Bookshelf Help

[SabertoothBunny]

Alright, the attached photo is of a bookshelf I am making for my daughter for her birthday. It is 40" x 80" and the body is made out of 3/4" maple. The maple plywood was only a $1 more per sheet than the other stuff.

With it being maple, I am trying to decide on the best way to add facing and shelves (which will be adjustable). Cost is a variable as well combined with my daughter wants me to stain it the same color as a desk I make her.

SO, should I try and face it off and make shelves out of maple or is there another wood that would match well at a lower cost? That question is mainly because it will be stained. I will have to go up to Raleigh (in Fayetteville) at this point to find dry maple in the size I need because the height of the side faces will be over 70" and the shelf width will be 13-14" (cannot recall exactly off the top of my head). I anticipate that the shelves will have to be laminated to get desired width. Plus the cost is a concern combined with time to get up to Raleigh during the limited store hours of places like Woodcraft or Klingspore's.

So yeah, advice is welcome and appreciated.

 

[marinosr]

Why not just keep on with maple plywood and face everything with maple veneers?

 

[Roy G]

I would definitely put a lip on the shelves at least 1" wide, or even a little wider. With a span of 40", books will cause the shelf to sag unless it is supported well. Also, plywood would be my choice for the shelves.

Roy G

 

[SabertoothBunny]

I would definitely put a lip on the shelves at least 1" wide, or even a little wider. With a span of 40", books will cause the shelf to sag unless it is supported well. Also, plywood would be my choice for the shelves.

Roy G

The shelves will be about 39" wide so I was concerned with plywood not having the strength and being more prone to sagging over time. And yes, the shelves are intended to have a lip that matches the facing on the frame. Would the plywood hold up to years of weight and abuse without giving out or splitting much less sagging?

 

[Bill Clemmons]

First, I would put a 'fixed' shelf at the mid point to add stability. Dado it into the sides at least 1/4". The shelves above and below that 'fixed' shelf can be adjustable w/ shelf pins.

Second, I would face the cabinet w/ narrow (~1.5 -1.75" x 3/4") strips of maple to match the plywood.

Third, w/ a 40" span, I would double the thickness of the shelves using two layers of the Maple plywood. A single layer of 3/4" plywood will sag in the middle. An alternative would be at least 1" thick solid Maple shelves. If you go w/ the plywood, cover the front edge w/ a piece of Maple at least 3/4" thick.

I made this bookcase for my Granddaughter. It is 21w x 68h.

 

[blackhawk]

Everything that Bill just said is spot on. I definitely would add the fixed shelf for rigidity.

 

[JohnnyR]

I think single layer of 3/4" ply is sufficient if faced with 1 1/4" hardwood. Somewhere on the web there's a calculator for shelf sag.

 

[SabertoothBunny]

First, I would put a 'fixed' shelf at the mid point to add stability. Dado it into the sides at least 1/4". The shelves above and below that 'fixed' shelf can be adjustable w/ shelf pins.

Second, I would face the cabinet w/ narrow (~1.5 -1.75" x 3/4") strips of maple to match the plywood.

Third, w/ a 40" span, I would double the thickness of the shelves using two layers of the Maple plywood. A single layer of 3/4" plywood will sag in the middle. An alternative would be at least 1" thick solid Maple shelves. If you go w/ the plywood, cover the front edge w/ a piece of Maple at least 3/4" thick.

I made this bookcase for my Granddaughter. It is 21w x 68h.

View attachment 188916

So I did add a fixed shelf, turned out lower than intended though because I measured from the bottom of the shelf rather than the top of the bottom support shelf. Minor error but it will still provide the intended support I think.

Where is a good place I can get the solid maple for facing of the frame and shelves? The concern I have is finding the lengths I need for the two tall sides.

 

[Gofor]

I do not notice any adjustment holes in the back. The shelves will need support along the back side as well as the front. I would suggest the back be thick enough to install 2 shelf pegs (dividing the length into thirds) . As for the lip, for a 40" width and holding books (which are VERY heavy per linear foot), I would lip the 3/4" ply with at least a 1 1/2" lip (preferably 1 3/4" to 2").

I made a shelf unit for our kitchen that has 40" long x 10" deep adjustable shelves. It holds things like crock pots, Vitamix base, griddler, etc. They are 3/4" oak ply (Lowe's grade) with 1 1/4" high x 1" deep solid oak lips on the front, and the adjustment pegs across the back as stated above in a 3/4" ply back. The shelves are fine and straight along the back, but will sag slightly in the front, depending on the load. A book load will be even worse unless the books are against the back wall.

I second the recommendation for a fixed shelf somewhere between 1/3 the height from the bottom to the half way point to prevent the sides from bowing like you have in your picture.

I would not laminate two 3/4" plys together for the shelves, due to the additional weight, and the loss of height between shelves. Books can be leaned over to slide onto the shelf clearing the lip, and that 3/4" loss mounts up over several shelves. Dadoing the front lip and supporting the back will still give the stiffness you need.

Another option would be to put a permanent vertical divider in the center to cut the working length of the shelves in half, at least tripling (probably quadrupling) their load capacity. It also gives more options on shelf placement on each side if she has a tall decorative vase or statue,etc she wants to display, or just a few tall books. With the shorter shelves, no back side support would be needed, and possibly no additional front lip support. (This would be my preferred solution).

 

[marinosr]

The Sagulator will let you play with various shelf configurations to calculate sag based on well-known physical equations. It also lets you calculate sag with a hardwood lip on the front.

For its purposes, you can assume 10-15kg of books per linear foot for medium-sized to large hardcover books. I plugged in plywood shelf, 15kg of books per foot, 40" long, floating, depth of 13", and found that 1" thick plywood was well within acceptable tolerances for sag. 3/4" was also acceptable for paperback and medium hardcover book weights (10kg/ft), but unacceptable at 15kg/ft.

 

[Jeff]

I think single layer of 3/4" ply is sufficient if faced with 1 1/4" hardwood. Somewhere on the web there's a calculator for shelf sag.

Here is "the sagulator". A single fixed shelf of 3/4" fir plywood sags about 1/32" (0.03") with a total load of 100 pounds (40" l x 14" deep). Floating shelves (adjustable shelves) will be more prone to sagging.

The Sagulator – WoodBin

And there is a caveat buried in the "Sagulator" information.

"The eye will notice a deflection of 1/32″ (0.03″) per running foot, or 3/32″ (0.09″) for a 3′ wide bookshelf. The Sagulator computes initial sag only. As an engineering rule of thumb, wood beams/shelves will sag an additional 50% over time beyond the initial deflection induced by the load. Thus, a suggested target for allowable sag is 0.02″ per foot or less."

 

[junquecol]

Over the years, I have built several book cases for both myself and clients. Most were 32" wide, X 80" tall. They had a 3 1/2" base around the bottom, with a .75" thick x 1.5" wide face frame around upper portion. Top rail was usually 3 1/2" wide. The shelves were 3/4 plywood, faced with a piece of 3/4" X 1 1/2" hardwood. Backs were melamine board like is used for shower / tub surrounds. Most had KV tracks for shelf adjustments, instead of shelf pins. Shelf pins wouldn't have been a problem, as I have a shelf pin jig that uses a plunge router. Cases were always birch plywood.