Tag Archive | kiln

General Tools MMD8P Moisture Meter Is Good On The Outside

The General MMD8P features a bright OLED display, built-in species correction, displays ambient temperature and humidity, and stores multiple readings.

The General MMD8P features a bright OLED display, built-in species correction, displays ambient temperature and humidity, and stores multiple readings.

When the General Tools & Instruments MMD8P moisture meter ($199) showed up to be reviewed, I was excited. I have moisture issues with wood – it seems like it’s always too wet to use and I don’t want to wait. Waiting takes all the fun out of opening up a log, and the longer I have to wait for wood to dry, the less of it I can sell. That is where the ol’ moisture meter comes into play. Much better than just guessing how wet the wood is, a moisture meter should tell me exactly how wet the wood is. It sounds simple enough, just put the meter on the wood or at most push two pins into the wood and take a reading, but it isn’t always that simple.

There are a range of moisture meters out there and they don’t all work the same and they don’t all read the same. I was hoping that the MMD8P from General that just showed up would be the meter of my dreams and for once make me feel confident that I knew just how wet my wood was. And it appeared that is just might.

Though I wasn’t impressed with the light, toy-like feel of the unit, it has more buttons and obviously, more features than I am used to in a moisture meter. It shows the relative humidity and temperature of the environment, which is pretty cool and has a menu for selecting different wood species, which is also cool. My first moisture meter (that I still own) has paper charts for species and temperature adjustment. I don’t bother with the charts, but I will gladly allow the meter to make the adjustments for me, and the General MMD8P does just that.

The first thing I did was play with the species correction. The interface, while obviously not from the great designers at Apple, worked fine and I was able to get to the species I wanted after a quick perusal of the owner’s manual. There are more than enough species to choose from and they are accessible by just pushing the up or down arrows until the desired species appears. It took only a few seconds to quickly flip through the alphabetical list, pick a species, and start jamming the pins into some boards.

A notable difference between this meter and other pin meters that I have used is the thickness of the pins. These are stout, less like pins and more like cones. My first thought was, “Now, these pins won’t break. Finally, pins that won’t break.” They are built like a tank compared to the pins on my Delmhorst (which often break), but after using them, I am not sure that it’s an advantage. I felt like the pins didn’t penetrate very deeply, which made my readings feel even more like surface readings instead of core readings. It also seemed like the pins wanted to eject themselves from the wood, and any difference in pressure while taking a reading resulted in a variance on the readout. If I pushed hard, the reading might be 9% and when I let up a little, the reading could be 12%. Unfortunately, there is no way to know which of those numbers is accurate. In my head I want it to be the drier number, but my heart knows it’s the wetter number, or even worse.

The display on this unit, which is touted as a major selling feature is big and bright and can be configured to display critical information in a few different ways, though I imagine that most users will pick one option and just stick with it (most likely the one that shows all of the information and not a truncated selection). I chose a display option which shows the moisture content reading very large, which seems to just make sense. After all, that’s what it’s for.

I moved around my shop from board to board checking to see how it worked and finding the moisture content of random boards – most of which were around 10%. That is fine if it is accurate, but at the same time very disheartening, and here is why, in the form of a little more background.

As I mentioned, I have a moisture meter, a Delmhorst J-lite, which was the first meter that I purchased. It is a pin-type meter, just like the General MMD8P and it always reads 9-10% or drier. Maybe not always, but it feels like always. I think it is a lazy meter and doesn’t try very hard. It says in a very monotone and cubical job sort of way, “10% boss. Next reading, 10%. The wood that you cut just a few weeks ago, 10%.” If it doesn’t read 10%, it will only read lower (even painfully low), unless I just cut the wood, where it may possibly read higher. I was so sure that the meter wasn’t working properly that I called Delmhorst. Officially, it checked out OK, but I still don’t trust it.

