I have been on a sycamore kick lately, and this sycamore slice keeps my streak going. There are three stacks of these rough sawn slices for sale in my shop, and though I have sold a few, this is the first one to officially get finished and installed.
The slice is 3″ thick and is a cross cut of a 48″ diameter hollow sycamore log that had the added benefit of having a long open wound that didn’t quite seal up. In the tree’s attempt to close the wound the new wood took on a curl shape on both ends that make the slice look more like an artistic expression than just a hollow log.
Since the tree was standing dead all of the sapwood is consistently spalted and marbled in appearance. There is some solid heartwood in the piece which isn’t spalted, but has a beautiful rust color.
I was planning on ditching this tree since it was hollow and didn’t seem to have any millable lumber in it, but when I saw the curl shape on the inside of the log I did a u-turn on my way to the dump. Solid logs with complete centers that are sliced like this tend to crack and fall apart because of the drying stresses in the log, but in this case all of the drying stresses were relieved since the center was gone. When the outside wood wanted to shrink it wasn’t restricted by wood on the inside and could freely reduce in diameter without any problems.
I installed the slice on the wall with two lag screws, just like a mantel. I drilled matching holes on the back of the wood and just slid it on the wall (with the help of my customer). This system works great since it allows the piece to get flush to the wall and enables it to be removed without tools should the need arise.
Overall, I am ecstatic to have one of these completed and out the door. Next up is to finish at least one extra to keep in the shop to show off. You wouldn’t believe how much faster they sell with a finished sample around to seal the deal.
This week I picked up a sycamore log at Grant’s Farm for a local woodworker. He has been commissioned to build a round table from the tree that has stood on the property since the time of Ulysses S. Grant.
Because the log was too heavy to load in one piece and was going to be cut into round slices anyway, I cut it in half to make it easier to handle. The log is a minimum of 60″ in diameter on the skinny end, and should make a few nice table tops.
I jokingly complained to my wife that I drove all the way to Grant’s Farm only to pick up two 3′ long logs – that, by the way, filled up the truck.
Recently, I set up three large hollow spalted sycamore logs to cut in the Lucas mill. They are all in the 48″ diameter range and most were cut 3″ thick. I see future tabletops (with glass) and wall decorations. Out of all the logs I had on the lot, these were drawing the most attention, so they got cut first.
“Be sure to let the wood acclimate before you use it.”
That’s what every knowledgable woodworker will tell you about wood. After all, it has to be in equilibrium with its environment to ensure a good, long-lasting result. I personally preach this to everyone I meet, if they are willing to listen (and sometimes when they are not). But, it’s not as simple as just letting the wood sit before you use it. Sometimes letting the wood acclimate to its new environment is actually a bad idea.
The logic behind letting wood acclimate before you use it is to have all of the craziness of wood movement happen before it is installed. If the wood is moved to a dry environment it is going to shrink and if it is moved into a wet environment it is going to expand. This “dry” or “wet” description is relative though – wood moisture in relation to the environmental moisture (humidity).
I often think of wood trim and casework when I think of acclimating wood to its environment, with a close second being hardwood flooring. In a perfect world, I would install both of these items on the 2nd of February after the heat has been running in the house for months and everything is shrunk up as much as possible. In this shrunk up world, I want my flooring or trim to be super dry and super shrunk so everything fits nice and tight and only tightens up as summer rolls around and the humidity rises. However, the opposite is usually true. I seem to only install woodwork around July 20th, when the humidity is a billion percent and everything is fat, which means in the winter everything will shrink and gaps will appear.
“Well pal, if you weren’t such an idiot and you let that wood acclimate before you installed it, everything would be great and the gaps that open in the winter would be a thing of the past.”
Not true, I say. Remember, the dry and wet thing is relative. Letting the wood acclimate in winter to a super dry environment is good. Your wood will most likely be shrinking (it definitely won’t be expanding if the heat is running all day long). You will install everything tight and it will only get tighter as the summer rolls around. This is good – in winter.
In summer, the opposite is true. Say that you take your wood flooring that is dried to 6% to a job site in the summer. Your flooring is shrunk, it is small and ready to be installed. Yes, it will swell up in the humidity of summer, but you want it installed when the wood is shrunk so it will expand and only tighten up. Letting it acclimate in the summer only ensures that you are installing fatter wood, which is guaranteed to open up in the winter. Flooring will show gaps between boards and casework will open up at the seams.
