# Slightly warped boards for table top



## daveinjersey (Feb 27, 2013)

Just noticed that a couple of the boards I bought a few weeks ago for a table top are slightly warped across the length. Six foot boards for a planned five foot table top are, when laid on a flat surface, maybe a quarter inch high at the center or ends. Not sure if I just failed to look closely when I picked them up, or if they warped a bit sitting in my garage.

What success should I expect from stacking them on a flat surface with heavy rails stacked above to flatten them out? Please tell me something good! I plan to edge-glue these six inch boards. Should I expect to be able to? Should I expect the top to be stable after glue-up?


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## BernieL (Oct 28, 2011)

Good and bad news - The boards that are bent can probably be pressed flat but once you release them and walk away, they will bend again. That's the nature of wood. That was probably the bad news...

The good news is that when it comes time to glue these boards together, alternate the grain on the boards and try using the bent ones between stable ones. Maybe someone else can advise you differently, but without seeing pictures of how badly these boards are bent... I stabbing in the dark. Other factors can play into the equation... like the atmosphere in your shop etc.


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## TylerJones (Dec 4, 2011)

Any reason you can't flatten the boards? When you purchase lumber, and again between each step in milling you need to have the boards stickered so that they can breathe on all sides evenly. You can try stickering them and see what happens. 

If you can't flatten them with a jointer then I would just glue them up as Bernie suggested and take down the high spots with a plane or (carefully) with a sander. This is one of the few times it's nice to have a belt sander. I would not try to push them all flat to glue them up, that's asking for trouble later. Realistically you could probably get away with pushing about 1/8" out of them and then just take down the rest until the panel is flat. 

Also just like Bernie said I wouldn't try to flatten them with weight, if they are still warped after they sit stickered for a bit then that's where the wood wants to be. Better to deal with the devil you know.


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## TylerJones (Dec 4, 2011)

Next time you set aside some cash for a new tool I would highly recommend a moisture meter. That and a $10 digital thermometer/humidity guage will go a long way towards eliminating guesswork with wood movement.


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## cabinetman (Jul 5, 2007)

You could try overbending. Put a spacer in the middle of board bowed up, and clamp it down past flat. Given time to air out, it may straighten out. Gluing up in that condition could cause the flat ones to bow.


















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## MNsawyergp (Jan 31, 2012)

I would rip the 6" boards to 3", square the edges on a jointer, and flip-flop the growth ring pattern when you glue up the panel. That is the only way to combat warping in boards or in a glued up panel. Six inch boards are prone to warping unless quarter sawed from the log.


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## woodnthings (Jan 24, 2009)

*this is always difficult*

Let's say you lay the board down on a flat surface. How much pressure is required to flatten it out? A 5 lb bag sugar? More? If it's not that much you are probably OK. 

Is the board just bowed or it it twisted as well? Can you push down the high corner with 5 lbs of pressure? If the boards can be flattened by that amount of pressure you are probably OK.

Lay out everything on a flat surface and see which boards can be used to counter-act each other and place them next to each other. 
Using cauls clamp them up dry and see how it goes. If it goes well, and they flatten out rather easily, then you are probably OK.

You are stuck with them probably by now, so go ahead and try the glue up and see how it goes after they dry out. Check the diagonals or have some means to keep the glue up flat on the bench until the glue sets up. Post back your results. :yes:


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## Al B Thayer (Dec 10, 2011)

MNsawyergp said:


> I would rip the 6" boards to 3", square the edges on a jointer, and flip-flop the growth ring pattern when you glue up the panel. That is the only way to combat warping in boards or in a glued up panel. Six inch boards are prone to warping unless quarter sawed from the log.


This seems the best way. I've flattened lot of boards by gluing them to other boards. I face everything under 8" so no need anymore.

Al

Nails only hold themselves.


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## daveinjersey (Feb 27, 2013)

*Just to be clear*

My board isn't cupped across it's width, but warped along it's length. Doesn't seem to be twisted, either. It deflects a little under 1/4" at the midpoint of it's six foot length.









