notbob wrote:
On 2009-09-18, Morris Dovey wrote:

http://www.beckerpumps.com/

They're more expensive but those who have 'em, love 'em.

You are paying insane amounts of money for vacuum overkill. A simple
vacuum cleaner will provide all the vacuum mecessary for holding down
verneer pieces, even lager ones. The mechanism at work here is not
vacuum. but the air pressure acting on the pieces to be held. IOW,
it's not the level or rate of vacuum, but the atmospheric pressure on
the other side of the work. You can buy a $10 million dollar vacuum
system, but the air pressure holding down the pieces will never exceed
14.7 psi.

I don't do veneering, so you won't get any argument from me in that context.

Joe mentioned production routing small parts - and in that context, the
choice of equipment will depend very much on the particular set-up
(whole table, with vacuum being pulled through a permeable spoilboard;
vacuum pucks on an impermeable spoilboard; or something in-between); the
material being routed - parameters will be very different for, say,
Lexan, baltic birch, and MDF workpieces; and how aggressive the feed is.

I've been pretty happy with pucks and an old recycled refrigerator
compressor - but I don't use vacuum hold down for parts under 16 in^2,
and I can't even consider vacuum hold-down for leaky materials like 1/4
in MDF. (If I really needed to do that I'd spring for a real vacuum pump
- probably a reconditioned Becker.)

I have a how-to for making inexpensive vacuum pucks at
http://www.iedu.com/DeSoto/Projects/VacuumPuck/ - I just daisy-chain 'em
together and connect to the intake side of the refrigerator compresor
with 3/8 in vinyl tubing.

For non-production (very small) quantities, I'm more likely to use
carpet tape - or for in-between (small) quantities, a purpose-built
clamping fixture like those shown at
http://www.iedu.com/DeSoto/Projects/Bevel/

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/