Wood movement

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tibi

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Hello,

I have seen many movements in my life so far. Political movements, civil rights movements, orchestral concerto movements, etc. But I would like to talk about the most elusive of them. The wood movement. Rules for wood movement are like Colombo's wife to me. I have read about wood movement everywhere, but I have never seen a list of rules that need to be kept to take wood movement into consideration when building furniture.

From the woodworking literature and youtube videos I have found out that:

1.Everybody experienced is taking wood movement into account when building their furniture.
2. Those who don't will get into trouble sooner or later.

I am a rather organized person and I like lists. But I have never come to a book, article or blog that deals with 10 ,14,8,97, etc. rules of wood movement. The only single rule I remember is to use buttons and elongated mortices on the table tops. But any other rules are still obscure to me.

Can you please give me some more ideas for rules on wood movement? Or can you point me to such a list, if already exists?

If anybody of you is writing woodworking books, I think that book about wood movement is still missing and could be a good topic.

Thank you.
 

RobinBHM

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Understand the basics and you won’t need to remember anything else.

wood shrinkage in relation to grain direction (figures shown are examples)

4% tangential
2% radial
0.1% longitudinal

and all construction methods for furniture will be based on that.

look at a board end, if it has a smiley face as per growth rings….that board will shrink twice as much around the growth rings as perpendicular to them. That will tell you what shape the board will end up.


 

dzj

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Depends where you live also. In some places there is hardly any annual change in moisture.
American forestry service has a pdf file where you can see the geographically relevant data.
They have formulas... It depends on the species too...
 

tibi

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Understand the basics and you won’t need to remember anything else.

wood shrinkage in relation to grain direction (figures shown are examples)

4% tangential
2% radial
0.1% longitudinal

and all construction methods for furniture will be based on that.

look at a board end, if it has a smiley face as per growth rings….that board will shrink twice as much around the growth rings as perpendicular to them. That will tell you what shape the board will end up.


Thank you Robin,

The information you provided tells me to what proportion the wood will shrink and in which direction. I know that the wood will shrink across the width of the board and it may twist.

My original question was more about:

1. What needs to be done with the joinery to take this movement into account. Are there more or less preferred types of joints, e.g. for beds, desks, carcase cabinets, etc.
2. Are there any places where glue must not be applied so that the wood may move and will not break?
3. Do I need to make some allowance gaps for wood to move (e.g. inside the mortice when the stretcher wants to twist)?
4. If you glue table top boards together, do you orient them all the same way, e.g. bark sides are all aligned? Also do you orient them, so that all the boards can be planed in the same direction, so if I finish the table top with a hand plane I do not get tearout because one board goes with the grain and the board next to it against the grain.
 

Adam W.

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To spanner things a bit more for you.

Those of us who live in the 16th. century don't worry about things like that and happily build our furniture with unseasoned timber and get away with it.

It's all about selecting the best timber and using quatersawn or riven boards. In Slovakia you will have access to historic furniture built in the same way, go and have a look to see how they overcame any problems.



16th. Century Carved Joined Chest (1).jpg



 
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Jacob

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One common fundamental is that panels in frames are free floating in their slots, or just loosely pinned if in a rebate, with sufficient clearance gap to allow them to move freely , without springing the frame outwards, or without the panel shrinking and cracking.
You get the same issue in other places such as draw runners in slots - as they are across the grain they need to be loose, just pinned at one point to allow movement. Common repair mistake is to glue them in - sooner or later the sides of the carcase may split.
Allowance for movement crops up all over the place - T&G boards, breadboard ends, buttons under table tops.
Pegs holding frames together (like Adam's above) need to be close to the join line so that any movement won't open the join...etc ..etc
Must be lots examples.
PS my old drawing board has the left hand straight edge with an ebony insert with gaps to allow movement, the battens behind it are attached by screws in slots and not glued.
Tibi is right - a long list would be useful!
 
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tibi

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To spanner things a bit more for you.

Those of us who live in the 16th. century don't worry about things like that and happily build our furniture with unseasoned timber and get away with it.

It's all about selecting the best timber and using quatersawn or riven boards. In Slovakia you will have access to historic furniture built in the same way, go and have a look to see how they overcame any problems.



View attachment 123741


Thank you Adam. Very nice build and carving. I am planning to visit some museums to observe antique furniture, but we have a lockdown here, so everything is closed. Maybe in summer it will be better. We have also a lot of historical churches here, so I can also observe how the 500 year old pews were made. It is daunting to see names and years scribed by kids on the top board of a church pew , like 1687, 1742, 1933, etc, knowing that they are all gone now.
 

tibi

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One common fundamental is that panels in frames are free floating in their slots, or just loosely pinned if in a rebate, with sufficient clearance gap to allow them to move freely , without springing the frame outwards, or without the panel shrinking and cracking.
You get the same issue in other places such as draw runners in slots - as they are across the grain they need to be loose, just pinned at one point to allow movement. Common repair mistake it's to glue them in - sooner or later the sides of the carcase may split.
Allowance for movement crops up all over the place - T&G boards, breadboard ends, buttons under table tops.
Pegs holding frames together (like Adam's above) need to be close to the join line so that any movement won't open the join...etc ..etc
Must be lots examples.
Thank you Jacob,

A lot of useful information for me. Such tips should have its own book, or at least an article.
 

Jacob

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Have a look at Katz Moses’ YouTube on this. He is working with US data but the information is transferable.

He rattles on!! Couldn't watch more than 3 minutes, in which he said a lot but which didn't amount to much!
Does he say anything particularly interesting?
 

Ttrees

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Have a look at Sgian dubh's (Richard Jones) posts, can't remember much of late, so maybe a google search of this forum might be a better idea.
You should be able to find a good bit of reading.

