I had my father's truck fixed a few months back because of an oil leak. Upon inspection it was found out that an oil seal was worn and causing the oil to leak from the vacuum pump part of the alternator. While the mechanic was working on that I suddenly had the idea of using the vacuum pump of the alternator to degass resin and the silicon rubber for casting after seeing how powerful the suction was.
That way it can save you a chunk of change if you have a diesel engine powered vehicle. Of course you have to make sure that you put it back very well otherwise your clutch or brake may not work. If you aren't handy around the car I'd not recommend this method for you.
Vacuum pressure is needed to power the brake booster and clutch booster systems of modern cars. For gasoline engines they can easily get the vacuum generated from the intake manifold of the engine, for diesel engines however its more complicated because of the different method needed for igniting their fuel supply. To solve this most diesel engines have a vacuum pump mounted at the back of their alternators.
Degassing is highly recommended during resin casting in order to get rid of the air in the resin or silicon rubber molds that results in nasty air bubbles forming on the mold and resin cast. The usual practice is to place the resin and silicon rubber in a vacuum chamber whose air is then sucked out using a vacuum pump.
Haven't tried it yet but am looking forward to if ever I decide to resurrect my long dead SF-3A Lancer project
