Replies

1. 
   JohnWW | Nov 02, 2004 06:12pm | #1

   For that large a span I would use a 3/4 inch thick by 2 or even 2 1/2 inches wide hardwood edging on the front of the shelf and possibly a additional 1 1/2 inch wide stiffener on the back edge.  Before you start building something this big make an experimental shelf and load it fully to be sure it won't sag.

   Along the top edge of the wide front face you could then add an additional small molding 3/4 inch to an 1 inch high, or a small bead along the top and bottom edges.

   John W.

1. 
   mudman | Nov 03, 2004 06:12am | #3

   Hi John,

   Thats great advise and, I already did. There is a little deflection, but it feels solid with 1 1/2" oak edging front and back.  I'm not shure that I understand you. Do you mean glue a small 3/4" x 3/4" piece with maybe a cove cut in it to the face of the edging and flush to the top? Or I supose it would look better flush with the bottom.

   Thanks,

   Mikeplease excuse my spelling.

1. 
   JohnWW | Nov 03, 2004 04:54pm | #4

   Mike,

   A small molding applied flush with the top edge is what I had in mind.  I would suggest a molding a bit flatter in profile than a cove molding, something that could take some bumping without denting or chipping.  Along with the applied top molding a small profile cut directly into the bottom edge of the facing would be quick to add and give a nice finished appearance.

   John W.  

2. 
   jackplane | Nov 02, 2004 06:19pm | #2

   Fluting the edge would look good...not dish cut but more like triple beading...

3. 
   notDusty | Nov 03, 2004 05:19pm | #5

                    Hi mike ,

        You didn't mention the shelf support system you will use on this job. My concern is this, there are recomended weight limits on the different systems , per each shelf mounting. If books are the only or main thing to be stored on these shelves , that is a whole lot of weight. I guess you could weigh 4' of books and the weight of the shelf, my guess is they would surpass the weight limit guideline.If possible design the bookcase with shorter shelf spans. Another option is to provide a shelf mounting clip in the center of the back and if you add a center stile you can tag one there in the front also , this would eliminate the need for larger nosings , while also preventing the sagging . The problem in using a much larger edge front and back is it cuts into the available shelf space and you will lose some storage space, maybe a whole shelf opening could get lost. Are the shelves going to be fixed ?

                              good  luck                      dusty

    

1. 
   mudman | Nov 04, 2004 08:20am | #6

   Dusty,

   I'll be using heavy duty mortised shelf standards, they will easily hold the wieght. I am providing 7 shelves per bay. It is up to them if they will use them all. I will loose 3/4" per shelf, which is not a concern. It is a common misconception that adding a pin in the back will signifigantly prevent sagging. More of the weight of the books is on the front edge so if the shelves are not up for the task they will still sag in the fronteven with a suport in the back. Don't ask me how I know that ;-(

   I am comfortable with the mechanics of the piece, now I am looking for a way to dress up the shelves. Looking around it seems that most are left square when they are this thick, wheather solid wood or edged. I cant think of a profile that will look perportional at that thickness without cutting into the ply. For example I would like to use a 1/2" cove on it, however by the time I get the perportions right it will cut into the ply.

   Thanks for the feedback,

   Mikeplease excuse my spelling.

1. 
   notDusty | Nov 04, 2004 05:36pm | #7

                    mike,

          I have used center supports on the back edge of shelves many times and , they definately reduce deflection and sagging. If the front edge still sags , it will be much less than without the rear support . The loss of space I spoke of was if you beef up the edge to say 2 - 1/2" you will lose 1-3/4" per space times 7 shelves, this is not counting the 3/4"shelf. Not all books will be only as deep as the shelves, therefore some may stick out past the edge of the shelves.I am curious how more of the weight of the books can be on the front edge of the shelf ? As far as a detail for the shelf edges , the beading that was mentioned could work and you could take the stock and cut a saw kerf say 1/8" deep 1/2" or so from each edge and then either cove or bullnose each edge. Try a few sample pieces , get creative , I'm sure you can do it. Sharing ideas and concepts , learning is an ongoing process for all of us. Ideally we need to agree to disagree , but continue to move forward and try and learn each day. Some people will not agree on what day of the week it is.

                                 good luck     dusty

                                 

1. 
   mudman | Nov 06, 2004 07:38am | #11

   Dusty,

   I meant 3/4" more than the unavoidable 3/4 ply for a total of 1 1/2". And yes adding a center pin or standard does help there is no doubt about that. As for there being more weight on the front of the shelves, If you think about it people pretty much always keep their books about 1" from the front edge of a shelf. The average book is only 6" (depends on if they have a lot of novels or college text books). So there ends up being considerably more weight on the front.

   Mikeplease excuse my spelling.

2. 
   Dan019 | Nov 04, 2004 06:54pm | #8

   Mike

   Try using a stopped cove (whichever size and depth look right after trial and error) on the front top and bottom of the shelf rails.

   Without a picture, try to visualize routing your cove with a bearing guided bit while the casework is lying on its back and you're routing on either side of the 1 1/4" nosing freehand with your router, and the edge of the router stops against the edge of the case. This will leave a cove that stops 2" or so short of the end of the nosing (depending on the distance from the edge of router base to the edge of the cutter).

   Now, instead of doing it freehand, set stops on your router table and run all the nosings on the router table.

   I hope this makes some sense. This is one of those things that is eaiser to see than to explain. I've used this technique on many bookshelves and I've seen it used alot on the woodwork at our church.

   Dan 

4. 
   Telemike | Nov 05, 2004 07:44am | #9

   I've spanned long unsupported shelves using "stress skin" shelves and hardwood nosing. I make the shelf itself from a sandwich using 1/4" hardwood plywood on the top, yellow glue, 1 1/2" styrofoam sheet, yellow glue, and 1/8" hardwood plywood on the bottom. Then, I've glued on a 3/4" x 1 1/2" hardwood edge with molding profiles appropriate to the piece with the plywood dadoed into the edging. The result is light weight, incredibly strong, and truly high tech.

   Besides, it's inexpensive, good looking, and can hold an elephant with minimal deflection.

1. 
   mudman | Nov 06, 2004 07:26am | #10

   Ive read a lot about stressed skin technology. I reciently GC'd a remodel job where the roof is stressed skin structural panels. Amazing stuff. You wouldn't belive the engineers report if you saw how light they are first. Instead of styrofoam you can actually use a honeycomb material made of cardboard that is a lot stronger. It can be tough to find a supplier though.

   Mikeplease excuse my spelling.