Hi all.
I’m building a table top out of ash. Roughly 36” X 22” X 1” including breadboard ends. I picked the boards in my wood shed (unheated, currently -20 degrees outside) to bring them in my shop (”isolated” and electrical ”heating”) for dimensioning.
Now that they are milled thicker and larger than needed, should I let them acclimate (sticker for some time) to the shop environnement or the house environnement (wood stove, a lot warmer and definately dryer) before gluing up and machining?
Thank you.
Fred
Replies
They need to acclimate to your shop environment or the boards will be changing in dimension and possibly warping as you work on them, which will make it very hard to do good work.
If you design and build the piece properly it shouldn't have any trouble later readjusting to the conditions in your home or seasonal changes.
John W.
It is always best, but not always possible, to acclimate wood to the environment in which it will ultimately reside. Coming from outside and into your shop, I would allow at least two weeks of being stacked and stickered.
Once acclimated to your shop, then just build the panel allowing for the expected wood movement. The only place that will be a problem is the breadboard end. If the final spot is going to be drier, then allow for the panel to shrink across it's width when it goes into a drier location. Of course, during the season when the air is more humid, the panel will want to expand and the breadboard end has to be constructed and attached to allow for the movement.
You can go to: http://www.woodbin.com and click on the "Shrinkulator". It's a calculator you can use to determine the amount of movement in wood as it dries or gets wetter. Input the species, change in relative humidity and initial width. The output will be the expansion/contraction to allow for.
Thank you.
My concerns are that if I acclimate the boards adequately in the house and then bring them back in the shop, they may move while I'm working on them instead of moving once the (hopefully) appropriate joinery/construction has been done.
All that because my projects often sit on the bench for some time.
Or maybe I should acclimate in the house, work in the shop and bring back the stock inside between shop sessions?
Fred
You will note that I said that acclimating to the house is not always possible.
Personally, I would acclimate to the shop and then use good engineering and building techniques to deal with any possible wood movement.
Even indoors, wood will expand and contract with seasonal changes in relative humidity. Unless you have a year round control of relative humidity, you must build with the idea that the wood will move.Howie.........
I had many problems of flip-flopping cup in 6 inch, 1 inch-thick boards before I had a shop heated to the same humidy as the house. The board would cup. I turned it over and the next day the cup would have flipped the other way, as the board redistributed its moisture between the air side and the floor side.
Eventually the boards were all sat in the house next to a radiator for 3 weeks and they settled down. (Happily, ash can be quick-dried like this without cracking - but don't try it with oak)!
As has been suggested, you can engineer the joints of furniture to accommodate movement. But a table top made when at 14% moisture content rather than the 10% it will have when installed, for example, will still show some cup in each board, even though the breadboard ends may keep the top as a whole pretty flat. (Assuming you alternated the ring pattern to alternate the cup in adjacent boards). The wider the board, the deeper the cup.
Of course, if you use quarter-sawn timber for your table top, this problem will not appear - but them qurtersawns are expensive.
In the end, you have to have broadly the same humidity in your shop as in your installation sites for the furniture. Engineering for movement is good, as furniture may alway be subject to the odd change in humidity; but some effects of humidity changes cannot be hidden, even though you engineered so that the piece doesn't self-destruct.
"a lot warmer and definately dryer" How warm? What's the RH? My shop, with the pellet stove running, is 60-65° and 20-25% RH. I wouldn't feel any need whatsoever to schlep the wood back and forth between the shop and the house. Even it were 55° and 30-35% RH, still wouldn't bother. I think John's right.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
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