Looong shelves - how?

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I'm looking at making a hutch/china cabinet/etc. Take a look at the two "Open step-back hutches" on this page:
http://www.camlenantiques.com/e/repro/cupboards.htm
This is pretty much exactly what I have in mind except I can't figure out how to do the shelves that long. I thought anything over 42" is a no-no without some center support/divider. My friend who wants the hutch is requesting just that; long open shelves with no partitions. I know it's possible, I just don't know how you do it! The shelves on these 2 cabinets look to be at least 5 and 6 feet long.
Guidance wanted!
Cheers! Duke
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I have built a number of shelves that needed to be supported over distances of up to twelve feet. What I did was to glue and screw some one by stock (on edge) to the bottom of the shelf. I then filled the holes with wood plugs. I used a minimum of two wood strips underneath the shelf. But more if needed. One shelf that was to support some heavy items received five wood support beams underneath.
I suppose you could even close in the bottom and make a torsion box. I never went that far though. The above operations definitely added to the labor involved. The extra materials did not amount to much though.
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I'm a big torsion box user. I have built tables with solid surface tops which protruded out from a wall by 4 feet...without legs. 16" overhang for breakfast bars are common...fully warranted. You need to prepare the wall ahead of time, mind you...but man, torsion boxes hold a ton of weight without sagging.
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Well, I checked it with that "sagulator" http://www.woodbin.com/calcs/sagulator.htm that someone posted the other day. A 6 foot shelf of Ponderosa Pine 1" thick and 8" wide with 10 lb load at the center only sagged .09 inches. Even with a 50lb center load it deflected less than 1/2" and a 50 lb uniform load deflected 1/4"
Just go with a full 1" thick shelf. Adding .25 to the thickness halved the deflection and going to a 3/4" shelf doubled the sag.
If you are worried about it you could go to a thicker shelf and/or you could attach a few screws through the back. as long as the back slats have some float you shouldn't have any problem or need slotted holes, etc.
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There's a good article on shelf engineering in Woodworking Magazine, the one currently on the shelves at the stores, with a Stickley inspired bookshelf on the front. This magazine, no ads, no subscriptions (yet), is written by the PopWood editors, and has, so far, been worth the price to pick it up.
Four pages or so on shelves - wood species, loading points, solid vs ply, thicknesses, length, face trim, etc. They did their homework, and seem to have gotten it right.
Patriarch
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The top shelf is screwed to the backboard, I'd bet, so it's extremely strong at the back. The lower shelf looks like it may have a piece of angle iron behind it. Getting a board with a little camber and putting it convex side up will help a lot. Remember, these aren't meant for books. Wilson

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How about a groove routed in the front bottom of the shelf with a piece of steel cable secured to the sides of the unit?
has anyone seen something like that done?
--
be safe.
flip
Ich habe keine Ahnung was das bedeutet, oder vielleicht doch?
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Regarding a steel cable under the shelf, it would have to be stretched pretty tight to make any difference, so you'd probably need to attach it very securely to the sides of the frame. A strong connection of cable to wood would be hard to hide, I think. Very interesting idea, but if it were up to me, I'd use a thicker shelf or put a band of thicker wood on the outer face of the shelf (which would also hide the plywood, if you choose to use it). Good luck - let us know what you end up doing! Andy
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What about a length of hardened steel rod? Maybe have it sitting in an underneath dado. Alternatives might be a length of square steel stock also sitting in an underneath dado, at least partially.
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I wouldn't expect a steel rod (under 1.5" dia) having much resistance to bending. Square stock, on the other hand would work.
scott
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Everything bends with enough force, however I've seen 6' lengths of 1/4" steel rod that I couldn't bend my hand. As well, it's not as if the rod would be supporting the entire load, it would just be reinforcing the shelf while the rear part of the shelf would be carrying the bulk of whatever is on the shelves.
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Everything bends with enough force, however I've seen 6' lengths of 1/4" steel rod that I couldn't bend my hand. As well, it's not as if the rod would be supporting the entire load, it would just be reinforcing the shelf while the rear part of the shelf would be carrying the bulk of whatever is on the shelves.
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Endless thread, slipped through a tube and anchored at both ends with recessed nuts/washers will work, I've seen industrial shelving made this way although haven't done it myself. Plugs can cover the nuts for a better finish.
This will still bend given enough pressure, but first the nuts will have to pull through the timbers... and if things get that bad the rod bending would be my last concern!
- Andy
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What's "endless thread"? Are you talking about threaded rod?
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Roy Smith wrote:

yes...
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You've gotten some excellent responses so far. Everything depends on how much weight your friend plans to load the shelf with.
Here's a few tricks I've used for long shelves in the past. - Use a stronger wood for the shelf. i.e. oak instead of pine. - Use a thicker shelf and put a chamfer on the underside of the front edge to maintain the visual effect of a thinner shelf. - Add a steel strap to the front and rear edges and hide it under a thin strip you previously cut off the shelf.
HTH.
Art

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Here's a couple options:
1. Fasten the back of the shelf to the back of the cabinet
2. Put a lip on the front, back or both to add strength to the shelf. If the lip is in the back it would be less noticable. Routing a detail on a front lip could make it appear less weighty.
3. A thicker shelf. If you don't care for the look of a thick shelf, taper the underside of the front edge, to create the illusion of thinness.
4. Imbed some angle iron or screw a steel plate to the back edge.
Personally I would favor 1,3 or both.
Steve

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First off, will a plain piece of 3/4" wood over 42" sag? No. This is a hutch, not a library with books.
How much weight is going to be put on the hutch? A few dishes, some glasses, maybe a candle holder. You'd be very hard pressed to hit over 15 pounds. IMO, nothing is needed, but if you ere to put a single screw though the back into the shelf, you can probably sit on it safely.
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Edwin Pawlowski wrote:

The subject of shelves sagging has been discussed over and over and most people don't seem to understand anything about what shelves will hold. Shelves supported at only the end, will sag with not that much weight, but shelves supported at the ends and at the back with a few screws/nails will support tremendous amounts of weight.
As an example I have a book case I made nearly 30 years ago. It is made of 3/4 ponderosa pine called yellow pine in the west (but not SYP which much denser and harder) except the back which is 1/4 plywood. The shelves are 46 inches between supports, 9 inches deep, and nailed through the back with 4 penny nails every 8" or so. None of the shelves have sagged and 2 of the shelves are fully loaded with magazines. Just imagine the weight of 46 inches of your favorite 8" x 10" magazines. Those shelves hold a lot of weight.
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Dukester wrote:

Those shelves are just what they appeat to be--long shelves w/ no center support. They're function is for display items of no significant weight, <not> storage of heavy items--that's reserved for the lower section... If you're expecting to load 'em up, you'll have to either add some support or go w/ some other technique.
I could see it possible to build a composite shelf w/ some steel support hidden in or some such, but in actuality, I'd probably just accept the limitation for the look...
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