DerbyDad03 wrote in news:d3404a22-c7c7-459a-a820-
:

Stolen without permission from:

http://www.woodworkerssource.com/shop/wmov.html

"A 36" wide top, made with flat sawn lumber, can move more than an inch
with a 10% change in moisture content."

That comment was included in the following paragraph:

"Allow tops to move freely. Attach tops with Figure 8 Connectors, Z clips,
shop made blocks or elongated screw holes. All of these methods will
securely attach the top but all (sic) it to move across its width. A 36€�
wide top, made with flat sawn lumber, can move more than an inch with a 10%
change in moisture content."

Yes, that's technically possible... but a 10% change in moisture content is *enormous*.
Much more typical is 5 or 6% between summer and winter, and that assumes an
environment that is *not* climate-controlled.

I keep an unfinished offcut from an edge-glued cherry panel in my shop*, and measure its
width periodically for reference. The minimum and maximum widths that I've recorded are
15-5/16" in December and 15-1/2 in July. That's an increase of 1.22% in 6 months. Given that
cherry has a dimensional change coefficient of 0.00248, that corresponds to a 4.9%
increase in moisture content.

* shop is in the basement: heated, air conditioned, and dehumidified.

I'm pretty sure that a Figure 8 connector is not going to handle movement
of "more than an inch" unless it's a *really* big one. ;-)

Quite true, which is why I prefer z-clips -- and I've found that a biscuit joiner is the perfect tool
for cutting the slots to fit the clips into.