On Sat, 16 Jan 2010 10:12:33 -0800 (PST), mkr5000
wrote:

I really need to route it because I need to plunge into it and don't
want the slot the total length of the board.

Been a long time since I've done this, so can't remember if I can
route that wide a slot (3/4") -- just 1/4" deep or even less, just
enough to fit another piece of 3/4" plywood into.

Do they even make a 3/4" bit or would I have to do multiple passes for
both the width and depth? (yuk).

thanks

I wonder the length of your board. A dado blade in the table saw will
work and is accurate but you will need to chisel out the end(s).

Another method that works well... Clamp on a straight-edge and make a
hardwood strip that is taped to the straight edge. Make the first
pass with a 1/2" , remove the strip, make the second pass. You may
need 3 or 4 test tries to get the groove width you need. After the
gauge strip is correct, the setup is repeatable.

A router sled jig is another consideration, good or not depending on
your setup.

I have not seen a 3/4" straight router bit, but that sounds hefty
(probably pricey), and you may need better at a slower speed.