Is Wood Movement a Myth?

[RFGuy]

JK Moses posted an excellent video on wood movement with an explanation for how to calculate wood movement for your particular area that you live. I agree with him in that I believe wood movement has been overblown and sensationalized in the online woodworking community. Not saying there aren't horror stories out there, but if you follow some basic principles and never use wood that isn't acclimated then to a 1st order you shouldn't have any issues. Don't believe the fear and paranoia around wood movement that other online influencers use to get views on their platforms.

Free Wood Movement Calculator Table:
https://kmtools.com/collections/digital ... calculator

US Forest Service Wood Handbook:
https://www.fpl.fs.fed.us/documnts/fplg ... gtr190.pdf

[Hobbyman2]

Hickory (True Hickory Group)
True hickories are found
throughout the eastern half
of the United States. The
species most important
commercially are shagbark
(Carya ovata), pignut
(C. glabra), shellbark
(C. laciniosa), and mockernut (C. tomentosa). The greatest commercial production
of the true hickories for all uses is in the Middle Atlantic
and Central States, with the Southern and South Atlantic
States rapidly expanding to handle nearly half of all hickory
lumber.
The sapwood of the true hickory group is white and usually quite wide, except in old, slow-growing trees. The
heartwood is reddish. The wood is exceptionally tough,
heavy, hard, and strong, and shrinks considerably in drying.
For some purposes, both rings per centimeter (or inch) and
weight are limiting factors where strength is important.
The major use for high quality hickory is for tool handles
that require high shock resistance. It is also used for ladder rungs, athletic goods, agricultural implements, dowels,
gymnasium apparatuses, poles, and furniture. Lower grade
hickory is not suitable for the special uses of high quality
hickory because of knottiness or other growth features and
low density. However, the lower grade is useful for pallets
and similar items. Hickory sawdust, chips, and some solid
wood are used to flavor meat by smoking.

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+1

[algale]

If wood movement is a myth, I'm going to give a serious talking to several doors inside my house that open and close smoothly in winter but stick in the summer.

[RFGuy]

If wood movement is a myth, I'm going to give a serious talking to several doors inside my house that open and close smoothly in winter but stick in the summer.

You are right, full size doors, inset cabinet drawers, and inset cabinet doors all have to fit with a uniform reveal that allows for "some" wood movement. Otherwise, there will be issues as you describe. Most likely your door is just slightly oversized for the opening would be my guess. The example JK Moses gave was quite interesting I thought. On that 40" wide breadboard end, it would only move 1/8" where he lives in CA. That is only a 1/16" on each side of movement total, which is not a lot in my opinion. I have seen countless woodworking videos where a breadboard end is made where they allowed 1/4" or more of movement because that is what they expected. I have seen the rare table top cup or buckle online, but usually this is due to working with wood with too high of a moisture content and improper grain orientation selection. My only intent in posting this thread is to point out wood movement has kind of been overblown/overthought by some in the online woodworking community. Wood moves a lot less than most people think, if the wood was fully acclimated to the environment to begin with, i.e. dry enough. JMO.

[algale]

You are right, full size doors, inset cabinet drawers, and inset cabinet doors all have to fit with a uniform reveal that allows for "some" wood movement. Otherwise, there will be issues as you describe. Most likely your door is just slightly oversized for the opening would be my guess. The example JK Moses gave was quite interesting I thought. On that 40" wide breadboard end, it would only move 1/8" where he lives in CA. That is only a 1/16" on each side of movement total, which is not a lot in my opinion. I have seen countless woodworking videos where a breadboard end is made where they allowed 1/4" or more of movement because that is what they expected. I have seen the rare table top cup or buckle online, but usually this is due to working with wood with too high of a moisture content and improper grain orientation selection. My only intent in posting this thread is to point out wood movement has kind of been overblown/overthought by some in the online woodworking community. Wood moves a lot less than most people think, if the wood was fully acclimated to the environment to begin with, i.e. dry enough. JMO.

Yes, I agree too much can be made of it. But the situations you identify call for paying attention to the issue.

[RFGuy]

Yes, I agree too much can be made of it. But the situations you identify call for paying attention to the issue.

Agreed. Of course, these applications that I mentioned are areas where spacing matters. In other words you have two different assemblies that are largely disconnected from each other and have to have freedom to move relative to each other. For assemblies that are connected, e.g. by joinery wood movement is much less of a concern generally. JK Moses has had people comment to him that his dovetail joints are going to blow out due to wood movement?!?!? These kinds of comments either come from extremely inexperienced woodworkers, or very experienced woodworkers who have downed the Kool-Aid™ relating to wood having excessive movement so we must take Draconian measures to compensate. For example, I built my dining room table nearly 30 years ago and it is still doing fine, but if I listen to the online community they would say it should have breadboard ends or else it will become warped like a potato chip from wood movement. Not saying wood doesn't move, but just that this mythology has developed around how much wood moves.

[edma194]

Half of my house is a log cabin. Interior walls, doors, door and window frames all wood. Wood movement is not a myth. But its importance is sometimes exaggerated. Wood is flexible, durable, and ductile, it adapts to changing stresses and wooden structures survive.

[RFGuy]

Half of my house is a log cabin. Interior walls, doors, door and window frames all wood. Wood movement is not a myth. But its importance is sometimes exaggerated. Wood is flexible, durable, and ductile, it adapts to changing stresses and wooden structures survive.

That goes back to scale right? As JK Moses pointed out in his example a 40" wide breadboard end, at his location, only moves 1/8" total (1/16" per side) over all extremes of annual weather. Now, take that and scale it up to the size of your log cabin and you'll say wow that moved a lot but in reality it is the scaling that made it seem large, but it still moved the same amount on a percentage basis as that breadboard end. Also, don't forget that a log cabin is "special" because it may not be sealed as well as a traditional house so air/humidity infiltration is higher. Do you heat it with a wood stove (very dry, hot heat)? Then that will exacerbate the humidity swings the wood will see as well, so you will likely see greater movement than forecasted by the US Forest Service manual indicates. In addition, how many log cabins are built with fully dry logs? Unless they are, then you will have even more wood movement. On the smaller scale of those of us building furniture or smaller projects, wood movement is much less of a concern than it is made out to be online IMHO.

[edma194]

Humidity is not all that noticeable because the large mass of wood absorbs it so readily. The construction accounts for expansion, however at the cost of some air leakage. But that leakage is not terribly bad and the house has found it's shape over the past 80 or so years and I doubt it ever would expand to the maximum possible. A log cabin is not the same as furniture, but in either case it's only a matter of considering the possible result of movement ahead of time. Movement is not unique to wood, metal and plastic move also, not from moisture but from temperature changes, and joining dissimilar materials has to account for that.

[RFGuy]

Agreed. Keep in mind I never said that wood movement is a myth. I said "if you follow some basic principles and never use wood that isn't acclimated then to a 1st order you shouldn't have any issues." The "to a 1st order" is a key part of that statement and there will always be exceptions and nuances.