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I’ve been working with wood for over 50 years, basic carpentry, fine (sorta) wood working, carving and here ship modeling, and a thought popped into my head (a rare occurrence, kind of hurts a little) when planing a piece of wood. Maybe everyone else in the world knows this except me. When working with or against the grain ( not cross grain) how does that relate to the direction the tree grows? I never thought about it before, just worked with the grain when ever possible. If I had to guess, I’d say working with the grain is working in direction towards the top of the tree. I spent a hour or so on line, reading wood working stuff, logging, wood mills, forestry, wood physical structure, tree growth and didn’t find the answer. Maybe its so obvious they knew they didn’t have to mention it. I now know about 100 different things about the grain of wood. I was a bio major in college, took several botany classes. Maybe it was that one time I cut class. I just don’t know up from down.

Kurt 🤥

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I have not looked this up, to verify, however:

up or down as a factor =  the length of the section that we work is a small percentage the whole and is not likely to matter.

Wood is essentially a bundle of tubes.  we are rarely able to work it with the plane of our surface being exactly parallel to the direction of the tubes and be bisecting an individual tube.

I am thinking that with the grain means that the direction that we are cutting hits the wall of the tube such that it is angled up in the direction of our cut.

The force of the cut wants the push the tube down.

Against the grain means that we would be hitting the open end of a tube before we hit its body an the force of the cut  would tend to peal a tube up and away from its neighbors.

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I had looked it up and couldn't find any mention of it. It will matter planing, carving and on any part of the board no matter how long it is. There are some trees, where the grain spirals, like a rope. A tree grows from its very top, adding new growth on top of older. That's why if some foreign object is stuck in it, the object will always the same height off of the ground no matter how tall the tree grows.  I would think everything would be laid out consistently throughout the tree. I guess if you marked the top end of a log before its milled, you would find out the answer. I'm sure one of our engineer buddies here would know. I never gave it a thought before but some one has to have.  Some trees are fairly consistent in width and I think there are less tubules and fibers as the trees get taller and thinner. Those areas will increase in girth with age and add more with time. It's not important but its one of those things that now I want to know now. I have to figure how to word my search, to stumble upon the answer.

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Trees grow out in concentric rings.  The tubes have to be open and continuous from root to growing tip to be able to transport water and salts up and sugar down.  Only an narrow band just under the bark can produce new tubes.  I am thinking that differences in thickness would be due to either the thickness of the wall of the tube or how much polymer fill is between the tubes.  For the to be differences in sapwood and heartwood there has to be

living cells throughout. They can fill in between the tubes, They just cannot add new tubes.  For a lot of the wood we use, the difference in diameter in the

section we have cut out is not that much.  And where it is significantly tapered, planks cut parallel to the pith,  "with the grain" would be toward the roots, no?

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Think of the tree as a long, narrow cone-shaped bundle of cone-shaped straws pointing upwards. If you planed downwards, but parallel to the straws in the cone, you'd be planning with the grain and, similarly, when you plain upwards, parallel to the straws, you'd be planning with the grain as well. It's only when the wood is milled and squared that you have what is called "grain runout" because to cut a square plank out of a cone of straws is going to cut through some of the straws. If you hit the edges of the cut straws head on when planning the side of the plank, you are "cutting against the grain."

 

Then there are trees which have their cones twisting in a spiral fashion from bottom to top, called "spiral grain," and there are those which have their straws all twisted up in various directions from bottom to top, called "interlocking grain."

 

If your plane is properly set and starts to chatter and dig in, time to plane in the opposite direction.

 

plangran.gifPlaning_wood_against_the_grain.PNG

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I think it doesn't matter which way the tree was growing as far as the grain is concerned for an individual board. If the grain in the board runs even a little diagonally you'll want to plane into the falling grain side. If you flip the board end for end you'll have problems regardless of where the boards position in the tree was.  BTW tree grow from the bark outward and only taller from the new growth on the tips of the branches.

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