Charley's observations about the TREND M&T JIG, and by extension
the Leigh FMT as well as the MultiRouter, and the difficulty in
doing
tenons where they're supposed to be - and the size you want for
the fit you're after - begs the question

WHY NOT GO WITH LOOSE TENON M&T JOINTS?

One router bit - and if it's +/- 0.005" - so what. The holes will be
the
same - and that's what's important. If you've got a planer - and bench
top planers that'll do the job, are available for $300 or less - mill
stock
to the bit diameter - whatever it is - and rip loose tenon stock to
width.
A pass or two with a block plane or even a sanding block on all for
edges
to chamfer them and you're ready to cut what ever length loose tenon
you need.. No worries about tenon shoulders either. AND you can make
the loose tenons in any wood you've got handy - or in the same wood
- or in a contrasting wood - if you want.

Of course, with any of the "router jigs"
a) you've got a dedicated router for it (OK - scratch that for the
TREND - but I think it's been ruled out - for tenon cutting
problems.
b) you've got to mark at least one mortise centerline-centerline
for each type of part in order to align the jig to it - and that's
if the mortise is layed out symetrically on two axis
or
if the mortise is offset from the centerline of the part's
thickness - then you have to mark the centerline-centerline
of BOTH ENDS of each type of part in order to align the jig
to it.

The more I reflect on the various ways to do loose tenon M&T
joints - the more I appreciate the DOMINO. I can plan what I
want to do - numerically - then - with NO LAYOUT - cut my mortises
where I want - with relatively (to the Leigh and MultiRouter) no
set up time.

Other than for the sheer fun of it, or for aesthetic reasons I
don't understand, I can't think of a reason for doing "real"
tenons - and I enjoy handcutting dovetails. Tenons - they aren't
even fun to do.

charlie b