Moisture Meter Suggestion

[Willyou]

Would electricity waste energy (amps?) in seeking 18% moisture at a slightly greater depth over the 14% moisture between the probes for less resistance? Moisture is present either way.

I don't know. Does current follow the path of least resistance? Does 18% moisture offer lower resistance than 14%? If you are using a short pin meter where the pins only penetrate 1/16" will the meter read only as deeply as the pins penetrate or will the current follow an arc down to the highest moisture (least resistance) and back up to the other pin. And if the latter, how does the electronics interpret that resistance reading? Does the amperage matter or is that just a cost of getting the job done. If, as Delmhorst seems to say on their website, the pins must be driven to various levels of the moisture gradient in order to get a usable "picture" of the overall moisture content, what possible good is a short pin meter? Can you touch the pins to some 1" brads and get better readings? Do you need to?

From what I read, the pinless meters, for woodworkers, seem like a better choice as they produce an electronic signal that penetrates the wood more deeply. However, I'm unclear whether the reading is an average or what?

[jteneyck]

I don't know. Does current follow the path of least resistance? Does 18% moisture offer lower resistance than 14%? If you are using a short pin meter where the pins only penetrate 1/16" will the meter read only as deeply as the pins penetrate or will the current follow an arc down to the highest moisture (least resistance) and back up to the other pin. And if the latter, how does the electronics interpret that resistance reading? Does the amperage matter or is that just a cost of getting the job done. If, as Delmhorst seems to say on their website, the pins must be driven to various levels of the moisture gradient in order to get a usable "picture" of the overall moisture content, what possible good is a short pin meter? Can you touch the pins to some 1" brads and get better readings? Do you need to?

From what I read, the pinless meters, for woodworkers, seem like a better choice as they produce an electronic signal that penetrates the wood more deeply. However, I'm unclear whether the reading is an average or what?

Pin meters measure around the depth of penetration.  Pins that extend 1/16" into the wood, to use your example, can't read the moisture at the center of the board.  That's clear from Ligno's literature.  They specifically say to cut the board and probe across the thickness of the cut edge if you want to know the MC deeper than the pins can penetrate.  But, yes, you can drive nails into the wood, using the same spacing as the pins, to get readings deeper in the wood.  They offer meters with longer probes as well as separate long probes for this purpose, too.  

Wagners info. clearly states that the measurement is from the surface "down to 1/4" or "down to 3/4" for the two depth settings, meaning it's an average value.    

John

[Willyou]

Pin meters measure around the depth of penetration.  Pins that extend 1/16" into the wood, to use your example, can't read the moisture at the center of the board.  That's clear from Ligno's literature.  They specifically say to cut the board and probe across the thickness of the cut edge if you want to know the MC deeper than the pins can penetrate.  But, yes, you can drive nails into the wood, using the same spacing as the pins, to get readings deeper in the wood.  They offer meters with longer probes as well as separate long probes for this purpose, too.  

Wagners info. clearly states that the measurement is from the surface "down to 1/4" or "down to 3/4" for the two depth settings, meaning it's an average value.    

John

So. It appears to me that if I'm going to check out some lumber someone has for sale, any pin tester is worthless unless the owner gives permission to punch holes in his lumber. I can punch holes in my own lumber to see how it's drying if I want to, but it appears that drying and weighing a sample is better than any meter. It seems to me that for use away from home or shop, a pinless meter is the best choice. The only questions remaining are how accurate is it and are the surfaces you are measuring flat.

A question regarding the use of nails: If measuring periodically over time the progress of drying lumber, can the same nails be left in place or do you need fresh placement for each measurement? I think that corrosion could (probably) be an issue, but I've heard of it being done.

[jteneyck]

So. It appears to me that if I'm going to check out some lumber someone has for sale, any pin tester is worthless unless the owner gives permission to punch holes in his lumber. I can punch holes in my own lumber to see how it's drying if I want to, but it appears that drying and weighing a sample is better than any meter. It seems to me that for use away from home or shop, a pinless meter is the best choice. The only questions remaining are how accurate is it and are the surfaces you are measuring flat.

A question regarding the use of nails: If measuring periodically over time the progress of drying lumber, can the same nails be left in place or do you need fresh placement for each measurement? I think that corrosion could (probably) be an issue, but I've heard of it being done.

Yes, absolutely.  Direct measurement always is best.  That's why kiln operators use weigh samples in the stack, and pull them out to weigh periodically.  Those MC readings help determine the drying schedule so that the lumber can be dried as fast as possible while minimizing the risk of inducing defects.  I used to weigh samples every day until I gained enough experience with my solar drier to no longer need to.  Now I use my dual depth moisture meter.  

The absolute accuracy of any meter really isn't that important as long as it's consistent.  You can easily determine its accuracy by comparing it to samples that you weigh/dry.  Rough sawn is flat enough for pinless meters.  

I think people who use nails in lumber in their kiln leave them in for the entire run.  I don't know if they use stainless nails, however.   

For me, a pin meter only is of value in checking the MC of lumber you know has been responsibly kiln dried, to determine if it's close to the EMC of your shop so you can use it.  

John

[Willyou]

Yes, absolutely.  Direct measurement always is best.  That's why kiln operators use weigh samples in the stack, and pull them out to weigh periodically.  Those MC readings help determine the drying schedule so that the lumber can be dried as fast as possible while minimizing the risk of inducing defects.  I used to weigh samples every day until I gained enough experience with my solar drier to no longer need to.  Now I use my dual depth moisture meter.  

The absolute accuracy of any meter really isn't that important as long as it's consistent.  You can easily determine its accuracy by comparing it to samples that you weigh/dry.  Rough sawn is flat enough for pinless meters.  

I think people who use nails in lumber in their kiln leave them in for the entire run.  I don't know if they use stainless nails, however.   

For me, a pin meter only is of value in checking the MC of lumber you know has been responsibly kiln dried, to determine if it's close to the EMC of your shop so you can use it.  

John

Thanks. Unless you use it in conjunction with long (er) nails, what good is a short pin meter. Maybe for some material other than lumber?

[jteneyck]

Thanks. Unless you use it in conjunction with long (er) nails, what good is a short pin meter. Maybe for some material other than lumber?

See the last sentence of my last post.  

John