Vacuum chuck pump used for veneer press?

[Jon McElwain]

I was wondering if any of you have converted your vacuum chuck system for use as a veneer press. I've got a little flat work project (I'm so ashamed :p) that I need a press for.

If you've done this, what did you have to do; what equipment did you need? Do I just need a vacuum bag and a connector? I'm running a Gast 0523 1/4 hp pump with all the gizmo's to support my vacuum chuck.

Thanks!

[Jim Underwood]

Well I've not used my Gast pump for a chuck or press, but a rep from Gast told me it was one of the most common pumps for both... I don't see why you couldn't use it for the press too.

[Faust M. Ruggiero]

Jon,
Your pump will probably work fine. My Vacupress pump (made for vacuum veneering) makes 6.5 cfm and reaches a maximum of 27 HG. Less cfm merely will make evacuating air from the bag a bit slower.
You will need a vinyl vacuum pressing bag with fittings to connect your pump to the bag. If you Google "Vacuum Veneering" you will find a couple companies dedicated to this type work. They describe the process and equipment needed on their sites. It's easy to do and works really well. I've done a bunch of it. Be sure to buy the appropriate glue for your application. It has to set slowly so you have lots of working time. If you are doing curved work you will need a glue that does not "creep". Good luck and have fun.
faust

[David Gilbert]

Jon,

I'm no expert in all of this but the veneer vacuum pumps that I have seen all have regulators that turn the pump on and off to maintain the vacuum. Since the vacuum bags take 6 - 12 hours to glue up the veneer, turning on and off is nice feature. Most turning vacuum systems are continuous running systems. Running a pump continuously for 12 hours might impact its lifetime because of overheating and wear. Your pump manual (if you have one) may mention operation times.

Good Luck and Cheers,
David

[Jon McCoy]

I just did exactly this over the past few weeks, and the setup works quite well for my veneering. I have the same Gast pump, which I'd previously bodged together to work on my mini-lathe, but never really got the plumbing leak-free, plus my adapted automotive vac gauge was pretty sketchy. After reading through several tutorials over at Joe Woodworker, I decided to scrap everything I already had (except the pump) and bought their CRS (Constant-Run System) kit -- they also have kits and free plans for systems with vacuum reservoirs, but I think they're more for pumps which pull low volume or maybe for evacuating really huge bags (or production volume veneering). I originally planned to build a manifold and run several vacuum lines around, but I liked their quick-disconnect so much, I just went with a long single line.

The veneer glue I use needs 45-60 minutes under vacuum to set the glue bond, then the piece is removed from the bag to dry and cure for another 3-4 hours. If you leave the piece under vacuum for longer, the glue won't properly cure, and some woods will actually start to mold or discolor. Running the Gast pump for an hour isn't concerning to me (it's rated continuous duty, although the pump head does get warm after an hour), and pulls full vacuum on my 2' square bag in under ten seconds.

If you already have a working vac chuck setup, you'll need a vacuum bag of the proper size, veneer, and veneer glue. Inside the bag, you'll need shop-made platens to evenly apply surface pressure to the veneer -- two pieces of melamine shelving work fine, with a grid of grooves cut into the bag-facing side of each platen to help evacuate the air. Alternately, you can use plastic mesh for the top platen and then you don't need to groove the bottom platen. Be sure to round over all the platen edges, so they can't damage the bag material -- wrapping the cut edges of the plastic mesh with duct tape to protect the bag.

-jon-