Joe Barta wrote:

Let's assume that if the jewlery box were 1" square, you would NOT
make a floating panel and just glue the top on. Given that, it stands
to reason that somewhere between 9" or so and 1", is your belief that
cross-grain gluing ceases to be a problem.

Can you tell me where that point is? At what length do you believe it
ceases to become a problem as a practical matter?

Joe (and Tom),
Both of you asked essentially the same question, but I notice that
nobody has given you a definitive answer. That's because no one can,
given the broad scope of the question.

All wood shrinks and swells with changes in moisture content which is
driven by relative humidity. All wood moves more tangetially (around
the circumference) than radially (from the center of the tree out) but
hardly at all lengthwise. So, a flatsawn board will change more than a
quartersawn board of the same species. Then, some species change
dimensions more than twice as much as others.

And we haven't even addressed the question of how much change in
relative humidity you expect to see. Some of our houses see huge
seasonal variations in relative humidity, and some stay nearly the same
year round.

Then there's the question of glue. Some glues will allow a little
"creep" without failing, while others hold fast until the wood splits.

The folks at the USDA Forest Products Lab are trying to interject some
science into our art of working with wood. You can get coefficients of
expansion for different species and other good information he
http://www.fpl.fs.fed.us/documnts/fp...tr113/ch12.pdf

However, this informations still doesn't tell you how much movement a
particular species will tolerate before it splits or buckles when
constrained by being glued to another piece with the grain running
crossways.

One of the things that makes woodworking interesting to me is that it
still remains somewhat of a black art, subject to many variables
imposed by the woodworking gods that be.

DonkeyHody
"I'd rather expect the best of people and be wrong than expect the
worst and be right."