"Jim Wilkins" on Wed, 20 May 2020 20:55:16
-0400 typed in rec.crafts.metalworking the following:

https://www.woodbin.com/calcs/sagulator/

Neat. Now to find out what the shelves I have are made of, so I
can retro calc their deflection.

{I have some Ikea Billy book cases. The wider shelves have sagged
visibly over the last fifteen years, but I can't just flip the shelves
so that they flatten. They work, and I've other things higher on the
priority list. Like fining space for the rest of the books.}

The simple fix is to insert upright supports in the middle of the spans.
Mine are simply a friction fit and none have shifted.

What braces the bookcase against tipping sideways?

That backboard. In the last move, the press board backs fell out
of mine, but that's okay, the shelves are from wall to all, so there's
no room for them to lean. Unless the whole place is out of kilter, in
which case, those cases will fit in just fine.
--
pyotr filipivich
"With Age comes Wisdom. Although far too often, Age travels alone."