An 8 pound weight seems to close it up. 









I can give it a few weeks to dry further, but if it's still bent, should I (hand) plane it flat before glue-up?


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## TylerJones (Dec 4, 2011)

MNsawyergp said:


> I would rip the 6" boards to 3", square the edges on a jointer, and flip-flop the growth ring pattern when you glue up the panel. That is the only way to combat warping in boards or in a glued up panel. Six inch boards are prone to warping unless quarter sawed from the log.


I just can't understand why we are still giving people this advice. It's just not true. We just touched on this discussion in another thread so I won't go into all over again. But I challenge you to go to ANY well respected furniture maker's shop and find a table top glued up with 3" strips. You won't, and they'll look at you like you're crazy if you suggest the 15" boards used in their table will warp because they aren't quarter sawn or the growth rings alternated.


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## cabinetman (Jul 5, 2007)

TylerJones said:


> I just can't understand why we are still giving people this advice. It's just not true. We just touched on this discussion in another thread so I won't go into all over again. But I challenge you to go to ANY well respected furniture maker's shop and find a table top glued up with 3" strips. You won't, and they'll look at you like you're crazy if you suggest the 15" boards used in their table will warp because they aren't quarter sawn or the growth rings alternated.


His statement was that it was what he would do. I agree that some advice is made to sound like gospel. Hard to tell where some get their information. Some get it from reading forums. Some get it from actually doing the work. So, whatever the case, don't let it get under your skin if you don't agree. Stating your beliefs entitles you your opinion. It would be unique in forums though, if there was some sort of 'truth filter'.:yes:


















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## Maylar (Sep 3, 2013)

daveinjersey said:


> My board isn't cupped across it's width, but warped along it's length. Doesn't seem to be twisted, either. It deflects a little under 1/4" at the midpoint of it's six foot length.
> 
> An 8 pound weight seems to close it up.
> 
> I can give it a few weeks to dry further, but if it's still bent, should I (hand) plane it flat before glue-up?


What you are experiencing is one reason I don't buy dimensioned lumber from the box stores - you start with 3/4" and by the time it's planed flat you don't have enough thickness for the project.

I would flatten it before gluing... but, a 1/4 inch is a lot to lose. Maybe you get lucky and the bowed part is toward the end that will get cut off?


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## woodnthings (Jan 24, 2009)

*This covers the basics of making a table top*

At the end is a video showing how to make a tongue and groove joint using a router table. This will align the boards to eliniate any mismatch along the edges, assuming they are held flat to the router table when processed and will take any warp into consideration as well. The warped boards must fit together using this joint and when clamped up are self aligning. A full length spline would do the same. A glue joint bit would do the same. A series of cauls would do the same.

http://www.fundamentalsofwoodworkin...g-Articles/edge-joining-panels-and-table-tops

A plank door build from 2 x 10's could also be a table top:
http://www.woodworkingtalk.com/f2/door-build-2-xs-1-4-ply-55717/


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## Al B Thayer (Dec 10, 2011)

TylerJones said:


> I just can't understand why we are still giving people this advice. It's just not true. We just touched on this discussion in another thread so I won't go into all over again. But I challenge you to go to ANY well respected furniture maker's shop and find a table top glued up with 3" strips. You won't, and they'll look at you like you're crazy if you suggest the 15" boards used in their table will warp because they aren't quarter sawn or the growth rings alternated.


I don't think he meant ALL boards would warp. 

After looking at the pictures. While not perfect, there doesn't seem to me to be a big enough problem to warrant calling the wood police. Alternate the glue up and deal with what you have left after. Gees. 

Al

Nails only hold themselves.


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## BernieL (Oct 28, 2011)

Daveinjersy - I see the boards have a slight problem and that's their nature. Left alone, even if you force them straight for a couple of weeks and dry them out, they will return to their natural state. But you can glue them straight by alternating the grain like Al stated above. The end result may give you a slight uneven edge but a simple cabinet scarper will make that disappear.

