Domino for long run of bookcases with single vertical supports?

[matonmacs]

Dug up a photo of the shelves I built. Might give you a feel for what you're thinking about. As someone else mentioned, a 36" span on 3/4 stock is very likely to sag. I put a 1-1/2" front on each shelf and screwed them to at least one stud. This will show you the look of 3/4" verticals with 1-1/2" (appearance) shelves.

Thanks, this is helpful. I do think I'll reinforce the shelves along their length, but looking at your photo I think maybe I should go with smaller bays, like 30". It would probably be best to prototype it to have a look at it in person. Following the suggestion above I found one of those online calculators which does seem to indicate that 36" would be okay in 3/4" ply.

http://www.woodbin.com/ref/shelf-sag-measurements/

 

[pixelated]

Much depends on the weight of your books and whether you leave some open space on the shelves. You will probably get some sag with 36 inches worth of large hardcovers. 30 inches will do a little better if they are loaded heavily. The other problem is that a lot of plywood isn't dead flat, it's not as much of a problem with the carcass, because the back and other elements of the structure will help straighten things. But the shelves are just boards, adding an edge piece will help with the load and help pull the shelf flat.

 

[Michael Kellough]

If shelves are plywood I’d limit the width to 30”. Half the grain is running the wrong way to support a load.

 

[Birdhunter]

As long as you have a project that requires shell pins, look at the Mafell DDF40. Perfect tool for that job.