Since then, when I really check for moisture I like to use a Wagner MMC220 pinless meter, which takes readings 3/4″ deep using electromagnetic waves. The numbers go up and down like I expect in different woods and even in different spots on the same board. It will read 10% too, but it can do 9% and 6% and even 13%. Heck, sometimes it even does 17% (crazy, I know). I am still not sure of its absolute accuracy, but at least there appears to be movement in the numbers, and in a logical fashion – wood that is newly cut is wetter than wood that has been on sticks for a while. It will even read accurately on rough cut wood and won’t leave holes when you are checking surfaced lumber or finished projects.

So, back to my review.

I used the General MMD8P meter, and seemed to get the usual 10%ish measurement. I was testing wood that had been dried and had been in the shop awhile, so 10% or somewhere from 9-11% made sense. Then I tried an 8/4 chunk of walnut that I had cut only two weeks earlier. Funny enough, I didn’t get 10% like I expected, but I apparently pushed the meter a bit and got it to go to 13%, which at least told me it was wetter than normal (for reference, it should have read off of the scale, or at lease 30%). I thought, “Here we go again – another ten percenter!”

Now it was officially time to get to the bottom of this, once and for all. This new meter has the right look, it has all the extra buttons, it has a fancy display, but why must it always read 10%. I knew the walnut that I tested was soaking wet on the inside. Sure, the surface was perhaps 10%, but if I was strong enough, I guarantee I could ring water out of the middle of that board. I grabbed the $8 per board foot wood and threw it on my chop saw to expose some of the wood in the middle and took some new readings.

The very center was very wet and read as very wet, above 40%. As I moved towards the outside of the board it got drier, and in logical increments, until the outside reading of, you guessed it, 10%. That was good news. At least this meter had the potential to read something other than 10%, and it seemed to be accurate.

I took it with me to check on the kiln progress and went through the same process with 8/4 walnut in the kiln that was nearly dry. The shells were reading dry, around 6-8%, so I trimmed an end to test the inside. The General MMD8P meter did a good job of showing me the moisture content in the middle of the board and the moisture gradient as I moved towards the outside, just like it did in the shop. The numbers read as I would expect for how long the wood was in the kiln with a high number of 13%, and did a good job of telling me that the inside was still a little wet. So far, so good, for a pin-type meter.

I continued using the General MMD8P meter for the next few weeks. If I found myself wondering about the moisture content of a piece of wood, I checked it with the meter. It turns out that it isn’t just a ten percenter. In the shop, I got a full range of readings, and in a logical fashion. Shells were drier and when I cut into boards, the centers were wetter. The drier shells even showed a wide range of readings, again, all that seemed accurate.

The only problem is that I had to cut into the board to get an accurate reading. I know (and everyone else reading this knows) that the outside is drier and probably around 10%, but I don’t need a meter for that. I need to know the moisture content inside the wood and therefore, the overall moisture content of the wood. I need to know if the wood is still shrinking and how much shrinking it has left inside it. This is especially true in a species like white oak, for example, that doesn’t give up water and can be completely wet in the middle for a long time, even when the shell reads as dry.

The question that was continually in my head as I was reviewing this meter was, “Why would I use a pin-type meter that punches holes in the wood and only gives me a reading near the surface?” Unfortunately, the answer is I wouldn’t. No matter how bright the display, no matter how big the numbers, no matter how many corrections are built-in, no matter how many readings it can store, I wouldn’t choose a pin-type meter and I wouldn’t recommend one, not even at half of the price of a pinless meter. I think the General MMD8P meter is good for a pin-type meter with all of the controls that I could ask for and more, but it just doesn’t do the job that a pinless meter, with quick, accurate and deeper readings, can do.

What is Going on at WunderWoods?

On a semi-regular basis I talk to someone who would have used me for their last project, but they didn’t because they didn’t know everything I do. My woodworking customers don’t know I mill lumber, my milling customers don’t know I sell lumber, my lumber customers don’t know I do custom woodworking, and I blame it all on my inept advertising department.

I am here to change all of that with a new video that shows what is really happening at WunderWoods (when I am working). With the help of a few of my customers, I have put together a montage of the goings on in a three-week span of my daily work life. The clips are chronological in order, but random in their approach. One day I cut a tree, the next day I finish a piece of furniture – just like real life.

The bottom line is that if it involves wood there is a good chance I do it.

