On Dec 4, 12:32*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.

Just for theory's sake, I wonder how much stiffening you'd get
from epoxying carbon fiber cloth to the bottoms of the shelves.
I doubt it'd be cheap.

On Dec 5, 5:00*pm, "Lew Hodgett" wrote:
"Father Haskell" *wrote:
Just for theory's sake, I wonder how much stiffening you'd get

from epoxying carbon fiber cloth to the bottoms of the shelves.

A layer of 17 OZ double bias (+\- 45 degree) knitted glass and epoxy
would also work at considerably less cost although it would still be
expensive.

If you put a layer of glass on both sides of the ply, then you would
probably use 1/2", 4 ply CDX as the core material.

The bottom is in tension, your best strength is with oriented
strand material (not knit).

The top is in compression, just use a cheap laminate (Formica)
that'll take the wear of books sliding. If you can attach it all
well at the ends of the shelving, the midspan can be
a lattice of wood strips,enough to hold the depth constant.
Like a hollow-core door, though, this would make a shelf
that cannot arbitrarily be cut to length. Solid wood is
easier.

On Dec 7, 4:11*pm, whit3rd wrote:
On Dec 5, 5:00*pm, "Lew Hodgett" wrote:

"Father Haskell" *wrote:
Just for theory's sake, I wonder how much stiffening you'd get

from epoxying carbon fiber cloth to the bottoms of the shelves.
A layer of 17 OZ double bias (+\- 45 degree) knitted glass and epoxy
would also work at considerably less cost although it would still be
expensive.

If you put a layer of glass on both sides of the ply, then you would
probably use 1/2", 4 ply CDX as the core material.

The bottom is in tension, your best strength is with oriented
strand material (not knit).

The top is in compression, just use a cheap laminate (Formica)
that'll take the wear of books sliding. * If you can attach it all
well at the ends of the shelving, the midspan can be
a lattice of wood strips,enough to hold the depth constant.
Like a hollow-core door, though, this would make a shelf
that cannot arbitrarily be cut to length. * Solid wood is
easier.

Leave the tops unlaminated. Wood is excellent in
compression, strong enough to build load bearing
walls from.