What to use as long moisture meter probe?

[Mark Gibney]

I need to know the core moisture content of thick pieces of douglas fir I have. My meter has short pins, it's a Delmhorst J-2000, and I don't want to spend the money for the longer pins.

I know I can use other metal prongs such as nails or long drill bits that I then connect to the meter with alligator clips and wire. Have any of you done this and what how did it go? I've read it's best to use something that is insulated up to the point of the prong.

The pieces are 8" x 8" x 48". The meter reads 10% surface moisture.

I've had them about 2 years, and I think they were laying around the lumber yard for a while before that.

They have not been kiln dried, and I can't find a kiln locally. Thank you.

[Kevin Jenness]

If your lumber has been in a stable environment for two years I would venture to say that the core is in balance with the shell. If you want some assurance, weigh the pieces on an accurate scale and compare the results in a month to see if they are still drying out. You might try posting on the kiln drying forum or on Woodweb for other opinions.

[Dan Hahr]

The only way your meter is going to give you an accurate measurement is to cut off a few inches and check the center. If it hasn't been drying for eight years or more it is probably still higher in the center.

Dan

[lowell holmes]

I have a Wagner MMC 205 moisture meter. I've had it for years. It is a pinless meter. I just had to have it when I bought it. I don't remember the last time I used it. :)

It still works though. It does not have probes.

[Rod Sheridan]

I've driven stainless steel nails into the core, then hooked up some wire and brought it out of the center of the stack.

It works fine, the core will be the lowest resistance, which will influence the readings the most.............Rod.

[Kevin Jenness]

From the Delmhorst FAQ page: " Even non-insulated pins, which measure the wettest fibers, will provide a good indication of how the wood is drying." So you should be able to see if there is a moisture gradient by driving pins up to 4" deep into your material. If you are not in a hurry the weight method will tell the same story without putting holes in the wood.

[Mark Gibney]

Thank you all for the replies. Lowell, I can see the advantage of a pinless meter but I think like you, I might use it once or twice in 10 years.

Tomorrow I'll drill in two thin drill bits and connect them up to my meter. Woodworking is an ever changing landscape...

[Bill Jobe]

Thought I'd mention they make devices that make your smartphone a moisture meter. Don't know much about them, but as with any meter I'd think new holes would be nessecary each time you test

[Wayne Lomman]

In my environment drying is an inch per year so I'm with Dan. It will still be wet but yes, find a way to monitor it. At least being DF it will eventually dry. Cheers

[John K Jordan]

Thank you all for the replies. Lowell, I can see the advantage of a pinless meter but I think like you, I might use it once or twice in 10 years.
Tomorrow I'll drill in two thin drill bits and connect them up to my meter. Woodworking is an ever changing landscape...

A pinless meter will only check near the surface, often no further than 3/4". Deep probes might work but I haven't seen that done. To avoid a false reading from local drying from a hot bit maybe drill then cover the holes and wait a bit?

The most accurate method of measuring the moisture in the center of thick wood is a destructive test: cut and remove a small section some distance from the ends of the board, weigh the section carefully, dry it in an oven, weigh it again, then calculate the moisture content. Subtract the oven-dry weight from the initial weight, divide the result by the oven-dry weight, and multiply by 100%. Google will give you the exact procedure and probably an on-line calculator if needed. According to expert Gene Wengert use an oven temperature of 215 to 217 F".

This will give you an average of the cross-sectional slice and not necessarily the exact moisture content at the core.

JKJ

[Mark Gibney]

John, that sounds like the most accurate method, but in the end I think I'm going to have to find that mythical working kiln around here. I'll re-watch the Monty Python Holy Grail film again, it's been about 30 years, there's got to be some clues in there.

[John K Jordan]

I'll re-watch the Monty Python Holy Grail film again, it's been about 30 years, there's got to be some clues in there.

I have the book somewhere if you want me to hunt through it.

JKJ

[lowell holmes]

I know, but remember the old saying:

"The difference between a man and a boy is the price of his toys" :)