Wood Movement

[thelittleboxshop]

The other day I posted a thread regarding wood movement. Some folks have their own philosophy on the subject and believe it to be correct. That is fine. Some even think that the larger the board, the more it will move. Size has absolutely nothing to do with wood movement. Yes, a large board is going to soak up more moisture than a small board BUT only because there is more wood to absorb moister. When you test the moister of a large board compared to a small board of the same species you will find that they contain the SAME percentage of moisture relative to their surface area. In other words, the smaller project will have the same moisture content as the larger board relative to its' size.

You can test this yourself by taking an 8' board and cut two feet off it. You now have two boards, one that is 6' long and another that is 2' long. Set them in the same environment and they will soak up the same amount of moisture relative to their size. The longer board will have more moisture only because it has more surface area. The two boards will have the same moisture level relative to their size however. What this means is that both boards have the same chance of movement because the moisture level in each is the same relative to their size.

Since I did not back up my asertions the other day, I humbly present the following attachment for your consideration. Through some math, calculate shrinkage, look at moisture movement beteween species. Thought it might be a helpful contribution.

http://www.thelittleboxshop.com/wood%20movement.htm

[DocWheeler]

Rollie,

That is a good link.
I think that what most people were saying the other day was that you were correct but the size of the glued figure was so small and thin that it would probably survive the small amount of movement that would occur in that small area. As I said earlier, I should have stated why I was going against known procedures.

I imagine that with your specialty, small boxes, that you have had joint failures that make you keenly aware of the problems involved.

Thanks for the link!

[liquidguitars]

ERROR #3
If you attach a solid-wood tabletop to a table base so that the top can’t expand and contract freely as relative humidity changes, the table will fail. The tabletop can expand enough in high humidity to blow apart the leg-to-apron joinery, or contract sufficiently in low humidity to crack down the middle. This principle also applies to frame-and-panel doors; a solid-wood panel must be allowed to float freely within the frame. Do not add glue to the joints.


Do not add glue to the joints.

I think it should read do not glue the "panals" as the joints will need glueing.. :rolleyes:

LG

[thelittleboxshop]

Your right LG...the frame joints need gluing but not the panel. Thank you!