Drawer-Leaf Table Problem - Top Cupping!

[OPJ]

Hi all,

I recently completed a drawer-leaf table for someone in solid English oak, stained to their requirements:

In case you don't know how it works, the two extension leaves slide out from underneath the main top, which is not fixed down to the frame in anyway, so that it can lift and tilt slightly to allow clearance for the leaves.

It has only been in its new home a few days but, already, the top has cupped to the point at which it now sits about 5mm proud of the outer leaves when extended. :?

Here's a shot of the underside of the top:

You can see that I've added strips of self-adhesive felt to prevent scratching and a few 'wide battens' to at least hold the centre flat, with slotted screw holes. Trouble is, I couldn't make these any longer as they'd either foul the frame or the outer leaves. Those end pieces 'locate' over the frame below (as I said before, no solid fixing here).

This next shot shows the under frame:

I'm wondering if there's anything that can be done now to reverse the effects of the top cupping? I've been off Googling for some time but I can't see to find anything on this.

Yes, using quarter-sawn boards probably would have helped. In the beginning, I did have just enough rift- and quarter-sawn oak to make the top but, when I came to plane them up, they were anything but straight! So, I went back to the timber yard and bought some through-sawn boards (they didn't have enough of the other boards to finish).

Moisture content was 13-14% when I bought the oak and, after a few weeks indoors, I got this down to less than 12% in average, which I thought was okay - I know, 10% is regarded as better but, I wanted to get the job done sooner. :roll: After I bought the finished job indoors, I did notice some movement but, it wasn't as severe as 5mm and it did seem to settle down after a week or so. The boards I used finished about 143mm wide. I didn't fancy using narrower boards as it might look "manufactured".

Please, don't mention veneered MDF!! Breadboard ends/end caps wouldn't have worked, I felt, because the extending leaves are only 250mm wide each.

I'm quietly confident that the same will happen here. Chances are that the recipient's home has a different humidity to our and that the oak will settle back down again if given a little time.

Anyone care to add to this? I know that xy mosian has a table like this but, I couldn't see any method to keeping the top flat on his design. Any thoughts would be greatly appreciated.

Thanks for looking,

Olly.

 

[9fingers]

Nice looking table Olly!

I'm no expert, but I wonder if the battens are slowing down the drying process from the underside surface when compared to the top surface.

I expect the table was made without the benefits (!) of heating and in the owners home the heating is likely to have been switched on in the last month.

Hopefully it will settle down with time but still might have some seasonal variations.

Bob

 

[Imperial]

I sorry to say you'll probably have to end up remaking it and buy drier timber to start with. Had similar problem, which just cupped and shrunk more :roll: Tylerhardwoods kiln to 8% then let it come back up to 10 to twelve in the barn, the oak I've had from them has stayed very flat.

I'd make new and use the wood on another project.

 

[Racers]

Hi, OPJ

Did you apply the finish to both sides equally?
I fished a couple of lab stools out of the skip after a wet weekend and the tops (finished on one side) had warped so badly they had pulled the screws out. but after a week in in the office they had settled back down.

I would be inclined to leave it for a month and see what happens, then if it is still warped rip it down the joints and remake the top.


Pete

 

[Sgian Dubh]

Hi all,

I recently completed a drawer-leaf table for someone in solid English oak, stained to their requirements:

It has only been in its new home a few days but, already, the top has cupped to the point at which it now sits about 5mm proud of the outer leaves when extended.

I'm wondering if there's anything that can be done now to reverse the effects of the top cupping? I've been off Googling for some time but I can't see to find anything on this. Olly.

You may have less of a problem than you think. Yes, the wood might have been better if was dryer when you made the piece, and it's also true that you'd have been safer using quarter sawn wood and, lastly, this is a job where veneered boards are a safer choice. However, what you've got through stacking one board one on top of the other is an unbalanced moisture gradient in the large leaf.

The top surface is experiencing a drying cycle due to the fact that heating is (almost certainly) being used in the house. This is reducing the average RH in the air, and RH will continue to reduce from now until about the end of February. The top surface is drying out whilst the underside of the leaf isn't, or at least not at the rate the top surface is. The dryer top surface is pulling the top surface into a concavity.

What I suggest you do is remove the top from the table and lean it against a wall in the customer's house for a few days or a week so that both surfaces are able to dry to the same moisture content, and any moisture gradient in the wood is balanced across the thickness. If the leaf is going to uncup, it will given these conditions. If it doesn't uncup after a week or two of this treatment, then you'll have to decide what to do next, eg, saw kerfs and flatten or, perhaps, make a new top with better suited materials; but you've not reached that stage yet, so there's no need at this point to run around like you're a helicopter with a blade missing. Slainte.

