A Word of CAUTION

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Did I say that flat won't work? I only said flat is highly prone to failure. The very thin canning lids work because they're dome shaped. The plexiglass undoubtedly works because it is a lot more flexible than corian. Bumblebees also can't fly, ask any aeronautics engineer, their wings are too small for their mass.[:D]
 
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Sorry, Eagle. This is my final post on the subject. I won't participate in a mud slinging contest, whether I know what I am talking about or not.

Just remember--if something CAN happen, sooner or later it will. that was the point I was trying to make. I don't understand why you made the comments that you did. It just seems obvious that a steel pipe would have a greater safety margin than a glass jar.

The weak spot in an glass jar is the flat bottom, as someone said.

If you look closely at a Champagne bottle, you will find that the bottom is concave, if you are looking at it from the outside. It is designed that way to reinforce the glass bottle.

A scratch in the glass is another potential weak spot.

Since an egg shell is convex on the outside, with the atmospheric pressure acting on the dome portion, you could probably make a vacuum chamber from an Ostrich egg.

How about a round fish bowl, or even a large light bulb? The possibilities are endless.

For what the people who make castings are doing, and I have never cast in either a pressure chamber or a vacuum chamber, a steel pipe would get it's strength, and along with the strength, safety from the tensile strength of the steel, and not depend on the domed shape, although a domed shape would obviously be stronger. Of course, I'm sure if someone put their mind to it, they could also collaspe or explode a closed up steel pipe.



That's the reason dams are built with the curve, or dome shape toward the water in the lake. An arc, with pressure acting on the high side, is one of the strongest geometrical shapes in existence. The same principal applies to bridges.

Threading each end can be done. In my younger years, I worked for a plumber. Ninety percent of my job was hand threading galvanized water pipe, from 1/2 inch diameter, up to eight inches in diameter. The eight inch diameter pipe was for water mains.

I have probably cut several miles of threads, so I definately do know what I am talking about when it comes to threading pipe and screwing fitings on the threaded part, whether the fitting was an elbow, tee, or a cap, then pressure testing it for leaks. Believe it or not, what I have just described actually works.

Bonefish
 
Just a couple of quick corrections:


Originally posted by its_virgil
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Scott Hettle, aka Mudder
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The name is Scott Hettel [:(!] (many folks spell it incorrectly) [;)]


Originally posted by DocRon

Have had no experience with the pickle jar vessel, just concerned that the flat base would not be strong enough.
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A pickle jar is not exactly flat on the bottom. I'm not sure how much of a curve you need but if you look closely you will see a slight curve on the bottom and at the edges.

The vase I use is also slightly curved at the bottom and is much thicker than a pickle jar. I use it because it holds a 1 quart mason jar very nicely for stabelizing and the wide opening allows my fat hamfists to get the jar inside without spilling.


If you do not feel safe using a pickle jar then I suggest that you do not use one. There are several other ways to make a vessel. Do a search on the net and you will find several.
 
Originally posted by bonefish
<br /> Believe it or not, what I have just described actually works.

Bonefish
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My advice would be to do it your way and let others do it their way. Plenty of information and misinformation has been posted, on this thread and others. There have also been sufficient warnings of consquences, dire and otherwise posted.

Don started a great thread with a valid warning. I personally think this subject is ready to lay to rest.
 
Originally posted by bonefish
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If you look closely at a Champagne bottle, you will find that the bottom is concave, if you are looking at it from the outside. It is designed that way to reinforce the glass bottle.
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Point of fact:

A Champagne bottle is under pressure, not vacuum.

Pickles come packed under vacuum, not pressure.

Exceed the strength of any material, be it flat or curved and it will fail.
 
If you look closely at a Champagne bottle, you will find that the bottom is concave
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When I look at a champagne bottle it's usually well on it's way to being empty.[8D] Glad to hear that your incident caused no bodily damage, Don. And thanks for the other "lessons learned". I love the practical education that you and others offer up.
 
As an engineering professor I'd like to add the following comments:

1) Glass jars and bottles have a slightly curved bottom so that will sit flat on a shelf, not for strength.
2) The bottoms of the jars and bottles are much thicker than the walls and this is where the strength comes from.
3) Failure from a vacuum is due to buckling of the structure, not failure of the material.
4) Resistance to buckling is a function of the thickness, radius of curvature and stiffness of the material.
5) There is little potential for damage/danger for objects outside of the vessel. The material goes inward and strikes the contents or material coming from the other direction. Very rarely will a piece go through this haelstrom without being stopped.
6) Cutting a hole in the center of a flat circular plate will reduce its resistance to buckling. Thus a solid disk of plexiglass will be lass likely to buckle than corian (of the same thickness) with a hole in the center for a window.

Hope this clears things up a little.

Paul in AR
 
Originally posted by pssherman
<br />As an engineering professor I'd like to add the following comments:

1) Glass jars and bottles have a slightly curved bottom so that will sit flat on a shelf, not for strength.
2) The bottoms of the jars and bottles are much thicker than the walls and this is where the strength comes from.
3) Failure from a vacuum is due to buckling of the structure, not failure of the material.
4) Resistance to buckling is a function of the thickness, radius of curvature and stiffness of the material.
5) There is little potential for damage/danger for objects outside of the vessel. The material goes inward and strikes the contents or material coming from the other direction. Very rarely will a piece go through this haelstrom without being stopped.
6) Cutting a hole in the center of a flat circular plate will reduce its resistance to buckling. Thus a solid disk of plexiglass will be lass likely to buckle than corian (of the same thickness) with a hole in the center for a window.

Hope this clears things up a little.

Paul in AR
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And as a dentist, I would like to add that you should brush and floss daily. [8D]
 
Originally posted by wood-of-1kind
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Originally posted by wdcav1952
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And as a dentist, I would like to add that you should brush and floss daily. [8D]
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William, when you go out business(from your good advice), will you please give me your turning tools at least[?]

-Peter-[;)]
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I'll give up my turning tools when they pry them from my cold dead fingers! [:D][:D][:D]

(With apologies to the author whose line I shamelessly stole and used for my own purposes. No animals were harmed in the posting of this response.)
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Originally posted by wdcav1952
(With apologies to the author whose line I shamelessly stole and used for my own purposes. No animals were harmed in the posting of this response.)
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There were, however, two flies and eleven ants harmed in the reading of that response.
 
Can I assume that those who are afraid of a vacuum in a Mason jar will never go into a grocery store because one of those hundreds of jars with a 29" vacuum inside of them might break?? Heaven forbid that they should pick one of them up and carry it home. [:0][:0]
 
Originally posted by RussFairfield
<br />Can I assume that those who are afraid of a vacuum in a Mason jar will never go into a grocery store because one of those hundreds of jars with a 29" vacuum inside of them might break?? Heaven forbid that they should pick one of them up and carry it home. [:0][:0]
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Dang Russ;

That's what I've been trying to say! [8)]
 
Guess you city boys never canned any vegetables and sat around at night waiting for the tops to "ping". Many a mason jar in this country currently under vacuum. Not sure how much vacuum compared to what's used her. But some have been under vacuum for long periods of time and some have been used over and over for years. My mother has been making her own pickle and putting some of those jars under vacuum for probably 40 years. Pickles are much better than those store bought too. Especially the pickle made from watermelon rhind [:D][:D][:p]
 
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