Box Building Question

[old_guy]

I'm working on a project that is featured in a woodworking book. One aspect of the project involves building a wooden box that is 10" x 7" x 7", with a top that opens with a hinge.

The author miters and then glues the 4 sides together -- no problemo. But then he says to GLUE the bottom to finish the box. On a box of this size, this seems to be asking for cross grain movement problems -- or am I missing something?

[Don]

Hey, Old Guy. I'm assuming your top and bottom are simply pieces of solid lumber, 10" long by 7" wide. The top is hinged, the bottom is fastened on the bottom, in this case the author instructs glue. 7" wide, I wouldn't worry about it too much for dried lumber. Figure that a box will sit on it's bottom for most of it's life, the interior is closed, you will probably finish the heck out of it. Cross-grain movement from moisture and or temps will not be enough to affect this too badly. Seems a little strange that the project would call for mitred sides and then a slab top or bottom. I may be misunderstanding the plans.

A better plan of a box like this would be to run a dado along the top and bottom of your side stock, mitre the sides, cut your top and bottom just large enough to allow for a rabbet along all four edges, assemble the thing as a whole. Once it's dried, cut the top off with the table saw, then hinge.

Cross grain movement comes into play the wider you go in width coupled with the conditions the wood will be subjected to. I see stile and rail door joints expand all the time, enough that you can see and feel the differences from when it was machined.

You are right to be concerned, though. It really depends on how important this box will be, the use, the expected service life, the wood specie, and most of all - how much time you are willing to expend on it.

All the best, Don

[old_guy]

Thanks Don --

After posting my question, I found the following website that addresses the issue of wood shrinkage/expansion and provides a calculator for figuring how much movement there will be. As you suggested, there shouldn't be enough movement in a piece 7" wide to be concerned.

http://www.woodbin.com/calcs/shrinkulator.htm

[Don]

Thanks for the link, I'll look at it when I get a bit of time.

dawjr