I've been looking around the archives here and have found some
information and a couple of great websites about building a vacuum
press for veneering. What I plan on doing is mostly smaller sized
panels, maybe 10" X 14" or so. I know I could go old school and use
cauls, etc., but I'm interested in piecing together some kind of
vacuum system, on the cheap if possible. My questions are as follows.
Harbor Freight sells vacuum pumps, not the venturi type, but actually
vacuum pumps for use in refrigeration and a/c systems. What I'm
looking at is the 2.5 CFM model (98076-4VGA ) that sells for about
$75. If I use this with a purchased vacuum bag, what more is there to
it than to hook up the appropriately sized hoses and switch it on? Do
I need an extra reservoir or additional electric parts? Will this
sized pump have enough power to adequately pull the veneer to the
substrate? Will the pump be running constantly or once it reaches
maximum pressure shut off and only cycle on when vacuum is lost due to
leakage? Any insight as to if this is a viable plan would be
I use an old (~25 years) refrigerator compressor with vacuum pucks to
hold boards and plywood to the table while they're being machined on a
CNC router. Not what you're doing, but I think you can save the $75 if
you're willing to recycle.
my 7500 cents worth :)
On Thu, 19 Mar 2009 20:45:37 -0700 (PDT), dale martin wrote:
I think the HF pump will work, but you'll probably need more than just
some tubing to hook it up.
No matter how hard you try, the bag won't hold a vacuum forever. During
the time you're waiting for the glue to set, you'll probably need to
start the pump a couple of times to maintain the vacuum (and the amount
of clamping pressure). With a partial vacuum already present, that pump
might not start. I bought a kit of parts from JoeWoodworker.com that
included a "MAC" valve - which is nothing more than a switch with a time
delay that lets the pump pull from ambient for a few seconds when it
starts, then switches over to the vacuum line.
Also, its a bit more convenient to use a vaccum switch to control the
pump. The one that came with the kit is adjustable, and it works very
If you look at the plans on the Joe Woodworker.com site, you'll see that
a vacuum reservoir is also used. This is to reduce the number of pump
startup cycles. Doing so extends the life of the pump.
I think you'd do well to look at a few different designs and some of the
free plans available before building your system.
Bill Nobel, who frequents the wood turner's news group "rec
crafts.woodturning", often has rebuilt Gast vacuum pumps that he sells
at very reasonable prices. You might want to check his site to see
what's currently available or put you name on his waiting list and he'll
notify you when something becomes available. The site is:
Also if you can find a repair shop that specializes in fixing small
duplicator printing presses, they use vacuum pumps to move the paper, Gast
is a common brand. They seem to last forever so a used one may be reasonable
in price. I have one that I haven't used yet to make a vacuum clamp. The
vane type pumps are particularly good because small bits of dust, lint and
sanding dust that gets sucked into them does not harm them at all. They are
built to take it.
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