Wide panels.

[PaulMarcel]

Kiln dried wood usually has its lignin 'set' by the fact that its water is liberated. As it's the glue between the long fibers, 'setting' it makes it less prone to move, but it's relative. That said, kiln dried wood isn't going to be rock steady. Figured woods with grain going everywhere have 'tangential' and 'radial' expansions happening in directions other than those proposed by where they were cut from the log. Even the cathedral grain of flat-sawn wood can have that effect if the slice isn't directly parallel to the main fibers.

Lovely stuff like tiger maple happens from maples in a valley with wind compressing the trunk on either side as it sways. That can't happen without some stresses. An analogy could be a bow. String a bow and nothing moves, just like dried plank, but cut the string and it'll move Same with machining.

I think a general rule about "no boards wider than 3"" is silly. It's a generalization... what if the boards are quarter-sawn or riff-sawn? QS Anigré is pretty dead-straight, QS Sapelé anything but. Beech has moved dramatically when I applied glue as it is hyper sensitive to moisture (that I found). Etc. Even in flat-sawn wood from the same log, motion will differ based on how close it was to the pith or how much cambium is in the sapwood on the board.

Generally if you have a plank that is roughly flat, you should machine it by removing the same amount from either flat face. There's a gradient of moisture in any board. If you take 1/8" off one side, you might be exposing a moister face and you'll cup/bow to toward the other side. If it is dryer, the opposite directly. You can clearly clearly see this happening when resawing a plank in half in Arizona. During the humid season, they bow toward the blade (outside faces are moister as moisture travels through the face to bring the core to equilibrium). During March, they splay outward dramatically (the outside is drier than the interior). This is regardless of kiln/air drying. The second wood is out of the kiln, moisture starts balancing. Kiln-drying isn't moisture-proofing.

Add to all this the fact that there are different types of kilns. Some kiln dry wood in a partial vacuum to dramatically lower the temperature to vaporize the water. I don't know the effects of this on the lignin bond, but there certainly could be one.

I'm feeling déjà vu... I swear I typed this before. Sorry it's long...

Back to your panel question...

I'm sitting here looking at a curly maple panel I glued up and planed by hand. It has been flat since 14 months ago. It is made of three 8" planks 40" long.

Two panels for the stringers of a small staircase were 8" wide poplar; 4 side by side.

A large panel of Sapelé made of three 11" wide boards; planed and shaped by hand. That step happened a month before it was needed and the panel stayed flat (it also stayed where it got air on all sides).

I have two 12" wide by 6' long strips of resawn walnut. Resawn and sanded to 1/4". They are still laying there dead flat, no waves. Someday an artsy-fartsy entertainment center... someday.

Two 48"x48" MDF panels and let me tell you they are still flat Seeing if you're awake...

[Bobby Slack]

I have been watching a lot of the free episodes of Tommy Mac and he uses a lot of wide boards. In the past I was told not to go over 2-1/2" and some of my friends told me you can go up to 4". Tom uses really wide boards.

Then Tommy continues saying that if you take time and mill it slow, then it should be OK and the board will not cup over time.

Hmmmmm.

With our technology today we should have with good dry kilned material, nothing should cup that bad.

Today, I use a maximum of 4" wide boards, I joint them and place a few domino's along the edges.

Should we plane the board 1/8" then let it sit for a week with sticks like Marc does, then do some more?

Is it that we go too fast between cutting a tree, sticking it in the oven and turning it into furniture or a door?

What do you think?

What is the widest boards you would use for a glue up panel?

