Re: Oak breakfast bar/dining table warping


wrote:

The table is (I think) 3 solid oak planks joined together. The only fixing at the 'big end' is a vertical pole under the middle So I can't see anything pulling against anything. I think it is just the effect where the upper side of the wood dries more than the underside and the whole thing bends. The same would happen if it wasn't attached to anything. At least that is what happens to our cork bath mat which is rather an extreme example :-)
If you leave a plank in the sun so the upper side is dried but the lower side is cooler and a little damp then the plank bows up at the edges. I think this is what is happening (but much more gently) here.
I was hoping I could reverse the shrinkage in the upper surface and slowly bring the wood back to true.
Are there accepted ways to add moisture (or oil) to wood to encourage it to expand?
Cheers Dave R
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On Wed, 6 Aug 2003 20:55:14 +0100, "David W.E. Roberts"

So this is literally just the three boards? Presumably they're biscuited together ?
It sounds like a lousy design, because of the warping problem. Depending on how you stack the three planks (whether you put them all the same way round, or alternate them), you can control some of this warping, or at least switch it between one big C curve, or a snake-like wiggle.
The boards are too wide. They should be narrower, even if this needs more of them. Three boards is too few for something the size of a table. My workbench top is 2" oak and that's ripped down to 3" & 4" wide strips to keep it flat, even though I got the timber in as 12" boards.
Much though depends on the tree's size (which is hard to guess for oak - they come in all sizes). If this was a big tree, then the boards would be a lot more stable than something small with highly curved rings.
I'm not keen on this sort of thickness for a tabletop. It's too thick to hold it flat by fastening it to a frame, and it's too thin to stay stable on its own. I'd think some warping is inevitable, but it ought to be controllable to reasonable limits. If you're going to do this sort of simplistic rustic style though, you need to use quartersawn timber - use radially cut boards, so that their movement is simply shrinkage, not curvature.
A table like this should also have breadboard ends, to give some control against movement.
To fix it, I think you've got no hope with trying to soak it, not much chance trying to nail it down to a new subframe, and the only option is awkward. If I had to do this, I'd saw each board in half, flip half of them over, join them back together and then thickness the lot flat again. A lot of work !
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wrote:

Ooops! My bad!
After reading this I went and had a proper look at the wood. I had assumed three planks because of the colour differences, but in fact it is made up of 120mm (just under 5") strips. The rings aren't highly curved, and some strips have been reversed so the rings curve down not up. The whole thing has bread board edges (in fact we also have two bread boards made by the kitchen company from the offcuts).
The problem area is the round(ish) end where the wood does not run the full length - this is effectively a 40" wide run of wood trimmed down to 28" on the shaft of the 'P' with the head of the 'P' angled off to make an octagon (or al least 6 segments of one - if you cut the other two the end would fall off!).
The overhanging bit has 3 faces of the octagon, and is not stabilised by running the full length of the table. On this piece the rings curve upwards and are not balanced by a downward curve - this is probably the source of the problem :-(
Because of the bread board edges even chopping a strip out and reversing it would still give a wierd effect because it would be undercut where the wood was reversed.
Guess we will just have to live with it.
Thanks Dave R
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wrote:

The whole thing is oiled but we have been neglectful in oiling to top, which may explain why it is drying out and bending.
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Andy Dingley wrote:

*-"Nail it to a new subframe"-* ? Goodness gracious.
If you can plane it back that might be an answer, I suppose, but it may be too warped for that, I don't know, not having seen it.
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Oh, ye of little faith!
I have been covering the top of the table where the warp is with damp teatowels for about a week now, and the table has slowly straightened out.
Picture (as requested) will appear eventually.
I guess I should now scrape the surface to remove old oil and other crap, and seal it with plenty of teak oil to stop it drying out again.
Amazing how it just flattened out over time.
The art of Bonsai with dead things?
Cheers Dave R
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<snip>

How will resurfacing help? I would have a table thinner on one side. It could still warp further. It could also 'unwarp' back to the original state. I have demonstrated that the warping is not a one way thing, so it is apparent that the table would not be stabilised when warped and resurfaced. Either way I would also have to recut the 'bread board' edges which would then look unbalanced because of the different thicknesses.
I will try to reduce moisture loss from the upper surface by treating it with oil.
Bearing in mind that it took 4 years to warp and one week to return to normal using damp tea towels I think this is a sustainable strategy.
Andy Dingley said previously "To fix it, I think you've got no hope with trying to soak it" (not picking on you Andy, just pointing out that opinions vary) but in fact keeping the top damp did the trick.
So I think that 'moisturising' may be the third way :-) So I think that any talk of recutting, resurfacing etc. is probably a little extreme.
Besides which, it would be a b*gger of a job removing the table from its fixings and then refitting.
Cheers Dave R
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