Can oven dry wood warp? - Page 2 - Woodworking Talk - Woodworkers Forum
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post #21 of 35 Old 06-02-2020, 03:15 PM Thread Starter
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post #22 of 35 Old 06-02-2020, 03:21 PM Thread Starter
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#Robert thank you for this. I am learning so much!!
(Working with wood is almost like taking care of an intelligent living being)

I will try your suggestion with the clamp as I think the warping is a relatively small one and then I will store it correctly.
post #23 of 35 Old 06-02-2020, 03:43 PM
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Many good suggestions above .....

Try to fix a warp or a slab that's splitting is one of the most challenging issues in woodworking, but there are solutions.


Look up "butterfies" in woodworking not the flying type. These are inset in the split to prevent it from opening any further:


A warp can't really be "fixed" and it may return or get worse. When first flattening the slab, remove equal amounts of material from both sides. Then as suggested, let it breathe, standing vertically to allow air to reach both sides. Then go at it again and repeat the process. A "fix" is as suggested, to rip the slab into parallel planks and reglue them. I would flip them end for end on a table top, but some folks don't mind the grain changing direction. The trick/issue will be getting a cut that is straight enough to reglue. A live edge slab can NOT be used against the fence on a table saw unless you scab on a straight board to register along the fence. A hand held circular saw may be your only solution, but you are only allowed one straight cut or the pieces will not match close enough to reglue. Use a new and sharp blade for this and go slow enough to avoid overheating it. I needed to rip some 2 1/2" hard Maple and I used 2 or 3 passes to make my cut, about 84" long.




The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #24 of 35 Old 06-02-2020, 04:04 PM
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That is one beautiful piece of wood. Is it European brown oak?

There's been some great comments already, especially the ones recommending letting the wood acclimate in your shop before working it, and taking wood from each side when milling. I have to say though, that cutting such a beautiful board into 3-4 inch pieces and gluing back together, while sometimes necessary, would be my last option. I'd let it sit for a bit, careful that each side gets air, and try again in a few weeks. Your piece is not flat but its not terribly cupped.

Also, are you able to clamp it flat with wood cauls? If so, you may be able to design some rippings to sit under the top, perpendicular to the grain and screwed in place. 3 screws, center one a normal countersunk hole, 2 outside ones in a slotted hole to allow movement. Try it out with clamps first to see if it flattens the board.

Sometimes you have to live with a piece that does not behave, I call it the romance of the wood. Perhaps a waterfall edge is not in the cards.

Best of luck
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post #25 of 35 Old 06-03-2020, 04:20 AM
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Eddie,

Your waterfall idea may actually help the issue. Dovetails are phenomenally strong joints and the right-angled turn will have the same effect as putting a breadboard end on. Just make sure the grain all runs in the same direction.

Firstly, cut your board down to it's finished piece lengths and sticker it (put sticks underneath and between boards) to let your board acclimatise to your shop environment before further flattening. I would be wary of standing a board up to acclimatise as this can impart a bow or twist and they can be even harder to get rid of than your slight cupping.

Shortening the boards to their finished lengths will help reduce the amount of tension and hopefully stop further cracking. You may only need to butterfly the one end. After you fit the butterfly some resin may enhance the appearance as you'll still have a crack, the butterfly will just stop it getting worse.

I would leave it a week or longer, your workshop will have different humidity to the kiln (oven) and you want the board to normalise and finish moving before final flattening and joining.

When you feel that the board has stopped moving, do a final flattening and thickness all three pieces to your finished dimension. Immediately cut your joinery, it's a long dovetail joint so I would suggest making your pins and tails almost equal width, with the tails on the ends and the pins on the top. Using a pattern router for the pins will speed up pin cutting and ensure they're accurately perpendicular to the ends - it will also make it easier to cut them on such a long board.

There's an article on my blog about using a pattern router bit to cut dovetail pins, you may find it helpful: click here

I hope that helps.

Grant.
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post #26 of 35 Old 06-03-2020, 06:01 AM
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Quote:
Originally Posted by [email protected] View Post
#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?
I'm not sure if I would do this unless I was guaranteed that the board has completely stabilized and only subjected to normal seasonal changes. Being that it was purchased at a sawmill and supposedly kiln dried by a third party makes me wonder if it was really kiln dried.
Anyway, the problem that I see with dovetailing the ends would be that in the time it takes to make the dove tails and assemble the desk, the dimensions might change and dovetails wont line up. Even then, if not fully stabilized, the dovetail joints themselves will create a whole new set of splits.
The way to settle this potential future problem would be to get a moisture meter and see if the wood is around 6-8% moisture content.
The slab itself is very attractive and a contrasting colored butterfly in the top would make a fine looking top. The go ahead with a standard design of table legs and an apron.