[Bob Rozaieski]

Wood movement is relative, so it really matters not what width boards you use to glue up a panel. As a theoretical example, let's say that a particular species of wood moves 10% radially and 5% tangentially, and you want to make a 24" panel. Whether you make that panel out of one 24" board, two 12" boards, three 8" boards, four 6" boards, six 4" boards, or eight 3" boards, it's still going to move 10% radially and 5% tangentially. Taking the two extremes:

The 24" wide board will move

24" x 0.10 = 2.4" radial; 24" x 0.05 = 1.2" tangential

For the 3" wide boards, each board will move

3" x 0.10 = 0.3" radial; 3" x 0.05 = 0.15" tangential

However, when you glue 8 of those 3" boards together to make a 24" wide panel you get

8 x 0.3" = 2.4" radial; 8 x 0.15" = 1.2" tangential

So in the end, that 24" panel is going to move the same amount regardless of how many boards you glue it up from. The trick to getting flat panels isn't to use more, narrower boards (which looks terrible to my eye). Instead, it is to start with good, stable, properly dried (whether air or kiln) stock. If a wide board is badly cupped in its rough sawn state, it is likely going to cup in its planed state as well. However, if you start with stock that is relatively flat, and properly dry, it should pretty much stay that way.

There are 200-300 year old pieces of furniture in museums that were made using single wide boards up to 30" wide or more for things like case sides and table tops. They still survive today and most are still as flat as the day they were made. And these pieces saw a much harder life than most pieces do in our climate controlled homes today.

Personally, I don't like to use more than 2 boards to glue up a wide panel if I can help it. I just think panels made from fewer, wider boards look much better and less like Ikea junk. I regularly work with boards 10-12" wide or more without any problems. I currently have a piece of walnut in my shop that I'm working with that is over 16" wide, and it is almost dead flat in rough sawn state. It should stay that way, because it was properly milled, dried and stacked by a reputable mill. If you get your lumber from a good, reputable supplier, who knows how to properly mill and dry wide boards, you should have no problem working with wide boards.

[Bobby Slack]

Rob,

Thank you so much for taking the time to answer this. My concern is cupping because the tangential move will happen and that is inevitable.

I buy my lumber in Los Angeles from Bohnhoff Lumber which is a great mill and they allow me to pick the stock from the pile at a reasonable price, so that is a huge plus.

My next stage in this woodworking business is to read better the wood, the grain, use ... or not the sapwood, etc.

Sticking with this issue, thank you for replying and I will start experimenting with wider boards. You know ... doors don't work well when they warp so is very important to make sure everything stays super stable.

Have a great day.

Wood movement is relative, so it really matters not what width boards you use to glue up a panel. As a theoretical example, let's say that a particular species of wood moves 10% radially and 5% tangentially, and you want to make a 24" panel. Whether you make that panel out of one 24" board, two 12" boards, three 8" boards, four 6" boards, six 4" boards, or eight 3" boards, it's still going to move 10% radially and 5% tangentially. Taking the two extremes:

The 24" wide board will move

24" x 0.10 = 2.4" radial; 24" x 0.05 = 1.2" tangential

For the 3" wide boards, each board will move

3" x 0.10 = 0.3" radial; 3" x 0.05 = 0.15" tangential

However, when you glue 8 of those 3" boards together to make a 24" wide panel you get

8 x 0.3" = 2.4" radial; 8 x 0.15" = 1.2" tangential

So in the end, that 24" panel is going to move the same amount regardless of how many boards you glue it up from. The trick to getting flat panels isn't to use more, narrower boards (which looks terrible to my eye). Instead, it is to start with good, stable, properly dried (whether air or kiln) stock. If a wide board is badly cupped in its rough sawn state, it is likely going to cup in its planed state as well. However, if you start with stock that is relatively flat, and properly dry, it should pretty much stay that way.

There are 200-300 year old pieces of furniture in museums that were made using single wide boards up to 30" wide or more for things like case sides and table tops. They still survive today and most are still as flat as the day they were made. And these pieces saw a much harder life than most pieces do in our climate controlled homes today.

Personally, I don't like to use more than 2 boards to glue up a wide panel if I can help it. I just think panels made from fewer, wider boards look much better and less like Ikea junk. I regularly work with boards 10-12" wide or more without any problems. I currently have a piece of walnut in my shop that I'm working with that is over 16" wide, and it is almost dead flat in rough sawn state. It should stay that way, because it was properly milled, dried and stacked by a reputable mill. If you get your lumber from a good, reputable supplier, who knows how to properly mill and dry wide boards, you should have no problem working with wide boards.

