Vacuum Dry 2

From: Brad James (bjames@exponent.com-DeleteThis)
Date: Wed Sep 16 1998 - 10:28:33 PDT


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Date: 16 Sep 1998 10:28:33 -0700
From: "Brad James" <bjames@exponent.com-DeleteThis>
Subject: Vacuum Dry 2
To: "wind_talk" <wind_talk@opus.hpl.hp.com-DeleteThis>
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I'll answer all the questions posted on Wind_talk (and emailed privately) so
far with this one message to save some time...

(1) If you want to get your board pumped, call me at work at (650) 688-7391
or e-mail me at bjames@exponent.com.-DeleteThis I'm located in Redwood City, and would
prefer to have you come by after 8pm on the weekdays. I may start charging
next week (like $30) if I feel like I know what I'm doing, that I'm providing
value, and have a scale to verify any weight loss - since this does take a
lot of time...

I did production board last night that was heavy, we had to drill into the
board to get a place to suck. We only got out a little water (like a few
tablespoons), so I'm not sure if the board was heavy from the extensive
marine tex and repairs, or if the system didn't work as well on a production
board (I don't know why it wouldn't work as well). I'd be interested on
trying more production boards!!! Also, if you have a custom that took in
water away from the vent plug - I think we'll probably have to drill a hole
at the water intake area instead of just from the vent plug.

(2) Jim, according to Eva - the "board lady" featured in Wind_Tracks, the
board needs to be under vacuum for about 48 hours to get completely dry.
However, she says you get about 90% of the water out in the first 2 hours -
after doing the boards I've done, I believe this. Right now I'm just pumping
for a few hours, I'm not sure if my pump can take hours on hours straight.

(3) I'm not really interested in making any money doing this as I already
have a good job, so I've got no problem sharing my system design. I have a
115V, 20 liters/ minute, 1/3 hp pump. I saw one just like it in a '97
Grainger catalog for $299. (I tested a 5.5 hp shop vac - not nearly enough
juice to get to low pressures) I hooked the pump to clear, 5/8ths OD tubing,
put in a valve to control the pressure, plumbed in a vacuum gage, put in a
trap (using vacuum bag tape and a glass jar- this was the hardest part) to
collect the water (and so it doesnt suck into the pump), and then drilled a
hole thru an ASD vent plug and attached it to the end of the hose. I then
just screw the plug into the board, open my vent/valve, turn on the pump, and
then slowly close the valve till I'm at my desired pressure.

(4) Chris, thanks for the pressure info... I am going to be carefull!!!
I've talked to others (including the Wind Tracks "board lady") who say that a
solid custom wave/b&j board should take 1/3 atm (20 in Hg) no problem. They
do say that for light constructions or race-boards to not go lower than 1/2
atm or 15 in Hg. So far the ASD's, Forsythe, and F2 all took 20 in. Hg no
problem.

Brad



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