Walnut table is bowing!
#39
  Re: RE: Walnut table is bowing! by MichaelMouse ([quote='Stwood_' pid...)
(01-12-2018, 07:34 AM)MichaelMouse Wrote: Years is immaterial.

Sure it is.



9-11


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#40
  Re: RE: Walnut table is bowing! by Stwood_ ([quote='MichaelMouse...)
(01-12-2018, 11:36 AM)Stwood_ Wrote: Sure it is.

MM is correct.  You can leave lumber outside for 50 years and it will only dry to a point relative to the environment. 

The advantage of very old air dried lumber is because of the slow cure, it is more equal distribution of moisture.  Which means it can be equally dry or wet, depending on the drying environment.  But if that 50 year old board is 12% you're gonna have issues with a finished piece moved into a climate controlled house.

I think the confusion may be stability vs. moisture.  They are not always the same.
Everything is a prototype so its a one of a kind.
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#41
  Re: RE: Walnut table is bowing! by rwe2156 ([quote='Stwood_' pid...)
(01-13-2018, 12:25 PM)rwe2156 Wrote: MM is correct.  You can leave lumber outside for 50 years and it will only dry to a point relative to the environment.  

Or indoors.  EMC (Equilibrium Moisture Content) is plotted against RH (Relative Humidity) and temperature both in the work first cited and https://wfs.swst.org/index.php/wfs/artic.../1560/1560  where experimental hysteresis data is compared to predicted.

Hysteresis is controlled through a stable relative humidity is museums and lumber rooms,  but a knowledgeable woodworker still builds to accommodate movement if he wants his work to last. 

Lumber in my heated basement is ~4% at the moment.  Come summer, at 50% RH, it will climb to ~10%.  So I build loose in winter, tight in summer, but never rigid, because the furniture may change locations even though Uncle Sam isn't moving ME any more.
Better to follow the leader than the pack. Less to step in.
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#42
  Re: RE: Walnut table is bowing! by petertay15 (Here are two pix: th...)
(01-08-2018, 02:44 PM)petertay15 Wrote: Here are two pix: the plan, and the top with a carpenter's level showing how it has bowed down 1/2 inch. Thanks for the replies. I will take the table apart and remake as necessary, but I don't plan to post any more on this thread.  --Peter

Do You have this general mistake?:




But must have:


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#43
  Re: RE: Walnut table is bowing! by MichaelMouse ([quote='rwe2156' pid...)
(01-13-2018, 12:25 PM)rwe2156 Wrote: MM is correct.  You can leave lumber outside for 50 years and it will only dry to a point relative to the environment. 

The advantage of very old air dried lumber is because of the slow cure, it is more equal distribution of moisture.  Which means it can be equally dry or wet, depending on the drying environment.  But if that 50 year old board is 12% you're gonna have issues with a finished piece moved into a climate controlled house.

I think the confusion may be stability vs. moisture.  They are not always the same.

(01-13-2018, 05:47 PM)MichaelMouse Wrote: Or indoors.  EMC (Equilibrium Moisture Content) is plotted against RH (Relative Humidity) and temperature both in the work first cited and https://wfs.swst.org/index.php/wfs/artic.../1560/1560  where experimental hysteresis data is compared to predicted.

Hysteresis is controlled through a stable relative humidity is museums and lumber rooms,  but a knowledgeable woodworker still builds to accommodate movement if he wants his work to last. 

Lumber in my heated basement is ~4% at the moment.  Come summer, at 50% RH, it will climb to ~10%.  So I build loose in winter, tight in summer, but never rigid, because the furniture may change locations even though Uncle Sam isn't moving ME any more.

No idea what you 2 are digging up in my post or dreaming about, but I said nothing about outside nor inside drying.

All I said was I don't trust 2 year old air dried lumber.
I've used wood, solar kiln dried it, milled it with my sawmill, logged it, or had something to do with wood since woodshop in high school.



9-11


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#44
  Re: Walnut table is bowing! by petertay15 (Last fall we built a...)
AJGST posts some arrows on wood grain asking if I made that mistake. Yes I did, and worse than that. I used some squirrelly crotch wood for the boards under the table top. When those two layers of wood were face-glued, problems were sure to develop (and did!). Anyway, the table has been salvaged. And all the discussion has been appreciated. Some important lessons were learned. -Peter
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#45
  Re: RE: Walnut table is bowing! by petertay15 (AJGST posts some arr...)
(01-14-2018, 11:28 PM)petertay15 Wrote: AJGST posts some arrows on wood grain asking if I made that mistake. Yes I did, and worse than that. I used some squirrelly crotch wood for the boards under the table top. When those two layers of wood were face-glued, problems were sure to develop (and did!). Anyway, the table has been salvaged. And all the discussion has been appreciated. Some important lessons were learned.  -Peter

Thanks for sharing this Peter. I learned something from it!
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#46
  Re: RE: Walnut table is bowing! by chriscos ([quote='petertay15' ...)
(11 hours ago)chriscos Wrote: Thanks for sharing this Peter. I learned something from it!

I feel the same way.  I appreciate the learning experience since I've been following this topic since it was posted.
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