Moisture meters which to buy?

[section1]

Getting a moisture meter is long over due on my list that is thankfully coming to a close, so as I know very little about them I do know that prefer the pin less type. I had a look at Carba tec and they range from $77-500. Ebay from $10 -30 except for one that was $700 but they all claim to. Have the same level of accuracy. So which meter is the one to go for? How much should I pay for one.
im only interested in measuring the moisture in wood nothing else

[Sawdust Maker]

I've been interested in getting one for a while probably a pin type
so the question is, why pinless??

[BobL]

Getting a moisture meter is long over due on my list that is thankfully coming to a close, so as I know very little about them I do know that prefer the pin less type. I had a look at Carba tec and they range from $77-500. Ebay from $10 -30 except for one that was $700 but they all claim to. Have the same level of accuracy. So which meter is the one to go for? How much should I pay for one.
im only interested in measuring the moisture in wood nothing else

Accuracy statements on MC meters are misleading as there is a lot more to measuring moisture than poking or placing a moister meter on a piece of wood.

For a start if you want absolute accuracy the meter has to be properly calibrated, and moisture readings have to be corrected for species. None of the meters for sale at the big box or wood workers stores provide species correction tables for Aussie timbers. There was a bloke on this forum that used to sell correction tables for several different meters and several different major species but I think he has retired, and there is a CSIRO species correction table floating around that covers about 6 different meters. There's also cross grain readings versus along grain to consider.

You can calibrate the meter yourself direct to a species but it takes a fair bit of time.

Pin type meters can only be accurate if the pins can reach the internal parts of a piece of wood so this means cutting into or drilling into the wood so that the pins can enter that far. I can illustrate this effect by some recent measurements I took of spotted gum I milled 7 years ago and it has been outside since then i.e. it should be well and truly air dry. It showed an MC of 15%. Another piece of green spotted gum milled in March also shows a MC reading of 15%. When I drilled into these two pieces the reading was over 25% for the later and 12% for the former. The drier the wood is the more important is it is to do this. Single readings can also be misleading so a number of readings need to be taken and an average taken - do you really want lots of little holes in your wood? This is where the pinless have an advantage.

If you buy a pinned MC meter off the shelf and just use it as is (provided you take the readings inside the wood) about the best you can hope for is reliability of what are called relative measurements.
This piece of wood of species X is dried/wetter than that piece of wood of the same species.
This piece of wood is drier/wetter than it was last month.

In summary, how you use the meter is more important than the type of meter and unless you have a calibrated meter and correct the readings for species the readings will never be accurate.

[section1]

I've been interested in getting one for a while probably a pin type
so the question is, why pinless??

So I don't have to poke the end grain, just scan it and get a reading. The idea is when I'm at the lumber yard mainly the home type ones I suspect are not truly either kiln or air dried.

[section1]

Thanks Bob that was very informative, what I have read today air dried timber left outside will read about 20% and in the shed or barn will never read under 12%. The yanks like their timber inside their shops to read between 6-8% but they say that humidity rises and falls in every shop unless you have a dehumidifier or some climate control like aircon or heater to maintain a constant temperature will rise and fall. So on a rainy day moisture will increase. So it seems to me that any old MC will do since are accurate but atleast will give me a ball park figure. So far I can't say I ever had any issues regarding moisture and I guess I'm lucky but there is one neew lumber yard which they operate from home I'm a bit weary of. When I asked if their are dry the kind of reply I got was well facial expressions just cannot hide the truth. The mouth can say whatever it wants but the face always tells the truth so I need to know what I'm paying for and if I need to dry it myself.

[BobL]

Thanks Bob that was very informative, what I have read today air dried timber left outside will read about 20% and in the shed or barn will never read under 12%.

That's for north america. Here in WA the MCs are generally lower especially on wood left outside after a couple of weeks of blistering WA Easterlies.

The yanks like their timber inside their shops to read between 6-8% but they say that humidity rises and falls in every shop unless you have a dehumidifier or some climate control like aircon or heater to maintain a constant temperature will rise and fall. So on a rainy day moisture will increase

It doesn't have to rain just high air humidity.

. So it seems to me that any old MC will do since are accurate but atleast will give me a ball park figure.

Well yes and no. The really cheap meters struggle to measure low and high MCs

Mine is a Dynatech 2 pin type and cost about $60 about 7 years ago. I see on envy this type is even cheaper still these days.
I thought I would use it much more given I mill and air dry timber but I have not used it that much, only if a customer asks me how dry something is.

[section1]

So I guess there is no meter designed for Australia then

[robbygard]

you can use an inductive moisture meter (pinless) and get a rough idea of the moisture content without calibration but it will only ever give you a rough idea although does give you trend if you do it over time (that is to say that i believe it will always be out to the same degree if it is out) ... i believe they vary also on the density of the timber (which is why you can calibrate and then use charts) ... some of them (probably the more expensive) have more settings for density ranges of timber and will therefore be more accurate ...

i believe the pinned ones can be used by driving a couple of nails into the centre of the wood and reading across the nails but for me i don't want to have the holes in my wood

i use a pinless one with four settings for density (about $50 i think) but know that it may be out by 4% or so

i don't really know enough about it to be sure (so don't rely on my info absolutely) but i know one local timber mill calibrates on oregon and then uses (CSIRO? FORESTRY? ) charts to get accuracy in their readings

regards david

[section1]

What I've read today in this taunton book and lol I don't remember the title is that the pinless ones are used for dense woods and the pinned ones are used for softwoods and rough sawn lumber.

