The Wood Magazine that arrived yesterday has a good article on wood movement.  Prior to getting it, the guys at the furniture bank and I were discussing wood movement problems.   I've seen a lot in imported furniture that had no understanding or allowance for wood movement.

The article says: 

1. Wood moves

2. Wood never stops moving

3. Attempts to constrain wood movement will cause problems.

Everything we need to know in three lines.

I've always used one line:
You cannot stop wood movement but you must accommodate it.

I remember reading in Sam Maloof's book an account of him going down to central America to build some stuff with the locals, using locally sourced lumber.  really nice work when he got done.  and some rich guy insisted that Sam ship a piece back to him in NY City.  ok.  well, the piece arrives, looks great, and in a matter of days, cracks appear and the piece is ruined.

 

lesson:  the wood was fine as long as it was in the native humid, and hot environment, but as soon as you put it in the dry AC of a NY City office, the wood had to lose some moisture, and move, and it fell apart.

 

wood moves in response to moisture changes.

I was reading an article about breadboard ends.  The author said to make three dowel holes - a round one in the middle and elongated ones closer to the ends.  It included a thorough explanation of proper gluing to allow for the movement.

4 hours ago, JimM said:

I was reading an article about breadboard ends.  The author said to make three dowel holes - a round one in the middle and elongated ones closer to the ends.  It included a thorough explanation of proper gluing to allow for the movement.

I have had people complain to me that there is an offset along the edge where the field meets the breadboard end.  I have to explain wood movement to them and the alternative.

My nephew spent a few years in Okinawa as a Marine a few years ago.   He visited some of the Asian furniture factories around the continent and said they were steamy hot and predicted the wood would not be very dry either.

While working on the piano this morning, I noticed two things they did to accommodate wood movement, all right in the front under the keyboard.   Across the piece is a series of pieces with a gap between them.   This allows each piece to move.   Secondly, though it's hard to see in this photo, there is about an 8" wide, 2" thick piece right across the front.  Since it is at a right angle to the edge pieces, there are two thru kerfs cut in a few inches.

14 hours ago, kmealy said:

Secondly, though it's hard to see in this photo, there is about an 8" wide, 2" thick piece right across the front.  Since it is at a right angle to the edge pieces, there are two thru kerfs cut in a few inches.

 

 

- you are right, I cannot tell in the pic what you were referring to.  What is a "thru kerf"?

 A couple of years back, I read an article that described pressure treating wood with epoxy to eliminate movement. I've seen this principal used here with woodworkers using pressure pots. 

So does it move when used with epoxy Under pressure?

7 minutes ago, Ron Altier said:

 A couple of years back, I read an article that described pressure treating wood with epoxy to eliminate movement. I've seen this principal used here with woodworkers using pressure pots. 

So does it move when used with epoxy Under pressure?

I am not positive of this but here goes. Wood that is stabilized is treated in a pressure pot with a epoxy compound (simplified for disguise of my ignorance of terms). When the epoxy hardens then there is no fibers for moisture to get in and therefore no seasonal movement ; or at least it is greatly reduced.  All this IMHO because even metal and stone move with heat and cold.

19 hours ago, Gerald said:

I am not positive of this but here goes. Wood that is stabilized is treated in a pressure pot with a epoxy compound (simplified for disguise of my ignorance of terms). When the epoxy hardens then there is no fibers for moisture to get in and therefore no seasonal movement ; or at least it is greatly reduced.  All this IMHO because even metal and stone move with heat and cold.

Thanks Gerald, I thought thats how it had to be, but I am wrong a lot too.

On 7/3/2021 at 10:12 AM, Cal said:

 

 

- you are right, I cannot tell in the pic what you were referring to.  What is a "thru kerf"?

This was the area under the keyboard.  It's about 1.5" thick and 6" wide and at a right angle to the side pieces that are grain going in the perpendicular direction (and thus won't move in that direction).  The cuts go all the way through the piece.  And the piece is quarter-sawn, having about 1/2 as much movement as it would if it was plain-sawn.  Wood movement is generally about twice as much tangentially (around the tree) as radially (from the center out).   It varies by species, but that's a general guideline. 

Thanks for the pic & explanation Keith.