Hello,
I am thinking of building a bookcase. I am wanting it to be done rather nicely(ie. dovetailed tops, wooden standards, sliding dovetails, ect.). However, I do not know what to do for the backing ,and I do not want plywood backing on it. Any suggestions?
One of the best reasons to use an engineered wood for something like this is it's stability when the relative humidity changes with the seasons, and how it helps stop racking forces. I guess you could tongue and groove some solid wood panels, the wider the better, of course. Tom
I think Tom is on the right track here. You can easily (and cheaply) add 2 - 3 pieces of solid wood (1 at the top, 1 at the bottom, and 1 in the middle) that would act as bracing. The remainder of the back of the bookcase can be open - especially if the bookcase will be against a wall.
I'm writing this next to my great grandmother's bookcase, a big old piece that's gotta be 100 years old if it's a day. It has 1/4" plywood back panels, set into a rabbet and glued. The plywood back adds tremendous strength to the finished piece. Set in a rabbet, or even better a dado, the back stiffens the piece against racking. I would be very loath to give up the strength of a solid plywood back for anything. You want the piece to be rugged enough to withstand getting hauled up two flights of stairs, and then overloaded with college text books by some yet to be born grandchild.
David Starr
You have two choices: plywood, or lapped boards.
As you probably know, wood shrinks with decreasing moisture. It shrinks widthways and radially, but not lengthways. A great deal of joinery isn't just about constructing boxes, it's about constructing boxes that don't warp or crack when they dry out.
Plywood doesn't shrink. So you can apply it rigidly to the back without worrying about splitting. This will stiffen up your carcase substantially. Overall this is the best way to make it -- it's entirely reasonable to use plywood here. You can of course use a good grade of veneered cabinetry ply.
If you use solid boards, then you need to deal with them shrinking. They're width-wise boards (probably the grain running vertically) in a cabinet built with a top board and shelves that won't shrink when dried out. So you need to allow for these boards shrinking in service (assuming you're not building it indoors in a heated workshop!), yetnot have them split or leave gaps between them.
The usual fix here is to half-lap the boards by cutting a wide, shallow rebate in the edge of each one and overlapping them. When they shrink, then move sideways over each other and don't leave a gap. Stain them before assembly, so that this gap isn't an obvious light stripe.
They're also at risk of splitting, so only fix each board with one nail at each end (or into each intermediate shelf) and place it in th emiddle of the board. Also space the boards out evenly.
To accurately estimate shrinkage, read Hoadley's excellent book "Understanding Wood". It's hard to say how much you might see from workshop to driest weather, but 5% isn't a bad start. It's about 10% tops for green wood to fully dry.
Of course fastening the boards with just a single nail means that they're no longer stiffening the carcase. This is the cost of not using plywood. You understand _why_ now, so it's your call as to choose which one.
snip
There is a third way, one Chris Beckvoort uses in his Bookcase with Doors. That is frame and panel with the panel flush with the frame. The panels are captured but not fastened. The shelves cannot be attached to the back. I think its a real classy look. :-)
You will find the case in the book "In the Shaker Style".
A very common old style is lapped slats. Vertical slats, say 4" wide with lapping joints that allow for expansion and contraction without causing any visible gaps. Look up some stickley design books for the exact joint but any simple lap is OK, you only need about 1/4" of play in in each joint. Just let them float in a channel at top and bottom.
How many panels does he use across the width?
Couldn't you attach to the frame at least? That would stiffen the carcase, even if you didn't attach every shelf.
I'll dig it out tonight, thanks.
The back panel on his book case has top and bottom rails, two outside stiles, and a center stile. There are two flush panels. The panels float inside the stiles and rails, held in position by space balls(?).
IIRC, he fastens the shelves to the middle stile with a nail from the back.
I am making the case, but I am using loose adjustable shelves. I think my back panel turned out pretty good. :-)
Thanks for all the suggestions. Now I will figure out what one I like best. Thanks again.
i just picked up some beaded plywood siding at menards, 4x8 sheet with i'd guess 2" wide bead kinda puts you in mind of old fashioned wains coat. oh also it's 3/8 thick. i'm puting it on a vaulted ceiling. might work fo your application. ross
I used 1/4" ply on my bookcases. It is stable, strong, lightweight and prevents racking. Nobody can tell I used ply, yet it looks old because I used cherry sawtooth standards. You could use lapped solid wood but this will add considerable weight, plus you will need to plan for the expansion/contraction,
Be careful with balance. If you use 1/4" ply in the back you lose a lot of weight. I've seen the mistake made on a bookcase with a glass door that didn't have a heavy enough weight in the back back and it would tip over when the door opened if it wasn't full of books.
I won't say exactly who made the msitake but i do see him in the mirror every morning.
Another mistake... I don't live in an earthquake zone anymore, but tall bookcases should be fastened at the top and into studs using L-brackets. Filing cabinets can easily tip too.
There is an article in the August issue of FWW that covers the backs for cabinets. It includes all that was discussed here as well as the frame and panel. :-)
Plywood. You won't see it once the bookcase is loaded.
Don't sweat over "crap" grade secondary wood. Some of the finest antiques had absolute crap backs and drawer bottoms.
And, some had very fine frame and panel, others used slats, ...
For the "rather nicely" finished, one would presume the use envisioned doesn't include loading it up completely w/ paperbacks...
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