Just curious if you guys are using a Holding tank with your Vacuum pump ?
My small one for RC airplanes will handle a mold the size of a board quite easily.
It has a Beer keg for a holding tank & takes a bit to empty the air.
I placed a check valve & a adjustable vacuum switch between the pump
and the holding tank.
There's a relay that goes from the switch to the pump. If you can get a mercury
relay because there Way more reliable; or clean the relay contacts every month
so Ya won't loose a part in your mold.
So-- the switch is adjustable from 3 to 29 Hg. if your using a light foam then
set it at a lower setting.Using Honneycomb then set the switch to a higher settting.
It will come-on when the tank goes below the setting
by a few Hg, then turn off when the desired setting is hit again. This makes the
pump run for only a few minutes each hour if you took care of all your leaks at the mold.
I posted this because i know of at least a hand full of guys that just let their pump
run all night ! (That's just silly)
Bille