Advice needed for 1st timer

[cooper]

Hi Everyone, I have just found this forum and would like to ask for some help if I may?

I have just attempted to try to wood turn, and thought it would be a good idea to "season" some wood given to me. I had a lump of English Cherry and thought great - just paint the end and leave it in the shed for a few years - job done. Or so I thought, four weeks later and the log is split radially from the centre to the bark.

What do I have to do to allow the logs (or any others) to season properly to use for wood turning later?

Thanks in advance for any help. 

[Kirk Allen]

Welcome to the forum Cooper. 
The best way is to cut the log into the thickness your looking for turning blanks.  I cut a lot of maple turning blanks that are 12/4 (3") and then stack them to dry in the barn with stickers between each layer of wood. 

Leaving it in log form will always lead to splitting and in some cases they will still rot from internal moisture. 

Depending on what your turning, you can turn it green then set it aside before the last stages of the turning and come back to it a month or two later.  I know quit a few guys that do that with bowls.  They rough out the basic design then set it aside to dry.

[Stevem]

What Kirk said and I would guess that you know not to have any pith in the turning stock.  If you have pith the blank might explode on the lathe but will always crack when drying.

Heres a web page you might like to look at from Oregon State U.

http://owic.oregonstate.edu/pubs/peg.pdf

[cooper]

Thanks guys,

As you have guessed, I don't know a great deal about wood working or wood turning. I am a toolmaker / engineer by trade so metal is my thing, but I would like to move into wood. Any help is gladly accepted!

When you say "pith" do you mean sap? How will this cause it to explode? I guess it is like a grinding wheel left to stand in coolant and then turned on - it becomes eccentric when rotated and "explodes" (very uncomfortable I can tell you!)

Sorry if my replies are a little slow in coming, I am in the UK (Portsmouth in Hampshire) and the time difference is not helping.

Cheers,

Paul

[Mr Mom]

pith is the center of the log or the heart wood of the log.
Dont worry about the time thing.

Thanks Alot Mr Mom

[Kirk Allen]

I am a toolmaker / engineer by trade so metal is my thing, but I would like to move into wood. Any help is gladly accepted!

One thing that was tough for me getting into wood working after years of metal machine work was the fact that wood moves and the tolarances I was used to with metal ment nothing with wood.  Wood is going to move and if I am off by .020 it wont hurt a thing.  Not the case with metal

[Stevem]

As wood drys there are stresses in the wood.  Wood is not homogeious the difference between the wood produced while growing fast is different than when the wood is growing slow.  Evidence of these different woods show up as the growth rings.  Generally the dark portion of the ring is slow growth wood, the lighter fast growth (not all trees are that way).  They dry at different rates.
And the wood towards the outside and ends drys first

I'm sure you've seen 1" board that cups as it drys and looks like it could be part of a wooden pipe.  That's caused by the different drying rates and the different shrinkage rates of the different woods (some people call the different wood summer and winter wood).  The bottom of the cup is always toward the outside of the tree.

As wood drys the ends and outside dry first, which causes cracks in the wood.  In essencence the outside becomes smaller than the inside and that situation is not stable.  There's hundreds of books written just on that subject and how to deal with it.

On a tree that leans the down side wood is different than the up side.  Compression wood verses tension wood.  Boards cut from leaning trees will tend to bow as they dry (and as they are sawn).

Limb wood is notorious for these kind of stresses as are burls.

The lower part of a tree (stump end) is different than the upper part of a tree.  It has had to grow and stay alive with a whole tree standing on it.   

The drying puts stress in all directions.  Over 50% of the weight of green construction wood (fir, pine, hemlock) is water. As the water leaves the wood shrinks.  (Some trees have more water weight as they do wood weight).

At the very center of a tree is the pith, another kind of wood and the weakest in the tree.  All the stresses center there and are pulling different directions. Not right, not left, not up, and not down, but all directions.   As a tree, all is in ballance, but when cut and the drying starts with the different shrinkage rates and different woods the ballance is upset.
 
If you cut wood with pith you release all the stresses and the wood will split. Great for fire wood. But add rotary motion and steel cutting tools and things could fly.   

This is long enough but I hope it helps. 
 
 

[Frank Pender - AKA "Tail Gunner"]

Not only do different woods dry at different rates, but the same wood can dry at different rates, depending on the location in the tree.