Sliding Dovetails for Bookshelves?

A practical discussion of bookshelf joinery. February 21, 2011

I am planning to build a bookcase out of solid 5/4 x 12" walnut for the sides and shelves with a frame and panel back and raised panel doors. I was wondering if it is okay to join the shelves to the sides with a sliding dovetail. Would that type of joint not be advised since I am using solid wood? I don't know if it would allow for any seasonal movement or not. My other option would be to join the shelves with multiple mortise and tenons.

Forum Responses
(Furniture Making Forum)
From contributor M:
Shelves and sides should have the grain in the same direction. Dado, sliding dovetail, M&T; use what you like, and glue it solid.

From contributor D:
Sliding dovetails are more work than necessary in my opinion, and take some tweaking to get a good fit. Dado works just fine in my experience... Never had one fail. Put in some biscuits or dowels if you want more strength.

From contributor L:
A 12" long sliding dovetail will be almost impossible to slide home once glue is put in unless it's really sloppy.

The traditional solution is:

a) tapered dovetail (a lot of setup unless you're doing a bunch of them),
b) half dovetail or half tapered dovetail, or
c) the stopped dovetail with dado behind. Basically a dado for most of the width but a dovetail for the front few inches. This is the easiest if you want the dovetail look and strength at the front. It's used on highboys, desks, etc.

I agree that dados or M&T are generally strong enough. Through M&T with wedges add strength and can be decorative. Sliding dovetails are better in solid wood than in plywood.

From contributor H:
I am making walnut bookcases now using sliding dovetails, but my case sides are veneer ply instead of hardwood. Not as deep, but they work fine. Just epoxy the last inch or so, and let the shelves expand rearward. Leave a 1/4" gap between the shelf and the back. Also easier to clean. I am able to push the dovetails home, while still tight in the joint. I started with 30 minute epoxy, but now use 5 minute to make it go faster. These cases are strong and square right off. Honestly, the dovetailing is the least amount of work compared to all the shelf preparation. I am glad I went this way.