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socceronly
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# Posted: 5 May 2021 10:50pm - Edited by: socceronly
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I saw some steel table legs for a DIY project.
The holes were elongated, in their words, to allow for wood to expand/contract.
The holes were perpendicular to the length of the table.
It seems counter to what I would have thought.
Does wood expand one way more than another wrt to the grain?
Made me wonder about leaving gaps in sheathing
Or was it just hokey pokey.
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Brettny
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# Posted: 6 May 2021 05:28am
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Wood for furniture shouldn't move much. I wouldnt make oval holes for it either.
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ICC
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# Posted: 6 May 2021 10:12am
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Wood does expand more across the grain than lengthwise. In furniture making, when using solid wood, expansion and shrinking are allowed for. Or at least should be. This is most apparent when building dining size tables and using solid lumber for the table top.
For example, a properly made solid wood table has the legs attached to an apron under the tabletop. That apron is attached to the tabletop using hardware or techniques that allow for the tabletop to change size with humidity and do that without buckling or opening splits.
There are different types of hardware and techniques where one uses wood blocks with tongues that fit into slots.
Here's an article on that
Not all of the methods shown allow for movement and would be okay for small tables.
As for the slots in the legs mentioned, perhaps the design is a little faulty if the slots are oriented in the grain length direction. Sometimes good ideas get messed up between conception and execution.
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ICC
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# Posted: 6 May 2021 10:17am - Edited by: ICC
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If the tabletop is a composite there is usually no movement or so little that it is not a factor.
Sheathing is supposed to be spaced for expansion as well. Materials like OSB can move equal amounts in all directions. T&G floor sheathing is designed to self space.
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toyota_mdt_tech
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# Posted: 7 May 2021 08:30am
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Quoting: socceronly Does wood expand one way more than another wrt to the grain?
Yes, absolutely. A log will shrink in diameter quite a bit but hardly any in length.
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gcrank1
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# Posted: 7 May 2021 09:33am
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Just look at deck boards, or what was green wood lumber siding.
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Aklogcabin
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# Posted: 8 May 2021 11:57am
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Wood moves. The holes are perpendicular to the top because wood expands through its width and very little in length. How much it expands depends on the climate. In a high humidity area like southeast America, Mississippi n such I would expect a 3' wide by 3/4" thick red oak table top to move as much as 3/8" wider in summer than winter. In AK not so much.
The woodworker who built that did it correctly. There are several techniques woodworkers imploy to control wood movement.
I would try to keep the wood i used to build furniture with in the shop for minimum 4 weeks to acclimated it to the shops relative humidity.
You can notice shrinkage on end joints when folks don't let wood used for flooring or ceilings and there's gaps on the end. I always stored wood used for those uses in this house unwrapped for minimum of 2 weeks prior to installation so it stabilizes with its environment.
A good wood worker has to understand wood movement n each wood is different. I was blessed to learn some old school ways from an old Swedish woodworker.
And even more blessed to be able to be a woodworker for part of my life.
Kinda long but I really enjoy wood.
Now go make something with a kid or someone from wood. There's been some metal peices showing up here lately that look really cool !
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socceronly
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# Posted: 8 May 2021 05:25pm
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Excellent article ICC, thank you.
Great information everyone, thanks.
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