Moisture Content Using Nails - Router Forums
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post #1 of 15 (permalink) Old 06-16-2014, 06:44 AM Thread Starter
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Default Moisture Content Using Nails

I used 2.1mm stainless nails 40mm length, the probes on the moisture meter are 2.0mm, probe length 12mm. The meter is a Japanese Sato with 4 settings for wood types.

In each of the readings I probed first then placed the nails in the same holes taking a reading off the nails. I then pulled the nails and used the probes again. All readings were taking with the holes parallel to the grain. Readings on the nails were the same at the whether taken on the head or at point of entry of the wood.

2X6 pine - Probes full depth into 3 readings were 13.5% and the nails same depth in the same holes also read 13.5%. One reading closer to the end was 12.5% both probe tips and nails. One other reading was 13.0% both probes and nails.

Japanese Oak 4/4 X 4in - I could only force the probes about 1/3 of their length. I then read nails set to 1/3 of the probe depth. I then drove the nails to full probe depth and took a reading. After pulling the nails I could get the probe to full depth. Full depth: Three readings were 12.5% and two others were at 12.0%.

Birch 5/4 X 5/4 - I also had to drive the nails to get the probe to full depth all the readings in it were 13.0%.

1X4 pine Ė probes at full depth were past the center of the thickness. I then probed from the opposite side to the approximate depth of the first reading. This reading was not full probe depth. Both sides gave a reading of 13.0% with the nails and probe. The center was 13.5%.

Conclusion: stainless nails will serve adequately and can remain in the boards during the drying process. To probe a sample in the middle of the stack requires unstacking it. The nails provide easy access.

Secondly, the nails can provide readings at greater depth effectively lengthening the probes.

Comments from the engineers please.

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post #2 of 15 (permalink) Old 06-16-2014, 08:33 AM
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Steve, per your request I have reviewed this. Let me first say that there will be many members more qualified than me to answer this question. Evaporation is certainly going to take place from ends, sides and faces of boards - rather than internally (duh). Per square inch ends will lose more moisture than sides and faces due to "wicking". When a probe goes into a forced hole - it seems to me that the derived moisture reading is going to be slightly "compromised" due to the resultant and obvious concentric compression around said penetrating member. I would personally feel safe in assuming that a more accurate moisure reading would be in a drilled hole. In [structural] engineering (from which I retired in 2001) it was often necessary for me to do forensic explorations. We had numerous insurance companies as clients and they always want to know WHY? buildings have failed. For heavy timber structures, we took core-drilled samples to testing labs for weighing on super-accurate scales. Good testing labs have numerous ways to determine moisture content in wood products - be it heavy timber, Glu-Lam, etc.

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post #3 of 15 (permalink) Old 06-16-2014, 11:36 AM
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So it does appear to work Steve. Since the tester is mostly a galvanometer it should try to measure across the easiest path of resistance which should be the wettest section in the board. That's my theory at least. Thanks for the test results, good to know.

Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.
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post #4 of 15 (permalink) Old 06-16-2014, 03:13 PM
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I'm no engineer and not even close to being a scientist, Steve, but I do believe in the pragmatic approach to problem solving and it looks like your empirical testing proves your system works. Since I get all my wood from the big box stores, I think the moisture content in the stuff I use is measured as "whatever".

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post #5 of 15 (permalink) Old 06-17-2014, 06:51 AM Thread Starter
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Otis, Chuck, and Oliver thanks to all of you for your comments.

Yes current always takes the path of least resistance, and the wettest portion should provide just that. I may coat the nails with something that doesnít rub off when driven into the wood, that should assure that I am actually reading the moisture content in the center of the board. I will have to experiment with the coatings.

Drilling a 1.5mm pilot hole would eliminate the compression factor; however, as the wood dries it may shrink away from the nail. I Think I read somewhere that a hole in green wood will shrink as it dries. I will have to ponder on the shrinking factor a bit.

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Originally Posted by Gaffboat View Post
Since I get all my wood from the big box stores, I think the moisture content in the stuff I use is measured as "whatever".
That was me too, no thought whatsoever, until I received 500 board feet of knotless cherry wood for nothing other than the sawmill charge and my time stickering and stacking. That awakened me to a whole new world of woodworking. I donít want to plane down a wet board and have it warp later.

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post #6 of 15 (permalink) Old 06-18-2014, 10:49 PM
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This topic is out of my pay grade vis-vis furniture making.
I bought my probe style moisture meter 20+/- yrs ago for doing diagnostic work on leaky condo projects.
When the mushrooms started sprouting on the drywall the Property Mgr. would give me a call...
In technical terms that's called 'soggy'.
If I got reading of 13% the owners would have thrown a party!
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post #7 of 15 (permalink) Old 06-19-2014, 10:07 AM
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Drywall growing mushrooms. Did your meter have a reading of "Holy Crap, this is wet"?

Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.
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post #8 of 15 (permalink) Old 06-20-2014, 03:21 AM
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This is the meter that I use, it cost about $20.00 on Ebay two or three years ago and it's readings check the same as a later model that a friend of mine has. It's accuracy to me is un-important as I use the figure as a comparison, 11% is perfect for my flat work, routing and turning. I'll be interested in the figures that other members consider ideal.

EDIT...I was done! take a look at this! http://www.ebay.com.au/itm/Digital-4...cce5058&_uhb=1
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post #9 of 15 (permalink) Old 06-20-2014, 07:32 AM Thread Starter
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Quote:
Originally Posted by Cherryville Chuck View Post
Drywall growing mushrooms. Did your meter have a reading of "Holy Crap, this is wet"?
Who needs a meter, just count the mushrooms. 1 = wet; 2 = Huston, I think we have a problem; 3=no doubt there is definitely a problem; a whole bunch = forget fixing it, let's start a farm.

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post #10 of 15 (permalink) Old 06-23-2014, 02:05 AM Thread Starter
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Quote:
Originally Posted by harrysin View Post
This is the meter that I use, it cost about $20.00 on Ebay two or three years ago and it's readings check the same as a later model that a friend of mine has. It's accuracy to me is un-important as I use the figure as a comparison, 11% is perfect for my flat work, routing and turning. I'll be interested in the figures that other members consider ideal.
Harry
I have to assume you already know this. Taking moisture reading on the end will likely not give a true reading (as in your pictures). Wood generally dries in this order: the ends, sides and then middle. The ends are generally the driest of any given piece of wood.

From what I have learned researching about moisture meters, you want place the probe in the same annual ring to get a correct reading. In testing you will consistently get a lower moisture reading when the probes are perpendicular to the annual rings than placed parallel (though some meters are designed to do that ďRead Instruction ManualĒ ouch, to determine the orientation).

With that said that leads to a problem. Who wants to take a reading in the middle of the expensive board and leave two holes in the face? One answer is to take the reading on the back of the piece in a place where they are not likely noticed. The second solution would be to probe where the wood will be cut or removed. The third answer is to buy an expensive non-pin dielectric moisture meter.

In the past, like Oliver, I was not concerned with the moisture content of the wood. I went to the store, bought it, and simply left it in the environment where it would be used for a week or so. That was to let the wood reach Equilibrium Moisture Content (EMC) of the environment before working on it. I have a couple of scrap pieces that I take micrometer readings of all three dimensions once a month or so to determine how much they move.

I started to study about moisture content when I started drying cherry wood; likely I still have much to learn. The oak right now is 9% cherry 8.5%. I assume the piles I am drying right now 15-19% will make it to less than 10% range at some point. Like I said I am new to this and like you I would like others feedback too.

Steve

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