Bookcase Question(s)

[Robert Wood]

Hello all. I've been reading the posts here for a while (and learning a lot! :) ) and I figure it's about time to actually post something. Unfortunately, I don't have a good gloat, but here goes...

I'm planning two 8' tall bookshelves (secured on back and side to wall) w/ fixed 10'' deep shelves approximately 40'' wide set into dados on the side panels. Planning on using 3/4'' sanded pine plywood for most components (side panels, back, and shelves) since they will be painted. So, here are my questions...

1. Is 40'' too wide for an "unsupported" shelf? Wasn't planning on any support other than the dados on the side panels, but could always run a dado in the back panel for additional support. This, of course, begs the next question...

2. Is it worthwhile to put a back on the bookcase? They aren't going anywhere, but I figure a back will add support to the case and the shelves if I run dados in them.

3. I was going to glue and screw the shelves into place. This might sound incredibly ignorant (I'm still pretty new to woodworking ;) ), but what type of screws should I use? My father-in-law suggests just going w/ good old drywall screws, but I wanted to get everyones expert opinion.

Thanks,
Bob

[Dave Falkenstein]

I would recommend adding a support member to the front of the shelves. This support member can be a 1X2 piece of solid wood that is compatible with your other materials. I'd use poplar, since it paints really well. The support member should be glued to the edge of the shelf. Because the support member is solid wood, it can be edged with a router for a decorative effect. I think it is a good idea to put a back on your bookcase. You can nail or screw the fixed shelves to the back, providing ample support at the back edge of the shelves. There is no need to dado the shelves into the back, but you should dado the back into the carcass.

I would also recommend that you make the bookcase in two pieces, for a total of eight feet tall. Two smaller pieces are much easier to handle and install, and you don't run as much risk of installation difficulties, tipping a tall cabinet into place.

Glue alone is strong enough for the dado joints. If you feel it is necessary to add screws, you can use coarse drywall screws, since their primary function is to hold the pieces in place until the glue dries.

Add a face frame of solid wood to cover the exposed edges of the carcass.

Edited to add thoughts on materials: Since you are going to paint these bookcases, please consider two alternative choices for materials. MDF is easy to work with, although it generates lots of dust when cutting it. MDF paints very well, since the surface is dead flat. Poplar is a good choice, as I mentioned earlier, for edge trim and face frames. If you want to invest a bit more money in materials, 1X12 poplar for the carcasses and shelves is a good alternative.

[Chris Fite]

IMHO, sanded pine plywood makes for woodwork that is poor in appearance because the uneven surface of the wood is telegraphed through the finish. Unless you have a source of sanded pine plywood that is truly flat on the surface, I would consider paint grade birch or maple.

[Roger Myers]

I'm planning two 8' tall bookshelves (secured on back and side to wall) w/ fixed 10'' deep shelves approximately 40'' wide set into dados on the side panels. Planning on using 3/4'' sanded pine plywood for most components (side panels, back, and shelves) since they will be painted. So, here are my questions...


1. Is 40'' too wide for an "unsupported" shelf? Wasn't planning on any support other than the dados on the side panels, but could always run a dado in the back panel for additional support. This, of course, begs the next question...

40" is wide for an unsupported shelf, and it will also depend on the material of a shelf. It is certainly too wide for an unsupported plywood shelf. Edging on the front and back of the shelves is one option, and given your design, perhaps the best. The alternative of a Dado all along the back for each shelf will also deal with the support on the back edge, but you will still want an edging on the front, especially with ply. At least with plywood, you will not be concerned about wood movement.


2. Is it worthwhile to put a back on the bookcase? They aren't going anywhere, but I figure a back will add support to the case and the shelves if I run dados in them.

A back the book case will help prevent the case from racking on you. Book cases carra a lot of weight, often unevenly distributed. The back will also allow you to secure the book case to the wall to prevent tipping. A 10" deep bookcase 8' tall, loaded with books can topple easier than you think, especially if a toddler reaches up to grab a book.


3. I was going to glue and screw the shelves into place. This might sound incredibly ignorant (I'm still pretty new to woodworking ;) ), but what type of screws should I use? My father-in-law suggests just going w/ good old drywall screws, but I wanted to get everyones expert opinion.

All questions here are welcome (and you will get lot's of answers, often times very different answers :) )
Drywall Screws are great for quickly assembly of jigs, etc...and for hanging drywall. They are not the best choice for general woodworking, and not the best for your application. Consider using regular woodscrews (phillips or even better, square drive)....

Best advice may be to get a book on beginning cabinet making, or simple bookcase construction. It will be worth the money you spend on it and you can store it on your new bookcase :) Bookcases, while simple projects in appearance, have quite a task to do, when you think about the weight of the books.... not saying the simplest appraoch won't work, but there are still easy, well designed answers...

Roger

[Von Bickley]

Robert,

Welcome to the Creek...

I agree with everything Dave and Chris said. I really like the idea of paint grade birch with poplar face frames.:)

[Barry O'Mahony]

For books (which are worst-case), 24" is the Convention Wisdom width for unsupported 3/4" wood. If you go wider you'll need support the shelf somehow. Either a front or back lip is commonly used.

[Steve Clardy]

Welcome to the creek Robert!
One thing to add. If you make it 8' tall, and it's going on a 8' wall, you won't be able to stand it up.
Suggested above, make it in two pieces.

[Bob Rufener]

There is a web site that will assist anyone with determining the strength of shelving. Just put in your dimensions and type of wood amount of load you anticipate putting on the shelves and it will determine deflection.

http://www.woodbin.com/calcs/sagulator.htm

[Dan Oelke]

I would suggest not trying 40" unsupported.

I did some ~46" wide shelves made of 3/4" oak faced plywood. The shelves had a 2 1/2" high strip of 3/4" oak on the back and a 1 1/4" high x 3/4" strip of oak on the front. Both of these strips had a rabbet cut in them and then the plywood was glued and nailed into it. These strips were to stiffen the shelf and the front one to cover the edge of the plywood. This set of shelves was then loaded up with magazines from one end to the other, or books from one end to the other. The shelves sagged. Now, the shelves were not attached to the back of the bookshelf - they were just supported on the ends with a couple of pegs so they could be adjusted for height.

A small divider that splits shelves into 2 20" sections would be better structurally. I would also put a back on the shelving unit that can then be screwed to the wall (be sure to hit a stud). A tipping bookshelf is dangerous.

And - after reading the above comments - I'll second the notion of building it in two units. Makes it much easier to manhandle. The units don't have to split it in half vertically. Make the bottom unit a little deeper and take it up to chair rail height. The top unit a little shallower can then sit on top of it and go from there to the ceiling.