A question regarding moisture meters.

[Kalimna]

Greetings folks,
I wonder if I could ask the collective wisdom of the forum about meters for measuring wood moisture. I think it is about time I invested in one (especially as I see mild moving more into the realm of guitar building), and would like to know if something like this £40 Stanley is a reasonably accurate device

http://www.axminster.co.uk/stanley-stan ... rod905677/

If not, can anyone suggest an alternative of a similar price? I am not interested in spending a fortune on one, however!

Cheers,
Adam

 

[Sgian Dubh]

Moisture meters can be a useful tool to indicate that the wood you are planning to use in a job is somewhere near a preferred moisture content. This tends to be the case if you're relatively inexperienced around wood and haven't yet developed the experience to 'read' what's in front of you. In reality I seldom use a moisture meter because I find that in the act of cutting and working the wood I can usually tell pretty well whether or not the moisture content is about right for what I want to do.

I haven't used that particular brand of moisture meter, but the technology for making them work is well known and generally reasonably reliable. You will probably find the instructions that come with the tool will say that readings are accurate to something like 2 - 3% either way. The two short pin electrodes penetrate the wood by 6- 10 mm (1/4”—3/8”) deep all dependent on their length. The electrodes should be pushed in following the long grain direction so that current flow also follows the grain, not crosses it. Electrical resistance across the grain is greater and results can be misleading. This applies particularly when testing wet wood, ie, wood over about 20 percent MC.

They work really rather accurately on fairly thin woods. There is almost always a moisture gradient from the surface of the wood to the core. The average moisture content is usually about halfway between the surface and the centre of the board thickness. In a board 25 mm (1”) thick this means the pins get a good median reading at about 6 or 7 mm deep (7/32”±) deep. Similarly, with a board 100 mm (4”) thick the pins should ideally penetrate 25-30 mm (1” to 1-5/32”) deep. Slainte.

 

[Reggie]

Just as a side note, if you have a digital multimeter, you may not need to buy a moisture meter, as you can use that to measure the resistance and convert with a bit of maths apparently.

http://woodgears.ca/lumber/moisture_meter.html

 

[Kalimna]

Richard/Reggie - thanks for the replies, and some useful info there. I think I may just hold off spending more at Axi for the time being, following your advice. I can always use the 'weigh it till it stops losing weight' method as well.

Cheers,
Adam