Here is a pic of some bookcases we will do in a stairway.
The shelves themselves are 10-1/2 deep, and in the center group, the widest, are 47-1/2″ wide.
We want as thin a look as possible for these shelves. What would you think of edging 3/4 maple plywood with hardwood strips 3/4 x 1, both front and back, to provide the necessary stiffness?
Or, how about 5/4 solid stock?
Replies
Bob ,
Will the shelves be adjustable ? will there be cabinet backs ? There are many options and ways of doing things but what comes to mind here would be either place a center stile in the middle of the wide shelves and fasten or place a adj shelf clip behind the face. Also you can use the back to help support the shelves with clips or again fasten them .
hope this helps good luck dusty
If you intend to load these shelves with books, you are going to get some sagging at those widths (even with the edging you specify).
On the other hand, it the shelves are meant for a few books, photos, vases, etc. then you should be fine.
3/4" ply over 48" sounds like you will likely get sagging. I would recomment the 5/4 solid wood.
If you want a thin looking shelf, try a deep taper on the shelf edge (say down to 1/2" tapered over 2". This will give the visual appearance of a very thin shelf. I do this all the time with shelves and table edges, and it really refines the piece.
I am having trouble visualizing how you taper a shelf edge from 1/2" to 2" -------
Edited 9/14/2004 10:39 am ET by nikkiwood
Sorry! That's tapering from the original board thickness down to 1/2" over 2".
Edited 9/14/2004 11:17 am ET by Frozen
I think too many of my brain cells have died. I still don't get it. Can you try again?
A picture
I was trying to imagine a 3/4" thick piece of edging that was somehow tapered 1/2 to 2".
I was thinking inside the box.
Thanks for the pic.
Over that kind of length even a 1" hardwood strip isn't going to provide much stiffness at all.
If you're looking for a "thin" appearance, then I'd think about doing what someone else suggested, namely using a fixed shelf that's attached in the back.
You might also get create a "thin" appearance using thicker stock for the shelves but then making the other features of the unit larger, i.e., scaling everything up.
Maybe there's some decorative items you can put between the shelves that will support them from top to bottom.
Attaching 3/4" thick 48" long shelf to the back of the cabinet will make it stiffer, but the front edge will still sag under a full load of books. A hardwood facing the same thickness as the shelves will add almost no additional strength. For a 48" span you will need a full 1 1/2" inch thick shelf in solid wood.
If you are planning to pack the shelves with books, you would be better off to add additional bays and drop the span down to 32" or even 24". For a 32" span I'd still use a milled 5/4, probably finishing out at 1 1/8" thick. For a 24" span you could probably get away with a 3/4" thick shelf if it were solid hardwood, but thicker would be better.
Even if they were strong enough to support the weight, thin shelves will look flimsy and out of proportion. If you want to save on materials, build the shelves out of 1/2" thick plywood with a 3/4" thick facing, 1 1/2" to 2" tall attached to the front and rear edges. A composite shelf has the additional advantage of staying flat when the humidity changes, something that solid wood shelves almost never do.
John W.
Here's another way, more work but quite thin. Start with 3/4" veneer plywood. About 2" in from the front and back, saw a kerf along the underside the length of the shelf just over 5/8" deep. Into each kerf epoxy 1/8" x 5/8" steel or aluminum strip. Smooth the kerfs with wood filler, then veneer over the bottom. Edge the front with edge banding.
I gave it up because it seemed to be taking over my life, but for about 5 years I was heavily into radio-controlled airplane building and flying. Much more building than flying. Big stuff, little stuff, unbelievably complex stuff, and everywhere in between.
One way I made wing structures (this is common in RC modeling) was to make or buy wire-cut rigid foam cores, then vacuum-bag fiberglass skins on them. Fuselages would be framed and skinned in wood, then glassed. For structural strength, I used carbon fiber to stiffen wings and fuses, laying it on and then glassing it over. Glass work is always done in RC with epoxies, not urethanes.
I think I will experiment a little with carbon fiber tape to stiffen these shelves. Could be just the ticket.
Two methods I've used successfully:
1. Inserting vertical supports mid-span and dye or paint them black to minimize their appearance;
2. Cut a rabbet on the bottom and front of the shelf, and attach a piece of angle iron. One side of the ell is screwed to the front of the shelf, while the the remainder of the ell is screwed to the bottom of the shelf. The rabbet keeps it flush. Then apply a hardwood strip to the front of the shelf to conceal the angle iron. Aluminum might even provide enough stiffness.
Good luck,
-Jazzdogg-
Whether you think you can, or you think you can't, you're right.
As I responded to a similar question, prototype it, load it with whatever you plan to put on it and measure the deflection. Anything you get here will only be a guess based on what we think you want to do.
Start with a board the depth and length you plan on. Raise the ends on some 2x4" block, load the shelf and measure the deflection. Then nail or screw on a front and or back lip, add center supports or a back support and try things until you get what you want.
That's the way we answered those types of questions in the shop I was involved with.
Bob I have solved this problem before by using an ogee edging that gives the appearance of 3/4" shelves on the face by cutting the bottom of the shelf edge back underneath. Similar to your bevel concept ... it works quite well and you can mock up a couple of small shelves to see it and make sure that you like it
If you use steel to stiffen the shelves I would be inclined to use something like 5/8" square tubing dadoed in and glued about two inches back of the shelf face. I doubt that you would get enough stiffness from such a small angle but tubing WILL do it. You'd want to glue it in with epoxy (I think) so that the front edges would not get weak. It is easy to support the rear of the shelf in the centers by drilling holes there for your shelf pins. So don't worry about stiffening the rear edges.
Baltic birch plywood is much stronger than standard veneered stuff and if you are painting them it could help with other marginal spans ... but it won't make a four foot span with a load of books and minimal sag.
Bob.... simply put, a wide span will definately need a deep brace on the lead edge of the shelf.... no way to get around that. If slender shelves are a must, you gotta reduce the span.
Mike Wallace
Stay safe....Have fun
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