Solid Oak Turf box

Lanshane

Hi,

Last summer we got a carpenter to build us a solid oak box for holding turf. It has an oak lid that you just lift up and is held up by a spring, as if it fell it would do damage! Anyway, we noticed last winter that the lid on the box started to warp slightly, looking like a 'U' but only very slightly. As the winter left and summer approached, the lid straightened up perfectly again. No that winter has come again we are seeing the same problem with the lid. I am a bit worried it might get damaged and am wondering is there anything I apply to the oak to prevent this from happening?? When should this be done, in Summer when the lid is flat? The carpenter put a coat or two of laquer on the wood, nothing else.
I noticed this happening to two attic doors (Red deel, varnished) also?
Is there anything that I can do as we spent a bit of money on this piece of furniture and would hate it anything happened to it? Tks a million.

Double Barrel

Lanshane,

What you or more precisely your oak turf box is experiencing is expansion and contraction of the wood. It is to be expected as weather changes throughout the year. Wood naturally expands when air is humid and contracts when air is dry.

These variables are usually allowed for by the person building the piece. Or your house may be experiencing larger than normal swings in the levels of relative humidity.

A couple of photos of the top and underside of the lid may shed some light.

Carlow52

+1 with DB.
in addition the top is going to be warmer and drier than the bottom: turf is never 100% dry so this could be adding to the problem.

If its one piece in the lid then I am not surprised.

Pics would help as it may be possible to add some cross pieces underneath when the top is flat, so as to counter the differential movement.

Same issue with red deal doors, pics would help

slowburner

+2
Chances are that the box is stored close to a fireplace.
Naturally enough, you light more fires in winter and the room may actually be dryer during this period, surprisingly.

What is probably happening is that the outside of the timber is drying and shrinking more than the interior of the box which is likely to be humid as C52 says. The extra dry side is being compressed and the humid underside is being extended.
You can see the same effect if you aim a blow dryer at a fresh leaf.

It might help to keep the box a bit further from the fire.

Another possible cause of cupping is that the growth rings of the boards in the lid might not have been arranged for stability - but this is less likely.
Sealing the wood might help. But to have any effect you need to seal it when the wood is bone dry inside and out.
Whatever finish you use you will need to completely seal the wood, even under the hinges - anywhere the wood is exposed to the air.
Even then, sealing the wood might not prevent the boards from cupping.

1chippy

An old joiner fom cork showed me a pretty nifty method to keep wide oak panels straight: you groove a dovetail shape tracks perpendicular to the grain . then machine up a narrow strip the same shape as the routed out dovetail shape. make this a snug fit, glue it and slot into track. sand it off and stops cupping. just remember to stop the grooves short of the front so you dont see the end grain.

slowburner

1chippy wrote: »

An old joiner fom cork showed me a pretty nifty method to keep wide oak panels straight: you groove a dovetail shape tracks perpendicular to the grain . then machine up a narrow strip the same shape as the routed out dovetail shape. make this a snug fit, glue it and slot into track. sand it off and stops cupping. just remember to stop the grooves short of the front so you dont see the end grain.

Will one trench do the job? I suppose it all depends on the panel's size.
Is there not a risk of the panel splitting from a cross grain situation?
Sounds like a good trick all the same.

Lanshane

Thanks for all the replies. I'll post some pics when I get home to give ye a better idea. Tks.

Lanshane

Hi all,

See pictures attached. I would just like to know what I could do to help prevent this from happening. I have also spotted a small crack which has just appeared this year so I have to do something. Could I take the lid off, dry it on both sides until the lid is completely level, seal it and add the cross pieces as mentioned in an earlier POST. What would be the best sealer to use, sanding sealer?

slowburner

I think the problem lies in the orientation of the growth rings. I have added arrows to your photo to show where the pith of the tree was in relation to the end grain.
Put simply, what this means is that all boards will cup away from the heartwood or pith of the tree - it is a bit complex to go into the details here.

When the panel was constructed, the maker should have alternated the growth rings so that as one board wants to cup upwards, it is counteracted by the tendency of the next board to cup downwards.
As far as I can see, only the first three boards in the panel have alternating growth rings - the fourth and sixth are upside down. Effectively, the panel is acting as one big board with the growth rings oriented in such a way that it is always going to cup.

I have sympathy for the maker. It looks to me as if the box is native Irish Oak. You could probably get away with not alternating the panel boards in any other timber. But Irish Oak is a demon with a mind of its own.
Chances are that the split you are seeing is a direct product of the nature of this particular wood.

What to do?
1. Go with 1chippy's suggestion when the lid is flat.

2. Just let it be.
It is a box made from Irish Oak - it will split and move and do all sorts of unpredictable things - that's what Irish Oak does. This is the box's character.

Carlow52

Some bend:)

Compounding the issues described by SB are the very wide boards used to the front.

The crack is along the glue line, not as serious as if in the grain itself.

If this was my piece I would take it off and turn it and let it straighten.
Then bring it back to the chippy who made it and have him rip the wide boards into at least 2, if not 3 and alternate the pieces before gluing back up and have some cross pieces added.

These could be added at the 2 sides to make the lid look deeper, with a smaller filler piece at front and back

As it stands the stresses in the wide boards are very strong and will be hard to tame

If u dont narrow the 3 wide boards and you try tame it the grain will split

Lanshane

Thanks again for the replies, much appreciated.

I had a good look at the piece last night and observed the following:


From the attached, as you look at the lid from the left, there are actually just 4 cut sections. The largest as pointed out by Carlow 52 is to the far left, then there are almost two of identical sizes and the far right cut is the smallest.