Tom
 

Sgian Dubh

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Does he say anything particularly interesting?
Actually, he does. At the end he provides a link to a table he's extracted from that massive publication, The Wood Handbook produced by the Forest Products Laboratory in the US. Couple the information in that table to a formula he provides earlier in the video (about 10 - 12 minutes in, I think) and you get pretty decent assessments of likely wood shrinkage or expansion as moisture content changes. Put it this way, the numbers he comes up with are similar to results I achieve using my own methodology.

I suppose there are a couple of comments worth making:
  1. Interestingly, in the table he's reproduced from the Wood Handbook he's labelled the column the authors describe as radially sawn wood as Rift Sawn in red. I can't really work out why he's done that, but perhaps it's because in the video he consistently talks about rift sawn when I think he intends to say radially sawn. Perhaps it was simply a slip of the tongue - I don't know.
  2. The table predominantly lists North American wood species, which makes it less useful for those outside that geographical area. Slainte.
 

Sgian Dubh

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Have a look at Sgian dubh's (Richard Jones) posts. You should be able to find a good bit of reading.
Ha, ha, Tom. I appreciate the recommendation, but I did a search in this forum as you suggest with my handle as part of the search criteria, and even I can't find anything truly useful I've said about anything ... ever, in a forum post, let alone useful and relevant about wood movement and related topics. And if I can't I suspect tibi might struggle even more. Slainte.
 
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Ttrees

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I'd reckon some of your posts is there for the hungry Richard.;)
Might try and dig up something of yours to post up here, as I recall learning a good few snippets
of info from your writings, but as to what they were I can't remember, but likely lodged in there somewhere.
Could likely do with a refresher, so possibly doing myself a favour aswell.

All the best
Tom
 

Inspector

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Here is an online calculator that will tell you how much a given piece of wood can move. Handy to know when you are designing a piece and have to account for the seasonal moisture changes. Like the length of the screw slots when fastening a table top or the slot and tenon when making a breadboard end. The other rules become instinctive after reading some good books and learning how to build from wood. There is no one size fits all list of rules in one place that I have ever seen. All the best on your journey.

Pete
 

doctor Bob

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Ha, ha, Tom. I appreciate the recommendation, but I did a search in this forum as you suggest with my handle as part of the search criteria, and even I can't find anything truly useful I've ever said about anything ... ever in a forum post

No, never, I'm not having that, I'm sure back in 2004 you said something useful ;);) ................................ oh hang on, no your right that was someone else.




Only Joking ......................... honest.
 

Oakay

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Hello,

I have seen many movements in my life so far. Political movements, civil rights movements, orchestral concerto movements, etc. But I would like to talk about the most elusive of them. The wood movement. Rules for wood movement are like Colombo's wife to me. I have read about wood movement everywhere, but I have never seen a list of rules that need to be kept to take wood movement into consideration when building furniture.

From the woodworking literature and youtube videos I have found out that:

1.Everybody experienced is taking wood movement into account when building their furniture.
2. Those who don't will get into trouble sooner or later.

I am a rather organized person and I like lists. But I have never come to a book, article or blog that deals with 10 ,14,8,97, etc. rules of wood movement. The only single rule I remember is to use buttons and elongated mortices on the table tops. But any other rules are still obscure to me.

Can you please give me some more ideas for rules on wood movement? Or can you point me to such a list, if already exists?

If anybody of you is writing woodworking books, I think that book about wood movement is still missing and could be a good topic.

Thank you.
It is useful to know the moisture content of your timber and whether it is consistent through its thickness. Expansion and contraction is negligible in its length. A board will expand or shrink about twice as much in its width if it is plain sawn compared to quarter-sawn. If a plain sawn board shrinks through reduced moisture content evenly on both sides, the annual rings will straighten, so you can predict which way it will cup. Generally timber movement is at its greatest in the 16% to 10% range which is why it matters to us so much as a home environment is generally about 10% and an unheated out-building can range between about 16% to 10% through the seasons. If your workshop environment is about 12% and a centrally heated home environment 8% you can certainly expect some shrinkage. I like to purchase timber well in advance of using, especially in the winter, because the moisture content through the thickness is often inconsistent when purchased due to being outside or semi-outside since its kilning. Generally, for internal work allow for some shrinkage, and for external work like joinery allow for both shrinkage and expansion.
 
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Adam W.

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Thank you Adam. Very nice build and carving. I am planning to visit some museums to observe antique furniture, but we have a lockdown here, so everything is closed. Maybe in summer it will be better. We have also a lot of historical churches here, so I can also observe how the 500 year old pews were made. It is daunting to see names and years scribed by kids on the top board of a church pew , like 1687, 1742, 1933, etc, knowing that they are all gone now.
We have friends in Zvolen and visited a few years ago, lovely country and people, with some amazing timber buildings.

I'm sure you'll find all the answers to your questions just by looking at the beautiful historic furniture and buildings that you have in Slovakia.
 

niall Y

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Hi All,
The worst case I came across of, not taking to account that wood d moves, was on a new-build where I was fitting a kitchen. The customer had taken delivery of the internal doors which were completely flush and looked to be oak veneered. Closer inspection, however, showed that they were solid 2 inch oak throughout. The stiles were 4 inches wide and what would have been the bottom, middle and top rail, and panels, was a glued up piece of oak 6ft 6 wide jointed into them. They were neatly made and beautifully finished but there was absolutely no understanding of the material.Neither the site carpenter nor I could fathom how someone with all the heavy duty kit to make such a set of doors, could have made such a fundamental mistake.
Needless to say,I got a call from the customer, after he had moved into his property, asking if there was anything that could be done to stop the middle section of his doors, cracking apart - which was alarmingly loud at times.
Niall
 
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