[justonething]

I got both the pinned and pinless types of mc meters, both from general instruments in the US. I never really given it much thought that different species of timber would presumably have different conductivity coefficient and hence incorrect when measured without calibration. I just use them around the home, trace leaks or for painting etc. I haven't even looked into what the definition of moisture content is but I reckon for a given volume of timber, weighing it would be the most accurate means if you care about how seasoned a piece of timber is. I've seen densities of a variety of timbers (both dried and green) listed on the net and with a bit of mathematics, you will get the overall mc for that given volume of lumber. Just a thought.

[BobL]

I got both the pinned and pinless types of mc meters, both from general instruments in the US. I never really given it much thought that different species of timber would presumably have different conductivity coefficient and hence incorrect when measured without calibration. I just use them around the home, trace leaks or for painting etc. I haven't even looked into what the definition of moisture content is but I reckon for a given volume of timber, weighing it would be the most accurate means if you care about how seasoned a piece of timber is. I've seen densities of a variety of timbers (both dried and green) listed on the net and with a bit of mathematics, you will get the overall mc for that given volume of lumber. Just a thought.

MC is % of weight of water in weight of wood so volume is not needed to perform these measurements.

Although the density of timber can be used to determine MC, because density at the same MC can vary on the same tree by ~10%, and between different trees by as much as 20%, it's better to use weight

[IanW]

Years ago, I desperately wanted a moisture meter, but there were too many other things I needed first. When I thought I had to know just what the MC was, I used multiple offcuts and oven-dried them. You don't get instant readings, but because I worked in labs that had very accurate scales and convenient drying ovens, it was easy enough to do. And by careful selection of representative samples, I probably got results that were far more accurate than even the most expensive meter can deliver.

Over time, by following the drying patterns of the various woods I worked with, I got used to their drying patterns, & found I rarely needed to know exactly what the MC was. For species I'm reasonably familiar with, I can tell that it's 'close enough' by rapping a sample on the bench (the drier a piece is, the more it 'rings'), or by the way it saws/planes. The design of any piece of solid wood furniture should accommodate a pretty wide range of movement, anyway, particularly if you live in areas that have wide relative humidity swings, or use winter heating. The upshot is, a moisture meter has long since dropped off my wish list.

If you have to buy wood in & use it straight away, I guess a meter could be helpful. It's hard to convince some people that storing allegedly kiln-dried wood in an open shed where rain can blow in on it isn't a very good idea....

Cheers,

[Bushmiller]

Section1

A few comments: The traditional aim is to bring moisture content of timber down to 12%. The further you go West (from the East Coast) the timber may have to be dried down to 10% or even less because of the low humidity. The timber will always absorb or dry to the environment and this is the cause of extensive problems in furniture.

The penetrating style of moisture meters read the moisture content only at the depth of the pins or knives. I can't offer opinion on modern meters as mine is an ancient old thing, but I believe still quite reliable.

The issue of measuring deep inside timber can be resolved by drilling into the timber to the required depth and inserting the pins (BobL suggested this), but you may get a false reading if taken immediately. Leave for a couple of days and then take a reading. My supposition here is that the drilling process imparts heat and may have the effect of drying the timber although this will only be temporary. The need to drill holes clearly only becomes important as the thickness of the timber increases (and with the hardness of timber as the pins/knives cannot penetrate). The accuracy on a 25mm timber board will be better than a 100mm board. A 50mm hole may be required for the 100mm board while the pins/knives may penetrate sufficiently on a thin board.

So what about all these holes? The way the timber mills get around this is that they have a sample board of the same thickness but only a short length. This is placed in the middle of the drying stack and is the piece that is measured. However, here I have to say that they use the oven drying method rather than the technique we are describing here. Ultimately oven drying measurement is more accurate.

You may like to have a look at this thread (which is horribly long) and some drying is discussed from post #30. The drilling and pin issues are broached in post #51.

https://www.woodworkforums.com/showth...=170760&page=3

Lastly, all moisture meters are calibrated for Douglas Fir (we call it Oregon) and you have to refer to correction tables to make the adjustment for whatever you are drying. These correction factors vary according to the moisture content. They are available on the net.

http://www.finlayson.com.au/download...ture_final.pdf

http://www.delmhorst.com/Product-Sup...rection-Tables

Looking at the second link reminded me that temperature also affects moisture content and some compensation has to be made there too. However, don't become too fazed by all this as providing you are within two or three % you will be doing well and shouldn't have too many problems. Your biggest issue on the Gold Coast is drying the timber in the first place because of high humidity.

Always measure across the grain.

Hope this helps.

Regards
Paul

[BobL]

. . . . . . Lastly, all moisture meters are calibrated for Douglas Fir (we call it Oregon) and you have to refer to correction tables to make the adjustment for whatever you are drying. These correction factors vary according to the moisture content. They are available on the net.

http://www.finlayson.com.au/download...ture_final.pdf
. . . . . .
http://www.delmhorst.com/Product-Sup...rection-Tables

Those corrections are for a specific meter.

The tabled figures arebased on the Deltron Moisture Meter. Figures may differ for other meters - refer FWPRDC report PN01.1306 ).

The CSIRO tested 6 different meters and found that corrections of as much as 6% are needed for other meters on Australian trees.

[section1]

Thanks very much guys for the info. I usually like to air dry my timbers for about two years but till then I purchase from various lumber yards to keep me going. This was a wealth of information you all have given me