I have no idea what the table top will be used for or if it will have a skirt around it... but would it be possible to put the bent boards in the middle of the build and screw a cross member across the bottom to snag those bent boards straight. Even a 1/2 plywood strip would suffice. 
If that doesn't work - just glue them up!


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## daveinjersey (Feb 27, 2013)

BernieL said:


> Daveinjersy - I see the boards have a slight problem and that's their nature. Left alone, even if you force them straight for a couple of weeks and dry them out, they will return to their natural state. But you can glue them straight by alternating the grain like Al stated above. The end result may give you a slight uneven edge but a simple cabinet scarper will make that disappear.
> 
> I have no idea what the table top will be used for or if it will have a skirt around it... but would it be possible to put the bent boards in the middle of the build and screw a cross member across the bottom to snag those bent boards straight. Even a 1/2 plywood strip would suffice.
> If that doesn't work - just glue them up!


Thanks, Bernie. It's for a coffee table without breadboard or skirt. I could do a cross member underneath, though. I think I'd be ok with alternating grain at the edge. Just to be sure I understand you - you mean something like this - right?


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## FrankC (Aug 24, 2012)

cabinetman said:


> His statement was that it was what he would do. I agree that some advice is made to sound like gospel. Hard to tell where some get their information. Some get it from reading forums. Some get it from actually doing the work. So, whatever the case, don't let it get under your skin if you don't agree. Stating your beliefs entitles you your opinion. It would be unique in forums though, if there was some sort of 'truth filter'.:yes:
> 
> 
> 
> ...


What would be handy around here sometimes is a second button beside the "THANKS", one that says "BULL$HIT".


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## cabinetman (Jul 5, 2007)

FrankC said:


> What would be handy around here sometimes is a second button beside the "THANKS", one that says "BULL$HIT".


Not a bad idea, but that's a little too direct don't ya think Frank? Maybe a bit more discrete...like Bull Puckey or NF Way. :laughing: 

Wait...I did see on another forum...BIOYA. :laughing:


















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## FrankC (Aug 24, 2012)

cabinetman said:


> Not a bad idea, but that's a little too direct don't ya think Frank? Maybe a bit more discrete...like Bull Puckey or NF Way. :laughing:
> 
> Wait...I did see on another forum...BIOYA. :laughing:
> 
> ...


What ever works.:laughing:


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## MNsawyergp (Jan 31, 2012)

TylerJones said:


> I just can't understand why we are still giving people this advice. It's just not true. We just touched on this discussion in another thread so I won't go into all over again. But I challenge you to go to ANY well respected furniture maker's shop and find a table top glued up with 3" strips. You won't, and they'll look at you like you're crazy if you suggest the 15" boards used in their table will warp because they aren't quarter sawn or the growth rings alternated.


(end quote)

Forgive me for being "old school", but that is how I was taught back in 1967-8 in high school shop and again in Woodworking 1 and 2 in college as part of my Industrial Arts Teaching major. I also owned and operated a furniture factory for several years. I would guess that I have glued up more solid wood panels than you will see in your lifetime. My experience tells me what I wrote in my first reply. I don't go by what others say. If you don't like my advice. That is your choice, but I do know that flip-flopping the growth ring direction does lessen the warping problem when gluing up panels. Another thing...factories that glue up panels very seldom use boards wider than 4". 

As for the 15" planks used by some furniture makers, Most of these wide planks come from a center cross section of the log and therefore do not have the curvature of the growth rings to distort (warp or cup) the plank. If you go to any lumber yard and look at 2 x 12 planks you will see the affect of warping on wide planks. All you have to do is look at the growth ring pattern on the ends of the planks and you will see what I mean.

Now, back to the problem at hand...the questioner uses the word "warped" along the length. That is the wrong term. Warping (cupping) happens across the width of a board. Bowing happens along the length.

For bowed boards to be used in a glued up panel, they need to be cancelled out. It is best to alternate bow up, bow down. I would put the bowed boards in the middle of the panel. If they are put at the outsides of the panel, they could cause the panel to twist.

