Planning projects for wood movement
I have just a question or two, and a few comments, to make on wood movement.
I just finished reading a few of the pfd files I got from Stick on this subject, and one file states to take into account the season in which the project is built. I have never done this. Thank goodness I have yet to attempt anything with drawers or doors. What sort of mistakes might I have made if I had? Disasterous one!
Just so I understand, there's no secret way of accounting for wood movement beyond relative rules of thumb, right? I read a general rule to follow when using flat or plain sawn wood is to allow about 1/4" of movement for every 12" of width across the grain, and I understood to figure a general starting point of where that expansion/shrinkage currently is at based on the current season, and based on all this I concluded the following: in summer projects the wood is likely at full expansion now and may see about 1/4" shrink in winter, in wintertime projects the wood is likely at the lowest shrinkage as may be expected and may expand by 1/4" in summer, and spring/fall projects the wood is at about half expansion currently and will gain or lose as the seasons progress one to the next.
I also read that in quarter sawn wood, this expansion rate is about 1/8" instead of the 1/4" seen in plain sawn wood.
Do you all keep this in mind each time you cut a board to fit? If you wanted several finished pieces to be the same dimensions, would you alter your measurements per board in the same projects built in different seasons?
Up to date, I have made most of my things using just plain old pine lumber from Lowe's. 2x and 1x stuff. Mostly shelves and other solid objects without moving parts, so I haven't had a lot of ill effects of shrinkage/expansion yet. But, I would expect this type of wood to be the most susceptible to the effects as any wood type available. Also, based on my understanding of shrinkage from the pfd's, I believe warpage and twist, which I have seen a LOT of in the pine wood, is also related to how the wood expands and contracts unevenly. Is this correct?
Currently, I am working to build several sets of shutters across my living room bow window, but to avoid wood movement problems I chose to simply use baltic birch plywood and finish them with paint. I really want to learn to understand wood shrinkage for future projects though.
Last edited by Duane Bledsoe; 10-11-2015 at 08:06 AM.