I think the whole acclimation just-do-it, don’t-think-about-it thing started because there are so many chances in life to have wood that is a little too wet going in to an environment that could use drier wood. This, perhaps, isn’t the case in the deep south, but I would say it is the norm for much of the country. Wood has too many opportunities to pick up extraneous moisture before it makes it into its final resting place. From sawmills and distributors to retailers, lumber is stored in environments that are not climate controlled, possibly for quite a while, picking up moisture the entire time. And, even after it makes its way into your hands it may spend time in a garage, shed or job site that isn’t climate controlled.
The default in all of these cases is to get the wood inside, in a climate controlled environment and let it acclimate to the environment, but what we really mean is to let the wood dry. I have never had an issue with interior woodwork being too dry and causing a problem after it swelled up. Again, in the high humidity of the deep south this might be a problem, but for most of us wood can’t be too dry. It is almost always a little wet.
So, what to do in summer. Say you’ve got wood that just came out of the kiln and is dried to a target of 6-8%. Do you take it to the job site and let it acclimate, knowing that it is going to pick up moisture and get fatter before you install it, just to shrink again in the winter? I say, “Heck no!” It makes zero sense to let the wood acclimate in this scenario. If the wood is dry, put it in – and fast.
The key in any scenario is knowing the moisture level of your wood and what the acclimating environment is going to do to it. A reliable moisture meter is a good place to start. Test your wood, and if it is dry based on your area of the country, start using it. Refer to the chart at the end of this post to see what moisture content your wood should be. If you don’t have a moisture meter, assume that the wood is a little wet (since it usually is).
In the dead of winter letting the wood acclimate is always a good idea because it can’t really cause a problem. It won’t improve your lumber if it is already dry, but it won’t hurt it, and it will only help wet lumber. Winter is by far the best time of the year to install interior woodwork.
In the spring and fall acclimating wood is likely to have little to no effect. Heat and air conditioning will be running less, windows will be open, and humidity levels will be closer to outdoor levels. Only let your wood acclimate during this time of year if you know it is wet and could benefit from some drying. If it reads as dry on a moisture meter and/or hasn’t spent awhile in an environment without any climate control, start using it.
Acclimating your wood in summer only really makes sense if you know that your wood is extra wet, either because your moisture meter told you so or because the lumber was stored in an environment that wasn’t climate controlled. If your lumber is in a condition that acclimating it during the summer makes sense, you may want to reevaluate your situation. In this case, additional drying, not just acclimating, may be necessary. Summer is the worst time to install interior woodwork.
Use common sense when deciding whether or not to acclimate wood. If the environment is extra dry, no matter the time of year, let it acclimate. If humidity levels are extra high, it probably makes sense to start using the lumber right away. Any other times, when the humidity is moderate, you are probably just kissing your sister (getting no benefit) and possibly making the wood worse by letting it acclimate.
Quartersawn lumber stays flat, but flatsawn lumber does not (ironic, I know). Flatsawn lumber cups during the drying process and it even cups after it’s dry if not cared for properly. Wide boards are especially fussy and panel glue-ups can be a giant pain in the tuchus.
I deal with cupped lumber all of the time, and I was reminded of this common problem when a friend of mine was trying to figure out why his wide panel glue-ups had cupped. Whenever I am asked about this, my first question is always, “How did you store your panels after they were assembled and surfaced?” The answer is usually that they laid the panels flat on a table. A quick bit of logic says that a flat panel on a flat table should stay flat, but that isn’t how it works, at least not with solid wood.
Solid wood needs to expand and contract evenly, on both sides, to stay flat. If the panels are placed flat on a table, they can breathe on one side but not on the other. The bottom side will remain as dry or wet as it started, but the top side will shrink or swell depending on the ambient humidity in the room. Usually, this problem arises when lumber is moved from a non climate-controlled environment (like a garage or barn) into a dry, climate-controlled shop, so the top of the panels will shrink and the lumber will cup up and away from the table as it dries.
