I’m going to start with my thoughts on this meter in case that’s all you care about, but afterwards I’m going to share my thoughts and struggles with moisture reading in general, because I think my experience can help.
I love the design and construction. It's well-sized. To turn the meter on you simply remove the cap. No button needed. Pop the cap off and take a reading. Pop the cap back on and you're done – the meter turns off. But there's even more to the cap than this neat trick and I think it’s quite an innovative solution. Embedded in the cap are two resistors and two sets of contacts. To be clear, this is a resistive meter, which means it works by passing a small current through and measuring the resistance of the material, which is simply compared to known readings of Douglass fir. It’s a specialized ohm meter. If you meter one set of contacts you can check the battery life. Measure across the other set and you get a reading that should be within a small range mentioned in the instructions that indicates that the meter is calibrated. I can tell you that there are meters out there that require expensive resistors to check the calibration, but this meter includes it.
For me, I couldn't care less about the digital bar graph because I'm happy with the absolute value. But it doesn't take away from the meter, either. It’s supposed to give you a more visual relative positioning on a scale.
The sole switch on the meter is used to change the range, similar to a digital multi-meter. Building materials, such as Sheetrock, are much drier than lumber and therefore need a smaller scale. For example, Sheetrock might be 1.5% versus 10% lumber. They could have made the meter smarter, IMO so the switch wouldn’t be necessary but it’s definitely not an issue at all.
My one complaint is the choice of batteries. This takes 3 CR-2032, which are large watch type batteries. I'd prefer AAA, but I will say that you can get a 5 pack for less than $5.
How can I be sure that the meter is accurate? I cannot. I can tell you that it has given me consistent readings on various lumber pieces that I’ve been using for the past few weeks. I’ve compared these readings to those from another meter that I’m currently reviewing. Unfortunately (and expectedly) they do not agree. As with this meter, the other has been consistent. I’m going to talk about what this means to me and what I think it could mean to you below. I will say, however, that I trust this meter’s readings more than the other’s based on a hunch, but I could be wrong. See below for why I don’t think it’s all that important, though.
In closing, I can absolutely recommend this meter, especially if you’re looking for something that’s portable for a job site. When I chose the meter for review I actually expected it to be inferior to the more expensive one that I chose at the same time. Assuming you don’t need the pinless mode that some meters offer (see below) I wouldn’t hesitate to recommend this meter. I rated the Value as Good only because the price is on par with similar offerings from other manufacturers.
### ON MEASURING MOISTURE IN LUMBER ###
As a woodworking hobbyist I've wanted a moisture meter for some time now. Unfortunately, I've been unable to pull the trigger on a specific meter, strangled by specs, reviews and most likely way too much over-thinking. I was excited about the opportunity to try two meters from The Home Depot and finally get see for myself.
If you’re looking for a moisture meter you’re surely expecting to find one that gives accurate readings. I read your mind, didn’t I? I know, not really. But, with meters ranging from $30 to $600 how much do you need to spend to get accuracy? I’d be lying if I could answer that question and it’s the reason I simply couldn’t make a decision on which one to buy. I even had a couple of models in my hands at two different stores and walked away. Once purchased, how would I even know if it’s accurate? I’ve read quite a bit on measuring lumber moisture content and it’s not as straightforward as I had assumed. There are factors that override the reading on a given piece of lumber regardless of the meter. Lumber temperature, your region’s relative humidity and the wood species, for instance. Regardless of the reading you need to adjust that value using various charts that you can find online. Some meters come with charts and some actually let you choose the wood species for automatic adjustment.
There are two types of wood meters. Resistive and electromagnetic wave technology. Resistive meters use pins that you press into the lumber or even drive in with a hammer. Electromagnetic meters are pinless – you simply pass them over the material and they react to changes in the capacitance of the material, which is affected my moisture content. Pin meters let you spot check moisture. If you use it on a wet spot you’ll get a skewed result. Likewise if the core of a thick piece is wetter than the outside and you’re using shallow pins. A pinless meter would let you see the bigger picture, supposedly reading up to four inches deep into the material. Also, a pinless meter might be your only option if you simply can’t make holes in the test piece.
The more I read the more I suspect that the absolute reading isn't as important as I'd think. Regardless, if a given meter provides consistent readings you can make your decisions on a relative basis. For me, I think my approach will be to use some reference lumber of various species for comparison with new test pieces. This is why I think the actual reading isn’t important. If I know it’s the same as my reference material, close to it, or twice the reading I’ve got a pretty good idea on how dry the test piece is. Considering I tend to work with a half dozen species mostly, having reference pieces is a non-issue for me.
I don’t think I’m allowed to include links here, but I found a great article on WoodshopNews titled “The Goldilocks rule of wood moisture” that brings together a lot of information on metering lumber. You can find it by googling that title. Also, search for wood species specific gravity charts, which will tell how to convert a given reading to the “actual” number, based on the wood species. I was surprised by how much it can differ, but again, if you use reference pieces for relative readings this wouldn’t matter.
For me, I think my goal isn’t to know the number of a test piece, but rather whether it’s dry enough for my project. Perhaps a fine furniture maker or one who dries their own lumber might have different needs.
Finally, I read about a tip on protecting your meters tips when reading dense lumber. Drive two nails into the lumber and simply read across them. I love that idea.
Easy to Use, Compact, Nice Design