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I am a novice woodworker. I have been told that modern glues are so strong that they make a bond which is stronger than the wood itself, and consequently complex interlocking joints are, in many cases, obsolete, and that, in fact, a glued joint may be stronger than a joint where the wood has been cut up, like a dovetail.
Is this true?
Dovetails can be obsolete in the sense they aren’t entirely needed depending on how strong the joint needs to be.
Glues can be stronger than the wood in the sense that the surface fibers the glue is adhered to will pull apart and fail before the glue does. That doesn’t mean a glued joint is stronger than one that is dovetailed and glued.
One of the advantages dovetails and things like box joints have is they create more long grain to long grain surface area that can be glued together. That greater area creates a stronger joint than a simple glued butt joint.
The other advantage that dovetail and box joints have is there is continuous wood fibers running into the joint from two directions. Wood fibers are much stronger along their length than they are in separating from each other the way wood in a simple glued joint fails.
In all destructive tests I’ve seen, dovetail joints beat a glued joint by a wide margin. Box joints are a little stronger than dovetails usually. And the greater the number of boxes or dovetails in a joint the stronger it is up to some point. See Matthias Wandel’s destructive test videos.
But that may not matter in a given application if the joint is strong enough, it may not be worth the extra work to create the dovetail or box joint.
As others mentioned it’s a matter of aesthetics and quality too though.
The simple answer is yes and no. It is true that modern glues are stronger than the wood but only on long grain to long grain joints, dovetail joints are mostly used on long to short grain joints like corners on drawer boxes.
Having said that many other corner joints will be very strong and durable, but much easer and quicker to make. Dovetail joints are not generally used in plywood, Baltic birch ply is my usual choice for drawer boxes as it is more stable and less expensive than solid wood. Do a search for drawer and/or box joints.
Not to repeat JustSaying, I would say the answer is no, they are not obsolete. While strength is one component of a joint, esthetic is another. Who doesn't love a good dovetail? It's a detail that makes one piece stand well above another that could be stronger.
