Strange problem

[Dale Cruea]

I am have a strange problem with a soft maple board I am trying to plane.
I started planing one side and when I was done the board had twisted about 1/16" or more.
I have had this happen with stress. Not a problem there.
I turned the board over and was going to plane some off of the other side.
I was tired so I loosed the vise and left it set for the night. Un-planed side up.
The next day the board had returned to almost as flat as when I had planed it the day before.

I turned the board back over to the side I had been planing on to flatten it a little.
As I was planing it I noticed the shims were getting loose again.
I loosened the vise and the board was bowed again.
I turned the board over again with the planed side down and left for another night.
Today the board is very flat again.

My bench is flat, I shim the board on the bottom so it will not rock.
My shop is heated and never gets below 60*.

I have used an 18" piece of this board a few weeks ago and never had a problem with that board.

Any ideas????


Thanks,
Dale

[Adam Petersen]

Are you sure it's not rubberwood.....

[Mel Fulks]

I think it's from having air on just one side . Better to leave it between two surfaces , or leaned against something so that both sides are exposed to air.

[Jim Matthews]

Not to be thick - how thick is the board?

You may be applying enough clamping force to bend it.

[Al Weber]

I suspect that the board was improperly dried in a kiln and has a lot of internal stress. I've seen this in soft maple before and it was consistent across the lot I purchased from a certain mill. If they try to dry it too quickly, the outside is okay but the interior isn't as dry and the minute you start removing portions, it begins to move. I never went back to that mill again as it was a very costly problem to me.

[Andrae Covington]

I suspect that the board was improperly dried in a kiln and has a lot of internal stress. I've seen this in soft maple before and it was consistent across the lot I purchased from a certain mill. If they try to dry it too quickly, the outside is okay but the interior isn't as dry and the minute you start removing portions, it begins to move. I never went back to that mill again as it was a very costly problem to me.

This happened to me one time, and it was maple. I had nicely squared up a narrow piece of ~6/4, I think, and set about ripping it in two. My saw started to bind almost immediately. I struggled and struggled to keep sawing, trying from both ends. Finally I resorted to a jigsaw, hence the rather wavy kerf line; but even that was tough going. As soon as I finally separated the pieces with the jigsaw, they sprung apart about 1/2". :( Wish I had a before picture of this board. It looked perfectly normal.
246423

[Dale Cruea]

The board is 4/4.
It was 8 1/2 - 9" wide and 40" long.
I ripped it down to about 3 1/2" wide and now no problems.
Very strange board.
The kerf did ope a little as I ripped it. About 1/16" or so.

[ian maybury]

The give-away is probably that it moved immediately when it was planed. Which perhaps suggests that removing some wood unbalanced a stress in the wood that had previously been balanced. Temporary moisture gradient, growth stresses, or stresses as a result of aggressive drying or maybe a temperature gradient (?) might sound like candidates - but from what's written it sounds like case hardening/drying stresses is the typical cause. Good discussion of the case hardening issue here: http://www.woodweb.com/knowledge_base/Understanding_Drying.html