Actually the balance seems just about right. The hole in the top of the
router plate is about 2", so about half the airflow is from the plate and
about half from the fence.

"Jim Bailey" wrote in message
.. .
Toller - with 4" at the bottom, you don't see any problem with the larger
line 'stealing' efficiency from the top, smaller line ? Or vice versa (I
don't know a lot about the velocity changes etc that would occur) ?

jim

"toller" wrote in message
news
I have a 4" port in the base of my router table to the DC, and a 2.5"
pipe
goes from the base to the back of the fence. It is pretty much dust free
when I use the fence. Without the fence it is still pretty dusty.