Can oven dry wood warp? - Woodworking Talk - Woodworkers Forum
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post #1 of 35 Old 06-01-2020, 11:09 AM Thread Starter
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Can oven dry wood warp?

Hi guys,

I recently bought a slab of oak for a desktop project. I flattened and straightened it to perfection only to find out the next day that it had cupped considerably. This is a typical beginners mistake I guess, and by reading through some posts on this forum I found out that I have bought flat sawn instead of quarter sawn and this might explain my misery. However, I thought that by buying oven dry wood 8-10% I would not have to worry about warping at all - is this true or false? Has my wood-dealer pulled my leg?

Another thing is: there is beginning to form crack lines down through the center along the grain of the piece, which for sure wasn’t there at the beginning. Can it be because I have taken off quite a bit of material and thereby stressing the wood too much? Is that possible?

And then the most important question: what can I do now?
If I once again flatten it, how do I know that it will not cup again?
Can I straighten it out with maybe moisture and clamping?
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post #2 of 35 Old 06-01-2020, 11:14 AM Thread Starter
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Here are some photos of the cup and the crack
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post #3 of 35 Old 06-01-2020, 11:25 AM
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wood moves for ever, 200 year old furniture will swell and make a drawer stick that never stuck before
that is a nice slab of wood, it appears to be one piece of wood
the way to minimize movement would be to cut into 4'' slices and alternate grain direction, alternately flip every other board
it would also be the only way to hide/minimize that crack on the end
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post #4 of 35 Old 06-01-2020, 11:25 AM
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welcome to the forum, Eddie.
I noticed that you have "DK" in your email screen name.
does that mean you are in Denmark ?? way back when I was in the
US Navy, I made several port calls in DK and I loved your country !!

this is an open forum with all levels of skills and talents.
please feel free to join in the conversations that you find interesting
and ask questions to expand your skill levels and share what you know.
if you would like to know more about something, you can start a new thread.
we like to see photos of projects to share with others.
when addressing specific issues or concerns, sketches, drawings and photos
will get you the most accurate responses. (and we can all be on the same page).
when you get time, you can complete your profile through the "User CP"
with your location and whatever you want in your signature line that will
show in all your posts. looking forward to seeing some of your projects.

we would much rather see posts of: "How do I do this"
~ vs ~ "How can I FIX this" . . . .

hope you enjoy your stay.

.

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post #5 of 35 Old 06-01-2020, 11:56 AM
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Wood moves, period. Kiln dried or not, it will move with changes in moisture content

I need cheaper hobby
etsy.com/shop/projectepicfail
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post #6 of 35 Old 06-01-2020, 02:07 PM
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The crack could possibly from expansion/contraction of the wood. I'm thinking this because the end board is a permanent solid connection which will not allow for wood movement. Although it is only a small section, if the wood was not actually down to 8% - 10% and the AC in your home/shop was on further drying and shrinking the wood.

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post #7 of 35 Old 06-01-2020, 02:12 PM
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Did you buy this from a sawmill. I have bought wood from sawmills that swore that they kiln dried the wood. Maybe they didn't dry it properly or maybe they flat out lied.
As for the flat sawn/quarter sawn thing, if the lumber was properly kiln dried, that shouldn't matter too much.

Also what Ogre said........... a wide board that size sometimes needs to be sawed into narrower slices and reglued.

The simplest solution is to saw the board into no more than 8" slices and re-glue. Your first slice should be made where the split is.
When you re-glue the slices, alternately flip the boards over so that you get the end grain running in opposite directions.

It is unfortunate u are having this problem because you probably paid a premium price for a wide slab.

Anyway, all is not lost

thyere are procedures for the end pieeces you added. This style is called a breadboard top. I am to short on time to explain the proper method right now, but there will be others here that will

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Last edited by Tony B; 06-01-2020 at 02:21 PM.
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post #8 of 35 Old 06-01-2020, 02:40 PM Thread Starter
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Thanks for your quick responses. Yes #John I am from Denmark. Great you liked it here.
Last summer I moved away from Copenhagen to a house in a small village and finally had the space to make my old dream come true: a woodworking workshop in my garage.
So I am brand new to this universe - but already quite a passionada.

