Growth center, vs geographical center?

[Nate Surveyor]

Do many of you guys mess with the growth center, vs the geographical center?

Here is how I heard it:

Often the growth center and the geographical center are not the same.

The side with TIGHTER growth rings, (growth center is closer to this side) is the PULL side.

The side with LOOSER rings is the push side. Most trees have this situation.

Now, draw a LINE between the growth center, and the geographical center. This is the PULL line in the log. When milling, make the smaller dimension of the lumber parallel to this pull line. This way, the lumber can me MADE to lay flat.

IF you make the LARGER dimension parallel to this pull line, then your board will be crooked. This is good if you are making a big beam, that will have a long distance between supports. Place the ARCH Upwards, and after installing, it is straight.

I am not being very concise, and the words to assemble this concept are of my own (non miller background) selection, so I am sure others could say it better.

But, do many of you mess with this?

I have found it very useful in making flooring.

Nate

[Bibbyman]

I think I know what you're saying but it would sure be better with pictures and or diagrams.

If I'm understanding you right,  most of the logs I see with this condition has some crook or curve in it.

[Dan_Shade]

i think you mean "geometrical".

if the pith is not in the center of the log, then you'll probably have some tension wood, there are some posts in the archives where Tom has explained it pretty well.  I try to keep from having tension and compression in the same board.

[beenthere]

Nate
Maybe refer to the pith center and the geometric center for clarity and 'log' terminology.

The annual growth rings are around the pith center, and the relative differences in shrinkage is associated with the annual rings (more tangential shrinkage than radial shrinkage) and moisture content loss.
And it depends on what you are after from the log...be it maximum volume, or maximum quality in the product.
Stresses are usually thought of as tension and compression, which relate to your term of Pull and Push. There is also wood referred to as tension wood (upper side of lean in hardwoods) and compression wood (lower side of wood in softwoods). These stresses and reaction woods will have an effect on the sawn products form a log, and knowledgable sawyers can reduce some of these effects by careful planning of their sawing patterns. Usually a trade-off with time spent vs value gained.

[Nate Surveyor]

I never understood STRESS in the log, that is released as you cut it, when I had the LOGOSOL mill. I learned what I learned about this from that guy that makes brand X sawmills. He is real talkative, and from what I learned from him, I have greatly improved my wood. 1 3 minute conversation, and now I run from memory.

I love milling.

I wish a guy could really make a GOOD living with it.

The economy is essentially broken, or we could do real well with it.

Nate