In a perfect world, rough lumber would be stored for months in the exact same, hermetically sealed environment where the processing is going to happen, but since we don’t live in a bubble, that’s not really possible. Even if you store the lumber in your climate-controlled shop and build in your climate-controlled shop, the climate still changes – in small increments from day to day and more dramatically from season to season. And, since you know that these changes will make your wood expand or contract, it is even more imperative to store surfaced lumber and panels properly to make sure your flat work stays flat.
Again, storage is the key, and there are two approaches to keep things flat. The most common way is to store the wood so that it can breathe on all sides. This is done by keeping it stacked flat on sticks or by storing it upright at an angle, perhaps leaning against a wall. The other approach is to not let the wood breathe at all and keep it wrapped or covered in plastic. I commonly use both tactics, leaning panels against the wall for short-term storage, usually during a day of processing and then covering them with a sheet of plastic for longer storage. Note that dramatic changes in flatness can happen in just hours if the conditions are right (or wrong, in this case).
Now, let’s say you didn’t follow this advice and your panels developed a cup in them. They were planed and sanded flat and ready to be put into the door frame before you left the shop, but when you returned the next morning they had a noticeable rock. Since everything was already to final thickness, what options do you have? There is no meat left to machine flat and the wood can’t really be bent back into shape… or can it?
No, it can’t really be bent back, but it can be coerced back by doing the reverse of what caused the cup in the first place. The key is understanding the cause of the problem.
First, you need to identify the wet side and the dry side. If you are looking at a cupped panel from the end and it is shaped like a rainbow with the legs down, then the bottom side is the drier side. It is drier, tighter and smaller, and the outside edges are pulling together. The top side is wetter, looser and bigger, and its outside edges are pushing apart. These two forces, one pushing and one pulling, are working together to make a cupped panel.
After you have identified the problem, the solution is to treat the panel to the opposite conditions. This can be done by drying the wet side or wetting the dry side, but since almost all problems in woodworking are from wood that is too wet (at least around here), you should choose to dry the wet side.
I recommend to use a hairdryer for convenience, but on nice sunny days you can put the sun to work for you too. Both work fine, but the sun can fix a lot of panels at a time, quickly and quietly. The sun works great because it focuses all of the drying energy on just one side, and it focuses it on the entire side, not on just one spot like a hairdryer. (Be aware that some woods, like cherry, change color quickly in the sun and may be a better choice for inside drying).
The process is simple. Put the dry side down on a flat surface, one that restricts air movement across the bottom of the wood. The wide board or panel will be sitting like a rainbow, with the two legs down and the center up. Then just proceed to dry the top side, either with the sun or a hair dryer. If you are not in a hurry, you can simply move the wood to a drier environment, like the inside of your house on a cold winter day and let it dry out on the top side overnight. Any way to dry the top side while the bottom remains as it is should do the trick.
Keep an eye on the panels and check them regularly. With a hair dryer you will probably end up propping it up in a position to blow on the panel and check it every thirty minutes. In the sun, check the progress every hour. If you just move them to a drier environment, check them once or twice a day. Even with regular checks it is not uncommon to go too far and overcorrect. If you let the wood bake too long on one side and it starts to cup the other way, just flip it and dry the other side. Eventually, you will get a feel for how long it takes and end up with a flat panel, and now a drier panel (both good things).
Follow these guidelines for flat wood:
- Build with quartersawn lumber. Quartersawn wood doesn’t cup.
- Store lumber in the rough. If the lumber goes wonky you will still have extra thickness to machine flat.
- Store lumber and build in an environment similar to where the piece will end up.
- Quickly build with lumber after it is machined. Don’t give it a chance to move on you.
- If you can’t build immediately, store wide boards and panel glue-ups properly. Give them air on all sides or no air at all.
- Make sure assembled furniture stays flat by finishing both sides of solid wood panels the same. This is especially important on wide glue-ups like tabletops.
Remember, wood moves and changes size all of the time. It is your job as a woodworker to understand how these changes happen, how to prepare for them and how to control them. And, luckily, in the case of wide wood, you may even have the chance to correct them.
All wood splits, some more than others, but it all splits. It even splits when paid professionals try to make it not split. This is good news for those of you wanting to snuggle by a warm fire, but not such good news for connoisseurs of split-free wood. And, it is especially bad news for anyone wanting to make a round table top out of a slice of tree.
