Choosing a Moisture Meter
A well-informed discussion comparing the cost and characteristics of various pin and pinless moisture meters. October 11, 2012
Question
I need to purchase a high quality moisture meter to check my solid wood production. I prefer a mid to high range quality unit, not entry level. What brand and model are you guys using and where is the best place to purchase from? This will be used in shop and on jobsites.
Forum Responses
(Cabinetmaking Forum)
From contributor W:
The pinless Wagner meters are nice. I have the MMC210. It runs about $375. They make a range of meters for woodworking, flooring, and finished wood applications.
From Professor Gene Wengert, forum technical advisor:
The pinless meter offers a quick and no-damage measurement, but the pin meter can measure moisture gradients and is not subject to density variations and does not need an air space behind the wood. So, you will find that both have advantages and disadvantages. Together, they are awesome. Wagner is certainly the leading pin-less, while Delmhorst and Lignomat are pin-types. I would get one with a digital display and a memory. Temperature compensation is also critical in your situation for the pin meter. I suggest you plan to spend no less than $400.
For the pin meter, get one with a remote probe as well. One example would be the Delmhorst J-2000 with the 26ES remote electrode. It is simple yet accurate. For the pinless, Wagner MCC 220 is a good one.
Naturally, other companies make similar equipment that performs just as well. In any case, consider getting one made in the USA to provide outstanding repair and calibration service, if needed, and to assure that North American species are accurately calibrated.
From the original questioner:
Thanks. The more I read about moisture meters, I think the pinless would be best for me, as I also check finished products on jobsites. Most of my work is with 4/4, but I occasionally resaw.
From Professor Gene Wengert, forum technical advisor:
I have a calibration block (actually, it is a pad) but it never has shown that the meter is out of calibration. However, as the meter might be treated roughly, a block would be a good idea. Should you ever have to go to court with your readings, the block would also give more credibility to your readings.
As previously mentioned, the wood does need an air space underneath to get the best reading, so a pin meter is also handy to have in some cases. A pin meter is also useful in measuring just the core MC. The core MC is almost always the same MC as the lumber had when it left the kiln, so that reading lets you know what the final MC was coming from the kiln. Useful if there is a discussion about wet lumber and you want to know if the lumber is wet because you mishandled it or wet because it was not dried initially.
From contributor G:
Lignomat manufactures pin and pinless moisture meters. Pin less meters can check many boards in a short time. The measuring depth for most pinless meters is limited to 3/4". When scanning boards from both sides, that works well for 3/4 up to 6/4 thick boards. If you want to measure thinner boards, Lignomat offers a pinless meter with selectable measuring depth of 3/4" and 1/4" deep.
Disadvantage: Pinless meters can only measure flat boards. Anything round cannot be measured. Pinless meters cannot measure a gradient within the board. If a board is freshly cut, pin meters with integral pins can measure the end grain and detect a gradient. If you cannot cut the boards, use a pin meter with slide hammer to show the gradient.
From the original questioner:
Does anyone know if a Lufft model HTAB-176 is a good hygrometer to have in the shop? Do they really need to be recalibrated every year if they only hang on the wall all the time?
From Professor Gene Wengert, forum technical advisor:
Will it work with dust? Most of these type do not. So, try a Radio Shack $30 digital instrument. For a shop, plus or minus 3% RH is fine. Mine is over 15 years old and is still right on.
From the original questioner:
Ordered the MMC220. The moisture measuring pad on the back is not flat when I put a straight edge on it - it is crowned up so that the middle does not touch the wood when pressed down. Also there is a little plastic pad on the battery door that sticks out farther then the measuring pad. Is this normal or did I get a defective product?
From Professor Gene Wengert, forum technical advisor:
Mine is flat and the measuring pad is the only thing that sticks out beyond the base frame.
From the original questioner:
How flat are you talking? Mine is .004 out of flat on one side and +.002 out on the other side. So when I place on flat wood, only the outside edges contact wood. Is this acceptable?
From Professor Gene Wengert, forum technical advisor:
That would be flat enough for safer woods indeed and very close for more dense woods. Ask the folks who made it if you can sand it a bit, as the electrode is not the plastic covering you see.
From contributor T:
Two months ago, I purchased a Quality MD912 Digital Moisture Meter from histest.com. It is a 2-pin and the sensor range is 2% - 70% RH. It works till now. But now I want to buy a 4-pin one.
From Professor Gene Wengert, forum technical advisor:
The pin moisture meter can only accurately read between 6.5% MC and 28% MC. The reason is that at very low MCs, the resistance is high that it is difficult to measure. Further, at higher MCs, the resistance changes very little with MC, as there is liquid water present which acts like a short circuit.
A typical wood MC meter has a calibration for many species, while the one you mention only has four species. It also will require a manual adjustment for the wood temperature if not close to 70 F. (It does adjust for ambient instrument temperature.)
The four needle probe was developed for veneer and would not normally be used for lumber today.
If you are selling lumber and your customer will check the MC, use a meter that your customer will be using. In my tests, there was considerable variation in MC recorded by some of the less popular meters. In Drying Hardwood Lumber, the Delmhorst and Lignomat pin meters did very well.
From contributor G:
Besides the limits mentioned above when using a resistance-type pin meter, lumber is very seldom at a moisture content of 2%. Lumber would only stay at 2% when the relative humidity of the surrounding air is less than 10%.
