Hello,
I have a client who would like a built in shelving unit installed into their library. I have expressed my concerns of deflection of the shelves after books are placed on them. The unit is going to be made of solid maple. The design obsticle however is creating shelves that are 1) strong enough to carry large weight capacities, and 2) the client would like to be able to adjust the shelves at variable heights.
Does ANYONE have any ideas on how to construct 54 inch shelves that could hold a lot of book without any deflection on the shelve and what would be the best hardware to utilize to make the shelving capable of being adjusted to various heights?
Best Regards,
Fredd
Replies
need a little more info-
Depth? what are the gables (sides) going to be?
Is there a thickness issue from a design standpoint?
54" span isn't the end of the world- I just made some shelves with a 7' span...
The older I get, the better I was....
>need a little more info-
>Depth? what are the gables (sides) going to be?
>Is there a thickness issue from a design standpoint?
>54" span isn't the end of the world- I just made some shelves with a 7' span...
>The older I get, the better I was....
Depth is going to be 12" deep. Side Client wnats solid maple ($$$$) but I would also try to convince them on using a good Plywood. ANy thoughts? Customer wants a "contemporary" look. So I'm thinging maybe something that is about 1.75" thick? Thoughts??
Thanks. P.S. Sorry for the fagueness...my mind is not quite up to speed yet. :)
One more thing -- is he/she going to put big books on the shelves, like encyclopedias or law books, or just random books? This would make a major difference in weight and deflection. Someone posted something called a "sagulator" here on Knots a while back. See if you can find it in the archives. P.S. I just found it at: woodbin.com/calcs/sagulator.htmEdited 2/7/2006 4:12 pm ET by Jimma
Edited 2/7/2006 4:13 pm ET by Jimma
Torsion box is the best way to go IMO. Also possible would be 2 layers of 3/4 maple plywood with a solid maple strip around all 4 sides1 - measure the board twice, 2 - cut it once, 3 - measure the space where it is supposed to go 4 - get a new board and go back to step 1
A torsion box would be the way. Honeycomb interior and 1/4" veneered plywood for skins would be strong and simple. I would suggest a test or I recall there was some kind of guide on the deflection of hineycomb panels. I'd put the question on ratings to the manufacturer. The torsion box will add to the rigidity. I'd probably go with an extra clip in the middle for the adjustable shelf. Look at Rockler, Hafele, etc. Bore holes at 1" or so intervals. Sometimes the client is just plain wrong. You could always do the...well, this is going to cost this much and this is going to cost half as much if we do it that way.
The other wqy to do it would be with a stiffening cleat across the back and front. It will visually be thicker but you left a lot of stuff out design wise.
Edited 2/7/2006 2:20 pm ET by RickL
Just make the shelves thicker, Fred. 1 1/4" maple should be fine. With that thickness you could put a nice looking edge on the front of the shelves and have a more substantial appearance than typical 3/4" material. Most adjustable shelf methods aren't restricted by thickness of the shelf.
Beat it to fit / Paint it to match
54" with a full stack of books is a lot of weight, some kind of support in the center would be needed. A solid back with dowels in the back of the shelves that can be put in at various heights will give additional support.
Torsion box. Layered plywood is still more liable to sag than an equal thickness of nominal wood. Build a test model torsion box to spec and load with twice as much as you think. Observe over time. Make similar models out of ply and nominal boards, edge-banded , etc. Show client results. I would still try to add some center support, a panel painted like a book? I've seen convincing photographic appliques, try a different one for each shelf, match the customer's books if possible. Torsion box I suspect would be best but safest (to your rep and the books) would add central supports.
Warning - heretic talking...
Isn't this a case for steel? Wouldn't a 1/2" steel C channel inlet into the rear shelf edge add considerable sag resistance?
But, the suggestion about a shelf support at the midpoint of the back would certainly make a HUGE difference - books tend to get pushed to the rear which would make rear support more important.
PS - I just tried the Sagulator for the first time last week - what a HOOT! I love it!