So I might go with the following based on the previous POSTS:

Cut the biggest piece twice and when glueing back together alternate the pieces. Apply 2 or maybe 4 cross pieces to help with support.

Unfortunately that little crack is in the grain, not the glue line but hopefully it will be fine??. The front bit is definitely too big, and this happens to be where the big bend mainly is! So, go with that?

slowburner

Ripping the boards again would reduce the dimensions of the lid by a minimum of 6-8 mm (two cuts). This might leave the lid without an overhang.
It could happen that the amount of timber lost could be even greater, if the mating edges need to be planed flat and they probably will need to be.

Personally, I wouldn't risk ripping the boards again unless you have access to matching timber to replace the amount lost.
I think I would wait until when and if the lid has gone back to its flat state and then go with the cross rails in rebates solution. Even with this solution, there is a risk of further splits and shakes due to a cross grain situation.

So, any solution to this problem has its risks - if you want to have a perfect box.
Could you live with it as box with 'character'?

Lanshane

slowburner wrote: »

Ripping the boards again would reduce the dimensions of the lid by a minimum of 6-8 mm (two cuts). This might leave the lid without an overhang.
It could happen that the amount of timber lost could be even greater, if the mating edges need to be planed flat and they probably will need to be.

Personally, I wouldn't risk ripping the boards again unless you have access to matching timber to replace the amount lost.
I think I would wait until when and if the lid has gone back to its flat state and then go with the cross rails in rebates solution. Even with this solution, there is a risk of further splits and shakes due to a cross grain situation.

So, any solution to this problem has its risks - if you want to have a perfect box.
Could you live with it as box with 'character'?

Yes of course I can and I agree with you, the character of the lid is an attraction I think. I don't mind the bend in wintertime or the small cracks that are present. I do realize that perfection will never be achieved! I am just worried about it TBH and just wanted to see if I should be doing anything to prolong the life of it. I do want the lid to last as it is a nice feature and cost a bit too!

Carlow52

it was implied in my post that the chippy would have to add in sufficient additional material to make up the required width, after all its a piece of furniture, not a dog kennel

2 final points

from the first pic of the inside of the lid I think the pieces are as shown by SB.

the lid seems propped up by the toy, not good.

Happy christmas

Lanshane

from the first pic of the inside of the lid I think the pieces are as shown by SB.

the lid seems propped up by the toy, not good.

Sorry Carlow 52 I'm not quite sure what you mean here?

Carlow52

Lanshane wrote: »

from the first pic of the inside of the lid I think the pieces are as shown by SB.

the lid seems propped up by the toy, not good.

Sorry Carlow 52 I'm not quite sure what you mean here?

5 sections not 4 , cant be certain with glare/sheen

Double Barrel

I pretty much agree with what being said by Carlow, Chippy & SB.

My tuppence ..... for what it's worth.

Unless I've misread the photos ( it would not be the first time) one side of the table top is releasing or absorbing moisture at a different rate then the other. It's my opinion that this is what you should focus on, and determine the best way to allow balanced moisture changes to both sides. The air acting on the top is much dryer than the bottom.
Remove the top from the box and put in in an unheated room, garage, barn or shed out of the elements. Hang it from a joist or rafter and let it equalise. If you lay it on a table or bench allow for air circulation all around. Watch it, when it comes back to normal or close it may need a bit of help, (apply some persuasion in the form of weight) it will more than likely spring back some. Bring it back in the house but keep it away from direct heat sources. Let it be for awhile and it will come into balance with its intended environment.
IMO the key is good air circulation / equilibrium between the interior and exterior of the box.
A long term solution may be to raise the box off the floor with feet or short legs and drill small air holes in the bottom, sides and top. Or plunge cut a circular saw through the top ( with the grain) and drill the sides. The saw cuts are the best remedy IMO as they relieve some of the tension in the boards.

Using some version of "strong backs" to hold the top flat may help, but they must be set up to allow the top to expand and contract (not an easy task, BTW).
A different approach to the strong backs would be to use cutting board cleats or ends to help restrain the boards from cupping. It is a relatively easy fix and will look pleasing when finished.
The method of joinery appears similar to a tongue-and-groove joint. However, unlike the T&G joint, the grain on both pieces runs parallel whereas the grain on both pieces runs parallel, the cleat is joining the panel at right angles.. A groove is cut along the grain of the cleat. The end of the panel, which receives the new end, has a tongue cut into the end grain. The parts are joined with wooden pegs or screws, in slotted holes so that the parts stay joined and are able to move with seasonal variations. No glue is used. The cleat and the groove should be slightly longer than the top to allow for movement.

Not a cutting board but a kitchen table, the end result is the same.

slowburner

Double Barrel wrote: »

I pretty much agree with what being said by Carlow, Chippy & SB.

My tuppence ..... for what it's worth.

A different approach to the strong backs would be to use cutting board cleats or ends to help restrain the boards from cupping. It is a relatively easy fix and will look pleasing when finished.
The method of joinery appears similar to a tongue-and-groove joint. However, unlike the T&G joint, the grain on both pieces runs parallel. A groove is cut along the grain of the cleat. The end of the panel, which receives the new end, has a tongue cut into the end grain. The parts are joined with wooden pegs or screws, in slotted holes so that the parts stay joined and are able to move with seasonal expansion. No glue is used. The cleat and the groove should be slightly longer than the top to allow for seasonal movement.

Not a cutting board but a kitchen table, the end result is the same.

Your tuppence is worth a euro (or maybe even a punt the way things are going)

The breadboard edge, brilliant idea.