Yet another wood movement question

[toller]

If I was building this for myself, I would just go ahead and do it. But it is for someone else, and it will be real embaressing if it falls apart.

I am building a butternut table/cabinet. I would like to use red oak as a secondary wood; partly to save money (oak is half the price of butternut here) and partly to add some strength in certain places. My handy dandy movement chart says that butternut moves 0.10"/ft and oak moves 0.13"/ft with a 7% moisture change. (I am only concerned with length; width will not matter). Is this enough of a different to matter where 4' pieces are screwed together? How about glued?

No other wood (except for cherry, which would be an obviously bad choice) is as close to butternut as oak. But is it close enough?

Another wood movement question... Everyone says plywood is stable. Does that mean it doesn't move at all (in which case edge gluing should be a problem), or that it only moves like other woods do with the grain?

[Jeff Gorman]

It certainly moves in thickness, usually to shrink over a period of time.

[Doug Miller]

Lengthwise movement is not an issue, regardless of the species. Changes in moisture content produce negligible changes in length.

Why do you say width will not matter?

If width really doesn't matter, and you're concerned only about movement along the length of the boards, well.... length doesn't matter.

It isn't completely stable. It will change in thickness with changes in moisture content, and it can warp as well.

-- Regards, Doug Miller (alphageek-at-milmac-dot-com)

Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter by sending email to autoresponder at filterinfo-at-milmac-dot-com You must use your REAL email address to get a response.

[Swingman]

Width is actually what "matters" ... dimensional instability of wood in "length" is generally negligible and can ususally be ignored in most woodworking applications.

I would say that you are smart in choosing woods with similar stability characteristics, as long as you understand how said wood reacts to factors like relative humidity.

Plywood does "move", so does MDF for that matter ... ANY wood, or wood product is subject to dimensional instability with changes in relative humidity and temperature.

However, the relative movement in sheet goods is generally so slight that it can be effectively ignored for most woodworking projects, particularly with the higher grade products.