Doug Miller writes:

And that's the crux of the problem: it's oriented on a different axis. With these machines, the
head (or table) tilts only in the plane parallel to the fence -- which means you can cut
mortises in, for example, a table or chair leg that are angled with respect to the long axis of
the leg but perpendicular to its sides. And that's exactly the opposite of what's needed: a
chair needs mortises that are angled with respect to the sides of the leg, and perpendicular
to the long axis so that the chair rails will be parallel to the floor.


I would have found a tilting mortiser to be quite valuable
when I was making handscrew clamps from the hardware kits. Much
faster than a chisel for making the ramped openings.