Veneering with vacuum bag

[Lincoln]

Looking at trying some veneer work and would like to get set up with a bag and pump. For reference, would be for furniture sized panels, small - med table tops etc.
Does anyone do this on a regular basis? Anything to look out for, as far as equipment goes? Some favourite 'how to' resources? The gear is definitely available to buy down here in Australia, but not as readily as other parts of the world by the look of it.
Thanks for any info/tips you might have.

 

[Steve1]

I do just a bit of veneering.
The cost of a good vacuum pump was a bit hard to swallow, so I bought Roarokit.
It uses a handpump rather that an electric pump.

It work fine.  And the price is easier to swallow.
The goop they use as a bag seal can be a bit tough to use, but it works.

You can find videos on Youtube to show it in action.

I'm not sure if its available down under.  Rockler sells it too, if that helps. 

By the way, the one thing that I struggled with the most in veneering, is glue bleeding through the veneer.  So make sure to buy a veneering glue (such as the Titebond), which will have fillers to help mitigate bleed through.  Still, I found best to first put a light coat of glue on the back of the veneer, and let it dry, as a seal coat.  My next veneer project, I am going to resaw my own veneer a little thicker.

EDIT -- turns out it is indeed available in Australia http://roarockit.com.au/index.php?

 

[Michael Kellough]

Great link [member=65451]Steve1[/member]  Interesting stuff at that skateboard building site.

For the more traditional vacuum bag stuff try Veneer Suplies, aka Joe woodworker

 

[ryanjg117]

Michael already listed the best source for DIY vacuum bagging, Veneer Supplies and their sister site, Joe Woodworker. The latter is great if you're just interested in learning more about the process, tools, techniques, without too much of a hard sell.

If you're looking to get the right pump size, start by checking out the comparison PDF at Michael's link below. I built my own Project EVS a few years back with a Thomas Dual Piston Pump, which I believe is somewhere in the 4 CFM range and suitable for vacuum bags about as big as 4x9 feet.

If you're looking to get started and won't be veneering all day, I would probably skip the auto-cycling kits and just look for continuous-running pumps. Auto-cycling is OK, but if you have even the tiniest of leaks in your vacuum bag, it will be turning on and off all the time, and not really much energy savings there. Also, keep in mind ~1-2 hours is about the max you want to veneer press most panel projects, as running it too long can cause issues with rippling. Joe mentions, "Pressing a panel with a standard veneer adhesive (such as X-Press™) for more than an hour can cause the veneer to ripple. This happens because moisture in the adhesive over-saturates the veneer and causes the wood cells to expand."

In looking for a pump, you'll want one that can maintain 21" of Hg. "It is well known that 21" of Hg is the ideal amount of vacuum for most veneering jobs. At this level, you get 1,470 lbs per square foot in force. If you're building a 15" x 42" veneered table top, a vacuum press can create the equivalent of 6,431 lbs of total pressure."

The CFM of the pump is what dictates how large of a bag you can use. But if you're only planning to do 4x4' or smaller, you could probably get away with a pump as small as 1.5 CFM.

Don't forget all the other super cool stuff you can do with a vacuum pump. Vacuum clamping is awesome for sanding and finishing panels as well.

 

[Michael Kellough]

Great primer from Ryan!

If you’re working with a tight system the auto shut-off is nice but if it’s leaky it’s less annoying if the pump runs continuously.

Even with a vacuum bag that is airtight you can use a continuous run pump and just shut it off when adequate vacuum is reached. Add a valve and gauge between the pump and bag with the gauge closer to the bag then close the valve and check the gauge occasionally. If the vacuum drops switch on the pump and open the valve for about ten seconds.

This the rig built with Joe’s stuff. Also a Thomas pump similar to Ryan’s. The copper fitting on the lower right fits the Festool 27mm vac hose and lets me quickly evacuate most of the air from a large bag. Using the dust extractor to start you can finish with a low cfm pump.

I’d suggest the lowest cost pump and a diy manifold for connecting to the bag.

Valve-tee-gauge-bag coupling. On the side of the tee add another valve and the copper fitting.
(3/4” female sweat x 1/2” npt adapter) the 27mm hose fits tight over the end.

 

[Michael Kellough]

I forgot out the skateboard link Steve posted. For starting I’d get stuff from the skateboard guys and supplement the hand pump with a manifold that lets you use the dust extractor.

 

[lwoirhaye]

I bought a used pump on ebay.  Here's a similar one to what I use.  Worked fine for veneering when I've used it, not a lot.  I mostly use it for clamping.