Has anyone tried this?

I'm thinking of building a vacuum chamber to hold a microwave oven. The idea is to lower the boiling point of water and hopefully get better results drying green wood.

Reply to
Joe and Daphne Bazer
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Atmospheric pressure is 14.7 pounds per square inch. That works out to a little over a ton per square foot as you approach vacuum. Are you doing small pieces of wood in a tiny microwave oven?

FWIW, you can build a cheap vacuum pump out of an old Ford auto air conditioner. Hook it up to an electric motor and connect your vacuum line to the inlet side of the pump. We use ours for vacuum packing survival supplies.

Bernadette

Reply to
BernadetteTS

This idea was researched several years ago, albeit slightly different, their idea used a vacuum chamber of sorts inside of the microwave. Try the link from google below, watch for word-wrap, and poke around a bit more in google using different searchwords.

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Reply to
James Barley

Ask Steve Knight on rec.woodworking. He was building a vacuum assisted drying system to speed making of his planes. I don't know how far he got or if he succeeded.

ARM

Reply to
Alan McClure

I'm thinking of building a vacuum chamber to hold a microwave oven. ^^^^^^^^^^^^^^ The first thought that crosses my mind is that you will affect the cooling of the microwave electronics. Doesn't it require air for cooling?

Reply to
Leo Lichtman

Easy answer, Leo. Just put a battery operated, all plastic fan in with the MW and it will blow the vacuum around to cool the MW electronics! *G*

P.S. I still think LDD is a bit easier!

Reply to
Leif Thorvaldson

You won't need a very good vacuum.

22 to 26" Hg will be plenty as the microwave heats the wood to 125 - 150 F.

My science teacher said that 26"HG is complete vacuum. So I guess you WILL need a pretty good vacuum. Or do your drying off-planet.

Dave Colorado

Reply to
Dave Sifers

Reply to
william_b_noble

Reply to
Jim M

Q. Why are all of your pressure products which measure vacuum scaled to 30" Hg? A. A perfect vacuum, if it were possible to obtain, would be the result of completely eliminating atmospheric pressure. Since atmospheric pressure is defined as 14.696 psi, which is equal to 29.92" Hg, manufacturers use 30" Hg as a nominal value for scaling their products.

Reply to
Jim M

Hello,

I would like to warn you about one thing : I wouldn't put the whole microwave oven inside a vacuum chamber : THAT MAY BE DANGEROUS !

I explain : there is an electrical law (I don't remember its name) about insulation vs pressure that tells there is a gap in insulation properties between athmospheric pressure and the vacuum (not a real gap but the insulation becomes rather low). Since a microwave oven involves high voltages, this low insulation properties may be a concern when the vacuum is made before it reaches # 0 atm.

A safer way to do it is to put the vacuum chamber inside the oven as James has pointed. But again here : beware of not breaking the electromagnetic shielding when you drill the vacuum ports ! You may end with dangerous radiations losses !

I'm not a real specialist of these topics, but I hope these warning could help :-)

JYS

Reply to
JYS

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