I saved this information that came across my desk intending to try it for myself. I have not tried it myself, so I can't vouch for it, but if it does what it's suppose to, it sounds great and economical.
I'm sorry I don't know who is responsible for this information, but we owe them if it works.
Good Luck building it, and I would like to hear about the results if anyone has built one or does build one before I do.
Sven
Here is the info:
Realizing the value of being able to vacuum seal many different food and non-food items, I began to look around the web at different vacuum sealing machines. What I began to see was that I could afford a nice generator for the prices of some "Vacuum Sealing Machines". Thinking that this process could not be that complicated (or expensive!) I set about trying to build a sealer that would do what the commercial machines would do for less dollars.
One of my hobbies for the last twenty-five years has been the construction of a working
X-ray machine based on much of the technology of the early inventors. Well, in this
process of gathering materials I have picked up a small refrigerator compressor to use as
a "roughing pump" for my X-ray tube.
This little compressor will pull 28 inches (725mm) of mercury which, by the way, is the
same that one company I saw said that their $549 machine was capable of. Now my curiosity
became obsessive.
I started by cutting an 8 inch long peice of 4 inch schedule 40 PVC plastic pipe (left from another project) on my bandsaw in order to make both ends as square as possible. I glued a 4 inch cap on one end (PVC glue). To get a better seal on the other end, I placed a piece of sandpaper (320 grit) on a pane of glass (it's a very flat surface) and proceeded to twist the end of the pipe against it, similar to cutting biscuits with a biscuit butter (except round, and round, and round...). When all of the saw marks were gone, I sanded the sharp corners slightly and removed any little burrs created by the circular sanding.
I then drilled and tapped a hole in the side of the pipe in order to screw in a 1/4 inch (NPT) hose barb for 1/4 inch hose (I could have just drilled a hole and siliconed a hose in it. The hose barb looks good though, and doesn't leak.). I drilled and tapped slowly because the plastic tends to get gooey if one drills too fast. Also, I used thread tape on the hose barb threads for a little more assurance of a vacuum-tight seal. A 1/4 inch ID vinyl hose was attached to the hose barb with the other end going to the intake side of my pump.
I then cut a rubber gasket (inner tube, etc.) using the pipe to draw the outline. I cut the outside just a little bigger than the outside diameter of the pipe, and cut the inside circle just a bit smaller than the inside diameter of the pipe. When finished cutting, the gasket was a circular gasket about 3/8 to 1/2 inch wide all the way around. When the pipe (vacuum chamber?) is sitting with the cap down, open end up, the gasket goes on the top of the pipe.
I next got a 5 inch square piece of 1/4 inch thick glass to close the top of the vacuum chamber. The glass is ideal for this as it comes from the factory smooth, hard, and flat (easier to make seal). I could have used other materials to do the same thing, but I also wanted to see what was happening on the inside. That's it. Now to see if it really works. At this point I had about $2.00 and an hour and a half of time (why rush, it was an experiment!) in my little home-brew vacuum chamber.
The hose leading from the hose barb to the pump was cut and a 1/4 inch "tee" inserted. To this was attached a vacuum gauge used to check automotive vacuum systems (About $10 or $15, Auto Parts store, Wal-Mart, etc.) so that I could monitor the strength of the vacuum.
To operate the system, I took off the glass and the gasket (neither of which is glued!)
and placed a pint jar into the chamber with the lid loosley placed on the jar (no ring). I
then put a bit of Vaseline around the rim (cheap vacuum grease), placed the rubber gasket
on the Vaselined rim (carefully centering it so no rim is exposed), and put a bit more
Vaseline
on the top of the gasket. Onto this whole affair I put the glass.
When the vacuum pump was turned on, the gauge needle began to fall and continued to do
so until it reached 28 inches of mercury, which I already knew to be about the practical
limit of my make-shift pump. I turned the pump off and pulled the hose off the hose barb
to release the vacuum in the chamber (don't even TRY to pull the glass top off until the
vacuum is released!). I removed the glass cover and took out my first, sucessful, vacuum
sealed jar (empty, just a test run). I was ecstactic! How many other experiments had I
done that had not worked on the hundredth time much less the first! Not to mention that I
only had a couple of dollars in a machine
that some companies wanted several hundred dollars for.
Since then I have had a couple of ideas for improvements, modifications, and operatation. They are;
1. Put a ball valve or similar in the vacuum line somewhere to release the vacuum. It's not necessary, but nice.
2. Be careful if you use inner tube rubber for the gasket. Sometimes, depending on how
you cut it, there are little "ridges" or other bumps that were made onto the
inner tube. These will make it hard to get a seal unless they are sanded or otherwise
removed.
-related note---If you are not getting a seal immediately when the pump is turned on, try
pressing down gently on the glass cover.
3. Check to see if more Vaseline is needed from time to time. When the glass will not seal it is a good indication regreasing is needed.
4. Make sure that the lid is sitting on the canning jar properly or it will not seal under ANY vacuum.
5. I've tried the same process with the rings loosely screwed to the jar and lid but notice no difference in the sealing.
6. If the air is readmitted too slowly into the chamber, it seems that there is a
greater chance that the jar will not seal on the first try. Pull
the hose fast or get a ball valve.
7. Use a 4 inch "test" cap to close the bottom of the chamber instead of a regular pipe cap. The test cap (although harder to find sometimes) is cheaper, less awkward, and seals just as good using PVC pipe glue.
Oh yeah, 4 inch pipe was used for the body because pint and quart canning jars would fit into a chamber made from it. Any size will work but, wasted space just takes longer to vacuum the air out of. My current project involves modifying an old (free) pressure canner to be able to vacuum seal seven jars at a time, no more useful but an interesting project.
One last thing. Someone may see this and, realizing the potential to profit from it (Capitalist pigs that we all are), try to do so. Please don't. It was my intent by posting this here to get this technology out to as many folks as possible as quickly as possible before the stink hits the fan. If you try to patent it or otherwise try to profit therefrom, I will personally redesign another one and publish it. That's my little contribution.