. The 11 lb weight of the V2 press makes that system very portable but compressed air is not as easy to find outside of the workshop. The continuously running system (CRS) weighs about 18 lbs on average but this ultimately depends on the weight of the pump you choose.

Build Time
Vacuum Press HelpProject: V2 System: 2 to 3 hours
Project: EVS Cycling Electric Pump System: 3 to 7 hours
Continuous-Run Pump: 20 to 30 minutes

Price
Project: V2 System: $190 - $350
Project: EVS Cycling Electric Pump System: $200 - $500
Continuous-Run Pump System: $300

Quality
All of the systems available described here are amazingly reliable pieces of equipment. I wouldn't offer anything less. Of course, anything mechanical is subject to occasional down-time. With that in mind, I think it's safe to assume that the system with the least amount of moving parts is the most durable. So I often recommend the V2 systems if you have a suitable air compressor.

Adjustability
The cycling vacuum systems can be adjusted to pull vacuum from 3" to 25.5" of Hg. For most veneer users, a setting between 18" and 21" is ideal. Setting the system to pull higher vacuum levels does not improve the bond of the veneer to the substrate. Instead, it only forces the vacuum to work harder. For electric pumps, the flow of air (referred to as "CFM" or cubic feet per minute) is much less at the high vacuum levels which strains the pump unnecessarily.

A continuous-run pump will pull a level of vacuum consistent with its manufacturer rating. Most often, this is 25.5" of Hg. However, there are several factors that can reduce the pulling capacity of the pump.

  • Altitude: Approximately 1" of Hg is lost for every 1,000 feet above sea level. If a pump is capable of pulling 25" of Hg at sea level, it will only pull 20" at 5000' above sea level.
     
  • Leaks: Small leaks will usually not affect the maximum vacuum level. Multiple leaks can drop pressure readings by a more significant amount.
     
  • Bottlenecks: Science has proven that restrictive air passages will not only limit the CFM but also have a small but noticeable effect on the maximum achievable vacuum level.

For vacuum press users who are using the system for non-veneer work (such as foam core molding), higher vacuum levels can be destructive. An adjustable system is better choice for this kind of use.

Performance

  • Maximum Vacuum: Each of these systems can pull more than enough vacuum for veneer work and assembling bent laminations. At VeneerSupplies.com, the electric vacuum pump versions can generate 25.5" of Hg and the venturi based systems can generate up to 27.5" of Hg. This equals a respective 1,785 and 1925 lbs per square foot of pressure. See this chart for details.
     
  • Initial CFM: The most common performance measure is the vacuum's flow rating at zero pressure. This rating coincides with the amount of time it takes to draw down an empty vacuum bag. Bags that have a large amount of air inside (such as those being used in curved veneer project) will benefit from the use of a higher rated CFM.
     
  • CFM Curve: A venturi is capable of pulling vacuum faster than an electric pump at high pressure levels. In real life terms, this simply means that recharging cycles for 3 CFM venturi can be 1/4 to 1/3 shorter than a 3 CFM electric pump.

Project/Vacuum Bag Size

There are basic rules that determine the size (or CFM) of the vacuum source needed for various projects. Check out this chart to see which system is right for you. Keep in mind, these are rough estimates.

Project Minimum Requirements  
4' x 4' or less vacuum bags 1 CFM for flat panels 3 CFM for curved panels
4' x 6' to 4' x 8' vacuum bags 3 CFM for flat panels 5 CFM for curved panels
Vacuum clamping .5 CFM for non-porous materials 3 CFM for porous materials
Vacuum chucking on a lathe 1 CFM for very small projects 3 CFM for small/medium projects

Noise Factor

  • Venturi based systems: These units operate at 68 dB during the run cycle. This is just marginally higher than conversational speech volume.
     
  • Electric pump systems: This depends on the vacuum pump. The piston based pumps offered at VeneerSupplies.com operate at 74 dB. This is just lower than a noisy office, electric shaver or alarm clock.
     
  • Continuous-run systems: The diaphragm based pump for most of these systems operates at 45 dB which is considered to be enough to wake the average sleeping person.

Annoyance Factor
Keep in mind that the acceptable decibel level can be severely impacted by pitch. A shrieking fire alarm may not produce the decibel level of a monster truck but it can be much more annoying. Electric vacuum pumps have a lower pitch making their noise levels somewhat more reasonable.

    

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