I found this great site that gives free plans for download of a vacuum veneering machine.
http://www.joewoodworker.com/veneering/downloads.htm

I have built his setup. It works okay. The biggest challenge is in getting the DIY bags made and sealed correctly.

I still have not found all the small leaks and have sealed the entire system three times but still get 4-5 cycle on times, so I am just going to set the pump for continuous operation... less wear in the long run. I don't know where some people are able to get 20 minutes to several hours between cycles... I have three layers of silicone on PVC joints, thread tape on fittings, duct tape and hose clamps on all joints and still can't hold the vacuum for more than 4 minutes... even with the vacuum switch set for 4Hg drop in vacuum. Add the bag with small pin-holes and I get less than 1 minute between cycles. :confused:

There are some $600 commercial systems that work great out of the box an I have about $400 in Joe's DIY system, so I would probably go commercial next time. His venturi system might be a better way if you can stand having the compressor running all the time...

As far as pressing, leaks not withstanding, it works well.

He has alot of great veneer and accessories as well... very reasonable prices. Great service.

I built the joewoodworker system about 2years ago and it works great. I'm currently vennering doors for my kitchen.

I didn't use any silicone in the fittings, just teflon tape and never had a leak. The only problem I 've seen is sealing the bag. I use 2 pieces of wood, routed to accept a 1/2" dowel, and clamp it closed (30 mil vinyl bag). I've found that it takes a while to fully seal. The longer It's in use, the better the seal. After about 10 minutes, It will only kick on every 5-10 minutes or so, and continually get better. The last time I used it two weeks ago, after I turned off the venturi, it still had 20"HG after another hour.

I bought the venturi from Harbor freight, the MAC valve from Ebay, and found a cheaper source for the switch (don't remember where right now). I spent less than $100 not counting the bag. I bought the Vinyl from a place online that was cheaper than JWW.

A good vacuum pump for vacuum bags is a refrigator motor. Not high volume but will pull 24"+

A good vacuum pump for vacuum bags is a refrigator motor. Not high volume but will pull 24"+
Thats a good tip.
Have you actuallly use a fridge motor yourself ?
This sounds like a really good cheap / scavangable soulution.

I think the JWW site used to have info on using a refrigerator motor/pump.

When using a compressor from a fridge as a vacuum pump remember to occasionally add several drops of oil into the suction side. Refrigerator systems are a closed loop system where oil and freon circulate together. When you open up the system you loose it all. Use either a synthetic oil like Mobil 1 or if you can find it Texico WF 32.

Originally used a refrigrator motor on my vacuum chuck on my wood lathe. Didn't really have enough volume for soft woods and I upgraded to a better pump. See http://www.turningaround.org/301Shop.htm for details.
Bought a new discontinued compressor from appliance repair company for $20. Though volume is low it works great for vacuum bags and is very quiet and pulls 26+".

heres a site that shows a refrigrator pump that i found a long time ago. I have a pump waiting to be put to work, just havent gotten that far yet. It must work well because this site was linked off a Berkut aircraft site detailing how to vacum bag full size aircraft wings.

Darren

When I was researching hovercraft construction some time back I remember reading about using a vacuum cleaner to reduce the volume in the bag and then a vacuum pump to draw down on the bag. I belief it used a t valve setup in the main draw area..... It's an idea anyway....