Alignment of the top beam

I was wondering what is the alignment of the face of the top beam and the material I will be cutting. I plan to do mainly 3/4 MDF.

It depends on your router and sled

you first mount things on your sled, and adjust the triangulation kit so that
the sled hangs level.

Then you want the top beam be at a distance so that cutting your normal
material, with your normal wasteboard, the chains are parallel to the frame (not
angled as you look at them from the side and compare them to the sprockets)

David Lang