The Compressor used as a vacuum pump is a refrigeration motor/compressor removed from an old household refrigerator.
A compressor from an aircon or freezer etc will also work fine.
The pipes connected to the compressor and the fridge were cut slightly to allow the gas to escape. Then both pipes cut leaving 200-300 mm attached to the compressor.
The wiring to the compressor was cut leaving as much wire attached as easily possible. Or undo terminals at nearest junction.
The power cord to the fridge is also used. Cut cord off or disconnect as long as possible.
That is all the electrics that is needed from the fridge.
Unbolt and remove the compressor from the fridge. Usually 3-4 bolts.
Take care not to tip the compressor upside down as it has oil inside it and will run out the tube pipes. We want the oil to remain in the compressor.
Cut the end of the two tubes going to the compressor off neatly so a piece of plastic tube can be “tightly” slid over the pipes.
These will become the vacuum line and the pressure line depending which tube is used.
Reconnect the wiring the correct way around in a safe manner. If you are not skilled or knowledgeable to mains wiring than best get some one who is, to reconnect the compressor to the cord from the fridge.
With wiring done.
Place both plastic tube ends in a container (such as a tub) as sometimes the compressors can blow a little oil out the pressure line.
Connect the cord to power and switch on compressor.
If you put your finger over the end of a tube it should suck on to it or feel air releasing
Now you know which tube is vacuum and which is pressure.
For use with vacuum bagging a vacuum gauge is desirable as you can never tell otherwise if you have a small pin prick hole/leak.
The gauges used are an old set of refrigeration mechanic gauges as there were the only vacuum gauges I had.
Any vacuum gauge that will read down to minus 100 kpa is fine.
Place a tee piece in the vacuum line and attach the gauge to it. Ensure all connections are sealed properly.
The use of a household water filter housing (no elements inside) in the vacuum line is to ensure no liquids get sucked down the line and into the compressor.
It is not essential to have it, if care is taken.
I use it as a safeguard when vacuum bagging fibreglass, as resin goes solid in lines and compressors.
The advantage of using a fridge compressor over a vacuum cleaner is the compressor is a more gentle source of vacuum and takes a little longer to remove the air allowing for things to be manipulated as the vacuum increases as well the negative force will be much, much greater than a vacuum cleaner. (With no leaks go down to –100Kpa)
A vacuum cleaner will suck it down too quickly and hard to work with. The motor will also run hot and burn out as there is no air going through the motor with a plastic bag attached to the hose. For this reason a vacuum cleaner not recommended.