The dovetail has one job: resist tension.
Not "look impressive." Not "prove you can cut one." Not "signal your commitment to hand tools." The dovetail exists because of a specific structural problem — you need a joint that locks against being pulled apart along its length — and it solves that problem through geometry, not glue.
Everything else follows from this.
The Angle Is Structural
The tail is wider at its tip than at its root. The socket mirrors it. When tension tries to pull the joint apart, the walls of the socket engage the angled faces of the tail and lock. The harder you pull, the harder it locks. You can assemble an unglued dovetail and it still resists withdrawal in the intended direction.
The ratios woodworkers use aren't tradition. A 1:6 ratio for hardwoods, 1:8 for softwoods — these are the ranges where the mechanical advantage works without creating the failure mode of a wall that's too steep. Go steeper than 1:5 on hard maple and you concentrate shear stress at the narrowest point. The socket wall splits instead of holds. Go too shallow and the geometry barely engages. You've built a box joint with chamfers.
Where It Matters
Drawer boxes. This is the dovetail's home territory. A drawer under load — silverware, tools, anything heavy in a long run of cabinets — pulls the front joint along its length every time someone opens it. Glue alone survives that for a decade, maybe. Geometry survives it for fifty years.
Tall case corners. A bookcase loaded asymmetrically, a wardrobe with a heavy door swung open — the racking stress has a tension component at the corner joint. The dovetail resists it. This is a minor concern on a small display case. It becomes a real concern as height and loading increase.
Breadboard ends. The sliding dovetail version locks the breadboard against pulling away from the top while still allowing seasonal movement. Different joint, same principle.
Where it doesn't matter: frame-and-panel doors, table apron-to-leg joints, chair rungs. These joints don't primarily face tension in the drawer-front direction. You can use dovetails there — they're structurally fine and can look beautiful — but the structural argument doesn't support the choice. You're choosing it as a design element. There's nothing wrong with that. Just name it to yourself.
Three Versions
Through dovetail: Tails pass entirely through the socket piece. End grain visible from both sides. Maximum glue surface. Used where the joint will be seen, or where you don't need to hide it.
Half-blind dovetail: Tails stop short of the outside face. The joint disappears behind a solid front. Standard drawer-front construction. Mechanically equivalent to the through version. You need at least 3/8" of material left in front of the tails — 1/4" works but gives you less margin against blowout.
Sliding dovetail: A single trapezoidal tongue in a matching groove. Used for shelf-to-case joinery, breadboard ends, some table connections. Holds by both compression and tension resistance. A shelf dadoed into a case side can be pulled up and out; a shelf dovetailed in can't. The constraint is fitting — a sliding dovetail has to slide in from one end, so it either needs a slight taper or you're using a mallet.
Handcut and Router Are the Same Joint
That's not what some people want to hear. The tension resistance is the same. The glue surface is the same. The geometry is the same.
The only real difference is the tolerance relationship. A handcut dovetail has slight variation across the joint — each tail fits its socket differently, and you correct those differences during fitting. A router dovetail is cut to a template. It's as good as the setup.
A poorly-tuned router setup produces a loose joint. A well-tuned setup produces a consistent, repeatable joint that holds across twenty drawer boxes. A sloppily-fitted handcut dovetail is still sloppy. The method doesn't save you from inattention.
If you're building one drawer box, cut them by hand if you enjoy it. If you're building a kitchen run, set up the router table once and stop fighting yourself.
The Baseline Is the Tell
When the joint is assembled, the line at the root of the tail and the shoulder of the socket should meet flush at the surface. No gap, no step, just two surfaces at the same plane.
A gap at the baseline means the tails are too long, the sockets too shallow, or the layout drifted somewhere. You'll see it when light hits at the right angle. You'll feel it every time you run a hand across the joint.
A step — one piece sitting proud of the other — means the socket isn't fully cleared at depth, or the tail shoulder isn't cut square.
The cleanest dovetails you've ever seen have clean baselines. Not because skilled woodworkers practice baselines specifically. Because a clean baseline is evidence that everything upstream was done accurately. The baseline doesn't lie.
The dovetail is not a difficulty credential. Most persistent beginners can cut one in a weekend. It's a joint type with a specific structural purpose, not a mark of mastery.
Use it where tension resistance matters. Cut it so the baseline closes clean. And stop treating it like the hardest thing you do.