The small amount of bowing showed in the pictures should be able to be pulled out as the panel is glued up by starting the clamping at the middle of the panel and working toward the ends. At the ends, use C-clamps to bring the boards into alignment. You can use a scrap board across the panel on top and bottom along with the clamps to draw all the boards into alignment.

You can use a spline or biscuits to align the boards, but I don't like the hassle of lining up biscuits while glue is drying on big panels. We had a glue joint 2 sided jointer at our factory that put a small tongue on one edge and a matching groove on the other. When we glued up the panels we would pound the boards into alignment with a mallet so the tongue and groove mated.


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## TylerJones (Dec 4, 2011)

MNsawyergp said:


> (end quote)
> 
> Forgive me for being "old school", but that is how I was taught back in 1967-8 in high school shop and again in Woodworking 1 and 2 in college as part of my Industrial Arts Teaching major. I also owned and operated a furniture factory for several years. I would guess that I have glued up more solid wood panels than you will see in your lifetime. My experience tells me what I wrote in my first reply. I don't go by what others say. If you don't like my advice. That is your choice, but I do know that flip-flopping the growth ring direction does lessen the warping problem when gluing up panels. Another thing...factories that glue up panels very seldom use boards wider than 4".


I can see that we aren't going to agree on this and that's ok. But basing advice to a hobbyist woodworker or single furniture maker upon what furniture factories do is silly. I have no interest in who's seen more glued up panels to be frank, and once again none of that information makes you correct. You know as well as I do that the reasons for factories using 4" planks are many, including but not limited to cost, machine and storage efficiency, process standardization etc. Yes they also use the thinner boards as a way to combat warping. The reason they do that is because the buy truckloads of lumber then stack it in a corner unstickered. You can find a couple of % points difference in moisture content in a single stack of lumber. So they use a way that is faster for them and cheaper, the resulting product isn't as nice but that's the obvious trade-off when you buy factory furniture.

Now a hobbyist woodworker has much more in common with a professional furniture maker than a furniture factory. I will never get on board with the tendency to teach hobbyists or new woodworkers how to do something the easy way instead of the best way. Will both result in a table? Yes. But side by side the table with the wide boards will look significantly better. Period. So if you can build THAT table without warping issues then why wouldn't you? It doesn't even take more time, just more information. 

What I took issue with was the statement that ripping and flipping was "the only way to combat warping in boards or a glued up panel." That's a ludicrous statement. This is one of the only crafts that I can think of that the prevalence of teaching towards making a mediocre product is so widespread. If it's just a hobby then you should do what makes you happy, but I find it hard to believe that it wouldn't make you happier to make a better piece. It often costs no more money and takes no more skill to make a piece significantly nicer.

Does that make me a furniture snob? Maybe. But I have too much of a passion for both fine furniture and teaching to just keep my mouth shut when someone is basically instructed to make a poorer piece of furniture. More and more in our everyday life and our products we are asked to accept an increasing level of mediocrity as the norm, I just refuse to do so with a craft with such a rich heritage. 

I'm sorry if this is offensive to some, that's not what I want. But as long as I'm commenting on something I'm going to be giving the advice that makes the finest product that your budget and skill potential allows. If that's not what you came looking for then just skip me over.


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## lilman (Nov 22, 2012)

I will never be a respected furniture maker....


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## woodnthings (Jan 24, 2009)

*warping terms*

To me "warp" is the general term for a condition which is less than straight, less than flat in both planes.

A board may lay flat on a reference surface, but looking down on it it may have a curved edge or edges.

A board that will not lay flat on a reference surface will have twist and have a high corner and a low corner.

A board may lay flat on a reference surface but not touch evenly on it's entire surface because it's cupped and will show that from looking at the ends.

