Longevity of Domino'd Solid Walnut to Plywood

[Sertfas]

Hello,

Just bidding a custom bookcase and wondering if anyone see's a red flag in this design before I go forward with it to the client.

The sides will be made of solid 15/16" Walnut. The top, shelves (adjustable with shelf pins, not fixed) and deck will be made of 3/4" Walnut veneer core plywood. There will be stretchers/nailers (1/2" Baltic Birch) spanning the back behind the 1/4" plywood back. These will be pocket screwed and Domino'd into the sides.

Assuming proper technique and consistency of materials, If I Domino the sides (Walnut) to the top (plywood) will that joint be stable enough to trust for 20-30+ years?

 

[JCLP]

If the client is willing to pay for the walnut sides, I would try and convince them that the shelves need to be walnut as well and not veneered plywood. It will look 100% better and with the price of walnut veneer, it would not be much more. I would glue up the walnut shelves with dominoes to give it shear strength. You don't want the shelves to sag over time. Dominoes help a lot.

 

[roblg3]

The only question I have about your design is the span of the shelves?  Since they are "free floating" (adjustable) the length and depth of the shelf is the only  issue i see.  That can be overcome by solid edging across the front with possibly a "stiffener" under the shelf towards the rear.  Turned flat or thinner than the edging, it would be invisible from the side if properly placed.  Half of the sheets in plywood that contact the side are long grain for glue-up purposes and makes a good LG to LG bond.  Thinking further about your design...creating an upside down tray for each shelf would make them super rigid.  I'm thinking at this point that using all solid wood is more time saving and less costly than the work to make the shelves rigid enough for the weight of all those books?

 

[Sertfas]

If the client is willing to pay for the walnut sides, I would try and convince them that the shelves need to be walnut as well and not veneered plywood. It will look 100% better and with the price of walnut veneer, it would not be much more. I would glue up the walnut shelves with dominoes to give it shear strength. You don't want the shelves to sag over time. Dominoes help a lot.

Nine times out of ten I would agree with you and push for it, but they actually have a ton of books and literally will never see them except for the shadowy undersides.

I will be using a solid walnut edging that I will mill myself, I think I will just make it a little wider to hopefully add rigidity to the shelves.

The only question I have about your design is the span of the shelves?  Since they are "free floating" (adjustable) the length and depth of the shelf is the only  issue i see.  That can be overcome by solid edging across the front with possibly a "stiffener" under the shelf towards the rear.  Turned flat or thinner than the edging, it would be invisible from the side if properly placed.  Half of the sheets in plywood that contact the side are long grain for glue-up purposes and makes a good LG to LG bond.  Thinking further about your design...creating an upside down tray for each shelf would make them super rigid.  I'm thinking at this point that using all solid wood is more time saving and less costly than the work to make the shelves rigid enough for the weight of all those books?

The span is 36" so something I may do too is place my nailers strategically so I can put a 5th shelf pin on the back side. I don't see it done too often, but it really doesn't look that bad, especially when books cover it. I may go with a beefier shelf pin, rather than the standard 5mm spoon type.

That's actually a really good idea about making them tray-like, I hadn't thought of that. It opens up the design possibilities too instead of just plain rectangles.

That's good to know about Domino's because the reason I posted this thread is I really am unfamiliar with them and their characteristics.

Thanks for the help guys, if anyone else wants to help out, please do, I enjoy collab work.

 

[w802h]

If you are planning on your shelf edging to be deeper than the shelf you can also rabbet the edge so the bottom of the shelf contacts it.

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[mouppe]

I think the structure will be solid enough, but I would make the edging quite thick to increase the strength and help prevent any shelf sag.

It's generally not a good idea to make your carcase from different materials. The sides will be subject to wood movement and the top will not, so you may see a discrepancy during certain seasons. If you do decide to go ahead, mortise the domino nearest the front on the narrowest setting, and the others on a wider setting. This means any discrepancy will be at the rear of the carcase, but the front will be flush all around.

 

[Michael Kellough]

The Dominoed joints will be good unless there is a lot of racking. If there is a back there won't be much racking.

I agree with the other comments that the bigger issue is that plywood shelves will sag. Plywood is only about half as stiff as solid wood since half the plies go the wrong way. I wouldn't go more than 30" with plywood if the shelve spacing is no more than 10". More height between shelves allows more weight per shelf so the width should be less to resist sag.

A tall solid wood edge mold and nailing the backs of the shelves to the backing will help a lot.

 

[NEW2FES]

Talk them into a back for the case to keep it all square and have the ability to add shelf pins or additional wood.

Ask them to put all the book they would put on one shelf aside and then weigh them. Books are a lot heavier then most people think.

 

[andvari]

I always check my bookcase designs for shelf sag with the sagulator...

http://www.woodbin.com/calcs/sagulator.htm