Anyway, a moisture meter would be my starting point. It will always come in handy if you intend to buy sawmill lumber. If the MC (moisture content) is not good, then dont buy or design furniture with lots of wood movement in mind.

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post #27 of 35 Old 06-03-2020, 02:31 PM Thread Starter
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Thank you everyone! I will take it from here, and hopefully I’ll be able to post a picture of the finished desktop in the near future.
post #28 of 35 Old 06-03-2020, 02:34 PM Thread Starter
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Quote:
Originally Posted by Frost View Post
That is one beautiful piece of wood. Is it European brown oak?

There's been some great comments already, especially the ones recommending letting the wood acclimate in your shop before working it, and taking wood from each side when milling. I have to say though, that cutting such a beautiful board into 3-4 inch pieces and gluing back together, while sometimes necessary, would be my last option. I'd let it sit for a bit, careful that each side gets air, and try again in a few weeks. Your piece is not flat but its not terribly cupped.

Also, are you able to clamp it flat with wood cauls? If so, you may be able to design some rippings to sit under the top, perpendicular to the grain and screwed in place. 3 screws, center one a normal countersunk hole, 2 outside ones in a slotted hole to allow movement. Try it out with clamps first to see if it flattens the board.

Sometimes you have to live with a piece that does not behave, I call it the romance of the wood. Perhaps a waterfall edge is not in the cards.

Best of luck
#Frost I don’t know. It is oak from Denmark, Europe, so maybe it is called Brown Oak. I will look into the ripping-idea. Hopefully I will not need it if the slab behaves well the next week or so.
post #29 of 35 Old 06-04-2020, 06:46 AM
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Quote:
Originally Posted by [email protected] View Post
#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.
I don't know if I have ever had a project go exactly as I planned. I watched 3 weeks of youtube videos and made this Box joint jig these past 3 days...after work last 2. I moved the tightening Knob and adjusted the fingers 3 times. It is working great and now all I have to do is sand it up and round some hand holds. Of course add a few more options!
http://readyrangers.tzo.com/2020BoxJ...oxJointJig.htm
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post #30 of 35 Old 06-04-2020, 10:18 PM
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I completely agree with Grant’s comments and Dr. Roberts’ too.

Dr. Bob’s comments are critical to understanding how to proceed on anything in the future and why. The key point is that all wood is cut from much larger trees that grow a certain way to remain vertical despite the ground slope, the wind, gravity, and who knows what other external forces — this is commonly known as “balancing the forces.“ Once we cut the tree down and into smaller pieces, the internal forces that the tree produced to resist those external forces suddenly have nothing to work against, and that leads to the shape changes you are seeing, so in milking the wood, which includes drying it, e have to again “balance the forces.”

And next are Grant’s fine words. Provided that you cut that one long plank into the 3 pieces you need for the top & sides AND keep the grain all aligned for that “waterfall” effect you want, then the dovetails should work great for keeping the top and sides as flat as they start out when you start the cutting/joint-making. Grant is spot-on WRT to the steps and stabilization of the wood, I suggest you follow his comments, specifically because you are using the same original plank for all the pieces and this will ensure the best possible behavior because it is all the same wood.

The comments about obtaining and using a moisture meter are essential: Buy one and learn how to use it properly. Delhorst is an excellent brand, and the probe versions give the most accurate results. The basic rule is that whatever you mill off one side must be matched on the other side and SLOW is better than fast when it comes to drying — retarding the drying is helpful and this often is accomplished by sealing the ends of the planks because the end grain exchanges moisture much faster than the face grain.

This is where I deviate a bit from Grant’s comments: I would cut the dovetail pins & tails 2-3mm over-long and then trim back to size after joining, if you want a flush fit. Stickley and other warts & Crafts designers used this technique as a cost saving exercise, but it also allows the Wood to be better equalized up and until the joint is finished (the tips of the end grain will naturally be drier than the stuff more inboard).
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post #31 of 35 Old 06-05-2020, 01:55 AM Thread Starter
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#Scurvy - this is excellent. Thanks for also explaining the physics behind warping. That makes a lot of sense to me.

