9 hours ago, 4DThinker said:

An evolved adaptation to gravity. Then a little homage paid to geometry.  Circumference =Pi (3.14ish) x diameter.  Tree adds a new 1/16" ring, getting 1/8" bigger in static diameter. The circumference though grew .125 x Pi or 0.39269908169" .  Moisture intake has the same ratio effect, swelling a tree 3+ more times in circumference than diameter.  So face cut boards expand/contract up to 3 times more than boards cut radially through the growth rings.  Seen it happen many times as seasons changed during a semester of furniture design classes.   

 

That really helped me to understand some of the why of it.  Thanks 4D.

 

 

I have a desk made of quartersawn White Oak and wrapped with 1.5" edging.  Sealed it all top and bottom and all edges.  It has not been a problem but is in a controlled environment. 

15 hours ago, DAB said:

wood is kind of like us:  we don't get taller, but we might get fatter or skinnier as time goes by.

yeah, I forgot about that analogy.  You also get a little wider but more front to back.  

11 hours ago, 4DThinker said:

An evolved adaptation to gravity. Then a little homage paid to geometry.  Circumference =Pi (3.14ish) x diameter.  Tree adds a new 1/16" ring, getting 1/8" bigger in static diameter. The circumference though grew .125 x Pi or 0.39269908169" .  Moisture intake has the same ratio effect, swelling a tree 3+ more times in circumference than diameter.  So face cut boards expand/contract up to 3 times more than boards cut radially through the growth rings.  Seen it happen many times as seasons changed during a semester of furniture design classes.   

Um, not sure that's right.  If I decrease the diameter 10%, then I also decrease the circumference 10%.  If I put something on a lathe and reduce the diameter 10%, it doesn't blow apart the piece.

 

The reason why wood cracks in a log is because the tangential (circumference) is shrinking twice as fast as the radial (diameter).

Edited March 21, 20242 yr by kmealy

36 minutes ago, kmealy said:

Um, not sure that's right.  If I decrease the diameter 10%, then I also decrease the circumference 10%.  

True,  10" diameter log has a 31.4" circumference. 10% off the diameter leaves 9", and  leaves you a 28.26" (3.14" smaller) circumference which is 90% of 31.4"  So same percentage, but different dimensions thanks to Pi.  Too bad wood isn't a normal part of most human diets, otherwise we could have our Pi and eat it too!

Too bad. It looks like he put a lot of work into it. The only way you can make that type of design work is using veneers. 
Paul

2 hours ago, 4DThinker said:

True,  10" diameter log has a 31.4" circumference. 10% off the diameter leaves 9", and  leaves you a 28.26" (3.14" smaller) circumference which is 90% of 31.4"  So same percentage, but different dimensions thanks to Pi.  Too bad wood isn't a normal part of most human diets, otherwise we could have our Pi and eat it too!

Reminds me of a Justin Wilson joke. Son comes home from LSU and father asks what he learned. Son says "pie r square" . Father says " that is not true pie r round , cornbread r square" paraphrase.

21 hours ago, 4DThinker said:

Too bad wood isn't a normal part of most human diets, otherwise we could have our Pi and eat it too!

 

Almost impossible to avoid it!

 

https://www.prevention.com/food-nutrition/healthy-eating/a20457107/31-foods-that-contain-sawdust/

 

And now that I've had my breakfast of Cheerio's sawdust, time for me to get on with the day

This morning's post online, "What happened to my farm table top?"    
"Did you have breadboard ends?"
"Yes, glued and pocket hole screwed.  I got the wood from Home Depot and thought it was dry."

'nough said

\

Today's example.  Very bad choice of wood for this application.  In one of the vintage FWW, I just re-read an article by R. Bruce Hoadley on wood movement, complete with a lot of technical information and data.

 

Edited January 10, 20251 yr by kmealy