Greetings and welcome to the forum Robert. I don't know that there is a set distance. If you look at some of the router tables in some of the gallery's and look at the sites below than maybe you can come up what you think and is comfortable to you. I just don't Think there is a "set dimension".
Wisdom: Where experience and knowledge combine and become one.
"We are all one decision away from Stupid!!"
"How often we sacrifice the permanent plans of God on the altar of immediate solutions"
I have a very good memory, just short is all.