[Pete Bennett]

Rob,

Thank you so much for taking the time to answer this. My concern is cupping because the tangential move will happen and that is inevitable.

I buy my lumber in Los Angeles from Bohnhoff Lumber which is a great mill and they allow me to pick the stock from the pile at a reasonable price, so that is a huge plus.

My next stage in this woodworking business is to read better the wood, the grain, use ... or not the sapwood, etc.

Sticking with this issue, thank you for replying and I will start experimenting with wider boards. You know ... doors don't work well when they warp so is very important to make sure everything stays super stable.

Have a great day.

A certain amount of what you say is true but it is a gross over simplifcation. It matters not how good your mill or you are and experience does help enormously in spotting the obvious boards that will degrade. However, the internal stresses that cause warpage etc. cannot be seen until it happens. Which can be immediately or some considerable time later. Your comments regarding Museums is also very misleading. quite apart from the fact that the pieces you see are the ones that have survived, their EMC will have been very carefully measured at reception and will have been eaqually carefully maintained eve since. Take any board no matter how well milled etc. at say 10% EMC place it in an environment at 6% or less or at 15% or more and watch it go. I regularly make very wide table tops in 60mm solid Oak almost always quarter sawn, the widest board I ever use is 8" but on thinner stuff I will never go beyond 4". So far in more than forty years I've had two tops that I had to do serious things to. Now I don't consider that to be too bad.

Pete

[Bobby Slack]

Pete. Fantastic reply. If I came across as misleading please forgive me. I noticed something and you pointed out that we are admiring the pieces that ... survived. Great point.

Oh boy this forum is fantastic.

A certain amount of what you say is true but it is a gross over simplifcation. It matters not how good your mill or you are and experience does help enormously in spotting the obvious boards that will degrade. However, the internal stresses that cause warpage etc. cannot be seen until it happens. Which can be immediately or some considerable time later. Your comments regarding Museums is also very misleading. quite apart from the fact that the pieces you see are the ones that have survived, their EMC will have been very carefully measured at reception and will have been eaqually carefully maintained eve since. Take any board no matter how well milled etc. at say 10% EMC place it in an environment at 6% or less or at 15% or more and watch it go. I regularly make very wide table tops in 60mm solid Oak almost always quarter sawn, the widest board I ever use is 8" but on thinner stuff I will never go beyond 4". So far in more than forty years I've had two tops that I had to do serious things to. Now I don't consider that to be too bad.

Pete

[Bob Rozaieski]

However, the internal stresses that cause warpage etc. cannot be seen until it happens. Which can be immediately or some considerable time later.

Absolutely. There's no way to tell if there are internal stresses in a board until you cut into it. However, if the board is flat and straight at the lumber yard, chance are, the stresses are minimal. If they were severe, the board would have likely warped straight off the mill's saw, and still be that way in the stack.

Your comments regarding Museums is also very misleading. Quite apart from the fact that the pieces you see are the ones that have survived, their EMC will have been very carefully measured at reception and will have been eaqually carefully maintained ever since.

I don't think it's misleading at all. The pieces may certainly have been placed in controlled environments when received by the museum, however, they survived for 200-250 years before being placed into these controlled environs by the museum. They were most certainly subjected to very large swings in temperature and humidity over the changing seasons of those 200-250 years before the museum took possession of the piece.

Take any board no matter how well milled etc. at say 10% EMC place it in an environment at 6% or less or at 15% or more and watch it go. I regularly make very wide table tops in 60mm solid Oak almost always quarter sawn, the widest board I ever use is 8" but on thinner stuff I will never go beyond 4". So far in more than forty years I've had two tops that I had to do serious things to. Now I don't consider that to be too bad.

I agree with your experience and have no reason to doubt it. I'll also add that wide boards that were properly dried should behave no differently, and my experience regularly working with boards up to 15" wide or more has confirmed this.

Perhaps I over simplified some, but the fact of the matter is that wood movement is relative to the width of the piece and the grain orientation. The fact that one person uses 4" boards to make a 24" panel while another person uses 12" boards doesn't really matter if the grain orientation and wood species are the same. Once the boards are turned into a 24" panel, both panels will behave the same.

