It locates rather than grips - the extension sits in a hole or slot, so the hold is mechanical and does not depend on tightening.

Cup and cone points resist rotation by cutting into the shaft; a flat point resists it by friction.

A dog point cannot rotate because the cylindrical extension physically obstructs movement.

That gives a repeatable angular position, which none of the others provide.

It also means the shaft is not damaged, so repeated assembly costs nothing.

The trade is that the shaft must be prepared with a matching hole or slot.

The length of the extension - a full dog is longer, engages deeper and needs a deeper feature.

Full dog points give more engagement and carry more load, and are used where there is material to accommodate them.

Half dog points suit thin walls, shallow flats and situations where a long extension would bottom out.

Both diameter and length are specified dimensions and should be matched to the hole or slot rather than approximated.

An extension that bottoms in a shallow hole carries load on its end face instead of its flank, which is the wrong way round.

Standards vary in the exact proportions, so the dimensions are worth reading rather than assumed.

Yes, and that is how sliding and adjustable assemblies are built.

In a slot the dog prevents rotation while allowing axial movement over the slot's length.

That gives an anti-rotation feature and a travel limit in one component.

Adjustable stops, sliding collars and telescoping assemblies commonly work this way.

The slot width should be a close fit on the dog diameter, or the assembly has backlash.

Slot ends act as hard stops, so their position defines the permitted travel.

Usually by drilling the shaft through the assembled hub, so the features are made in position.

Aligning a tapped hole in a hub with a separately drilled hole in a shaft to the accuracy a dog point needs is difficult otherwise.

Drilling through the tapped hole guarantees concentricity and gives the correct angular position at the same time.

The hub must be at its final axial position when this is done, since the feature is then fixed.

Where the shaft is hardened, the hole is normally produced before hardening.

A misaligned hole leaves the dog bearing on the hole edge, which concentrates load on a corner and can shear the extension.

It needs to be secure, but the hold does not depend on clamping force the way other styles do.

The extension carries the load, so the screw's job is mainly to stay where it is put.

That makes the joint far less sensitive to installation torque than a cup or cone point.

The screw can still back off under vibration, which would let the dog withdraw from the hole.

Thread-locking adhesive or a nylon-patch thread is the usual precaution.

Over-tightening achieves nothing useful and risks the socket.

Considerably more than friction-based styles, limited by the shear strength of the extension and the bearing strength of the hole.

The extension is loaded in shear across its diameter, which is a strong and predictable arrangement.

Bearing on the shaft hole wall is the other limit, particularly in soft shaft materials.

Extension diameter is smaller than the thread size, so it is the governing dimension rather than the screw's nominal size.

Shock and reversing loads are handled far better than by biting points, because nothing has to stay penetrated.

For serious torque transmission a key or spline is still the correct feature.

Where a joint must return to exactly the same position, and where the shaft must not be marked.

Indexed and timed assemblies need a repeatable angular position that friction cannot provide.

Instrument, optical and precision assemblies avoid shaft damage as a matter of course.

Anti-rotation features on sliding components are a natural fit through a slot.

Hardened shafts suit it, since no biting is required.

The reason it is not universal is simply that it requires a machining operation on the shaft that the other styles do not.