Hi Jim,
Here's another design that you might consider:
This is one of five bookcases I'm building for our church library.
Inside dimensions are 9-1/2" deep, 31" wide, 74" tall
Outside dimensions are 10-3/4" deep (including 3/4" face trim),32-1/2" wide, 80-1/2" tall (includes toe kick, top trim backer and top wall bracket anchor strip.
This is a close up view of the pilaster dados with the pilaster mounting holes already drilled, and the holes to screw the adjacent cabinets or the end trim panels (I like to hide the hardware). BTW, pilasters are those metal, horizontal slotted adjustable shelf mounts.
Here is a closeup view of the toe kick and the bottom trim support strip. The top and bottom shelves are set into dados and are glued and screwed to ensure stability.
This is the trim detail mockup. Trim will be 3/4" x 1-1/2" poplar with the triple bead per the customer's request. The 1-1/2" square blocks are at each corner and may be engraved (if I have time).
Here is an end view of the trim. I purchased the triple bead router bit at Klingspor's Woodworking Shop in Winston Salem to match the existing cabinets in the library.
For the cabinet sides, supports, trim supports and shelves, I used 3/4" paint-grade maple plywood from Rugby in Kernersville, and 1/4" paint-grade maple plywood for the back. Cabinet grade plywood is SO much nicer than "whitewood" from the big box stores, and is actually less expensive!
This will be painted flat black per the customer's request and all bookcase interior surfaces will receive a matte water-based poly top coat to keep the books from sticking to the paint. If the cold weather persists, this will be a rolled finish, if it warms up, I'll spray them.
I will install the trim after the bookcases are in place and secured to the wall. Each bookcase will be connected to its neighbor with glue and screws, and then with the 1-1/2" wide trim. Please note, most 3/4" plywood is 0.72" thick (nominally) and so there will be about 0.030" overhang on the trim to the interior and exterior ... which will get a slight easing with sandpaper rather than trying to get it exactly flush. Nice thing is that I am matching existing work, so I can take advantage of prior construction techniques.
The only plywood end grain that would be visible were the left and right end panels at the bottom of the toe kick. I covered these with a thin strip of poplar and sanded flush. Anyone inspecting the bookcases from the floor MAY see the joint, but I doubt it.
I'll post more photos once complete, but thought I'd show you what can be done that looks nice and is strong.
One sheet of 3/4" plywood makes all the parts and two adjustable shelves. You'll need an additional sheet to make the end panels (if you desire), plus you get 5 additional adjustable shelves.
I also am cutting one additional sheet of 3/4" plywood to make an additional 10 adjustable shelves ... your needs may vary.
Hope this helps.
Regards,
Rick