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#1
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There is a website describing how to use a discarded 'fridge compressor
for vacuum bagging. The fellow who tried it used a vaccum gauge from an automobile in his configuration and claims he got 25 psi vacuum for his project. He just used standard plumbing fittings to connect the vacuum bag. I do not have the website address. I was browsing on a computer at the public library at the time and did not write it down. However you can find it by going to www.boat-links.com, clicking on "The Mother of All Boat Links", clicking on the first box "amateur boatbuildign and repair" and scrolling down untill you find the link about vacuum bagging. Nowadays all discarded 'fridges go to a recyling depot where they "vacuum bag" the freon gas to protect the ozone layer of the atmosphere. It should be easy to get a compressor by telephoning the miniciapl garbage department. Since compressors do wear out it would be a good idea to look for ones off later model 'fridges (the date of manufacure should be on a label on the 'fridge) bring home 2 or 3 to try. -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned |
#2
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#3
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On Sun, 19 Oct 2003 19:23:55 -0400, "sour (max camirand)"
wrote: On 18 Oct 2003 14:47:14 GMT, (William R. Watt) wrote: There is a website describing how to use a discarded 'fridge compressor for vacuum bagging. The fellow who tried it used a vaccum gauge from an automobile in his configuration and claims he got 25 psi vacuum for his project. He just used standard plumbing fittings to connect the vacuum bag. I remember reading about this, too. Seems very feasible. If I ever have any vacuum bagging to do, I'll give it a shot. Has anyone tried it? -m Fridge compressors blow out their oil then seize up in 1 to 10 hours, in my experience. If you trap the oil, or keep adding it, I hear you can keep 'em running. Brian Whatcott |
#4
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If you can find an old, and I mean REALLY old, compressor with single
intake and output ports and maybe cooling fins it will last an acceptable time but anything built after they changed from latches to magnetic sealing strips will crap out very quickly. William R. Watt wrote: There is a website describing how to use a discarded 'fridge compressor for vacuum bagging. The fellow who tried it used a vaccum gauge from an automobile in his configuration and claims he got 25 psi vacuum for his project. He just used standard plumbing fittings to connect the vacuum bag. I do not have the website address. I was browsing on a computer at the public library at the time and did not write it down. However you can find it by going to www.boat-links.com, clicking on "The Mother of All Boat Links", clicking on the first box "amateur boatbuildign and repair" and scrolling down untill you find the link about vacuum bagging. Nowadays all discarded 'fridges go to a recyling depot where they "vacuum bag" the freon gas to protect the ozone layer of the atmosphere. It should be easy to get a compressor by telephoning the miniciapl garbage department. Since compressors do wear out it would be a good idea to look for ones off later model 'fridges (the date of manufacure should be on a label on the 'fridge) bring home 2 or 3 to try. -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com |
#5
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![]() "William R. Watt" wrote in message ... There is a website describing how to use a discarded 'fridge compressor for vacuum bagging. The fellow who tried it used a vaccum gauge from an automobile in his configuration and claims he got 25 psi vacuum for his project. He just used standard plumbing fittings to connect the vacuum bag. hahaha.. good one. he claims he got 25 psi vacuum..... do not pass go, do not collect $200. go to jail. hugh p.s. my old engineering profs would fail you the whole year for saying somthing like that in any individual exam.... |
#6
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I see that mistake so often that I just automatically think inches Hg.
Any decent vacuum pump should be able to reach 25 to 28" Hg in a really well sealed bag but a perfect seal is very hard to get. While laminating plywood requires as much vacuum as you can get most glass bagging is done below 15" so pump volume is usually a lot more important than ultimate pressure. hugh wrote: "William R. Watt" wrote in message ... There is a website describing how to use a discarded 'fridge compressor for vacuum bagging. The fellow who tried it used a vaccum gauge from an automobile in his configuration and claims he got 25 psi vacuum for his project. He just used standard plumbing fittings to connect the vacuum bag. hahaha.. good one. he claims he got 25 psi vacuum..... do not pass go, do not collect $200. go to jail. hugh p.s. my old engineering profs would fail you the whole year for saying somthing like that in any individual exam.... -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com |
#7
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"Glenn Ashmore" wrote in message
news ![]() I see that mistake so often that I just automatically think inches Hg. Any decent vacuum pump should be able to reach 25 to 28" Hg in a really well sealed bag but a perfect seal is very hard to get. While laminating plywood requires as much vacuum as you can get most glass bagging is done below 15" so pump volume is usually a lot more important than ultimate pressure. true. the mercury thing can confuse people. i'm living in SI-land so a unit like psi is already wierd enough. if you started talking about inches of mercury here people would start looking up the address and phone number of the nearest loony-bin. 'twould be like using a unit like a furlong per fortnight or a slug/acre or something.... just unbelievably arcane and difficult. ah well. us SI people owe the french for something.... still, every time i see that mistake i laugh because our engineering profs did have a habit of trying it out on students and if you went for it you were in BIG trouble. hugh p.s. i also always wonder if maybe people are vacuum bagging composites on venus or half way down the atmosphere of jupiter. |
#8
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William R. Watt ) writes:
claims he got 25 psi vacuum for his right. change "psi" to "lb". -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned |
#9
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Hugh,
How about laughing to yourself next time and explain to the guys that didn't go to engineering school why it's wrong. No need to be rude. Regards, Ron |
#10
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Standard atmospheric pressure is a bit over 14 PSI so that is as much
pressure as a vacuum can produce. The first proven vacuum was produced by Evalgelista Torricelli, Galileo's assistant, by filling a glass tube with mercury and turning it upside down. The mercury dropped until the weight of the mercury in the tube equalled the pressure of the air outside. That was about 30". Torricelli almost got in a lot of trouble about this because the Pope had decreed that there was no such thing as a vacuum so he sent the idea to a Frenchman named Pascal to work on. For many years we have happily used the height of the mercury to describe a vacuum. We and the English used inches and everyone else used milimeters. Then the French and Itallians conspired to change everything at an international standards conference and we ended up with Torr as the official measure. Being Itallian the unit had to be totally irrational so a Torr is 1/760th of an atmosphere. To add to the confusion the "Bar", (short for barometer) was used to describe one standard unit of atmospheric pressure so vacuums are measured in fractions of a bar called millibars. Also the French did not like for an Itallian to get any credit so in an evil pact with the British, they came up with the Pascal to describe one atmosphere of pressure. To get the British to go along the Pascal was based on a unit named after an Englishman, the Newton, but to keep the English in their proper place they made the Pascal equal to a million Newtons. The thing is, the measurement of "standard Atomspheric pressure" that they used to set the actual values was off a bit so all of these units are not quite accurate. That is why I still use inches of Mercury. :-) Ron Thornton wrote: Hugh, How about laughing to yourself next time and explain to the guys that didn't go to engineering school why it's wrong. No need to be rude. Regards, Ron -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com |
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