Everything You Need to Know about Pin Moisture Meters
If you’ve browsed through the Bessemeter website, you may have noticed that we talked about different types of meters.
Some have pins, and some don’t.
You might be wondering…
“What’s a pin meter?”
“Should I buy a pin or pinless?”
“How do these work?”
If that sounds like you, you’re in the right place.
On this page, specifically, you’re going to learn all you need to know about pin meters.
This page is jam-packed with information you need to know about buying a moisture meter, so keep reading!
What is a pin moisture meter?
The first thing you might notice about a pin moisture meter is that it has pins.
Sounds pretty obvious, I know.
But the presence of pins is actually an important observation because they are the defining feature of a pin meter!
So, a pin moisture meter is a device that measures the moisture content (MC) of wood using metal pins that penetrate the surface of the wood.
These are sometimes also called electric resistance meters since they use the resistance of the electric current going between the pins to measure the moisture content.
That sounds a little complicated, so let’s explore it a bit more!
How does a pin moisture meter work?
The technology of a pin moisture meter is really what sets it apart from pinless moisture meters.
Here’s how a pin meter’s technology works.
Moisture is a great conductor of electricity; wood, not so much.
So when the meter is turned on and the pins from the meter puncture the wood’s surface, an electric current flows between the pins.
The key to the MC measurement is in how much resistance the meter picks up:
- The more moisture, the less resistance because electricity travels easily through moisture
- The less moisture, the more resistance because wood is a poor conductor of electricity.
There are a couple of factors that influence the MC reading on a pin meter that might not impact a pinless meter. Let’s check a few of them out.
A moisture gradient is simply how wet the wood is at a given depth. With a typical moisture gradient, wood is going to dry faster on the surface and remain wetter in the center. This is also called case hardening.
How does this affect your MC reading from a pin moisture meter?
Well, depending on the thickness of the wood piece that you are measuring, the pins may not reach the wettest part of the wood. This could give you an inaccurate MC reading.
That’s why it’s especially important to compare the thickness of the piece of wood to the length of the pin.
Speaking of which…
The length of the pin on your meter is something that can greatly affect the kind of reading that you get.
For a meter with longer pins, if the pins are driven to a depth in the wood that contains a wet pocket, the overall picture of the MC could be significantly skewed by that wet spot.
On the other hand, inexpensive pin meters tend to have really short pins that may not reach to the center of the wood, failing to pinpoint–pun absolutely intended–the moisture problem.
So based on the project or the average thickness of the wood you measure, you will want to carefully select the length of the pin in order to get an accurate idea of the MC of your wood.
Pin moisture meters can have both insulated pins and uninsulated pins.
Uninsulated pins are just that: uninsulated. The metal of the probes is completely exposed. However, the insulated pins have a thin layer of insulation covering the shaft of the pin, leaving the tips uncovered.
One advantage of using insulated pins is that they can help identify the precise location of any significant moisture in the wood. This is because the insulated pins only measure the moisture in the area between the uninsulated pin tips.
Because you must puncture the surface of the wood in order to get a reading with a pin meter, you may run into issues with wood hardness.
In fact, some hardwoods are so hard that you might not be able to get the pins into the wood, especially to measure to the center, where the wood is likely the wettest.
If the wood is too hard for you to insert the longer pins required to get an accurate reading, then you won’t have a useful MC reading. If, on the other hand, you are able to force the pins in, it’s likely that they might break! Without replacement pins, your meter is essentially a dud until you can buy new pins unless you have spare pins.
Now that we know some ways that the MC can be impacted when using a pin meter, let’s talk about some of the pros and cons of a pin meter!
What are the pros and cons of a pin moisture meter?
Like all pieces of technology, there are pros and cons. Let’s go over a few of them so that you know what to expect while you consider a moisture meter.
Pin moisture meter pros
There are several pros to pin moisture meters! Including accurate depth readings, being unaffected by surface moisture with insulated pins, useful for different wood projects, and usually being quite cost-effective. Let’s look at each of these in-depth.
