Moisture reading vary by turning meter 90 degrees

[Alan Lightstone]

Can't figure this one out. With a Lignomat scanner D meter, a sample of wood I tested gives a reading of 10.1% with the meter's long axis parallel to the length of the wood. When I turn the meter 90 degrees, so that its long axis is perpendicular to the long axis of the board, the meter gives a reading of 9.1%.

The boards I am measuring are 4/4 teak, about 48" x 10".

Can anyone explain why this is happening?

[Neil Brooks]

Have you tried taking readings -- whether you hold it in the original direction OR in the 90* direction -- in various other parts of the same board ?

Maybe it's less about direction than it is inconsistency in the MC of the wood.

:confused:

[Alan Lightstone]

Have you tried taking readings -- whether you hold it in the original direction OR in the 90* direction -- in various other parts of the same board ?

Maybe it's less about direction than it is inconsistency in the MC of the wood.

:confused:
No, it consistently has that difference throughout the board.

[Ken Fitzgerald]

Is it the "pin" type?

Could it be that when both pins are in the same grain, the readings are higher?

Is it a digital meter or an analog meter movement?

[Nelson Howe]

The instruction manual on mine says to run it with the long grain. I think it is calibrated for differences in resistance with and across the grain.

Nelson

[John Coloccia]

It's because it's a pinless meter and they do that. I had a pinless Wagner that I hated. I eventually switch to a Delmhorst with pins and an analog gauge and now I'm happy again. :D

[Alan Lightstone]

The instruction manual on mine says to run it with the long grain. I think it is calibrated for differences in resistance with and across the grain.

Nelson
Ah!!!! Never knew that.

[joe milana]

I bought a Wagner pin-less once (Paid about $400 for it) and it about drove me nuts. Readings were all over the board (no pun intended!). It was supposed to read to a depth of 3/4" but if I hung a board over the edge of the bench and set the meter on it I would get one reading, If I waived my hand 6" below the board, the reading would change. If I rotated it 180 deg., the reading would change. If I set the board on the bench, the reading would change. I exchanged the meter for a new one and got the same results. Needless to say, I returned the meter.

[Scott T Smith]

The instruction manual on mine says to run it with the long grain. I think it is calibrated for differences in resistance with and across the grain.

Nelson


This is correct. Additionally, you should operate a pin type meter the same way.

[Chris Padilla]

This makes sense.

If you think about wood as a bunch of soda straws bundled together, you'll have a decent idea why they suggest reading along the grain....

[Dan Hintz]

But wouldn't being off just a single tube/grain result in the same (or mostly same) reading as going across many tubes/grain? If the grain wall is causing the issue...

[Scott T Smith]

But wouldn't being off just a single tube/grain result in the same (or mostly same) reading as going across many tubes/grain? If the grain wall is causing the issue...

Dan, good question. If you study wood cells, they are not round - they are oblong. Thus, there are more cell walls in a given distance "across the grain" as opposed to "with the grain". This in turn affects the amount of resistance between the probes.