Well, temptation won, Houtslager's bargain moisture meter must be the thing at a tenner, I thought. But is it? A follow up on the original post suggested it mght not be, but too late, mine was in the post. First impression, ooh! it's tiny, and look at those diddy (5mm) pins. A quick look in 'Understanding Wood' suggests these are about the right length for timber ~25mm thick, and so it proved. Don't worry if you use thicker stuff, read on.
According to the meter, some rough sawn 25mm 'builders' softwood' which has been outdoors under cover here in Devon for at least 2 years, measured just over 17%. Our RH varies between 75 and 95% (and it rains a lot) so 17% moisture content (MC) would be about right. In the workshop there's a dehumidifier set to 50%, and some 32mm maple that's been there for over 10 months measured around 7%MC which doesn't seem unreasonable either.
Resistance meters (ie those with pins) will measure the wettest route they can find between the pins. Path of least resistance, Ha ha. As the wood is wetter the further in you go, pin meters will read higher the further in you push the pins. According to Hoadley's book, the pins need to go in between 1/5 and 1/4 of the timber thickness, as the MC at this depth approximates to the average - the figure everyone talks about.
If your sample is over 25mm thick, prick a pair of pin marks with the meter and bang in a couple of nails till the points penetrate to around 1/4 thickness, and then put the meter's pins on the nail heads. Sophisticates could make up a pair of leads with small crocodile clips (Maplin)
Hoadley also points out the wood's electrical properties are different along/across the grain. Pins should go parallel to the grain, cross grain readings will show higher resistance (too low MC%). This can be ignored at low MC levels.
According to Hoadley, pinless meters often read half way into the stock. Thus, on a particular sample, they may show a higher reading than one with pins. Determining a true average MC for a whole board, even with pro meters, seems therefore not an exact science, even if you have correction tables for different species supplied.
It is unreasonable to expect this (ten quid) device to take on all comers, and nor does the maker provide correction tables. The spec does not include one for accuracy either, although the results above appear sensibly accurate. However it is robust enough for light use, and will work on thicker timber with the aid of a couple of nails. Some expensive meters also require this step. It would be ideal for checking that bought in (or newly dimensioned) timber had finished acclimatising to the workshop and was ready for further use.
According to the meter, some rough sawn 25mm 'builders' softwood' which has been outdoors under cover here in Devon for at least 2 years, measured just over 17%. Our RH varies between 75 and 95% (and it rains a lot) so 17% moisture content (MC) would be about right. In the workshop there's a dehumidifier set to 50%, and some 32mm maple that's been there for over 10 months measured around 7%MC which doesn't seem unreasonable either.
Resistance meters (ie those with pins) will measure the wettest route they can find between the pins. Path of least resistance, Ha ha. As the wood is wetter the further in you go, pin meters will read higher the further in you push the pins. According to Hoadley's book, the pins need to go in between 1/5 and 1/4 of the timber thickness, as the MC at this depth approximates to the average - the figure everyone talks about.
If your sample is over 25mm thick, prick a pair of pin marks with the meter and bang in a couple of nails till the points penetrate to around 1/4 thickness, and then put the meter's pins on the nail heads. Sophisticates could make up a pair of leads with small crocodile clips (Maplin)
Hoadley also points out the wood's electrical properties are different along/across the grain. Pins should go parallel to the grain, cross grain readings will show higher resistance (too low MC%). This can be ignored at low MC levels.
According to Hoadley, pinless meters often read half way into the stock. Thus, on a particular sample, they may show a higher reading than one with pins. Determining a true average MC for a whole board, even with pro meters, seems therefore not an exact science, even if you have correction tables for different species supplied.
It is unreasonable to expect this (ten quid) device to take on all comers, and nor does the maker provide correction tables. The spec does not include one for accuracy either, although the results above appear sensibly accurate. However it is robust enough for light use, and will work on thicker timber with the aid of a couple of nails. Some expensive meters also require this step. It would be ideal for checking that bought in (or newly dimensioned) timber had finished acclimatising to the workshop and was ready for further use.
