Re: Digest Number 54
Posted by
Andrew Werby
on 1999-06-16 07:30:02 UTC
Message: 18
Date: Wed, 16 Jun 1999 13:49:39 EDT
From: MIADsgns@...
Subject: Re: re vac forming
In a message dated 6/16/99 2:36:14 AM SA Eastern Standard Time,
timg@... writes:
<< I have done some composite wing vacuum bagging and used one of the old
commercial freon tanks as a vacuum reservoir and it held 24" hg no problem.
I now use a section of 4" PVC pipe with endcaps for my vacuum tank and I
have tested it to 24" hg with no problems. >>
Ok now you are getting me creative :), how about a cacuum system using PVC
tubing including the reservoir tank, lines, What is hg? and can you give me
an idea what the 24" hg translates to? Please bare with me I don't have
much experience with vacuum systems so I am learning.
Thanks,
Mario
[At the risk of being off-topic, I'll throw in my 2 cents worth. First of
all, "hg" stands for "Inches of mercury displaced by vacuum pressure. Water
boils at about 29 inches, so this is what you need for investment casting,
where you need to get rid of air-bubbles in your mix. Auto parts stores
sell cheap vacuum gauges for measuring it.
For vacuum-forming, you don't need this much pressure, but volume is
important. I don't think the "reservoir" will give you enough extra to be
worth messing with. You do want to use a good inline filter to preserve
your pump. I've gotten about 27" by putting a manifold on the intake port
of my air compressor- this would probably work for vacuum-forming. But if
your compressor has reed-valves, you'll need to use retainer flaps to keep
the vacuum from snapping them off (I found this out the hard way.)
Refrigeration pumps also make vacuum, as do the set-ups that used to be
used for refilling auto air-conditioning systems - if you can find one, it
should be cheap, since they now have to use fancier systems that recover
the freon.
If you want, we could talk about this more in alt.sculpture; but it's
getting somewhat far afield for this list.]
Andrew Werby
Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
http://unitedartworks.com
Date: Wed, 16 Jun 1999 13:49:39 EDT
From: MIADsgns@...
Subject: Re: re vac forming
In a message dated 6/16/99 2:36:14 AM SA Eastern Standard Time,
timg@... writes:
<< I have done some composite wing vacuum bagging and used one of the old
commercial freon tanks as a vacuum reservoir and it held 24" hg no problem.
I now use a section of 4" PVC pipe with endcaps for my vacuum tank and I
have tested it to 24" hg with no problems. >>
Ok now you are getting me creative :), how about a cacuum system using PVC
tubing including the reservoir tank, lines, What is hg? and can you give me
an idea what the 24" hg translates to? Please bare with me I don't have
much experience with vacuum systems so I am learning.
Thanks,
Mario
[At the risk of being off-topic, I'll throw in my 2 cents worth. First of
all, "hg" stands for "Inches of mercury displaced by vacuum pressure. Water
boils at about 29 inches, so this is what you need for investment casting,
where you need to get rid of air-bubbles in your mix. Auto parts stores
sell cheap vacuum gauges for measuring it.
For vacuum-forming, you don't need this much pressure, but volume is
important. I don't think the "reservoir" will give you enough extra to be
worth messing with. You do want to use a good inline filter to preserve
your pump. I've gotten about 27" by putting a manifold on the intake port
of my air compressor- this would probably work for vacuum-forming. But if
your compressor has reed-valves, you'll need to use retainer flaps to keep
the vacuum from snapping them off (I found this out the hard way.)
Refrigeration pumps also make vacuum, as do the set-ups that used to be
used for refilling auto air-conditioning systems - if you can find one, it
should be cheap, since they now have to use fancier systems that recover
the freon.
If you want, we could talk about this more in alt.sculpture; but it's
getting somewhat far afield for this list.]
Andrew Werby
Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
http://unitedartworks.com