On Dec 4, 1:25Â*pm, RP wrote:
On Dec 4, 12:32Â*pm, garage woodworker wrote:

My son wants a no-frame bookcase 14" x 39.5" x 52.75" from either 5/8" 11
ply Baltic Birch Plywood or 3/4" 13 ply Baltic Birch Plywood. Will 5/8"
really hold up? I have my doubts.

3/4" would be better. If the length of the shelving is 39 1/2" you
should put on a dropped edge so that it won't sag. Books are heavy.

RP

I think that, if you Google "sagulator" you will find detailed answers
to your question as well as links to various approaches to stiffen
your forty-inch shelves

Engineer Shelves With The Sagulator - Fine Woodworking Article
Online calculator determines thickness and length to prevent shelves
from sagging.
http://www.finewoodworking.com/.../S...sArticle.aspx?

The Sagulator - talkFestool
Mar 27, 2009 ... Check this out for figuring out sag in shelves.
Pretty cool huh? The Sagulator.
www.talkfestool.com ۼ

The Sagulator €“ Shelf Sag Calculator
The Sagulator €“ Shelf Sag Calculator. Posted on October 1st, 2010 by
TheCadSetterOut. Check out this handy guide for calculating weather
your shelf will ...
cadsetterout.com/woodworking/the-sagulator-shelf-sag-calculator/