If you are building with eps then yes you need to limit the vacuum. For a TT with corecell or woodcore the harder the vacuum the better. To limit the vacuum on the eps core boards I just put a needle valve and a gauge btween the pump and bag. The natural leaks you have will bleed off and you can set the needle to the desired vac. These kind of pumps can run forever so don't worry about switches and stuff. KISS principle. If you build up a fridge compressor with all the other requirements to cycle it on and off you will probably spend more money than just getting a decent pump and it will last you forever. Mine is strong after ahemmm ....30years, from early days of windsurfing till now.
I have an HVAC pump similar to what Bigdog has shown and all i use to control the vacuum is a reservoir made from an old kite pump with a garden hose valve to let air in and a vacuum gauge to measure the vacuum. Works pretty well for laminating corecell or wood veneers over EPS:
I have an old Edwards pump that is overkill. I don''t have the model offhand but any rotary vane with oil will rock. There are also membrane pumps that I have used for other apps that run 24/7 continuous for a year before the membranes need replacement.
found something, in the hospital ( was tere 3 last days, just got a little girl !! )
they have vacuum control gauges ( a gauge and ajustement ) on the walls, to ajust and mesure the vac from main vac.
this thing, not bleeding tech, no idea how it warks but, you can adjust the vac amount, from no to max, without electronics and whithout on and of, whitout bleeding, it will ajust from itself to pull as ordered.
i'm going to schearch for one used on ebay. looks like the perfect thing to use from itself with a continous pump, that's it.
i'll let you know in 4 5 week when the baby finaly sleeps a night.
any further sugestions further sugestions are welcome.......