It seems easy enough to just slice a cookie, or coin, or round, or whatever you want to call it, off the end of a log and use it as a table top, but it rarely works out. The problem (especially when swimming) is shrinkage, and in the wood realm it’s uneven and unproportional shrinkage.
I talk to customers a lot about this uncomfortable subject, and even though it isn’t pleasant, someone has to do it. As woodworkers, it is critical to understand how wood shrinks (read an earlier post about shrinkage by clicking here), and as customers it is important to understand the limitations of wood.
Drying quartersawn lumber is easy, relatively speaking, and almost always produces wood that doesn’t split. Drying flatsawn lumber without splits is more difficult, but if the ends are sealed and the lumber is dried at a slow, consistent pace, it can be done reliably. Drying round cuts from the end of a log, however, is a totally different story, and almost always results in split wood, and not just a small split, but usually large, unsightly, unrepairable and often devastating splits. So much so, that I tell customers I will cut rounds for them only if they take the milled pieces directly from my sawmill as soon as they are cut. That way I can prove that I had nothing to do with them falling apart – they do that all on their own.
It all goes back to the way wood shrinks and the way it does so unevenly. As wood dries, it shrinks twice as much with the rings as it does from the center. When viewing a log at the end (not a round cut off the end of a log but an actual log), this produces cracks that resemble spokes in a wheel. Sometimes there are larger cracks mixed in with the smaller ones, but they are always in multiples. The end wood wants to split, but since it is attached to a log which is holding it in place, the end cracks with many smaller splits to even out the pressure.
If that piece is cut from the end of a log all bets are off. There is no log holding things together, so the end result is usually one large split that relieves all of the pressure at once. With wood that is known to split easily, like oak, the round cuts will not only have large splits, but will often just break in two or more pieces.
Here are some examples of dried wood cookies. All of these were cut from the end of the log when the wood was wet and then air dried slowly in the shop. They are all about 18″ in diameter and 2″ thick.
So, now you know that the cool round table that you were planning to build is probably going to split if you do nothing about it, but can you do something about it? Well, maybe, kinda, sorta.
One way I know to work, from personal experience and from other local sawyers, is to cut the rounds at an angle. This will reduce or completely eliminate the cracks because the stress is going more up and down than in a circle, but it will turn your round table top into an ellipse. And, while a piece that stays together is probably better than a piece that falls apart, an ellipse is not always acceptable. I personally expect to see a round piece of wood when you tell me it was cut from the end of a round log, and find the ellipse shape a bit unnatural.
Another alternative is to remove the pith (center of the log). Removing the pith can stop the devastating splits, but it obviously puts a hole in the piece of wood, and it is still a gamble because it is hard to tell from tree to tree how much pith needs to be removed to stop the splits from happening. A larger hole is better, but at some point the missing wood in the center will demand creativity, and perhaps more wood or glass to make a complete top.
The last and most widely used solution is to use a wood stabilizer like Pentacryl or PEG (polyethylene glycol). Originally developed to stabilize wood from archeological sites, Pentacryl works well to stabilize all kinds of wood from punky wood to crotches and will help with wood cookies. It works by replacing the water in the wood and keeping the cells at their original size, even when dry. Know that while Pentacryl will reduce and often eliminate cracks, wood cookies are by far the most difficult to dry and may still crack.
Pentacryl is not perfect. It works well, but it is expensive at $60 per gallon and adds a yellow tint to the finished piece. And, wood cookies which could normally be dried relatively quickly need to be dried extremely slowly. So slow, in fact, that thicker pieces could still take over a year to safely dry.
PEG is applied like Pentacryl, but has drawbacks that make it less than perfect too. Like Pentacryl, it is also expensive and the resulting wood surface may not accept the finish of your choice. It also takes extra time to apply and may require additional equipment to make it work correctly.
The bottom line is that you can make a table out of a round end cut from a log, but you’ve got to be prepared for failure and/or be prepared to throw plenty of time and money at the problem. I still steer away from cutting wood cookies and do my best to direct customers away from them as well. And, if I do end up cutting wood cookies for a customer, I literally cut and run.
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.
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