I've been reading up on joints, particularly drop-in joints. Some of the drawings have a curved cut on the underside leading up to the tenon, sometimes labeled a "scoop cut".
Curves make construction more difficult and time consuming. How important are they to this kind of joint? Why aren't they ever used on through or blind mortise and tenon joints?
Notches in structural members such as floor joists cause stress risers that decrease the strength greater than the material removed. A scoop cut reduces the strength only by the removed material and no more. The scoop can be freehanded if it does not show, so it may be faster than carefully cutting a notch.
In constructions where the member is significantly stronger than necessary the scoop is not required and a square cut will yield a neater, tighter joint. Even though there is overlap, the goals and techniques of building construction and rough carpentry are often much different than cabinetry and fine carpentry.
