Strange planer problem...

[keith ouellette]

I face jointed some 5 and 1/2 in wide 4/4 hard maple till it was dead flat. I then ran it through the planer 3 times to flatten the other side. I then laid the piece on my jointer bed with the face jointed side down and it wasn't flat any more. one was bowed and another was crooked.
What happened?

[Gary Herrmann]

That can happen if you remove significantly more material from one side of the board than the other. Internal stresses within the board cause it to move more in one direction.

How much did you remove from each side approximately?

[Jason Beam]

What Gary said ... exposing previously hidden wood will affect the overal stability of the board and you'll likely get movement. The general method is to mill everything CLOSE (like within 1/16"), let it do what it does for a couple weeks, then take it to final dimensions. Time consuming, huh?

That's just the nature of wood. The closer to perfection we strive for, the work it takes to get there goes up exponentially. If taking the board to within 1/16" causes more movement than that extra 1/16" can correct, you may be working with some reactionary wood that might not be so good for the accuracies you're after anyway. So stock selection comes into play, here, too. If you're using straight grained, vertical growth, trunk-only wood, it shouldn't move TOO much - shouldn't being the operative word. It's not 100% trustworthy, but it's as close as most of us can get with these organic materials. Sometimes a board warps after you expose it's inner self - better to have it warp before you cut all the joinery or glue it up, i guess, huh?

[Dale Lesak]

One of the masgs did a article on something like that. They call it case hardening. If the wood is dryer to fast it causes the outside of the wood to hold the wood movement in until it is cut . they showed a test to do on how to check for it. If any one knows what book that was in help me out, I thought it was wood but not sure. Dale:confused:

[keith ouellette]

That can happen if you remove significantly more material from one side of the board than the other. Internal stresses within the board cause it to move more in one direction.

How much did you remove from each side approximately?

It was a little more than 4/4 rough lumber and I jointed and planed it down to a little more than 3/4. (about .82 on my new digital caliper). After I wrote the thread I had ripped a few pieces that were less than 3/4 thick and only 1 and 1/4 in wide.
They all bowed as I was cutting them. Now I can see why none of the s3s stock I have bought has been very flat. I am afraid to see what will happen tomorrow.

[Peter M. Spirito]

When removing a lot of material I take it off of both sides equally by flipping the board over after each pass thru the planner. Here is a link to a one piece auxilary planner table i use to eliminate snipe and to make handling long pieces a lot easier. http://www.peterspirito.com/planer.htm