All:

I just wanted to take a moment to thank ALL of you who provided such
good information and opinions on my project. Your advice was very
helpful.

I modified my cabinet design to include a 3/8" dado for the TV shelf
rather than the 1/4" I had originally intended. I've also added a
vertical cross-section of plywood beneath the rear edge of the shelf.

I further added a vertical shelf support that subdivides the formerly
open large area into two equally sized compartments. The vertical
support should transfer most of the sag to the cabinet floor, and I'll
also add an additional member under the shelf to transfer that load
directly to the floor.

The cabinet went together better than I expected, and I'm down to a few
niggling oops-shouldn't-have-done-that-so-I-hafta-fix-it items, then I
can trim it out and prepare for finish. Inevtiably, I suppose, it's
tending to twist a bit at the top, but I suspect that once it's in
place that won't be as prevalent a problem (I hope). Suggestions for
that welcome, too

Thanks again, all.

David


wrote:
All:

I'm trying to become better educated about the relative strengths of
different types of plywood, and right now I'm dealing with a 3/4" block
of seven-layer oak-veneer plywood.

I'm wondering what would you folks would consider to be the maximum
reasonable span that type of plywood should be expected to sustain for
a shelf holding a 27" tube TV? I'm presently planning a 36" span 22"
deep, secured to the sides of a cabinet via 1/4" dadoes in a solid oak
frame. The cabinet will be backed by 1/4" plywood, glued and screwed to
the shelf from the backside.

I've read some posts that say this type of plywood would be more than
adequate for even larger TV's, but a few others that say it will sag,
but none of the discussions I've seen have talked about how that sag
tendency varies with the number of layers in the plywood, so I have to
plead uncertainty.

Thanks for your kind help in advance.

David