#Orge: yes that is a beautiful creature. It is one piece and it will be a single-piece top on the desktop-project- but great idea alternating grain direction.
Would you mind spelling out for me what you mean by cutting 4” into the piece?

Does anyone else have some ideas how to continue with the piece from here? I imagine this problem is a common one...

Also I would be interested in knowing how to avoid it the next time I have a flat sawn slab to work on.
post #9 of 35 Old 06-01-2020, 02:44 PM Thread Starter
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Oh great Tony. You just answered my question in my previous post. I just didn’t see your response before posting.
I will try this.
Yes I got it from a sawmill - but they didn’t oven dry the wood themselves so maybe I should cut of this middle link next time to be sure I know what I get.
post #10 of 35 Old 06-01-2020, 03:00 PM Thread Starter
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#Tony and #Orge I finally wrapped my head around your suggestion (cutting in smaller pieces and reglueing) and I get it now. I also looked up the breadboard technique. I must admit though that both of these ideas would really take some of the beauty out of this one piece slab with its unique and connected grain figures. Isn’t there another way? I mean, I see one piece tabletops around quite often....

And to make things even more complicated/interesting my original design plan included dovetails on each ends of the top joining to smaller vertical pieces giving it a bit of a waterfall effect on both ends. But with all this warping I think this plan is doomed...
post #11 of 35 Old 06-01-2020, 03:48 PM
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I just looked again at the second photo. I saw a board with dowels in it, I mistakenly thought it was a 'breadboard' end. Anty, I looked at it again, this time looking at the grain pattern on the end. Although not ideal, it dont look all that problematic. Ideally, the end grain should be dead flat. Good luck with that happening. Anway, just for knowledge purposes, If a board is going to 'cup', look at the end grain and envision the grain trying to straighten itself flat. That will be the direction of the cupping.

Next time if at all possible, purchase a 'moisture gauge' and also, find a new source for your lumber.

Here is one possible solution: IF the wood stabilizes in a week or so, and you can live with the slight cup, you can get a contrasting wood and make maybe just one or 2 'butterflies' to go across the split. It is quite common in modern custom furniture.

I also would scrap the idea of a waterfall.

In the US where most members are located, we refer to oven dried as "Kiln Dried", however; dont change your vocabulary because of us. Just stated that to get familiar with our terminology so if u see it you will know what we are talking about. Obviously, we all understood what you meant by oven dried.

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Last edited by Tony B; 06-01-2020 at 03:52 PM.
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post #12 of 35 Old 06-01-2020, 03:55 PM
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When you get ready to attach the top to the legs, if you could show us your plan, we could let you know if it will work. We understand that you are fairly new to this.

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post #13 of 35 Old 06-01-2020, 05:29 PM Thread Starter
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Thank you Tony that is incredibly helpful. I will give this a week to see if it stabilizes. - and yes, I really like the butterflies design Wise. And tomorrow I’ll try to post a picture of my design idea.
post #14 of 35 Old 06-01-2020, 07:05 PM
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Will be looking forward to it.

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post #15 of 35 Old 06-02-2020, 06:51 AM
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after you surfaced you new board, a common mistake people make is to lay the board flat before working with it again. with the new surfaces, they absorb or release moisture quickly. a board laying flat, say on a table, will have one exposed face and one face that will not be exposed. a board can warp just from this. one face will absork (or release) moisture and the other cannot, causing the board to warp!

it is best to lean a board against something to expose all surfaces, if it is going to be s while before working with it, to eliminate this reason to warp.

but the cutting method is your answer now. we seldom leave boards over 5" in the shop.

