I was having a brain fart. I meant 10 psi, not 10 inches of mercury. At 10
psi, the numbers are correct. And it is not too hard to pull 10 psi of
vacuum.

Joe


"Doug Miller" wrote in message
. ..
In article 1109979204.fad47d4df84da263be0314fbc737ff5f@teran ews, "Joe
Wilding" wrote:
vacuum bagin works very well in this application. you get very uniform
clamping pressure with a vacuum bag, and do not need extra boards to
distribute the load, like with clamps. Like the other poster said, just
make
sure you have it supported flat when you glue it up. Assuming you get 10
inches of mecury vacuum pressure (which is real easy to do near sea level,
even with an old worn out vacuum pump), you will be applying over 12,000
lb
total force to your glueup. It is hard to match that with weight.

Not sure your math is quite right here... It's a lot of force, I grant
you,
but I don't think it's quite that much. Here's how I figure it:

10" mercury = approx 1/3 atmosphere = approx 5 lb / sq inch.
13"x96" = 1248 sq in.
5 psi * 1248 sq in = approx 6250 lb.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?