Toller wrote:
I just got a LN 12" Delta at an auction for $80.

Ebay has a mortising attachment locally. Do they work, or are they just
aggravation?

Like many, I bought a mortise attachment (cheap, used) only to find it
didn't fit my drill press.

Then I analyzed the parts. My drill press has less than 2.5" of
spindle travel, and a mortise
chisel might reasonably make 4" cuts. The force to press a 1/2"
mortise chisel into wood
is larger than a paring cut with a 1" chisel going perpendicular to
grain, which is a task
I usually use a mallet for; my drill press isn't (I disassembled it to
be sure) really intended
to apply that much force.

And the drill press column, with higher than intended force, might not
be up to the load,
i.e. might be too flexible. The Delta dedicated mortiser has a
different kind of column.
It's not an insurmountable problem, I've doodled up a design with
cable/pulley construction
that has zero flex on the column, and with the right cable you can put
a ton of force
on the cutterhead- might even build it some day.

For the foreseeable future, hand-cut will be just fine for my needs.
I've hand-cut some mortises, and with a Forstner bit start it isn't too
hard. Even
for a bevel chisel (no, I haven't got a REAL mortise chisel in the
toolbox), and even
in plywood and softwoods.

By the way, I highly recommend doing practice dovetails in plywood
and in softwood; it's instructive, and doing one in oak afterward is
SUCH a relief!