In this instructable I'll show you how to make a vacuum bag stem (also called a vacuum breach valve/unit). These are important in vacuum bagging because taping the hose on the seam of the bag is a recipe for leaks and disaster.
This adds on to the excellent guide on vacuum bagging basics
It also goes well with the bicycle-turned-vacuum pump guide if you want to do some hand powered vacuum bagging, or the great tire-inflator-turned-vacuum-pump guide.
Step 1: Gather Your Parts
4 3/8" steel washers
2 3/8" ID, 7/8" OD neoprene washers
1 1/8" F nut (dunno what they're called)
1 1/8" M to M threaded tube connector (the shorter the better)
1 1/8" F NPT to hose connector
Vacuum bagging plastic sheet/film
Step 2: Assemble Everything
You're going to need to assemble the parts in the following order:
Rubber tube connector, M M threaded connector, 3 steel washers, 1 neoprene washer, plastic to be vacuum bagged, 1 neoprene washer, 1 steel washer, nut.
Note: When you put the vacuum bagging material on you will need to punch a hole in the bag to get the tube through. Make sure this hole is smaller than the tube, and stretch it around the tube to help prevent leaks.
Step 3: Done! Enjoy Your Breach Valve
There it is!
On a side note: The neoprene washers should be a tight fit around the tube. This is good because if it doesn't happen, you'll have air leaking around the rubber and killing your vacuum.
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