Invisible shelving system

[HHR]

Ron has a method of shelving he calls "invisible" meaning it has no visible means of support.  I have a project where I think this might be just the answer but I have one concern, length and sagging.  I have a recessed opening in a wall that is probably 6 feet wide and about a foot deep.  It's original intended use was probably to display artwork or pottery or something since there is recessed lighting above.   I can support the shelves on three sides with cleats but due to the length and the intended use (book storage) I'm wondering if the shelves will sag in the center over time.  Anybody built any of these shelves this length and do they eventually sag with weight?  Thanks.

[yopauly]

What are you using for shelving material?  if it is 3/4 to a inch  you could run a saw kerf on the bottom side and insert a piece of angle steel. it will be virtually invisible and would hold a lot of weight. If it's more than an inch I wouldn't worry. It should hold the weight. Any shelving I have put up that has to look good, I always face it with a peice of 3/8 thick trim for the illusion of thickness and for support to keep the middle from sagging.

[HHR]

I think the solid piece across the front of shelf will provide enough strength although the angle metal solution sounds interesting although I have a question about it.  I use metal frequently when making something like a door header that has a lot of weight above it.  I'll sandwich a piece of 1/4" steel between 2 2 X's and bolt it all together.  It makes an extremely strong beam.  In regard to the shelf I don't see where I would put the steel.  Two of the sides (top and bottom) will have plywood nailed to the surfaces of the shelf frame.  The front will have a piece of solid wood nailed to it and the back of the frame wood will have the short support pieces nailed to it.  Where does the kerf and angle steel go?  Thanks for the suggestions.

[yopauly]

Say the shelf is 3/4 inch thick. Run the kerf about 3/8 deep 1 inch back from the edge, parallel to the front edge, on the bottom side of the shelf. Use a piece of 3/8 angle with one leg buried in the kerf. You don't have to run the kerf all the way to the end. You can stop it a inch or two from the end because sagging only occurs in the middle. Attach with, epoxy, Gorilla glue, small countersunk flat head screws or a combination of adhesive and screws.
But if you use a piece of molding on the front of the shelf, you won't need anything else unless you park your pickup truck on it!  LOL

[HHR]

Got it. Thanks a lot.  I measured the opening again yesterday and the shelves will be alittle over 7 feet long.  I may use both methods due to the length the shelves will be (the "belt and suspenders" method).  Thanks again for the input.

[yopauly]

If you're going to use both, you could run the steel angle right below the shelf with no kerf and hide it with the molding. That way you could use a much wider angle like the perforated steel  angle you can buy at home improvement stores.