Releasing the Tension

[Brad Wood]

Hi,

So, I posted last night about a walnut slab I got yesterday. I spent a fair amount of time with the Sawyer (is that the right term?), going through his massive pile of walnut slabs, looking for the right piece that would yield my final stock needs, etc.

We also talked about how the wood would react once cut, bowing, etc.

My question to you all is this... once I make the initial cuts, should I expect to see that tension released right away, or is this something that will take a week or so to develop?

My plan is to cut to well oversized dimensions, mill it a little, let it sit for a week, then to final milling to size... I've already made the initial cuts to the rough dimensions and I was sort of expecting to see the wood move right away but it didn't.

I would appreciate you thoughts and wisdom.

thanks

[Myk Rian]

If you cut a piece off the slab, and you don't get a bowl right away, that's a good sign. Let it sit and see what happens. It can take a day or so.

[John Thompson]

Depends... if high tension it will bow rigth off the back of the BS blade after being severed. As Myk mentioned.. that didn't happen and a good sign but.. some bow could occur so let it sit for a few days..

Good luck...

[Tom Veatch]

...My question to you all is this... once I make the initial cuts, should I expect to see that tension released right away, or is this something that will take a week or so to develop?...

Yes, and Yes.

If the internal stresses in the wood have a component perpendicular to the cut line, those stresses will be released immediately upon making the cut. The remaining stress will then be unbalanced and the wood will move in a direction to rebalance the stress. So you can get immediate movement when you make the cut.

If the moisture content of the wood isn't the same throughout the piece or is not in equilibrium with the environment where the wood is stored, the newly cut surface will absorb or evaporate moisture until the moisture content reaches equilibrium. That change in moisture content will cause the wood to shrink or expand unevenly and change the internal stresses so that they are no longer balanced. The wood will move to re-balance those stresses. So you can get movement over time as the moisture content of the wood adjusts to the environment.

[Cliff Rohrabacher]

If you cut a piece off the slab, and you don't get a bowl right away, that's a good sign. Let it sit and see what happens. It can take a day or so.

Don't forget to cover it. Moisture can settle on one side and warp your wood.

[Phil Thien]

Movement that occurs right away is tension release. Movement that occurs over a day or two is probably a moisture imbalance.

[Brad Wood]

thanks guys. as of this morning everything is still perfectly straight, so it looks like I got past the tension issue. I guess I'll see how the moisture balancing goes over the next week.

[David DeCristoforo]

You might want to consider clamping the pieces back together but with a few small spacer blocks between them This will hold them straight but allow air to circulate. After a week or so, remove the clamps and if the pieces remain straight, you should be good to go. There is no guarantee that they will but the fact that your wood did not distort when it was cut is a good indicator. They could still do so, however so you want to do everything you can to minimize the possibility. Such is the nature of wood and one of the things we "love most" about it...NOT!