That is exactly what I did in my home. I built 50" long shelves, 1.75" think out of walnut with a concealed piece of steel running the length of the shelf. In the two years since I built the shelves (that are loaded down, end to end, with books) there has been no noticeable sag. I'd do it the exact same way if I had to do it again.
I'm glad your shelves are working out. However, bookshelves that are 1 3/4 inches thick don't need any steel to span 50 inches.
"I'm glad your shelves are working out. However, bookshelves that are 1 3/4 inches thick don't need any steel to span 50 inches."
They do if they are not solid.
Another idea would be aluminum L angle.
Set the angle into a shallow mortise, and cut a deeper groove to accept the leg of the angle. Glue another sheet of plywood (or solid...) over top, and you're good to go.
use 3 pieces of 1/2" x 1/2" x 1/8" angle. It's light and the shelf won't sag under a non-industrial load.The older I get, the better I was....
I always do my best to talk my customers out of adjustable shelves. Books only come in a few sizes and it is easy to build the case with all the shelves in the right place to begin with. 54 inch long shelves are no problem when they are attached to the plywood back of the case. All those holes look lousy also.
Just say no!
Plough one or two 1/2" -deep kerfs the length of the shelf, epoxy a piece of 1/8" x 1/2" steel in the cut(s), cover the cut(s) with veneer, whatever.
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I sort of agree.. However I use 'L' shaped.. I feel it was MUCH stronger.. But I'm a NUT.. I posted this once and I got all kinds of 'flack'.. HAY I works!EDIT: My Son-In-Law is a PHd or somethin' He got more books than my local Library.. I had to use two 'L' in the shelves for the bookcase I made him.. 'NO Sag AT-ALL'
Edited 2/18/2006 8:17 am by WillGeorge
I agree talk them out of the adjustable shelves, most people think they need that, but once you get the books in there many rarely adjust the shelves.
I made some shelves out of an old hollowcore door cut it down to 12" wide by 48" and inserted a 1x pine along the back cut out, same idea as the torsion box.
Jeff
Hi FMG, 54" shelves constructed from 1.5" maple should have negligble deflection. Starting with clear stock, rip your material into 4" to 6" strips, oppose the grain direction, and glue them up. With a semetrical nosing detail the shelves could be flipped over 'if' there was any deflection. Consider the climate. Moist/Dry. Also mid-span holes in the back of the cabinet are unsightly. Laminate materials rarely hold up over time. HF
There's a bunch of different ways to make shelving adjustable ranging from off the shelf systems to adjustable clips or pegs pushed into drilled holes in the case uprights. Creating a shelf that size strong enough to take a useable load needs a bit more thought. That said, its not rocket science...
The shelf itself need only be 1/2" thick material as its ssole purpose is to give the books a flat surface to rest on. That said, 1/2" won't be strong enough to resist deflection, so it needs reinforcing along its edges. The key to resisting deflection is in the depth of the material used, not its mass (the same principle that allows I section beams to be so strong). Braces of suitable depth will have far more resistance to deflection than solid shelving while using far less material, saving both in cost and overall weight of the piece.
3" deep braces should be strong enough for a span of that length. The recess they create can be used to house things like concealed lighting etc.
Mike Wallace
Stay safe....Have fun
I'm doing exactly that now, not 54", but rather 51 1/4"
They are two inches thick. Top and bottom are of 1/2" VC maple with a 1 1/16 mdf corebox interior construction. Fronts are 1/4" solid maple .
I was concerned about the flex, but these appear to be rock solid.despite their length.
Eric
I would make a divider to be placed mid point on the shelf length. The divider does not have to be permanent. Drill two holes (if 1"shelving, make the holes 1/4") on the underside and top of the bookshelf at the mid point. The divider will have two dowels to line up with the holes and voila!, you have a support at the mid point. The dividers must start at the bottom shelf, but of course, need not be located on the top shelf. As one post said, once you put books on a shelf, you seldom if ever change the location of adjustable shelves. Have your client review the books to be stored and make the shelf permanent.
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