Baltic Birch plywood bookcase

[garage woodworker]

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.

[Dr. Deb]

Yes, if you put a couple of center supports in it.. If you are really worried about the joinery, you can always extend the top and bottom of the case and put glue block below the bottom shelf and above the top shelf. As for the center shelves, just make your normal rabbit.

If it were me, I would opt for the 3/4.

Deb

garage woodworker wrote:

[RP]

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

[Leon]

It will do fine, in fact 1/2" will do fine if you are using true Baltic Birch. Like anything else you need to reinforce the bottoms of the shelves with a front and back ledger strip if they are going to be of any significant length.

[J. Clarke]

Run the sagulator on it .

You'll find that the shelves need some reinforcement--if they are attached to the back that should do it, if they're removable they need a reinforcing strip--you can play with the dimensions in the sagulator.

Note that the sagulator doesn't list birch ply, just fir--use those numbers and you'll have good margins.

[Zz Yzx]

'k, here's your answer for everything BUT baltic birch plywood. Sawwwwwwry.

-Zz

[Martin Eastburn]

Baltic Birch is a hardwood ply from Russia in the first place. If it is true and only Birch it is tough.

It all depends on what you put on it. I built 40+ book cases for this house and limited shelf length. Only on one shelf - that of paperbacks those are longer like you say - It is build out of 3/4" pine and is 46". It has been loaded with paperbacks and small books for 6 years. Not a bend. All of the others are 30" or less. We have just about 4000 books so books are our things. Kinda depends on what is put in them!

We use 30" shelves for DVD's and Tapes. More than ample.

Martin

[Lew Hodgett]

------------------------------- "Baltic Birch" plywood is produced in Finland, Russia as well as other Eastern European countries.

Finnish Birch uses exterior glue, can be laser cut, and is the most expensive.

Russian uses interior glue and produces a total mess if you attempt to laser cut it.

Birch ply is also available as "die board" for temporary tooling.

None of the above applies to book case construction.

BTW, I'd use 13 ply with front and back flange supports for shelves.

Lew

[Hoosierpopi]

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.

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

=E2=80=BA

The Sagulator =E2=80=93 Shelf Sag Calculator The Sagulator =E2=80=93 Shelf Sag Calculator. Posted on October 1st, 2010 b= y TheCadSetterOut. Check out this handy guide for calculating weather your shelf will ... cadsetterout.com/woodworking/the-sagulator-shelf-sag-calculator/

[whit3rd]

For uprights, 5/8" is more than enough; I've got 1/2" plywood holding fine on seven-foot shelf units from decades gone by. For a shelf 39" wide, though, use solid wood, or some kind of frontedge/backedge stiffener (like, 2" oak, tongue-groove and glue) that's deeper than 5/8 or 3/4".

Was there a plan to cover the plywood edges? Or to apply a finish?

[Father Haskell]

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.

[Lew Hodgett]

from epoxying carbon fiber cloth to the bottoms of the shelves. I doubt it'd be cheap.

---------------------------------- 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.

Strong like bull, but still be expensive for book case shelves.

Lew

[http://www.Towood.com/ Birch P]

[whit3rd]

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.

[Father Haskell]

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

[charles.beach]

did you complete the baltic birch bookcase? my son wants a baltic birch album case (3 shelves, 3/4"x96"x14" top and

3/4"x44"x14" sides). i am planning on 16" between vertical pieces. he plans to store his 5,000 vinyl record albums in this shelving. he also wants it urethaned including the edging (showing the plies)

[Larry Jaques]

I'd go 3/4", for sure. That's 39.5" wide, right? What's being stored on it? If anything over half a dozen pounds, I'd want some kind of stiffener on/under the front of the shelving. A piece of aluminum angle iron or a 1.5" strip of the same ply on the front.

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3/4"x44"x14" sides). i am planning on 16" between vertical pieces.

Should be OK. All the weight will be roughly 8" back from the front, unsupported edge. 16" width isn't too wide, but it may sag over time with that much weight. (Suggest 3/4" aluminum strap or angle tacked onto/under the face of the shelves if they start to sag later.) Regular books would be harder on the shelving, with weight all the way out to the front edge.

And go with a waterborne urethane, allowing plenty of time (in a WARM shop or indoors) to dry and finish hardening before he loads them.

-- Intuition isn't the enemy, but the ally, of reason. -- John Kord Lagemann

[whit3rd]

For uprights, sure, it's fine. I've made 7' tall shelf units with 1/2" plywood uprights, and a thin plywood back for bracing.

For shelves, plywood has half the plies running the wrong direction, so you will get better stiffness with solid wood. Even if it's softwood, and has flaws and knots, it at least has the grain running the long dimension for best compressive strength (bottom of the shelf) as well as best tensile strength (on the top of the shelf).

[Lew Hodgett]

-------------------------------------------------- Rip some 11 ply strips, 1-1/2" x shelf length, and attach front and back of shelf for supports.

Make the back from some 1/4" (5 ply) birch and you are good to go.

Without support strips, never going to happen.

Lew