Here's some examples:
*From Wikipedia, the free encyclopedia*

 

*Wood warping* is a deviation from flatness as a result of stresses and shrinkage from the uneven drying of lumber.
The types of wood warping include:

*bow* : a warp along the length of the face
*crook*: a warp along the length of the edge
*kink*: a localized crook, often due to a knot
*cup*: a warp across the width of the face, in which the edges are higher or lower than the center
*twist*: a distortion in which the two ends do not lie on the same plane.
For reference:
http://en.wikipedia.org/wiki/Quarter_sawing

http://www.horizon-custom-homes.com/QuarterSawnLumber.html

The wider the board the greater the chance it may cup or twist, because of the internal stress within unless it is totally acclimated to the environment in which it will live. A quartersawn board where the end grain is more vertical than arcing, will not tend to cup as much or if at all. A 12" wide flat sawn board with large arcing growth rings can be ripped down the center, reglued into 2 - 6" boards and will tend to be more stable.


I agree that furniture factories want to make the greatest use of their material and will join several narrow boards for economy reasons. Fine furniture builders can and will join wide boards successfully because they can control the wood grain and select the best for the conditions. They can use joining methods including splines, glue joints etc that may not be economical in a factory. The factory has the advantage of wide belt sanders, high pressure glue and laminating presses and other technology that the home or small shop does not have access to. The two are really separate approaches to the same issue. JMO.


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## FrankC (Aug 24, 2012)

To me warp is a verb, to bed or twist out of shape, which would cover any deviation in a board from being flat and straight.


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## cabinetman (Jul 5, 2007)

Production furniture manufacturers, and custom high end shops that make door panels and table tops from solid wood use KD lumber, and make provisions for storing. It's less important which way the grain is orientated on the individual boards than what their good side faces look like. They are selected and matched for color, grain, and character. The board widths are not sized down, as well managed and selected boards fare well. They may be sized appropriately for the overall size, so they will look contiguous, and uniform.


















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## MNsawyergp (Jan 31, 2012)

Thanks "woodnthings". I agree with you all the way. 

To "TylerJones": I would say that you are as in error as you claim I am, if you suggest to newbies that you can just take any 15" plank and use it and it will not "cup"/warp. Now, if you go forward and explain to the newbies, as "woodnthings" did, just how wood moves, the proper terms, and just what to look for in a wide plank so that it will not cup, then I see no reason for contention or harsh words.

I also agree that a panel made from wide boards or one piece is much more beautiful than a bunch of glued up narrow boards. Here is something that a conscientious woodworker should be able to do, though, is to match grain and color to produce a glued up panel which doesn't have stripes of odd color and weird grain patterns. You call gluing up panels of narrow boards inferior and mediocre, which can be true, but in the hands of a true craftsman, that is not so. A good example is raised panel kitchen cabinet doors. They are mostly glued up from narrow boards. Doors from a high quality company will be grain and color matched so the panel seems to be one board. That is an art. Quality furniture can be made the same way. I see no need for snobbery or the exclusion of glued up panels in the world of fine furniture.


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## Al B Thayer (Dec 10, 2011)

MNsawyergp said:


> (end quote)
> 
> Forgive me for being "old school", but that is how I was taught back in 1967-8 in high school shop and again in Woodworking 1 and 2 in college as part of my Industrial Arts Teaching major. I also owned and operated a furniture factory for several years. I would guess that I have glued up more solid wood panels than you will see in your lifetime. My experience tells me what I wrote in my first reply. I don't go by what others say. If you don't like my advice. That is your choice, but I do know that flip-flopping the growth ring direction does lessen the warping problem when gluing up panels. Another thing...factories that glue up panels very seldom use boards wider than 4".
> 
> ...


Well said. Kickin butt and takin names on a different thread. We are such an opinionated bunch aren't we? Bow cup and warp crossed my mind but couldn't muster the energy to respond.

8 lbs required to straighten a board that long isn't much at all. Wouldn't bother me to flip flop and glue. 

Al

Nails only hold themselves.


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## BernieL (Oct 28, 2011)

Daveinjersey - in case there is any doubt about the info you need... you got it right in post #16. That's what we're talking about when we talk about alternating the wood grain.


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## daveinjersey (Feb 27, 2013)

Thanks, Bernie. I think I'll go with your suggestion of a cleat or two across the bottom of the boards. That should work fine in my application.


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## woodnthings (Jan 24, 2009)

*cupped boards*

how to fix cupped boards


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