About WunderWoods cover photo

Click to watch a short video and see what really happens at WunderWoods.

Thanks to Dwayne Tiggs from Crafty Naturals, Jermain Todd from Mwanzi, and Martin Goebel from Goebel and Company Furniture for starring in the video.

The following photos are of the finished products shown in progress in the video:

Elm is one of my favorite woods. In this case, we used all of the tree, including some big knots with lots of spunk.

Elm is one of my favorite woods. In this case, we used all of the tree, including some big knots with lots of spunk.

After seeing other cricket tables that the customer liked, she ordered this one in a bit smaller size. The top is 23" in diameter.

After seeing other cricket tables that the customer liked, she ordered this walnut version in a bit smaller size. The top is 23″ in diameter.

 

 

 

Kiln-Dried Walnut Is Not Steamed Walnut

I mill, dry, and use walnut on a regular basis, especially now that walnut is back in style. It wasn’t that long ago that everyone was tearing out dark cabinets and putting in the maple to lighten things up. Now, walnut is used regularly and often stained to an “espresso” color, which means really dark. Some folks would swear off staining walnut because it is naturally so nice, but I am not one of them. I, personally, almost always stain walnut, even if I just want it to look like walnut (more about this in a later posting). This got me thinking about the color of walnut, and no discussion about walnut color can start without talking about steaming.

This walnut sample was not steamed before drying. Notice the distinct line between sapwood and heartwood.

Steaming has one purpose and one purpose only – to change the color of walnut. Here’s the deal. Walnut logs, like the one shown in the first photo, have a rich, chocolate-colored heartwood and light vanilla-colored sapwood. The contrast is stark and to those that want all dark heartwood, the light sapwood is seen as a defect, something to be removed or hidden. But removing it can be costly to mills in that they will be discarding the outside of the log, which usually has the clearest lumber with the fewest knots. Additionally, the sapwood can be inches thick, and not using it results in a loss of board feet production. So, to make the sapwood more acceptable, mills use a separate process to steam the lumber after it is cut to darken the sapwood.

When I say “mills”, I mean larger production mills, those that are focused on efficiency and willing to spend the money to steam the lumber. At smaller mills like mine there is no steamer and much of the sapwood is removed on the mill. If a piece of lumber has a significant amount of sapwood, I usually grade it lower because I know it is less desirable.

In this steamed walnut panel, the sapwood can be seen as a lighter stripe down the middle.

The steaming process, as shown in the second photo, makes the walnut lumber more uniform in color – but at a cost. The sapwood does darken, but at the same time the heartwood lightens and the entire board turns to a washed-out gray color. Compare this with the walnut heartwood that is not steamed and is usually a medium-dark brown which will lean in color towards red, green, or even purple.

The idea of steaming walnut (at least my guess) must have come from sawyers that milled walnut on a regular basis. They surely noticed that when walnut logs sat for awhile before being milled that the sapwood would begin to darken. In these types of logs, much like the third photo, the colors can become quite homogeneous. In some cases it is difficult to distinguish between the heartwood and sapwood if the logs are milled at the right time. Somewhere along the line, this natural process was forced along with steaming.

This sample was not steamed, but the log sat for months before milling, causing the sapwood to darken considerably.

Steaming, as mentioned before, is a separate process. Lumber is milled, then put in “dead” stacks (without sticks to separate the lumber), and then put in a steam chamber. After steaming, the lumber is stacked with sticks and put in a kiln to dry.

I have met many customers that were under the impression that the kiln changes the color and this is not the case. The steaming changes the color. Kiln-dried walnut and air-dried walnut look the same if they haven’t been through the steamer. Just remember that steaming is an entirely separate process from the kiln.

The last thing you should know is that there is a lot of more detailed information available about steaming walnut (optimum temperatures for best color, optimum timing, etc.), but most of it is geared to those that are actually doing the steaming and can get boring in a hurry. Since most of us won’t be steaming our walnut, I think it is best to stop here.

Walnut steamer at Mueller Brothers Timber with walnut just unloaded. Notice that all of the wood is brown with no light sapwood.

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