Now if you compare a panel made from 4" quarter sawn walnut boards to a panel made from 12" flat sawn red oak, of course there will be huge differences in the warping of the two panels due to the difference in the ratio of tangential to radial movement in the two different cuts (tangential movement being the direction of greatest expansion). For one, the flat sawn boards are going to cup more (relative to their dimensions) due to being flat sawn. And the closer to the outside of the tree it was sawn, the more it will cup as there will be a greater contribution of tangential movement across the board's width. In contrast, the QS board will increase in thickness more (again, relative to its dimensions) because there will be a greater contribution in tangential movement across the thickness. Also, the red oak is much less dimensionally stable than the walnut, relatively speaking.

I'm not suggesting that narrow boards shouldn't be used for wide panels. Of course that works fine. My main point was that we should not be afraid of using wide boards to glue up a panel. With proper board selection, milling and drying, wide boards are just as stable as narrow ones in a panel of equal width. I've used wide boards sucessfully for almost 20 years of woodworking. But more importantly, the pieces that continue to survive in museums, that spent the majority of their existence outside of museums, with boards up to 24" wide or more, have survived just fine.

[Vic]

Bobby, I can tell you that the lumber I buy is air dried, typically for about three years. Rob Bois, did an experiment recently to follow up an article that, I think, was in PWW. The idea is that letting wood acclimate isn't as important as taking an equal amount of each side, so it will be dealing with equal pressure from moisture migration. I've set my shop up to deal in 12" width and have had no problems. That's not to say that I won't at some point, but if it's been dried and stickered properly at the beginning and allowed to dry well, chances are good you won't have any problems. Many times, kiln dried lumber can have serious internal problems due to drying too fast. They can appear stable and yet warp severely once they are cut due to a term call case hardening. Since I don't actually work with kiln dried wood, assume what I say about it has ass matter on it.

[thewoodwhisperer]

You'll see in an upcoming video Bobby, that I actually try to use the widest boards possible in my work. In fact, the trestle desk has two 12" wide boards making up the top. And although partial milling can be pretty effective, I have to admit that I don't often do it. Most of my wood is about as dry as its going to get so its typically pretty stable. In my book, the wider the better!

[Bobby Slack]

Vic, thanks. when I run the boards through my thickness planer I can say "always" take material from one side, then flip it, then flip it .... so in effect I am doing what you said just because it makes sense to balance what you do on one side with the other.

I see your point on drying wood too quick. I need to discuss this with my lumber supplier and ask him, of course, he will tell me that is done the right way.

I got to tell you that the wood that I am saving for my doors in Colorado will be staying in the garage for at least six months and will do the final milling in the summer when the wood is at the maximum expansion.

Bobby, I can tell you that the lumber I buy is air dried, typically for about three years. Rob Bois, did an experiment recently to follow up an article that, I think, was in PWW. The idea is that letting wood acclimate isn't as important as taking an equal amount of each side, so it will be dealing with equal pressure from moisture migration. I've set my shop up to deal in 12" width and have had no problems. That's not to say that I won't at some point, but if it's been dried and stickered properly at the beginning and allowed to dry well, chances are good you won't have any problems. Many times, kiln dried lumber can have serious internal problems due to drying too fast. They can appear stable and yet warp severely once they are cut due to a term call case hardening. Since I don't actually work with kiln dried wood, assume what I say about it has ass matter on it.

[Bobby Slack]

The wider the better. Is amazing how I can see things today that six months ago did not matter at all. Now I would never pick a board from the center of the tree. This means it will take forever for me to pick lumber. But that is OK is all about delivering maximum quality.

Probably next time I pick lumber I will go with a couple of saw horses to layout the wood, also some chalk to mark the pieces properly. They are not going to like this ...

You'll see in an upcoming video Bobby, that I actually try to use the widest boards possible in my work. In fact, the trestle desk has two 12" wide boards making up the top. And although partial milling can be pretty effective, I have to admit that I don't often do it. Most of my wood is about as dry as its going to get so its typically pretty stable. In my book, the wider the better!