Accurate depth readings
Because a pin moisture meter measures where the tips of the insulated pins are, you can know exactly the depth that the measurement is being taken from as long as you have a depth gauge.
Also, some pinless meters often have fixed-depth readings, a pin moisture meter can measure at different depths, all depending on where the pins are placed within the wood.
Unaffected by surface moisture
If your wood has been sitting outside in the rain, you would have to worry about this when using a pinless moisture meter.
However, if you have insulated pins, the meter measurement is taken within the wood instead of on the wood’s surface, you don’t have to worry if the wood has any surface moisture in which case only the tips are exposed to the wood and recording the MC.
Great for rough, curved, or uneven surfaces
This is where the pin meter really shines. Whenever you have to measure rounded surfaces (think: turned table legs or other architectural or design pieces), surfaces with debris, and surfaces that are rough or uneven, a pin meter is ideal.
Its pins make it extremely versatile in these situations, and because a pinless meter needs a flat, smooth surface in order to make an accurate MC reading, a pin meter is truly the only way to go in these situations.
On the whole, pin meters tend to be less expensive than their pinless counterparts. This is a great option for woodworkers or craftspeople that are just beginning their craft and want to do a proper job of analyzing MC without spending big bucks.
Even higher-quality pin meters, are less expensive than pinless meters, and depending on your craft, they might be exactly what you need.
Pin moisture meter cons
Now that we’ve discussed the pros of pin moisture meters, let’s look at some of the cons:
- Sensitive to temperature
- Holes in the wood
- Pins are breakable
- Not good for larger volumes of wood
Sensitive to temperature
Pin moisture meters can be sensitive to temperature. This is particularly true if the temperatures lean to either extreme: very hot or very cold.
In fact, because of this, a high-quality pin meter will come with a temperature correction chart to help you get a more accurate MC measurement. Unfortunately, a lot of pin meters don’t offer a temperature correction chart. This means you have no easy way to compensate for the effect of temperature extremes.
One big con of pin meters is that, in order to take an MC measurement, the wood must be probed with the pins. While not a big deal for some projects, having holes–likely many of them–in your work can definitely be an aesthetic downside.
Pins, particularly the longer ones you might need to reach the center of the wood, can easily break.
This can be a huge hassle for several reasons. First, every time they break, you will have to reinstall. Second, depending on how often they break, you might end up spending a lot of money on pins. Third, a pin might potentially break off inside a piece of wood, which can complicate your entire project.
Pin breaking is definitely a concern, particularly if you’re working with mostly thick, hard pieces of wood.
Not ideal for large projects
If your project involves a large volume of wood, the use of a pin meter may not be your best choice. That’s because inserting the pins for each reading takes extra time, and this can be especially frustrating when inserting pins into hardwood. A pinless meter is usually a better choice for larger projects.
Now that you know the pros and cons, take a look at our brief buying guide to know exactly what to look for when purchasing your pin meter!
Pin meter buying guide – what to look for
If you’re not in the mood to read an extensive buying guide, no worries. Here are the pieces that are essential to making a smart pin meter purchase.
Whatever you do, as you’re searching for a pin meter, the most important thing is to identify what makes a meter a high-quality one.
When it comes to pin meters, you truly get what you pay for. Now, if you’re just wanting to check your firewood, an inexpensive meter will be fine. But if you’re working on client projects or your own heirloom projects, a high-quality meter is an absolute essential.
Here are some quick features that you can use to identify a good quality pin meter.
First, make sure that the meter will give you readings at lower moisture content. This is certainly telling of the quality of the technology.
Second, a high-quality meter should include an input for the type of species. The species of wood will certainly impact the MC reading when using a pin meter, so having the option to select the wood species is indicative of a good quality meter.
Third, a high-quality meter will include either a temperature correction chart or a way to enter the temperature of the wood into the meter itself as a way to adjust for temperature. Because pin meters are sensitive to temperature, it is helpful to have a way to address this to keep your measurements as accurate as possible.
So there you have it! Everything you need to know about pin moisture meters.
Whether you’re checking the MC of beautifully turned table legs or a rough surface, a pin meter is a great choice.