Thread: Moisture Meters.............Yes Again.

G'day.

If the moisture meter can be or is calibrated to Douglas Fir, Than you can get correction tables for Australian and overseas species.
I have a correction table right here beside me as I type.
What specie do you want?

Or you can go to the CSIRO website and download the tables.

Please remember, the tables are for old growth timber.
Thay may not be absolutely accurate to regrowth or plantation hardwood.

With Moisture meters, you get what you pay for. I have 4 meters here and the cheapest cost $1800.
I have tried the $100 to $1000 range of meters and they are crap. No repeatability of readings from the same samples tested.

Hooroo.
Regards, Trevor
Grafton

Thanks Glock, I was sorta hoping you might find this. I know you are onto this stuff after I did the search thing.


Upon further investigation, the Carbatec model is touted as a "comparison" type. The LV is advertised as, being able to be used to obtain an actual reading. They supply a chart with a few Aus timbers. I'll go hunting around CSIRO and see what I find.
I realise you get what you pay for, I just want a BMW for a Hyundai price, no different to anyone else.

Whilst I have your attention, I realise that fallen timber, that is, dead and fallen for some time, can actaully have a really high MC, do I just apply the correction factors as per my table, or what?

Fer crikeys' sake Trev, tell the man
In other words Outback, as far as I am aware & concerned yes you should apply those same correction figures as per species. Just as a matter of interest some old bridge girders pulled out and replaced have been 100 years old and still not reached much better than EMC :eek: friggin resiliant stuff timber.

It doesn't really take much to calibrate the meter to the actual timber you are using.
But dont get carried away in all the techno stuff, absolutes aint necessary for cabinetry etc. If they were there wouldn't have ever been any antique furniture.
Just use a meter as a guide

Originally Posted by echnidna

It doesn't really take much to calibrate the meter to the actual timber you are using.

Really???
Tell that to the CSIRO, QFRI, DPIQLD, Forests NSW.
And the meter manufacturers...WAGNER, Delmhorst, Deltron, Etc etc etc

They would love to save Umpteen thousands of $ every year by not having to produce calibration tables for Moisture meters.

Hooroo.
Regards, Trevor

Let me rephrase, it dont take much to prepare and measure the particular species that you use with varying moisture contents. From this you can determine the correction factors you should use. Now if yer wanna do all the species in Oz thats a bit different

Originally Posted by echnidna

Let me rephrase, it dont take much to prepare and measure the particular species that you use with varying moisture contents. From this you can determine the correction factors you should use. Now if yer wanna do all the species in Oz thats a bit different

I am assuming that you would be sampling over 66 samples against oven dry testing of the exact same 66 samples?
And then do it all again with another 66 samples to verify that the first set of readings are repeatable by the second set of readings.
Then calculate the R squared goodness of fit figure that can then be applied to your readings for use in future testing.

There is a lot more to moisture meters than meet the eye.
That is why we rely on oven dry testing. It is the most accurate you can get. and it is recognized in the Australian Standard..

Hooroo.
Regards, Trevor.
Grafton.

If you are after a reliable Moisture Meter, Talk to Mark Heath @ The Moisture Meter Company in Coffs harbour.

Originally Posted by glock40sw

There is a lot more to moisture meters than meet the eye.
That is why we rely on oven dry testing. It is the most accurate you can get. and it is recognized in the Australian Standard..

I think you might have just confused some of your own arguments there, Glocky ol' fella.....

The best method of checking moisture is the absolute method, alright. Weigh and dry a couple of samples. No correction tables necessary, just a simple calculation. (You can buy a very accurate set of digital kitchen scales these days, for about 50 bucks.)

Of course, this precise MC you've just determined, is as applicable to the rest of the pile only so far as your sampling was truly representative. Same thing goes for the most infinitesimally-accurate moisture meter money can buy.....

So I'd like to support what I think Echidna is trying to say, that given the likely variability of the woodpile, and all the potential sources of error, even a dubious meter is probably going to be within the mean error for each individual reading. An estimate of within a few % is plenty accurate enough, and isn't going to amount to a hill of beans if the MC is in the ball-park, andyour designs allow for wood movement.

By the time you p'ss'd about with multiple samples, checked them against your tables and drew multiple regression curves, caculated your confidence limits, etc., last night's storm will have raised it by a point or two anyway, and you'll have to start all over again....

Which is wot I think Echidna was saying, i.e. a lot of furniture that gets admired was built without the aid of any moisture meter. I imagine the makers estimated the MC of by giving it a whack with a stick or the back of the axe like my old man did.
Cheers,

I thought this had sort of died, I'm glad it didn't.

From my purely untrained and non technical viewpoint.

A really good, (expensive) meter will more likely give me a more repeatable, and possibly more reliable figure when compared to the holy grail of "exact moisture content"


A not so good, (less expensive) meter will more likely give variable readings, even on the same piece of timber, these readings may vary by a couple of puss scent from the holy grail.

Sounds like a cheapo model for me, assuming what I assume is correct. If the metere says its wet, then its wet, if it says its bone dry, at worst it's probably Ok, if it says it's dodgy, wait awhile, test again, and keep going till it drops, or at least stabilises.

Any holes in this theory?

Can you give me some contact details trev of your man in Coofs?

G'day Ian.

You are probably right.
I am over thinking echnidna's original statement.
For joe blow P!ssing around of a weekend with questionable vintage wood, A $2 moisture meter is probably going to be better than none at all.

In my situation, where a faulty moisture content can cost you tens of thousands of folding stuff. I need all my moisture monitoring equipment to be spot on and repeatable. Moisture content is so critical nowdays, that I run an Inline moisture meter behind my moulders so that every board gets checked.
Each specie setting is calibrated against O.D. with the sampling as I stated above. Regression for all species is between .78 to .91.

Any boards that get rejected are then cut and oven tested to verify the Meter.

Thanks.
Hooroo.
Regards, Trevor.
Grafton.

Originally Posted by glock40sw

For joe blow P!ssing around of a weekend with questionable vintage wood, A $2 moisture meter is probably going to be better than none at all.

That's me, That's me.

Joe Blow, not to be confused with joegee.

The Moisture Meter Company in Coffs

These guys know there stuff and they send the same day in the mail around aus, i have brought a couple off them and are happy with my purchase. plus if i lose my correction table i will know where to get another one from.

Originally Posted by outback

That's me, That's me.

Joe Blow, not to be confused with joegee.

The Moisture Meter Company are in the Book.
They don't have a web site, But if you google Wagner Moisture Meter.
It will take you the the U.S. wagner site.

PM me your Phone number and I can ring his number to you on monday when I get to work.

Hooroo.
Regards, Trevor.

P.S. timbercon website have merlin moisture meters.
Of them. the only one that met my level of accuracy by testing, was the blue Merlin for $999.00

Originally Posted by glock40sw

Each specie setting is calibrated against O.D. with the sampling as I stated above. Regression for all species is between .78 to .91.

Trevor - I wish you were my wood supplier!
I can't for the life of me see why absolute MC is so critical, but I'm sure you wouldn't be going to all that trouble (and expense!) if it weren't. My guess is you're supplying a machine-based manufacturing process where maintaing dimensional stability through the process is critical. (?)

But we can agree that for the average JB like Outback and myself, it's more important to work with stock which is at 'equilibrium' MC plus or minus a percent. That will probably do for 99% of our projects, as long as we design or build around wood movement, and work with stock that is within reasonable limits (and all at the same EMC).

Avagoodweekend,