I have decided to go for the dovetails for the reasons you and others have written and also because the boards seem pretty stable. I think that they are properly kiln dried but that I made the mistake of quickly making a true face on the one size and then removing tons of material from the other side. Then putting it flat on my work bench for a day or two. Recipe for disaster &#x1f642;

Concerning the dovetails: visually I would prefer the pins on the top and the tails on the side (the waterfall) but since gravity pulls down I am thinking that the joint is stronger with the pins on the side and tails on the top. There is some physics behind this design that is not so obvious to me since there are no legs on the desktop. It’s wall mounted. I imagine that all the weight goes to the back panel and to the lower corner on the side pieces towards the wall - (the more weight there is being put on the top the more push there will be on the back corners of the sides).
Do you think that has implication for how to make the dovetail joints?

This forum is a great ressource. I feel that I have just taken a masterclass in wood warping. Thanks guys.
post #32 of 35 Old 06-05-2020, 09:05 AM
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I'm questioning the 8-10 percent moisture content they quoted you. For future verification I would purchase a moisture meter to verify.
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post #33 of 35 Old 06-05-2020, 11:06 AM
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I was in a house yesterday installing broadband internet and they had a nice oak table with 3" to 4" wide slats and there was still splits in the boards. I thought it looked great! I personally think those things are a good part of it. I think the mortised in keys look like a after thought and to me in my opinion are not what I would put in.

When we build stuff so tight that it can't move but split there in lies our mistake. Let it breath and let it move. I have built stuff both ways. I built a chess board with maple and walnut with a drawer in it. Then it got shifted up into the attic over time in a box. After many years up there It's in pieces now. Controlling the heat and moisture is important if you don't want something to split. Even at that it's hard to predict.
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post #34 of 35 Old 06-05-2020, 11:10 AM
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This would be far easier than dovetails .....

Just as strong but easier to make are finger joints on the ends. All the edges are at right angles and are parallel to one another which makes for easier spacing and duplication of the fingers:
https://www.popularwoodworking.com/p...r-joint-table/


This method using separate pieces glued together will not work on a slab table, but the idea is the same:



I did some further research on You Tube to see if there was an easier way to make the fingers equally spaced and possibly use power tools rather than a handsaw and chisels. I found this which I thought was pretty slick:
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Last edited by woodnthings; 06-05-2020 at 12:38 PM.
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post #35 of 35 Old 06-05-2020, 07:05 PM
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Eddie,

On re-reading my last post I don't think I was clear about the pins & tails positions. The tails should be cut into the waterfall (the vertical boards) and the pins cut into the top (tabletop). I understand that's what you wanted anyway. I'll try and explain why. Your tabletop is longer than the sides, so it has more power in its ability to cup than the waterfall ends. The dovetail tails will encapsulate the pins and limit the cupping movement.

However, if you put the tails on the tabletop, there is a possibility they could pull out from the pins. Although with today's modern PVA adhesives (and I would use Titebond II here for the longer open time), the glue joint will actually be stronger than the wood.

I would be strongly tempted to make the tails and pins equal in size, not like a London dovetail with their skinny pins and wide tails, but more like a traditional European dovetail. The reason for this is that while the London style looks pretty it's probably not strong enough here, and the pins may break.

There is more power in wood movement than you can imagine, and I've seen wood (pine) break apart welded steel frames when it's expanded. Anyway, don't get too hung up on the moisture content as that's not a big issue here. You're working with one board, its moisture content is going to be reasonably similar throughout its length and it will expand and contract across the width roughly equally everywhere.

The biggest issue is the way it's been cut, your board is flat sawn and goes very close to the centre. If you look at the rings on the end you'll see what I mean. Oak does have a tendency to split down the middle as the tension forces at the edges pull on the centre. You'll probably see small cracks appear all over the board in time, they're thin but you can see and feel them. It is part of the character of oak. You can learn to work with them and live with it, or you can fill them with resin, or you can rip the board down and joint all the edges (lose about 10% of the width and 90% of the character in the process) and glue it all back together.

Whether you leave the pins protruding slightly, in an Arts & Crafts style, or plane them flush is up to your design aesthetic. Personally, for a waterfall style end, I would flush them, maybe even round the corner over and I would definitely mitre the end 1/2 pins so you have a mitre joint on the edge.

Whatever you do finally end up doing, I'd love to see the finished project. I'm sure it will look awesome.

Take care and stay safe,

Grant.

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