Replies

1. 
   SteveSchoene | Oct 05, 2009 05:51am | #1

   Were are you buying your maple, and what do you do to aclimatize it to your shop before machining it.  When the kerf closes like that it often points to "case hardening" which is the result of improper drying which leaves stresses in the wood.  That could also lead to warping, but so could other things, such as wood that is undergoing a change in moisture content--getting wetter, or drier. 

2. 
   DHAM | Oct 05, 2009 03:43pm | #2

   Some logs develop natural stress as they grow.  Then when you cut these logs into lumber, some of the stress is released, but it all may not be.  When you rip the boards, more stress is released.

   On some logs that I have sawn on my sawmill, the boards will rise up off the log as you move the sawhead through the log so that when you reach the end of the cut, the end that was first sawn is sticking up in the air by 4' to 6" and sometimes more.  This lumber hardly ever dries flat.  There are techniques to minimize this stress in the boards by how you turn and saw the log, but sometimes nature put the stress there,and you can do nothing about it.

   Also, as been pointed out, kiln drying with too fast a schedule can cause the outer shell to dry much faster than the inner core, setting up drying stress that is released when you rip the boards.

   
   

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   Edited 10/5/2009 5:37 pm ET by DHAM

1. 
   forestgirl | Oct 05, 2009 07:53pm | #3

   Good point, dham.  This "Tree Dictionary" page has some great pictures of compression  and reaction wood.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

2. 
   zolton | Oct 05, 2009 09:44pm | #4

   DHAM,

   You've got it right. A cello bowmaker told me a long time ago that whenever you cut a piece of wood you release some stresses and set up others. That's one major reason why wood warps after it's cut...

   Zolton

    If you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

3. 
   oldusty | Oct 05, 2009 10:18pm | #5

     If you bring this Maple home and rip it right away and it reacts the way you describe it is not stable when you buy it , now if it sits in your shop for some time before you use it all bets are off.

       Ask the lumber yard how it is dried and if they have a moisture meter to check for themselves ?

      Often times material is KD to 6-9% then may get shipped in a rail car to a more humid local and the RH factor will change and the MC% will change and the wood may move more .The lumber yard storage area may be moist or hot and dry.

         Do other hardwoods react the same in your shop ?

         It Could  just be this particular run of Maple ?

                  regards         dusty