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What is it? Set 512

Greetings, all. I was in the "lurking" phase before joining this group because I am retired now and have vague ideas about finishing my basement. I intended to wait a few weeks before exposing myself here, to learn the vocabulary and group norms. (& outspoken personalities, etc.)

But I just could not resist the idea that came into my head about using magnetic resonance imaging to measure water content in wood. Of course, not very many people have a few million dollars to spare, a workshop with a few hundred cubic meters of spare space, and a few kilowatts of spare fusebox capacity.

Then it struck me like a cartoon "light bulb" balloon. You don't need to do MRI! You can do molecular microwave resonance measurements using a microwave oven, which is already tuned for the water molecule.

All you need to do is put a fixed quantity of water at a known temperature (i.e. exacly 100 ml of water at exactly 0 C) along with your piece of wood.

Then you fire up the oven for a fixed time, (i.e. exacly 100 seconds) and measure the resultant temperature of the water. If you know the effective power of your magnetron[1], you should be able to easily calculate the fraction of the total water content in the oven as it is divided between your wood piece and the container with the liquid water.

If you are worried about damaging the wood, just use a smaller time period. The result will be less accurate of course.

[1] You can calculate it just by seeing how long it takes to boil the water when there is no wood in the oven.
Reply to
Mike Duffy
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Probably -- if you can tell when the wood reaches a sufficiently dry state to re-weigh it. :-) Perhaps bake it at a specified temperature until another two hours does not produce more than a 1% change in the weight.

Presumably, the sap constitution is sufficiently standard so it produces the needed salts when in the just cut state. And thus the drying would move the resistance along a known curve.

Nor is it clear that anyone needs the measurement to sufficient precision to provide a market for such a device. :-)

Since the exposed part of the pins has two diameters, I would expect that you drive it in until the shoulder touches the surface of the wood. (Given that said surface in the raw state is rather inconsistent even if you strip off the bark first). :-)

I'm not sure that there is insulation in the tool shown, nor on the shanks of the pins -- but by loosening the screws in the sides, you could withdraw the body and then measure the resistance between the pins with no danger of the body shorting them. I think that the primary function of the body is to be strong enough to drive them in without problems, and built-in insulation appropriate to the apparent period of the device may not survive that process with a serious hardwood. What the tool *does* do is place the two pins at a precise spacing, and if driven to the shoulders of the pins, at a repeatable depth, too.

Enjoy, DoN.

Reply to
DoN. Nichols

I can imagine two more reasons to remove the body. It would be easier to connect the meter without shorting, and the pins could best be extracted one by one.

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The chart is for 8mm penetration. On the tool, it looks like 15mm to the shoulders. If 8mm were adequate for a given job, the pins would be easier to drive and extract. I wonder if the tool was used with a wood block as a spacer for a chosen depth.

Reply to
J Burns

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