 

[xy mosian]

Olly, sorry to hear of your cupped table top.

Sadly mine has a veneered ply top. Shame as it needs re-polishing and I cannot decide whether to repair the veneer or re-make the top.

xy

 

[OPJ]

Thanks to everyone for the replies.

Richard, I understand what you are saying but, I don't know how suitable it would be for the client to remove the top and leave it to one side for a few days... Do you think placing it in 'in stick' (1in. sticks) on top of the frame would have a similar effect?

It weighs a considerable amount so, it's unlikely to go sliding off during a meal!

 

[jasonB]

You could just ask then to leave in in the extended position for a week this would allow air all round.

Jason

 

[Mr Ed]

I feel for you there Olly - if this was in your own house you'd just leave it a few weeks and see what happens, but a different game with paying customers.

I think I'd be tempted to ask them to leave it in the open position for a few weeks and see if it goes back. The other option is to take the cupped bit off and lay it a flat surface face down (cupped side down) to see if it returns. I did this with an oak panel of smaller dimensions in my cloakroom and it went back over a couple of days and has stayed flat since, that said it was a lot smaller.

Only you know how tolerant your customer will be of pratting about with different remedies before you have to agree to remake it.

Best of luck

Ed

 

[big soft moose]

I feel for you there Olly - if this was in your own house you'd just leave it a few weeks and see what happens, but a different game with paying customers.

I think I'd be tempted to ask them to leave it in the open position for a few weeks and see if it goes back. The other option is to take the cupped bit off and lay it a flat surface face down (cupped side down) to see if it returns. I did this with an oak panel of smaller dimensions in my cloakroom and it went back over a couple of days and has stayed flat since, that said it was a lot smaller.

Only you know how tolerant your customer will be of pratting about with different remedies before you have to agree to remake it.

Best of luck

Ed

The customer concerned is my mother so i think I can talk her into tolerating a certain ammount of olly "pratting about" before she demands a rebuild.

(the obvious downside being that it 'll be me that gets the flak in the meantime rather than him)

her principle concern at the moment is that she wants a table (cupped or not) for the run up to xmas - so i doubt she'll want to remove the top but would probably be happy to leave it extended in the short term

The other point needing urgent attention is that she currently has the top weighed down with books to correct the cup - will that be helping the situation or making it worse ?

Lastly I would mention in ollys defence that as my sister suffers from M.E and subsequently feels very cold very easily my mums house quite a lot warmer than average with both the gas CH on and a log burner in frequent use.

 

[JonnyD]

The underside does look a little more unfinished than the top but that might just be the pictures. In my experience not finishing the underside the same as the top can cause problems as Pete suggested Even stable MDF can cup if unevenly finished each side. Cant give you any more advice other than whats already been suggested.

I personally as a furniture maker wont take on any extending table commisions unless the tops are veneered either using commercial or shop made bandsawn veneers as the potential for things to go wrong outweigh the profit margins. I assume a bespoke table like this will be in the region of 1-1.5k and if it needs remaking all the profit from the job is gone.

Cheers

Jon

 

[Sgian Dubh]

she currently has the top weighed down with books to correct the cup - will that be helping the situation or making it worse ?

Lastly I would mention in ollys defence that as my sister suffers from M.E and subsequently feels very cold very easily my mums house quite a lot warmer than average with both the gas CH on and a log burner in frequent use.

The books aren't doing anything useful. You need to get a balanced moisture gradient from both outside faces to the centre of the panel, eg, 8% on both faces dropping to 6% MC at the core giving an average MC of about 7%. You can only do that by exposing both sides of the panel to the same RH, whether that is high or low. You can extend the leaves to do it as others have suggested, or you can take the top off and lean it up against a wall, or sticker it up.

It's quite possible the RH in the house is very low because you describe central heating and supplementary heating in use. That could equal a wood MC of as little as 5% to 6% MC on the top face if the average RH is down at about 25% or 30%, and the shielded bottom face might still be up at 8% or 10% MC-- that condition will cause quite a concavity on the upper face.

Only when you've let the panel develop a balanced moisture gradient as described above will you be able to decide what to do. With luck the panel will uncup to an acceptable flatness. If you're unlucky it may have taken on a permanent set and will stay cupped. As things are right now you don't know, so you have to find out. Slainte.

 

[big soft moose]

Okay - ive spoken to the great grey maternal one and she is going to remove the books and exctend the table and then we'll reevaluate in a week or so - hopefully it will settle down.

Without discussing the exact price as thats a private matter between olly and the client (if he wants to disclose it thats fine by us , but its not my place to do so) I will say that as olly was a lot more reasonable than the 1.5k suggested above if a remake is necessary we will try and reach an equitable compromise so we dont kill the profit margin entirely.