That's dead-on advise :sold:ejant said:I have found if not sure start with shallow passes and get the feel for the material/bit and how they are reacting together. Then adjust accordingly.
As an example of it, I was cutting a 28" long slot through a piece of finished 3/4" particle board today (It's the adjustable pivot point slot for a band saw circle cutting jig).
The first plunge cut with a 1/4" spiral up-cut bit seemed to go rather quickly so I tentatively began a full-depth route. I went quite slowly, but it just didn't seem "quite right".
I changed over to making an 1/8th- deep pass and WOW! The bit bore across that material as if there were no tomorrow. So shallow cuts it was.
I think I was finished and cleaned up after making several passes in less time than it would have taken me to make a single dep pass. (And I'm sure the router bit liked the several-passes way of doing it better as well )
So yeah, playing it by the feel of the material is the only realistic way to go. Some stuff just cuts faster and cleaner than other stuff -- but you aren't going to know 'til you get into it