Hi all,

I am planning a couple of bookshelves to be made from a 1/2 inch plywood,
35x11 inches in size; some shelves will be fixed in 1/4 inch deep dadoes in
the sides of the bookcase and others will be "floating", supported by pins
inserted in 1/2 inch deep holes. The shelves will only be supported on the
sides; not along the length. Should I worry about the sag of the plywood?
What's a good length of the shelf that can sustain a load full of books
without additional lengthwise support?
Thanks!
Vlad