Let me just start by saying that I'm new here and the only experience with composites I've had is some simple fiberglass lay up by hand. 

I want to make a rectangular carbon fiber tube. I've done some preliminary research here but failed to find a thread about this specific type of project. I was, however, able to determine that I probably want to use the vacuum-bagging method.

When laying up on the metal tube Mandrel  (I use Stainless steel or hard Aluminium) close off one end of the CF tube with a strong "End wrap over"

The mandrel is plugged with a plug as well at that end, but with one or more small holes to let the air get from the inside of the mandrel tube to the outside, between the Mandrel and CF tube.
(I put a small piece of release tape over the holes to avoid sucking resin inside the mandrel tube while vacuum is on.)

At the other end of the Mandrel I put a plug with a short piece of tubing that fits my compressed air "handle" for inflating tyres.. that way the amount of pressure can be controlled better, so you do not blow apart the CF tube by adding 8 bar of pressure in one "rush" ---

I use that system to release parts from other types of moulds too ..

"Sapere Aude"... Dare to KNOW!

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