When the middle of the tree is in board

[Andy Kev.]

I've been told that if a board straddles the middle of the tree i.e. a look at the narrow edge of the board reveals a cross section of completely circular growth rings, then you have to saw the middle out which leaves you with two narrower boards from either side. This is apparently because a board with the middle of the tree in it would have so much seasonal movement that it is effectively unusable in a piece of furniture. As a result of this advice I have cut boards accordingly. The fact that a cross sectional view showed a shallow "V" shape centred on the growth rings seemed to back the view.

However, there's one board which I've not touched as yet (it's a bit knotty) and it seems to be very stable (I've had it four months now) i.e. its shallow V seems not to have moved. Is it therefore worth experimenting with i.e. plane it flat while retaining the centre of the tree and then monitor it for subsequent movement? The reason I ask is an obvious one: if you don't actually have to get rid of the middle of such boards, you've got more of the wood you bought available for use.

Then there's the matter of the centres which I have cut out. Are they usable as e.g. potential chair legs?

 

[Jacob]

Google timber conversion images

 

[swb58]

I talked to guy with a mobile saw mill about cutting an Ash tree, he said, from his experience, that it has to be cut up the centre to avoid splitting. I don't know if that was Ash in particular or just in general.
As you've already got such a board just see how it goes.

 

[Random Orbital Bob]

You're right to be wary because wood does dry fastest from the pith outwards. This is why you see radial cracking in the ends of logs that have been left uncut. However, it's more complicated than that, particularly with kiln dried timber.

I recommend you read thoroughly some of the work published by Richard Jones (Sgian Dubh) of this parish as he is extremely well versed in the science of drying wood carefully and correctly.

I would start here

 

[Andy Kev.]

Thanks for the replies, gentlemen.

Jacob, a couple of the pics in the link you provided show a central plank cut with the middle of the tree in its centre. I take that as implying that such a piece is indeed usable. Therefore I will plane my rough sawn piece flat, keep an eye on it and report any movement which may occur.

 

[RobinBHM]

Although there are loads of drawings around showing numerous conversion configurations, I think almost all conversion nowadays is through and through. Although that means 1 board will include the heart when converting a tree, it doesnt mean that board can be used in its full width. Generally good practice is to cut around the heart. Of course the 2 boards yielded are 1/4 sawn and very stable.

 

[Corneel]

For my dining table I had bought a compete trunk of wallnut, sawed through and through. The centre was divided over two boards, so one side of these boards contained part of the centre of the tree full of cracks, the other side looked fine. I watched the boards for half a year, and they didn't cup any further. Because these were the nicest and widest boards, I decided to use them like that. Until now they behaved well.

I wouldn't do this to save money though. Often the centre of the tree is pretty bad wood. It is the remains from the young tree, while it shoot up as high as possible in the forest. Only later the rest of the trunk is formed. The centre is usually full of knots and cracks. You often find the centre in thick construction wood, but for finer work it is usually better to cut it up for fire wood.

 

[David C]

In most cases the heart is sawn out as it tends to have shakes.

There may be some exceptions?

David

 

[custard]

I wouldn't use the pithy centre in any piece of furniture. Ever.

When I first started woodworking I tried to be economical and use every possible scrap, as time went on I became reconciled to the fact that if you want to make attractive furniture then wastage will actually be much, much higher than you ever thought possible. Having a wood burning stove helps get you over that early misconception!

 

[Jacob]

On the other hand!
The thing I like about nice old but cheap furniture is the way that as much as possible gets used. As you progress from drawer fronts through to drawer bottoms, back boards, dust boards the quality of the wood and the standard of finish goes downhill rapidly. Quite nice stuff carefully done upfront to back boards with saw marks, giant knots and splits, useless for anything else.
You can see before your very eyes the thought processes which went on in the makers head and his priorities/actions under pressure; the overcut DTs, the nailed-on drawer runners etc. And you can work out what tools he was using and so on.
Posh stuff can be less interesting - the maker covers his tracks, over-finishes, and you know a lot of material was wasted.
Whether or not you could sell stuff made in the old fashioned utilitarian way is another question. Paradoxically you might need a very discerning buyer to see the virtue of it. But then what with conservation/sustainability/austerity this could be a strong selling point?

 

[Random Orbital Bob]

I've salvaged loads of gorgeous wood from old beaten up furniture that's going for a song from a charity shop or even from skips. All sorts of mahogany, walnut. It's amazing what you find in some of these pieces of "brown" furniture. The oak in the period French stuff is incredible.

 

[woodfarmer]

I kept the middle plank from a piece of horse chestnut from last xmas to make a shallow bowl. All went well until I ramped up the speed to polish it where upon it exploded. The stresses in the pith were too great, they were such that the two halves simply don't mate but have bent to comply with the shrinkage. Pity because the figuring in the pith livened up the piece. But you takes your chances.


Its going to be difficult to save

 

[Sgian Dubh]

The main reason for cutting out the pith of such boards is much as others have said. The pith, of course, is the original stem of the tree in its first few years of growth, and its structure is somewhat different to mature growth. It tends to be spongier and softer. As a result, its reaction to changes in moisture content are more extreme than the rest of the wood in the log. It shrinks and expands laterally to a greater extent than the rest of the wood. It also frequently shows much greater longitudinal shrinkage (up to twenty times greater). These characteristics largely explain why a centre board containing the pith develop more pronounced faults, e.g., longitudinal splits following the pith, shallow V shaped board profile with the point of the V centred on the pith, etc. It's not often you see pith included in furniture - most people cut it out for the reasons given. On the other hand, it's quite common to see pith in construction grade wood, e.g., nominal softwood sizes such as 4" X 4", 4" X 2", 2" X 1", etc, and also occasionally in stuff like larger sections of oak and other hardwood used in buildings, e.g., garages, houses, verandas, etc.

It's highly likely I'd cut the pith part out of you board as others have suggested, and I wouldn't contemplate using the pith section cut from a centre board for chair legs, to answer your final question. Slainte.

 

[Corneel]

Wasn't that called "juvenile wood"?

 

[Sgian Dubh]

Wasn't that called "juvenile wood"?

Yes. The pith is also called juvenile wood. Slainte.

 

[Andy Kev.]

The main reason for cutting out the pith of such boards is much as others have said. The pith, of course, is the original stem of the tree in its first few years of growth, and its structure is somewhat different to mature growth. It tends to be spongier and softer. As a result, its reaction to changes in moisture content are more extreme than the rest of the wood in the log. It shrinks and expands laterally to a greater extent than the rest of the wood. It also frequently shows much greater longitudinal shrinkage (up to twenty times greater). These characteristics largely explain why a centre board containing the pith develop more pronounced faults, e.g., longitudinal splits following the pith, shallow V shaped board profile with the point of the V centred on the pith, etc. It's not often you see pith included in furniture - most people cut it out for the reasons given. On the other hand, it's quite common to see pith in construction grade wood, e.g., nominal softwood sizes such as 4" X 4", 4" X 2", 2" X 1", etc, and also occasionally in stuff like larger sections of oak and other hardwood used in buildings, e.g., garages, houses, verandas, etc.

It's highly likely I'd cut the pith part out of you board as others have suggested, and I wouldn't contemplate using the pith section cut from a centre board for chair legs, to answer your final question. Slainte.

That seems pretty conclusive for which thanks. As I said, I've only got the one board with the heart in it (I had followed advice and cut it out of all the others). So just for experimental purposes I'll plane this remaining one, maybe try to make something simple with it and see what happens.