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.

 

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.

 

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".

 

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 doesn’t 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.

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 don’t want to plane down a wet board and have it warp later.

 

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!

 

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.:lol:

 

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-...ector-Tester-CM-/360723664984?pt=LH_DefaultDomain_15&hash=item53fcce5058&_uhb=1

 

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 “Read Instruction Manual” :fieuch, 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

 

Living in the desert has it's rewards. I haul wet wood from soggy climes to my house, sticker and stack it outside and cover it with a tarp (leaving circulation gaps at the sides and ends of the stacks) and in 4-6 months, it's ready to use.
I don't use a meter. However, were I living in a more humid area, I'd have one. I'd also welcome some fungus. Spalting is nice!

 

I spalted some by accident Gene. I covered some lumber with sawdust and it got wet without me knowing it. When I checked it in 2-3 months it was spalted perfectly.