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post #16 of 35 Old 06-02-2020, 08:04 AM
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One thing I have learned in 30 years. If it's a wide board it will most likely split and warp and cup. I almost always rip it down to about 3" wide and glue up the 3" pieces to the width of board I need.

It's fun and a beautiful piece of wood. Yet it's value or beauty is still there when it's cut into smaller boards. Even with a big split in it I find those things add character and I have gone into a lot of nice eating establishments and found tables there that had all kinds of splits and cracks and warps and it just added to the atmosphere. I have projects that have character in them. I smile when I look back at them. Next project maybe I will change it bit or I may forget about it and do the same thing again! HA!


Looks good keep up the work!
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post #17 of 35 Old 06-02-2020, 08:41 AM
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Eddie,

Kiln (oven) dried wood will always have more tension in it than slowly air-dried wood, but wood will move all the time. That's just how it goes. The wider the piece the more it will move, and it will mostly only move across the grain (there is a minuscule amount of movement with the grain). Work with the movement, don't try to overcome it.

For a slab that wide I would not want to chop it up into strips, it's beautiful as it is. I would seriously consider using breadboard ends to keep it flat(ish), but you'll find it almost impossible to keep completely flat. You can deal with the crack using bow-ties or butterflies, but they can be any shape you like so long as there is a dovetailing effect (even something like a cloverleaf will work).

Another way to deal with the crack is to suck epoxy resin into it using a shop vac, you can either make it a feature or disguise it. Don't try and close it up as you'll just add more tension to the board.

I hope this gives you some alternative ideas.

Grant.
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Last edited by GrantCrawley.uk; 06-02-2020 at 08:59 AM. Reason: Grammar correction and adding additional ideas
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post #18 of 35 Old 06-02-2020, 02:38 PM
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IMO this subject s one of the most important things to learn about in ww'ing. You are correct flat sawn lumber is the least stable. By the same token, finding a quarter sawn board that wide would not be an easy task!

The two factors are : moisture balance & internal stresses.

Several things to know about in milling lumber (and keeping them flat) such as:

1. Removing equal amounts of material off both sides during the milling process. This keeps the moisture balance equal.

2. Mill incrementally and let the board relax between sessions.

3. A stable environment is a factor, those of us with open air shops have the most difficult time.

4. Maintain equal air flow on both sides of the board at all times. Can be as simple as standing the board vertical, or on top of stickers. NEVER lay a panel or wide board down on a table top because this only exposes one side to the air.

5. Internal stresses are the most difficult to deal with. In spite of doing all the right things, certain boards just will not behave. This can be due to natural internal stresses, or as Grant mentioned in his excellent response, rapid kiln drying can result in "case hardening", where the board has not achieved its lowest energy state. We've all seen the occasional board come off the rip saw with a big bend.

Air dried lumber is the most stable because the stresses in the board can release slowly as is dries.

The best fix for a problem like this is usually making one or more rip cuts to separate the board into narrower strips, followed by jointing and regluing. Using a band saw will minimize wood loss.

In your case, you might try clamping the board using cauls and see if it will go flat. If it does, stow it away properly for a week and see what happens.

Minor cups in a table top can be dealt with during the mounting simply fastening it down to remove the cup.
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Last edited by DrRobert; 06-02-2020 at 02:43 PM.
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post #19 of 35 Old 06-02-2020, 03:07 PM Thread Starter
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#Timpa - thats exactly what I did - chopped off a lot of material and then put it laying flat on my work bench. Lesson learned. The hard way.

#Greg - thanks for the tip about not wood filling the cracks - I seriously considered it, but now I will go with butterflies.

#Mark - I like the way you think - that wood pieces has it own unique character, and as I am learning these days: there is no such thing as perfect in wood working.
post #20 of 35 Old 06-02-2020, 03:15 PM Thread Starter
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#Tony and others - here is a simple sketch of my original plan - a wall mounted work desktop. Leaving aesthetics aside, is this project possible you think given that the wood seem to warp so much?
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